Phase shift mask and phase shift mask blank

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a phase shift mask used when exposing and transferring a fine pattern, a phase shift mask blank as a base material thereof, and the like, and more particularly to a halftone type phase shift mask and a phase shift mask blank.

【0002】

[Conventional technology]

The high integration of DRAM, which started at 1Mbit, has reached the point where mass production system for 64Mbit and 256Mbit DRAM has been established today. In this technological innovation, the exposure light source has been shortened from the g-line (436 nm) of the ultra-high pressure mercury lamp to the i-line (365 nm). And even now, shortening the exposure wavelength is being studied with the aim of further increasing the integration. However, in a normal optical lithography method, shortening the exposure wavelength improves the resolution but causes a decrease in the depth of focus. This not only increases the burden on the design of the exposure optics, but also causes a problem that the stability of the process is significantly reduced, which in turn adversely affects the yield of the product.

【0003】

The phase shift method is one of the effective super-resolution pattern transfer methods for such a problem. In the phase shift method, a phase shift mask is used as a mask for transferring a fine pattern.

【0004】

The phase shift mask is composed of, for example, a phase shifter portion that forms a pattern portion on the mask and a non-pattern portion (exposed substrate portion) that does not have a phase shifter, and shifts the phase of light transmitted through both by about 180 °. This causes light to interfere with each other at the pattern boundary portion, and this effect improves the contrast of the transferred image. Furthermore, by using the phase shift method, it is possible to increase the depth of focus to obtain the required resolution, and compared to the transfer process using a normal mask having a general light-shielding pattern made of a chromium film or the like. It is possible to improve the resolution and increase the applicability of the process at the same time while using the same wavelength of light.

【0005】

The phase shift mask can be roughly classified into a completely transmissive type (Shibuya / Levenson type) phase shift mask and a halftone type phase shift mask according to the light transmission characteristics of the phase shifter portion. The former is a mask in which the light transmittance of the phase shifter portion is equivalent to that of the non-patterned portion (exposed substrate portion) and is almost transparent to the exposure wavelength, and is generally effective for line-and-space transfer. It is said. On the other hand, the latter has a light transmittance of several percent to several tens of percent of the non-patterned portion (exposed substrate portion) of the phase shifter portion, and is said to be effective for producing contact holes and isolated patterns in the semiconductor manufacturing process. ing.

【0006】

Fig. 1 shows the basic structure of the halftone type phase shift mask blank, and Fig. 2 shows the basic structure of the halftone type phase shift mask. The antireflection layer and etching stop layer that may be used in the lithography process are omitted. The halftone type phase shift mask blank is a transparent substrate 1 on which a semitransparent film (halftone phase shifter film) 2 is formed. Further, the halftone type phase shift mask includes a phase shifter portion 3 that forms a pattern portion on the mask and a non-pattern portion (board exposed portion) 4 that does not have a phase shifter. Here, the phase shifter portion 3 functions as a phase shifter by shifting the phase of the exposure light transmitted through the edge vicinity portion thereof, and substantially emits the exposure light to the resist on the transfer substrate. It has a light-shielding function to block.

【0007】

Among the halftone type phase shift masks, there is a single layer type halftone type phase shift mask which has a simple structure and is easy to manufacture. As such a single-layer type halftone type phase shift mask, for example, CrO as described in Japanese Patent Application Laid-Open No. 5-127361._x, CrN, CrO_xN_y, Cr_xON_yC₂Those having a phase shifter made of a chromium-based material such as JP-A-6-332152, those having a phase shifter made of a MoSi-based material such as MoSiO and MoSiON described in JP-A-6-332152, or JP-A-7-261370. Some have a phase shifter made of SiN-based or SiO-based material described in the publication.

【0008】

[Problems to be Solved by the Invention]

In recent years, the use of halftone type phase shift masks has been progressing along with the shortening of the exposure wavelength, and recently, krypton fluoride (KrF) excimer laser light (248 nm) has been used as light having a wavelength shorter than that of the i-line. It has become. The use of argon fluoride (ArF) excimer laser light (193 nm) or argon chloride (ArCl) excimer laser light (175 nm) has also been proposed as further short wavelength light.

【0009】

With such a shortening of the exposure wavelength, what is important in the corresponding phase shift mask and phase shift mask blank is the control of optical coefficients such as transmittance and refractive index at the exposure wavelength to be used. Unlike the case of the visible to near-ultraviolet region, in the region where the wavelength is shorter than 250 nm, the degree of light absorption becomes remarkably large in many substances, and it becomes difficult to control the desired transmittance. Therefore, the halftone type phase shift mask for i-line cannot be used as it is as a halftone type phase shift mask for exposure light shorter than 250 nm. The setting of the transmittance in the halftone type phase shifter depends on the sensitivity of the resist used in the pattern transfer and the patterning process. For example, in the case of the halftone type phase shift mask, the phase that shifts the phase of the exposure light by a predetermined angle. It is desirable that the transmittance of the exposure light can be controlled in the range of 3% to 20% in the thickness of the shifter.

【0010】

Further, even if the above basic required characteristics such as the transmittance and the refractive index at the exposure wavelength are satisfied in response to the shortening of the exposure wavelength, the transmittance for the wavelength of the inspection light (for example, 364 nm, 488 nm, 633 nm) is high. There is a problem that it is not suitable for practical use because it cannot be inspected. Therefore, for practical use, it is required that the transmittance of the inspection light with respect to the wavelength can be controlled to a desired value.

【0011】

Furthermore, in addition to the above characteristics, the halftone type phase shift mask and the halftone type phase shift mask blank that is the base material for producing the halftone type phase shift mask must be stable to the excimer laser irradiation used (light resistance), and the mask. It is required to have chemical durability (chemical resistance) in the cleaning process, which is indispensable for the process, and to minimize minute defects in the blank (low defect density), which significantly deteriorates the quality of the mask. ..

【0012】

Specifically, shortening the exposure wavelength means that the energy density irradiated per unit time increases at the same time. Correspondingly, the film material forming the phase shifter layer is required not to impair the function as a phase shift mask due to damage caused by high-energy light irradiation. The term damage as used herein means a change in the optical characteristics (refractive index, transmittance, etc.) of the shifter film due to light irradiation, the occurrence of color defects, a change in film thickness, deterioration of film quality, and the like. For example, when an excimer laser with a wavelength in the deep ultraviolet region is irradiated, the substance in the film is excited by the two-photon process, which is said to lead to changes in the optical properties and quality of the film, but the details are still clear. Not made. In any case, it is one of the indispensable conditions that the phase shifter film has high irradiation resistance in the irradiation of high-energy light accompanying the shortening of the exposure wavelength.

【0013】

Further, when considering the material of the shifter film from the viewpoint of the mask material, the film must not be altered or dissolved by cleaning with an acid or an alkali in the mask manufacturing process. That is, the phase shifter film is required to have chemical durability regardless of the length of the exposure wavelength.

【0014】

Furthermore, from the viewpoint that the phase shift mask is a tool for performing microfabrication, it is necessary to have microfabrication that can achieve the processing (patterning, etching, etc.) of the phase shift mask blank with higher accuracy. Is required to have a homogeneous phase shifter film and no defects in the film. In the future, it is said that the mask pattern will be further miniaturized as the exposure wavelength is shortened, and defects in the phase shifter film will be an important problem that affects the reliability of pattern transfer.

【0015】

However, the conventional halftone phase shift mask and its blank sufficiently satisfy all of the basic required characteristics such as transmittance and refractive index due to the shortening of the exposure wavelength, and the other required characteristics described above. Has not been obtained.

【0016】

The present invention has been made under the above-mentioned background, and an object of the present invention is to provide an excellent halftone type phase shift mask corresponding to a shorter wavelength of exposure light and a blank thereof.

【0017】

[Means for solving problems]

In order to achieve the above object, the present invention has the following configuration.

【0018】

(Structure 1) A phase shift mask blank for producing a phase shift mask, which has a function of causing a predetermined amount of phase difference between light transmitted through a translucent film and light transmitted directly through a transparent substrate. In a halftone type phase shift mask blank in which a translucent film having a function of attenuating the strength of is formed on a transparent substrate, the translucent film is at least one selected from silicon, nickel, nitrogen, oxygen and hydrogen. A halftone type phase shift mask blank, further comprising, and further characterized in that silicon and nickel contained in the translucent film have a relationship represented by the following formula.

[Number 1]

【0019】

(Structure 2) The halftone type phase shift mask blank according to the configuration 1, wherein at least one selected from nitrogen, oxygen and hydrogen contained in the translucent film forms a chemical bond with silicon. ..

【0020】

(Structure 3) A phase shift mask blank for producing a phase shift mask, which has a function of causing a predetermined amount of phase difference between light transmitted through a translucent film and light transmitted directly through a transparent substrate. In a halftone type phase shift mask blank in which a translucent film having a function of attenuating the strength of is formed on a transparent substrate, the translucent film is at least one element M (M) selected from a metal and a transition metal. A halftone phase shift mask blank comprising (referring to a metal other than Ni or a transition metal), silicon and nickel, and at least one selected from nitrogen, oxygen and hydrogen.

【0021】

(Structure 4) A phase shift mask blank for producing a phase shift mask, which has a function of causing a predetermined amount of phase difference between light transmitted through a translucent film and light transmitted directly through a transparent substrate. In a halftone type phase shift mask blank in which a translucent film having a function of attenuating the strength of is formed on a transparent substrate, the translucent film is at least one element M (M) selected from a metal and a transition metal. (Refers to metals other than Ni or transition metals), silicon and nickel, and at least one selected from nitrogen, oxygen and hydrogen, and silicon and nickel contained in the translucent film have a relationship represented by the following formula. A halftone type phase shift mask blank characterized by being present.

[Number 2]

【0022】

(Structure 5) The halftone type phase shift according to the configuration 3 or 4, wherein at least one selected from nitrogen, oxygen and hydrogen contained in the translucent film forms a chemical bond with silicon. Mask blank.

【0023】

(Structure 6) The metal or transition metal that is the main constituent element of the translucent film is cobalt, tantalum, tungsten, molybdenum, chromium, vanadium, palladium, titanium, niobium, zinc, zirconium, hafnium, germanium, aluminum, platinum, The halftone type phase shift mask blank according to the constitution 3 to 5, which is composed of at least one element selected from manganese and iron.

【0024】

(Structure 7) The translucent film is characterized in that the transmittance of the phase shift mask blank and the inspection light of the phase shift mask in the wavelength range of 190 nm to 650 nm with respect to the desired inspection light is 40% or less. Halftone type phase shift mask blank according to 1 to 6.

【0025】

(Structure 8) In the translucent film according to the composition 1 to 7, the content of nitrogen and / or oxygen contained in the film is 0 to 60 atomic% for nitrogen and 0 to 65 atomic% for oxygen. A halftone type phase shift mask blank characterized by being.

【0026】

(Structure 9) The translucent film is characterized in that the content of nitrogen and / or oxygen contained in the film is 0 to 50 atomic% for nitrogen and 3 to 50 atomic% for oxygen. The halftone type phase shift mask blank according to the configuration 8 described above.

【0027】

(Structure 10) A halftone characterized by forming a translucent film on a transparent substrate by a sputtering method using a sputtering target and a gas containing the constituent elements of the translucent film according to any one of configurations 1 to 9. A method for manufacturing a mold phase shift mask blank.

【0028】

(Structure 11) The translucent film in the halftone type phase shift mask blank according to the configurations 1 to 9 is etched by dry etching using a gas containing chlorine and / or a gas containing fluorine. A method for manufacturing a halftone phase shift mask.

【0029】

(Structure 12) The halftone type phase shift mask blank according to any one of configurations 1 to 9 is used to form a semitransparent mask pattern to be transferred to a wafer on a transparent substrate. Shift mask.

【0030】

(Structure 13) It has a transmittance of 3% to 20% for the desired exposure light in the wavelength range of 150 nm to 370 nm, and is optically designed to function as a phase shift mask. The halftone type phase shift mask according to the configuration 12, which comprises.

【0031】

(Structure 14) A pattern transfer method comprising performing pattern transfer using the halftone type phase shift mask according to any one of configurations 12 or 13.

【0032】

[Action]

The basic condition of the present invention is that it can be used for an exposure wavelength region from ultraviolet to deep ultraviolet, and therefore the phase shifter film oscillates at a desired exposure wavelength, such as a krypton fluoride excimer laser. It must be semitransparent to 248 nm, which is the wavelength, or 193 nm, which is the oscillation wavelength of the argon fluoride excimer laser, or other wavelengths, and must be able to control this semitransmissive light in film fabrication. In addition to the light semitransparency, it must have an optical refractive index and can be controlled in the same manner as the light semitransparency. The refractive index correlates with the film thickness of the phase shifter to determine the phase shift angle, which is an important requirement of the phase shift mask. For example, when the refractive index is 2, the film thickness at which a phase shift angle of 180 ° can be obtained is 124 nm (× N: natural number) at a wavelength of 248 nm, and 96.5 nm (× N: natural number) at a wavelength of 193 nm. Therefore, since the desired light semi-transmittance is actually required on the premise that the film thickness condition for achieving the set phase shift angle is satisfied, it is very important to be able to control these values.

【0033】

On the other hand, in particular, in the present invention, transmission with respect to the exposure wavelength is performed by containing Ni and selecting and controlling the film composition (constituent elements and their ratios) and film quality (including the bonding state and film structure). In addition to satisfying the basic required characteristics such as rate and refractive index, it is possible to obtain a translucent film having a desired transmittance for a desired test light in the wavelength range of 190 nm to 650 nm of the test light.

【0034】

According to the above configuration 1, the translucent film contains silicon and nickel, and at least one selected from nitrogen, oxygen and hydrogen, and further, by specifying the ratio of silicon and nickel contained in the translucent film, It is possible to satisfy all the required characteristics as a halftone type phase shift mask. That is, the translucent film of configuration 1 has basic required characteristics such as transmittance and refractive index with respect to the exposure wavelength, as well as transmittance with respect to the wavelength of the inspection light, light resistance, chemical durability (chemical resistance), and low defects. Meet all required characteristics such as density.

If the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] is less than 0.15, the light transmittance increases over the entire wavelength range, but the inspection light The transmittance in the wavelength range becomes 40% or more, which makes it practically difficult to inspect the film. When it exceeds 0.5, the transmittance in the entire wavelength range, especially near the exposure wavelength, decreases, and the function as a halftone type phase shifter deteriorates. As described above, by setting the ratio of silicon to nickel within the above range and further containing at least one selected from nitrogen, oxygen and hydrogen, characteristics such as transmittance and refractive index can be controlled.

【0035】

In the above configuration 2, the translucent film satisfying the requirements of the above configuration 1 is composed of an amorphous structural film containing a Si-N bond, a Si-O bond, and a Si-H bond in order to control and improve the required characteristics. Is preferable.

【0036】

According to the above configuration 3, the main constituent elements of the translucent film are a quaternary system or more of a metal and / or a transition metal M, silicon, nickel, nitrogen, oxygen, and at least one selected from hydrogen. It is possible to satisfy all the required characteristics as a tone type phase shift mask. Further, in the configuration 3, by adding a metal and / or a transition metal, it becomes easy to control and improve the required characteristics.

【0037】

According to the above configuration 4, the translucent film contains a metal and / or a transition metal M, silicon, nickel, at least one selected from nitrogen, oxygen and hydrogen, and further contains silicon contained in the translucent film. By specifying the nickel ratio, it is possible to satisfy all the required characteristics as a halftone type phase shift mask.

If the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] is less than 0.1, the light transmittance increases over the entire wavelength range, but the inspection light The transmittance in the wavelength range becomes 40% or more, which makes it practically difficult to inspect the film. When it exceeds 0.6, the transmittance in the entire wavelength range, especially near the exposure wavelength, decreases, and the function as a halftone type phase shifter deteriorates.

【0038】

In the above configuration 5, the semi-transparent film satisfying the requirements of the above configuration 3 or 4 is composed of an amorphous structural film containing a Si-N bond, a Si-O bond, and a Si-H bond, which controls and improves the required characteristics. Preferred for.

【0039】

According to the above configuration 6, by using these elements as the metal and / or the transition metal M, not only the desired optical properties can be achieved, but also the electrical properties, optical properties and chemical durability of the film are effectively improved. Is. Specifically, improvement of the conductivity of the film is an improvement in electrical characteristics, and control of transmittance at the exposure wavelength and improvement of transmittance in the inspection light wavelength range of the mask are chemical durability as improvement of optical characteristics. As an improvement in properties, durability against acids and alkalis used in the mask cleaning process can be improved.

【0040】

According to the above configuration 7, in the above configurations 1 to 6, by selecting and controlling the film composition (constituent elements and their ratios) and the film quality (including the bonding state and the film structure), the wavelength range of the inspection light is 190 nm to A translucent film having a transmittance of 40% or less with respect to a desired inspection light at 650 nm can be obtained, and therefore a mask capable of performing a highly reliable inspection can be produced.

【0041】

According to the above configuration 8, if the nitrogen content in the translucent film exceeds 60 atomic%, the transmittance increases over the entire wavelength range, which makes the inspection difficult. Further, the resistivity of the film increases, which causes adverse effects such as charge-up of the film when drawing a blank electron beam. When the oxygen content exceeds 65 atomic%, the transmittance increases over the entire wavelength range, making inspection difficult. In addition, the resistivity of the film increases and the refractive index of the film decreases, resulting in electrical and optical. Characteristics do not meet the requirements.

【0042】

In the above configuration 9, from the same viewpoint as the above configuration 8, the preferable content of nitrogen and / or oxygen contained in the translucent film is further defined.

【0043】

In the above configuration 10, it is currently preferable to form a translucent film by a sputtering method in consideration of the wide controllability of the film quality and mass productivity.

【0044】

According to the above configuration 11, excellent microfabrication can be realized by combining the translucent film obtained in the present invention with a dry etching process using a gas containing chlorine and / or a gas containing fluorine.

【0045】

According to the above configuration 12, by patterning the blank, a halftone type phase shift mask that satisfies all the required characteristics can be obtained.

【0046】

According to the above configuration 13, a halftone type phase shift mask having desired optical characteristics and the like can be obtained. In particular, desired optics for exposure light such as krypton fluoride (KrF) excimer laser light (248 nm), argon fluoride (ArF) excimer laser light (193 nm), or argon chloride (ArCl) excimer laser light (175 nm). A halftone type phase shift mask having characteristics and the like can be obtained.

【0047】

According to the above configuration 14, by performing pattern transfer using the halftone type phase shift mask of the present invention, a transfer process corresponding to a shorter exposure wavelength can be realized.

【0048】

Hereinafter, the present invention will be described in detail.

【0049】

In the present invention, the main constituent elements of the translucent film (halftone type phase shifter film) act synergistically to transmit basic required characteristics such as transmittance and refractive index with respect to the exposure wavelength and transmission with respect to the wavelength of the inspection light. It is possible to satisfy all the required characteristics as a halftone type phase shift mask such as rate, light resistance to exposure light, chemical durability (chemical resistance), and low defect density, but each element When used alone, it mainly has the following effects. It is important to select and control the ratio of constituent elements, film quality (including bond state and film structure), etc. in order to actually satisfy all the required characteristics as well as the possibility.

【0050】

Silicon contained in the translucent film combines with nitrogen, oxygen, and hydrogen also contained in the film to form silicon nitride, silicon oxide, and silicon hydride, and becomes the main structure of the translucent film. It has the effect of hardening the structure of silicon and improving thermal and chemical stability. Aluminum has the same function as silicon.

【0051】

Nitrogen, oxygen, and hydrogen contained in the film change their characteristics as a halftone type phase shifter film, either alone or in combination.

【0052】

Nitrogen in the membrane is effective mainly for changing the refractive index in addition to controlling the transmittance.

【0053】

Oxygen in the membrane is mainly effective in controlling the transmittance. In particular, in the ultraviolet wavelength region where light absorption occurs in many materials, it is necessary to introduce oxygen into the translucent film in order to control the light absorption characteristics and the light transmission characteristics in a well-balanced manner to obtain a desired translucent film. It is effective. However, the introduction of excess oxygen into the film may increase the proportion of oxides in the film and, in some cases, reduce the refractive index of the translucent film. As described above, the phase shift angle is determined by the refractive index and the film thickness for a certain wavelength of light, so that the decrease in the refractive index means the increase in the film thickness required to obtain the phase shift angle of 180 °. Therefore, as a result, a desired transmittance (permeation amount) cannot be obtained. For this reason, in order to function as a phase shifter for a desired exposure wavelength, it is important to achieve a sufficient transmittance and at the same time have a certain degree of refractive index. In order to avoid a decrease in the refractive index due to excessive addition of oxygen, it is effective to improve the refractive index by introducing a nitride into the film due to the addition of nitrogen.

【0054】

Hydrogen in the film is effective in controlling the transmittance like nitrogen and oxygen, and at the same time, effectively terminates the dungling bond of the component element in the film, and short-wavelength high-energy light such as ultraviolet light. It is also effective in improving the stability of the film against UV rays. It is necessary to determine the amount to be introduced in consideration of thermal stability and photochemical stability in the membrane.

【0055】

Ni in the film is basic such as transmittance and refractive index with respect to the exposure wavelength by selecting and controlling the composition (constituent elements and their ratios) and film quality (including the bonding state and film structure) of the film containing Ni. It is effective not only for satisfying the required characteristics but also for obtaining a translucent film having a transmittance of 40% or less with respect to a desired test light in the wavelength range of 190 nm to 650 nm of the test light. In addition, Ni in the film, alone or together with other metals or transition metal elements, is effective in improving the electrical properties, optical properties and chemical durability of the film. Specifically, improvement of the conductivity of the film is an improvement in electrical characteristics, and control of transmittance at the exposure wavelength and improvement of transmittance in the inspection light wavelength range of the mask are chemical durability as improvement of optical characteristics. As an improvement in properties, durability against acids and alkalis used in the mask cleaning process can be improved.

【0056】

As the metal or transition metal element M in the film, a metal or transition metal element that can achieve desired optical properties may be appropriately selected. Among them, cobalt, tantalum, tungsten, molybdenum, chromium, vanadium, palladium, and titanium. , Niobium, zinc, zirconium, hafnium, germanium, aluminum, platinum, manganese, iron and the like are effective in controlling and improving the electrical properties, optical properties and chemical durability of the film.

【0057】

Even if the elements contained in the film and their ratios are the same, the optical properties and other properties of the film are exhibited by the substantial bonds contained in the film, so that the elements contained in the film are substantially contained. It is important to specify the bond. Further, it is important that these bonds are contained in a predetermined amount in order to exhibit predetermined characteristics, are uniformly distributed, and form a film having an amorphous structure depending on the bonded state. Specifically, for example, if there are few bonds between silicon and at least one selected from nitrogen, oxygen, and hydrogen, it becomes difficult to improve the denseness of the film, and silicon that exists alone in the film. If the proportion of the above is large, the chemical durability and optical properties of the film may deteriorate. With respect to other bonds, the density, chemical durability, optical properties, light resistance, etc. of the film deteriorate depending on the presence or absence or the degree thereof. The fact that the film structure is amorphous means that not only the stress generated in the film can be appropriately controlled to a desired value, but also phenomena such as birefringence and scattering that optically deteriorate the transfer characteristics are unlikely to occur. Further, in the lithography process of finally producing the mask by patterning, the processability of the fine pattern is remarkably improved. In order to control the substantial bonds contained in the film, it is necessary to select the film forming method, film forming conditions, film composition, target composition and the like. From the above, the translucent film in the present invention has at least Ni-Si bond, Ni-N bond, Ni-O bond or Ni-H bond, Si-N bond, Si-O bond or Si-. It is preferable that the H bond is substantially contained, the M-Si bond and the MN bond are substantially contained as required, and the film is composed of an amorphous structural film in order to control and improve the required characteristics. The "-" symbol in each bond type means a bond between atoms, and is not limited to a single bond, but is a multiple bond or another bond state (for example, between a single bond and a double bond). ) Etc. are also included.

【0058】

In the halftone type phase shift mask blank of the present invention, other layers such as an antireflection layer, an etching stop layer, and an etching mask layer can be formed, if necessary. Further, the transparent substrate may be transparent to exposure light and inspection light, and the material thereof and the like are not particularly limited.

【0059】

Next, a method for manufacturing the halftone type phase shift mask blank of the present invention will be described.

【0060】

Examples of the semitransparent film forming method include various thin film forming methods such as a sputtering film forming method, a vapor deposition method, a chemical vapor deposition method (CVD), an ion beam deposition method, and an electron beam deposition method. Of these, when considering mass productivity as a mask material, manufacturing yield, stability, etc., a sputtering film formation method using a sputtering target containing a constituent element of a translucent film and a gas is currently effective.

【0061】

Among the main constituent elements of the translucent film, for nitrogen, oxygen, and hydrogen, a method of introducing these elements into the film by a reactive sputtering method using a sputtering gas containing these elements, and targeting these elements. There is a method of incorporating it into the membrane and introducing it into the membrane.

【0062】

In the case of plasma discharge (reactive sputtering method) in which oxygen gas is introduced, abnormal discharge due to an insulating oxide formed on the target surface is often a problem. The abnormal discharge occurs on the surface of the target and generates minute particles. These particles are incorporated into the translucent film and cause defects in the film, which significantly deteriorates the quality of the halftone phase shifter. In the material system of the present invention, it is possible to preliminarily contain an oxide in the target. For example, in the case of a target composed of silicon and nickel, silicon oxide or nickel oxide may be contained in the target. In the case of high-frequency discharge, the discharge is possible regardless of the conductivity of the target, so there is no limit to the proportion of oxides. In the case of DC discharge or AC discharge, the oxide may be contained in the target within the range of conductivity suitable for each discharge method. By containing the oxide as an oxide in the target in this way, it becomes possible to efficiently introduce the oxide into the film while reducing abnormal discharge. By adding nitrogen or hydrogen instead of oxygen, it is effective in reducing the abnormal discharge in the plasma that tends to occur during oxygen-reactive sputtering and reducing the number of defects in the translucent film. As for nitrogen, by incorporating it in the target as a nitride or an acid nitride as in the case of oxygen, it becomes possible to efficiently introduce the nitride into the film. Since nitrogen and hydrogen are less likely to cause abnormal discharge during reactive sputtering as compared with oxygen, they may be introduced into the membrane via a sputtering gas.

【0063】

Examples of the sputter gas include nitrogen, oxygen, and hydrogen, as well as gases containing these, such as nitric oxide, nitrogen dioxide, nitrous oxide, laughing gas, ammonia gas, ozone, and water. Nitrogen, oxygen, and hydrogen can be easily incorporated into the membrane by using these gases alone or in combination, or by mixing them with gases such as helium, argon, and xenon. Finally, the desired membrane composition, the target composition so as to obtain the membrane characteristics, and the gas composition may be appropriately selected. In addition, regarding the selection of sputtering methods (DC sputtering, high frequency sputtering, AC sputtering, etc.) and the selection of sputtering conditions such as sputtering output, gas pressure, and presence / absence of substrate heating, the material system of the translucent film and the target film composition are also selected. , It may be appropriately selected according to the film characteristics.

【0064】

The halftone type phase shift mask of the present invention can be obtained by forming a translucent mask pattern to be transferred to a wafer on a transparent substrate by using the above-mentioned halftone type phase shift mask blank of the present invention.

【0065】

A lithography method is used for patterning a translucent film or the like on a blank. As the lithography method, a method used in a general mask manufacturing process can be applied. For example, for the patterning of the translucent film of the present invention, CF₄, C₂F₆, CHF₃,SCIENCE FICTION₆, NF₃Fluorine-containing gas such as Cl₂, CH₂Cl₂Gas containing chlorine, such as O₂, O₃, H₂A dry etching method in which an etching gas such as a gas containing oxygen such as O is appropriately mixed and used can be preferably used. In dry etching, it is also effective to control the etching characteristics by mixing argon, hydrogen, helium, or other gas with the etching gas.

【0066】

[Example]

Hereinafter, examples will be described.

【0067】

Example 1 In Example 1, Ar and N were used using a sputtering target prepared by mixing silicon and nickel in a molar ratio of about 4: 1.₂A translucent film (halftone phase shifter film) was formed on the quartz substrate by direct current sputter film formation using a gas mixed with and at a flow rate ratio of about 2 to 8 as a sputter gas. The conditions for introducing the sputter gas were set so that the total amount of the mixed gas introduced was 30 SCCM and the pressure inside the device during sputtering was 3 m Torr with the pressure regulator directly above the exhaust pump.

【0068】

When the film thickness of the halftone phase shifter film thus produced on the quartz substrate was measured by the stylus method and the transmittance was measured by the spectrophotometer, the film thickness was 770 ongstrom and at 193 nm. The spectral transmittance was 3.6% (Fig. 3). Similarly, when the refractive index (n) was calculated from the reflectance, transmittance, and film thickness of the film measured using a spectrophotometer, the value of the refractive index (n) was 2.25, and the film thickness was 770 ounces. It was confirmed that it was sufficient to shift the phase of light having a wavelength of 193 nm by 180 ° in the strom. Furthermore, the spectral transmittance at the inspection light wavelength (364 nm) was measured in the same manner and found to be 39.6%.

【0069】

For the prepared halftone phase shifter film, the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] was 0.25 (25%). This measurement was performed by X-ray photoelectron spectroscopy (XPS). Moreover, when the prepared halftone phase shifter film was also measured using XPS, the nitrogen content in the film was 50 atomic%.

【0070】

The chemical durability of the prepared halftone phase shifter film was evaluated by immersion in acid and changes in film quality before and after immersion. The halftone phase shifter film having a film thickness of 770 ongstrom and a spectral transmittance of 3.6% at 193 nm was immersed in hot concentrated sulfuric acid heated to 90 ° C to 100 ° C for 120 minutes, and then the same as above. The film thickness was 766 ounce strom, the spectral transmittance at 193 nm was 3.8%, and the phase shift angle shift caused by immersion in acid was within 1 °, which is sufficient resistance to hot concentrated sulfuric acid. Was. Similarly, it was confirmed that the product had sufficient chemical resistance even when immersed in a perwater sulfuric acid solution in which hydrogen peroxide solution and sulfuric acid were mixed at a ratio of 1: 4 at 120 ° C. for 120 minutes. ..

【0071】

Regarding the light irradiation resistance of the prepared halftone phase shifter film, an ArF excimer laser having an oscillation wavelength at 193 nm was irradiated, and the transmittance, refractive index, and film thickness of the film were evaluated before and after the irradiation. As a result, the irradiation energy density per single pulse is 1 mJ / cm.²10 ArF excimer lasers⁷No significant change was observed in the transmittance, refractive index, and film thickness before and after pulse irradiation, and the characteristics of the halftone phase shifter film were very stable.

【0072】

The etching of the produced halftone phase shifter film was performed by reactive ion etching. At this time, a gas obtained by mixing chlorine and oxygen at a flow rate ratio of 4: 1 was used as the etching gas. As a result, it was confirmed that good etching can be performed while having an etching selectivity of about 10 times that of the quartz substrate. Moreover, since the film structure is amorphous, the side wall of the etching pattern is also smooth.

【0073】

As shown in Example 1 above, it has been possible to easily produce a thin film having good film quality as a halftone phase shifter film and optical characteristics.

【0074】

For comparison, the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] is less than 0.15 and more than 0.5. As a result of the same evaluation as above, the spectral transmittance at the inspection light wavelength exceeded 40% when the value was less than 0.15, and the spectral transmittance at the exposure wavelength was less than 3% when the frequency exceeded 0.5.

【0075】

Example 2 In Example 2, Ar and N were used using a sputtering target prepared by mixing silicon and nickel in a molar ratio of about 3: 1.₂And O₂A translucent film (halftone phase shifter film) was formed on the quartz substrate by direct current sputter film formation using a gas mixed with and at a flow rate ratio of about 10:39: 1. The conditions for introducing the sputter gas were set so that the total amount of the mixed gas introduced was 30 SCCM and the pressure inside the device during sputtering was 3 m Torr with the pressure regulator directly above the exhaust pump.

【0076】

When the film thickness of the halftone phase shifter film thus produced on the quartz substrate was measured by the stylus method and the transmittance was measured using a spectrophotometer, the film thickness was 1010 ongstrom, at 193 nm. The spectral transmittance was 8.3%. Similarly, when the refractive index (n) was calculated from the reflectance, transmittance, and film thickness of the film measured using a spectrophotometer, the value of the refractive index (n) was 1.96, and the film thickness was 1010 ounces. It was confirmed that it was sufficient to shift the phase of light having a wavelength of 193 nm by 180 ° in the strom. Furthermore, the spectral transmittance at the inspection light wavelength (364 nm) was measured in the same manner and found to be 38.8%.

【0077】

For the prepared halftone phase shifter film, the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] was 0.32 (32%). Further, when the prepared halftone phase shifter film was also measured using XPS, the nitrogen content in the film was 30 atomic% and the oxygen content was 20 atomic%.

【0078】

The chemical durability of the prepared halftone phase shifter film was evaluated by changes in film quality and optical properties before and after immersion in acid, as in Example 1. As a result, the phase shift angle shift before and after immersion in hot concentrated sulfuric acid and hydrogen peroxide sulfuric acid is 1 ° or less, and the change in transmittance is 0.2% or less, and it has sufficient chemical resistance. It was confirmed.

【0079】

Regarding the light irradiation resistance of the prepared halftone phase shifter film, it has an oscillation wavelength of 193 nm as in Example 1, and the irradiation energy density per single pulse is 1 mJ / cm.²10 ArF excimer lasers⁷Changes in transmittance, refractive index, and film thickness were measured before and after pulse irradiation, but no significant difference was observed in the measured values, and the characteristics of the halftone phase shifter film were very stable.

【0080】

The prepared halftone phase shifter film was etched by reactive ion etching in the same manner as in Example 1. At this time, a gas obtained by mixing chlorine and oxygen at a flow rate ratio of 9: 2 was used as the etching gas. As a result, it was confirmed that good etching can be performed while having an etching selectivity of about 10 times that of the quartz substrate. Moreover, since the film structure is amorphous, the side wall of the etching pattern is also smooth.

【0081】

As shown in Example 2 above, it has been possible to easily produce a thin film having good film quality as a halftone phase shifter film and optical characteristics.

【0082】

In Example 2, the transmittance in the exposure wavelength range is improved by introducing oxygen into the film, and the high refractive index is maintained by the action of nitrogen in the film. Here, by introducing an appropriate amount of Ni into the film, the light absorption characteristics and the light transmission characteristics are controlled in a well-balanced manner.

【0083】

Example 3 In Example 3, Ar and N were used using a sputtering target prepared by mixing silicon and nickel in a molar ratio of about 3: 1.₂And O₂And H₂A translucent film (halftone phase shifter film) was formed on the quartz substrate by direct current sputter film formation using a gas mixed at a flow rate ratio of about 20:74: 1: 5 as a sputter gas. The conditions for introducing the sputter gas were set so that the total amount of the mixed gas introduced was 30 SCCM and the pressure inside the device during sputtering was 3 m Torr with the pressure regulator directly above the exhaust pump.

【0084】

When the film thickness of the halftone phase shifter film thus produced on the quartz substrate was measured by the stylus method and the transmittance was measured using a spectrophotometer, the film thickness was 885 ongstrom, at 193 nm. The spectral transmittance was 7.7%. Similarly, when the refractive index (n) was calculated from the reflectance, transmittance, and film thickness of the film measured using a spectrophotometer, the value of the refractive index (n) was 2.09, and the film thickness was 885 ounces. It was confirmed that it was sufficient to shift the phase of light with a wavelength of 193 nm by 180 ° in the strom. Furthermore, the spectral transmittance at the inspection light wavelength (364 nm) was measured in the same manner and found to be 39.1%.

【0085】

For the prepared halftone phase shifter film, the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] was 0.32 (32%). Moreover, when the prepared halftone phase shifter film was also measured using XPS, the nitrogen content in the film was 24 atomic% and the oxygen content was 16 atomic%. Hydrogen was separately measured using hydrogen forward scattering to confirm its content in the membrane.

【0086】

The chemical durability of the prepared halftone phase shifter film was evaluated by changes in film quality and optical properties before and after immersion in acid, as in Example 1. As a result, the phase shift angle shift before and after immersion in hot concentrated sulfuric acid and hydrogen peroxide sulfuric acid is 1 ° or less, and the change in transmittance is 0.2% or less, and it has sufficient chemical resistance. It was confirmed.

【0087】

Regarding the light irradiation resistance of the prepared halftone phase shifter film, it has an oscillation wavelength of 193 nm as in Example 1, and the irradiation energy density per single pulse is 1 mJ / cm.²10 ArF excimer lasers⁷Changes in transmittance, refractive index, and film thickness were measured before and after pulse irradiation, but no significant difference was observed in the measured values, and the characteristics of the halftone phase shifter film were very stable. It was confirmed that the stability of the film against short-wavelength high-energy light was improved by adding hydrogen.

【0088】

The prepared halftone phase shifter film was etched by reactive ion etching in the same manner as in Example 1. At this time, a gas obtained by mixing chlorine and oxygen at a flow rate ratio of 9: 1 was used as the etching gas. As a result, it was confirmed that good etching can be performed while having an etching selectivity of about 10 times that of the quartz substrate. Moreover, since the film structure is amorphous, the side wall of the etching pattern is also smooth.

【0089】

As shown in Example 3 above, it has been possible to easily produce a thin film having good film quality as a halftone phase shifter film and optical characteristics.

【0090】

In Example 3, the transmittance and light resistance are improved by introducing oxygen and hydrogen into the film.

【0091】

Example 4 In Example 4, Ar and N were used using a sputtering target prepared by mixing silicon and nickel in a molar ratio of about 4: 1.₂And H₂A translucent film (halftone phase shifter film) was formed on the quartz substrate by direct current sputter film formation using a gas mixed with and at a flow rate ratio of about 2: 7: 1. The conditions for introducing the sputter gas were set so that the total amount of the mixed gas introduced was 30 SCCM and the pressure inside the device during sputtering was 3 m Torr with the pressure regulator directly above the exhaust pump.

【0092】

When the film thickness of the halftone phase shifter film thus produced on the quartz substrate was measured by the stylus method and the transmittance was measured using a spectrophotometer, the film thickness was 860 angstrom and at 193 nm. The spectral transmittance was 6.5%. Similarly, when the refractive index (n) was calculated from the reflectance, transmittance, and film thickness of the film measured using a spectrophotometer, the value of the refractive index (n) was 2.12, and the film thickness was 860 ounces. It was confirmed that it was sufficient to shift the phase of light having a wavelength of 193 nm by 180 ° in the strom. Furthermore, the spectral transmittance at the inspection light wavelength (364 nm) was measured in the same manner and found to be 37.9%.

【0093】

For the prepared halftone phase shifter film, the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] was 0.25 (25%). Moreover, when the prepared halftone phase shifter film was also measured using XPS, the nitrogen content in the film was 40 atomic%. Hydrogen was separately measured using hydrogen forward scattering to confirm its content in the membrane.

【0094】

The chemical durability of the prepared halftone phase shifter film was evaluated by changes in film quality and optical properties before and after immersion in acid, as in Example 1. As a result, the phase shift angle shifts before and after immersion in hot concentrated sulfuric acid and hydrogen peroxide sulfuric acid are both 1.5 ° or less, and the change in transmittance is 0.3% or less, and they have sufficient chemical resistance. It was confirmed.

【0095】

Regarding the light irradiation resistance of the prepared halftone phase shifter film, it has an oscillation wavelength of 193 nm as in Example 1, and the irradiation energy density per single pulse is 1 mJ / cm2.^so10 ArF excimer lasers⁷Changes in transmittance, refractive index, and film thickness were measured before and after pulse irradiation, but no significant difference was observed in the measured values, and the characteristics of the halftone phase shifter film were very stable. It was confirmed that the stability of the film against short-wavelength high-energy light was improved by adding hydrogen.

【0096】

The prepared halftone phase shifter film was etched by reactive ion etching in the same manner as in Example 1. At this time, a gas obtained by mixing chlorine and oxygen at a flow rate ratio of 9: 2 was used as the etching gas. As a result, it was confirmed that good etching can be performed while having an etching selectivity of about 12 times that of the quartz substrate. Moreover, since the film structure is amorphous, the side wall of the etching pattern is also smooth.

【0097】

As shown in Example 4 above, it has been possible to easily produce a thin film having good film quality as a halftone phase shifter film and optical characteristics.

【0098】

In Example 4, by introducing hydrogen into the film, the transmittance and the light resistance are improved, and at the same time, the etching selectivity with respect to the quartz substrate is improved.

【0099】

Example 5 In Example 5, Ar and N were used using a sputtering target prepared by mixing silicon, nickel, and tantalum in a molar ratio of about 7: 1: 1.₂A translucent film (halftone phase shifter film) was formed on the quartz substrate by DC sputter film formation using a gas mixed with and at a flow rate ratio of about 1: 4 as a sputter gas. The conditions for introducing the sputter gas were set so that the total amount of the mixed gas introduced was 30 SCCM and the pressure inside the device during sputtering was 3 m Torr with the pressure regulator directly above the exhaust pump.

【0100】

When the film thickness of the halftone phase shifter film thus formed on the quartz substrate was measured by the stylus method and the transmittance was measured using a spectrophotometer, the film thickness was 750 ongstrom and at 193 nm. The spectral transmittance was 4.1%. Similarly, when the refractive index (n) was calculated from the reflectance, transmittance, and film thickness of the film measured using a spectrophotometer, the value of the refractive index (n) was 2.29, and the film thickness was 750 ounces. It was confirmed that it was sufficient to shift the phase of light with a wavelength of 193 nm by 180 ° in the strom. Furthermore, the spectral transmittance at the inspection light wavelength (364 nm) was measured in the same manner and found to be 36.1%.

【0101】

For the prepared halftone phase shifter film, the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] was 0.16 (16%).

【0102】

The chemical durability of the prepared halftone phase shifter film was evaluated by changes in film quality and optical properties before and after immersion in acid, as in Example 1. As a result, the phase shift angle shifts before and after immersion in hot concentrated sulfuric acid and hydrogen peroxide sulfuric acid are both 1.5 ° or less, and the change in transmittance is 0.2% or less, and they have sufficient chemical resistance. It was confirmed.

【0103】

Regarding the light irradiation resistance of the prepared halftone phase shifter film, it has an oscillation wavelength of 193 nm as in Example 1, and the irradiation energy density per single pulse is 1 mJ / cm.²10 ArF excimer lasers⁷Changes in transmittance, refractive index, and film thickness were measured before and after pulse irradiation, but no significant difference was observed in the measured values, and the characteristics of the halftone phase shifter film were very stable.

【0104】

The prepared halftone phase shifter film was etched by reactive ion etching in the same manner as in Example 1. At this time, a gas obtained by mixing chlorine and oxygen at a flow rate ratio of 10: 1 was used as the etching gas. As a result, it was confirmed that good etching can be performed while having an etching selectivity of about 8.0 times that of the quartz substrate. Moreover, since the film structure is amorphous, the side walls of the etching pattern are also smooth.

【0105】

As shown in Example 5 above, by adopting a quaternary system, the control range of the refractive index is widened, and it is possible to easily produce a thin film having good film quality as a halftone phase shifter film and optical characteristics. It was.

【0106】

For comparison, the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] is less than 0.1 and more than 0.6, the same as above. When it was less than 0.1, the spectral transmittance at the inspection light wavelength exceeded 40%, and when it was more than 0.6, the spectral transmittance at the exposure wavelength was less than 3%.

【0107】

Example 6 In Example 6, Ar and N were used using a sputter target prepared by mixing silicon, silicon oxide, nickel, and tantalum in a molar ratio of about 5: 2: 2: 1.₂A translucent film (halftone phase shifter film) was formed on the quartz substrate by direct current sputter film formation using a gas mixed with and at a flow rate ratio of about 4: 6. The conditions for introducing the sputter gas were set so that the total amount of the mixed gas introduced was 30 SCCM and the pressure inside the device during sputtering was 3 m Torr with the pressure regulator directly above the exhaust pump.

【0108】

When the film thickness of the halftone phase shifter film thus produced on the quartz substrate was measured by the stylus method and the transmittance was measured using a spectrophotometer, the film thickness was 910 ongstrom and at 193 nm. The spectral transmittance was 7.3% (Fig. 4). Similarly, when the refractive index (n) was calculated from the reflectance, transmittance, and film thickness of the film measured using a spectrophotometer, the value of the refractive index (n) was 2.07, and the film thickness was 910 ounces. It was confirmed that it was sufficient to shift the phase of light having a wavelength of 193 nm by 180 ° in the strom. Furthermore, the spectral transmittance at the inspection light wavelength (364 nm) was measured in the same manner and found to be 38.3%.

【0109】

For the prepared halftone phase shifter film, the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] was 0.28 (28%).

【0110】

The chemical durability of the prepared halftone phase shifter film was evaluated by changes in film quality and optical properties before and after immersion in acid, as in Example 1. As a result, the phase shift angle shift before and after immersion in hot concentrated sulfuric acid and hydrogen peroxide sulfuric acid is 1 ° or less, and the change in transmittance is 0.2% or less, and it has sufficient chemical resistance. It was confirmed.

【0111】

Regarding the light irradiation resistance of the prepared halftone phase shifter film, it has an oscillation wavelength of 193 nm as in Example 1, and the irradiation energy density per single pulse is 1 mJ / cm.²10 ArF excimer lasers⁷Changes in transmittance, refractive index, and film thickness were measured before and after pulse irradiation, but no significant difference was observed in the measured values, and the characteristics of the halftone phase shifter film were very stable.

【0112】

The prepared halftone phase shifter film was etched by reactive ion etching in the same manner as in Example 1. At this time, a gas obtained by mixing chlorine and oxygen at a flow rate ratio of 5: 1 was used as the etching gas. As a result, it was confirmed that good etching can be performed while having an etching selectivity of about 8.5 times that of the quartz substrate. Moreover, since the film structure is amorphous, the side wall of the etching pattern is also smooth.

【0113】

As shown in Example 6 above, particularly excellent chemical resistance can be obtained by using a quintuple system, and it is possible to easily produce a thin film having good film quality as a halftone phase shifter film and optical characteristics. there were.

【0114】

Example 7 In Example 7, Ar and N were used using a sputter target prepared by mixing silicon, silicon oxide, nickel, and tantalum in a molar ratio of about 5: 2: 2: 1.₂And H₂A translucent film (halftone phase shifter film) was formed on the quartz substrate by direct current sputter film formation using a gas mixed with and at a flow rate ratio of about 3: 6: 1. The conditions for introducing the sputter gas were set so that the total amount of the mixed gas introduced was 30 SCCM and the pressure inside the device during sputtering was 3 m Torr with the pressure regulator directly above the exhaust pump.

【0115】

When the film thickness of the halftone phase shifter film thus produced on the quartz substrate was measured by the stylus method and the transmittance was measured using a spectrophotometer, the film thickness was 1040 ongstrom and at 193 nm. The spectral transmittance was 10.5%. Similarly, when the refractive index (n) was calculated from the reflectance, transmittance, and film thickness of the film measured using a spectrophotometer, the value of the refractive index (n) was 1.93, and the film thickness was 1040 ounces. It was confirmed that it was sufficient to shift the phase of light with a wavelength of 193 nm by 180 ° in the strom. Furthermore, the spectral transmittance at the inspection light wavelength (364 nm) was measured in the same manner and found to be 39.3%.

【0116】

For the prepared halftone phase shifter film, the ratio of [Atom% of nickel in the film] to [Atom% of nickel in the film + Atom% of silicon in the film] was 0.28 (28%).

【0117】

The chemical durability of the prepared halftone phase shifter film was evaluated by changes in film quality and optical properties before and after immersion in acid, as in Example 1. As a result, the phase shift angle shifts before and after immersion in hot concentrated sulfuric acid and hydrogen peroxide sulfuric acid are both 1 ° or less, and the change in transmittance is 0.4% or less, and they have sufficient chemical resistance. It was confirmed.

【0118】

Regarding the light irradiation resistance of the prepared halftone phase shifter film, it has an oscillation wavelength of 193 nm as in Example 1, and the irradiation energy density per single pulse is 1 mJ / cm.²10 ArF excimer lasers⁷Changes in transmittance, refractive index, and film thickness were measured before and after pulse irradiation, but no significant difference was observed in the measured values, and the characteristics of the halftone phase shifter film were very stable.

【0119】

The prepared halftone phase shifter film was etched by reactive ion etching in the same manner as in Example 1. At this time, a gas obtained by mixing chlorine and oxygen at a flow rate ratio of 9: 2 was used as the etching gas. As a result, it was confirmed that good etching can be performed while having an etching selectivity of about 10 times that of the quartz substrate. Moreover, since the film structure is amorphous, the side wall of the etching pattern is also smooth.

【0120】

As shown in Example 7 above, by adopting a hexagonal system containing hydrogen, the transmittance at the exposure wavelength is further improved, and a thin film having good film quality as a halftone phase shifter film and optical characteristics can be produced. It was easily possible.

【0121】

Example 8 Cobalt, tungsten, molybdenum, chromium, vanadium, palladium, titanium, niobium, zinc, zirconium, hafnium, germanium, aluminum, platinum, manganese, and iron were used instead of tantalum, except that the target composition and gas composition were adjusted as appropriate. Was evaluated in the same manner as in Examples 5 to 7. As a result, it was confirmed that it is possible to easily produce a thin film having good film quality and optical characteristics as a halftone phase shifter film as in Examples 5 to 7.

【0122】

Although the present invention has been described above with reference to examples, the examples shown above are examples that embody the present invention, and the present invention is not limited by the conditions and the contents of the embodiment.

【0123】

For example, in the examples, in order to carry out DC sputtering, it is a necessary condition that the sputter target has a certain degree of conductivity, but the material constituting the target is a semi-insulator or a non-conductor (non-conductor). When direct current discharge is difficult as in the above, a small amount of a material that imparts conductivity to the target, such as boron, is used within a range that does not interfere with the characteristics of the finally formed film as a halftone phase shifter. It may be added. On the contrary, when the target material has excellent conductivity, an insulator or a semiconductor material may be added to the target as long as the discharge and the film characteristics are not impaired. As for the discharge method, in addition to the DC discharge method, it is practically possible to use a high frequency discharge method in which plasma discharge is not easily affected by the conductivity of the target, or an AC discharge method. However, in any case, it is important to reduce defects in the film as much as possible in producing the desired film.

【0124】

Further, the gas used for sputtering is not limited to the substance and the mixing ratio shown in the examples, and for example, Xe gas or He gas is used instead of Ar.₂NH instead of₃, N₂O, NO₂, NO and other nitrogen-containing gases, or gases containing these components can be appropriately selected and mixed for use.

【0125】

Further, the etching of the phase shifter film is not limited to the method shown in the examples, and the etching method, the etching gas, detailed etching conditions, and the like can be optimally selected and set.

【0126】

Further, as the transparent substrate, fluorite or other various glass substrates (for example, fluoric acid-based glass, fluoric acid-based glass, etc.) may be used instead of the quartz substrate.

【0127】

[Effect of the invention]

As described above, according to the present invention, it is possible to satisfy all the required characteristics of the halftone type phase shift mask and the phase shift mask blank as the material thereof. That is, the translucent film (halftone phase shifter film) in the present invention has a desired transmittance and refractive index for an exposure wavelength such as 248 nm or 193 nm. Therefore, it is basically possible to shorten the wavelength of the exposure light. Further, the translucent film in the present invention has a desired transmittance with respect to the inspection light wavelength. Therefore, it is possible to manufacture a mask suitable for practical use capable of performing a highly reliable inspection. Further, the translucent film in the present invention is stable to high-energy short-wavelength light, has sufficient resistance to chemicals used in the mask manufacturing process, and has few defects in the film. Excellent in fine workability. Therefore, it is possible to easily provide an excellent phase shift mask corresponding to a shorter wavelength of the exposure light under high mass productivity.

[Simple explanation of drawings]

[Figure 1]

It is a schematic cross-sectional view which shows the halftone type phase shift mask blank.

[Figure 2]

It is a schematic cross-sectional view which shows the halftone type phase shift mask.

[Fig. 3]

It is a figure which shows the spectral transmittance in the ultraviolet to visible light region of the translucent film in Example 1. FIG.

[Fig. 4]

It is a figure which shows the spectral transmittance in the ultraviolet to visible light region of the translucent film in Example 6.

[Explanation of symbols]

1 Transparent substrate 2 Translucent film (halftone phase shifter film) 3 Phase shifter 4 Non-patterned part