Lithographic method

Lithography method

The invention relates to a lithography method.

A lithography device is a machine that applies a desired pattern on a substrate, generally on a target portion of the substrate. The lithography device can be used, for example, to manufacture integrated circuits (ICs). In this example, a patterning device, also called a photomask or a main photomask, is used to produce a circuit pattern that will be formed on a different layer of the IC. This pattern can be transferred to a target part (for example, a part including one or more dies) on a substrate (for example, a silicon wafer). Pattern transfer is generally via a layer of photosensitive material (resist) placed on the substrate via imaging. Roughly, a single substrate will contain a network of adjacent target portions that are continuously patterned. The conventional lithography device includes a so-called stepper, in which each target part is illuminated by exposing an entire pattern on the target part at a time, and a so-called scanner, in which a known direction (scanning direction) is borrowed The scanning pattern irradiates each target part through the radiation beam, and simultaneously scans the substrate in parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by printing the pattern on the substrate.

It has been proposed to immerse the substrate in the lithographic projection device in a liquid with a higher refractive index, such as water, to fill the space between the final element of the projection system and the substrate. The purpose is to image smaller features because the exposure radiation will have a shorter wavelength in the liquid. (The liquid effect can also be viewed as increasing the effective numerical aperture (NA) of the system and also increasing the depth of focus). Other immersion liquids are also proposed, including water with solid particles (such as quartz) suspended in it.

However, immersing the substrate or the substrate and the substrate stage in a solution bath (for example, refer to US Patent No. 4,509,852, the content of which is incorporated herein by reference) means that a large amount of liquid must be accelerated during scanning exposure. This requires additional or higher power motors, and turbulence in the liquid can cause undesirable and unpredictable effects.

A solution for a liquid supply system has been proposed to provide liquid only on a partial area of the substrate, and to provide liquid between the last element of the projection system and the substrate (the substrate roughly has a larger surface area than the last element of the projection system). A way to configure this has been proposed as disclosed in PCT Patent Application No. WO 99/49504, the content of which is incorporated herein by reference. As shown in Figures 2 and 3, the liquid is supplied on the substrate through at least one inlet (IN), preferably along the moving direction of the substrate relative to the final element, and after passing under the projection system by at least one Exit (OUT) and remove. That is, when the substrate is scanned under the element in the -X direction, the liquid is supplied on the +X side of the element and received on the -X side. Figure 2 schematically shows this configuration, in which liquid is supplied via an inlet (IN) and received on the other side of the element via an outlet (OUT), which is connected to a low-pressure source. In the illustration of FIG. 2, the liquid is supplied along the direction of movement of the substrate relative to the last element, although this need not be the case. The number of inlets and outlets and the orientation of the positions around the last element can be changed in various ways. An example of various directions is shown in Fig. 3, in which there are four sets of inlets, which have an outlet on either side and are arranged around the last element in a normal pattern.

All lithography devices need at least some calibration before use, and generally, the higher the resolution of the device, the more calibration steps will be required to obtain the best possible performance of the device. An important performance measurement of a lithography device is its coverage performance, which measures the device's ability to image a pattern on a substrate at a desired position relative to an existing pattern on the substrate. Coverage errors are due to various factors, such as systematic errors in the interferometer position or displacement measurement system. In order to calibrate the coverage performance of the lithography device, a series of test structures are generally printed across an entire substrate, and the positions of the test structures are measured. For example, the test structure is an alignment mark so that the alignment tool provided in the device can be used to measure its position, or the test structure is a covering sensitive structure, such as a frame mark, so that the coverage error can be directly measured using a conventional offline tool. The result is a coverage error map across the area of the substrate, which can be used to calibrate the device, such as using it as an offset when positioning the substrate during production exposure.

In a lithography device (used for immersion or not for immersion), the temperature of all components and fluids in contact with the substrate are strictly controlled to be equal and stable. However, the inventor understands that in an immersion lithography device, that is, a lithography device in which at least a part of the space between the final element of the projection system and the substrate is filled with a high refractive index liquid, some coverage errors are caused by the substrate cooling effect , It is about the vaporization of high refractive index liquid on the substrate. These coverage errors depend not only on the location but also on the history of the test exposure sequence. Therefore, if the device is calibrated using the coverage error measured by the conventional method, the coverage error cannot be removed and it will actually be worse.

Therefore, it would be advantageous, for example, to provide an improved method of calibrating a lithography device.

According to a feature of the present invention, a lithography method is provided, which includes:-using a first lithography projection device including a first projection system to print a first set of test structures on a first substrate, the first substrate being Proceed relative to a first route of the first projection system to realize the printing of the first set of test structures;-print a second set of test structures with a second lithographic projection device including a second projection system On the second substrate, the second substrate advances in a second route relative to the second projection system to realize the printing of the second set of test structures, the second route is different from the first route;-measuring the first route One of the first set of position data in a set of test structures;-measure a second set of position data in the second set of test structures;-calculate a third set of position error data from the first and second sets of position data; And-use the third set of position error data to calibrate one or more lithographic projection devices.

According to a feature of the present invention, a lithography method is provided, which includes: printing a first set of test structures on a first substrate with a first lithography projection device including a first projection system, and the first substrate is opposed to Go on a first route of the first projection system to realize the printing of the first set of test structures; use the first lithographic projection device to print a second set of test structures on a second substrate, the second substrate Take a second route relative to the first projection system to achieve the printing of the second set of test structures, the second route is different from the first route; measure one of the first set of test structures in the first set Coverage data; measure one of the second set of coverage data in the second set of test structures; calculate a third set of position error data from the first and second sets of coverage data; and use the third set of position error data to calibrate the The first lithography projection device.

According to a feature of the present invention, a lithography method is provided, which includes:-printing a first set of test structures on a first substrate with a first lithography projection device according to a first test exposure sequence, the first substrate having a first value for a heat transfer characteristics of, and a second value for a characteristic of heat dissipation; - in a second test in accordance with a second micro-lithographic projection exposure apparatus of sequentially printing a second set of test results configuration On a second substrate, the second substrate has a third value for a heat conduction characteristic, and a fourth value for a heat dissipation characteristic, wherein the second test exposure sequence, the third value, and At least one of the fourth value is different from at least one of the first test exposure sequence, the first value, and the second value;-measuring a first set of position data in the first set of test structures; -Measure a second set of position data in the second set of test structures; calculate a third set of position error data from the first and second sets of position data; and-use the third set of position error data to calibrate one or Multiple lithography projection devices.

Fig. 1 schematically shows a lithography device used in an embodiment of the present invention. The device includes:-an illumination system (illuminator) IL, which is configured to adjust a radiation beam PB (such as UV radiation or DUV radiation);-a support structure (such as a mask stage) MT, which is constructed to support a patterning A device (such as a photomask) MA is connected to a first positioner PM, which is configured to correctly position the patterning device according to certain parameters;-a substrate table (such as a wafer table) WT, which constitutes a support A substrate (such as a resist coated wafer) W, and connected to a second positioner PW, which is configured to correctly position the substrate according to certain parameters; and-a projection system (such as a refractive projection lens system) ) PL, which is configured to project a pattern onto the radiation beam PB on the target portion C (for example, including one or more dies) of the substrate W by the patterning device MA.

The lighting system includes various types of optical components, such as refraction, reflection, magnetic, electromagnetic, electrostatic, or other types of optical components, or combinations thereof, to guide, shape, or control radiation.

The support structure supports, that is, supports the weight of the patterning device. The way it supports the patterning device depends on the direction of the patterning device, the design of the lithography device, and other conditions, such as whether the patterning device is supported in a vacuum environment. The support structure can use mechanical, vacuum, electrostatic, or other clamping techniques to support the patterning device. The supporting structure is, for example, a frame or a table, which can be fixed or movable as required. The support structure ensures that the patterning device is in a desired position, for example relative to the projection system. Any use of the term "primary mask" or "mask" should be regarded as synonymous with the more general term "patterned device".

The term "patterned device" as used herein should be interpreted broadly to mean any device that can be used to transmit a radiation beam in a pattern in its cross-section so as to produce a pattern in the target portion of the substrate. It should be noted that the pattern transmitted to the radiation beam does not necessarily correspond exactly to the desired pattern of the target portion of the substrate, for example if the pattern includes phase shift features or so-called assist features. Roughly, the pattern transmitted to the radiation beam will correspond to a special functional layer in the device generated in the target part, such as an integrated circuit.

The patterning device can be transmissive or reflective. Examples of patterning devices include photomasks, programmable mirror arrays, and programmable LCD panels. Photomasks are well-known in lithography and include some types of photomasks such as binary, alternating phase shift, and attenuated phase shift, as well as various hybrid photomask types. A programmable mirror array uses a matrix configuration of multiple small mirrors, and each mirror can be individually tilted to reflect incoming radiation beams in different directions. The tilted mirror conveys a pattern in a radiation beam, which is reflected by the mirror matrix.

The term "projection system" used here should be broadly interpreted as including any type of projection system, including refraction, reflection, both reflection and refraction, magnetic, electromagnetic and electrostatic optical systems, or combinations thereof, depending on It depends on the exposure radiation that is suitable for use, or due to other factors such as the use of immersion liquid or the use of vacuum. Any use of the term "projection lens" here should be regarded as synonymous with the more general term "projection system".

As shown in this drawing, the device is a transmissive type (for example, a transmissive mask is used). Alternatively, the device is reflective (such as using a programmable mirror array as described above, or using a reflective mask).

The lithography device may be a type with two (dual stage) or more substrate stages (and/or 2 or more mask stages). In this "multi-stage machine", additional stages can be used in parallel, or multiple preparatory steps can be performed on one or more stages, while one or more other stages are used for exposure.

Referring to FIG. 1, the illuminator IL receives a radiation beam from a radiation source SO. The source and the lithography device are separate entities, for example when the source is an excitation laser. In these examples, the source is not considered to form part of the lithography device, and with the help of the beam delivery system BD (which includes, for example, suitable guide mirrors and/or a beam expander), the radiation beam From this source SO is passed to the luminaire IL. In other examples, the source is an essential part of the lithography device, for example when the source is a mercury lamp. The source SO and the illuminator IL, if necessary, are collectively referred to as a radiation system together with the beam delivery system BD.

The illuminator IL includes an adjuster AD for adjusting the angular intensity distribution of the radiation beam. Roughly speaking, at least the outer and/or inner radial extent of the intensity distribution in the pupil plane of the illuminator (commonly referred to as σ outer and σ inner respectively) can be adjusted. In addition, the illuminator IL includes various other components, such as an integrator IN and a condenser CO. The illuminator is used to adjust the radiation beam to have a desired uniformity and intensity distribution in its cross-section.

The radiation beam PB is incident on a patterning device (such as a mask MA), which is supported on a supporting structure (such as a mask table MT), and is patterned by the patterning device. Having passed the mask MA, the radiation beam PB passes through the projection system PL, which focuses the beam on the target portion C of the substrate W. An immersion cover IH, as described in detail below, supplies immersion liquid to the space between the last element of the projection system PL and the substrate W.

With the help of the second positioner PW and position sensor IF (such as interferometer device, linear encoder or capacitive sensor), the substrate table WT can be moved correctly, such as positioning different target parts C in the path of the radiation beam PB middle. Similarly, after mechanically capturing from the mask library or during scanning, the first positioner PM and another position sensor (not shown in FIG. 1) can be used to align the light with respect to the path of the radiation beam PB. The cover MA is positioned correctly. Generally, with the help of the long-stroke module (coarse positioning) and the short-stroke module (fine positioning) forming a part of the first positioner PM, the movement of the mask table MT can be achieved. Similarly, the movement of the substrate table WT can be achieved by using the long-stroke module and the short-stroke module that form a part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the mask stage MT can be connected to a short-stroke actuator only, or fixed. Mask alignment marks M1, M2 and substrate alignment marks P1, P2 can be used to align the mask MA and the substrate W. Although the substrate alignment mark in the figure occupies a dedicated target portion, it can also be located in the space between multiple target portions (these marks are called cut lane alignment marks). Similarly, in some cases where more than one die is provided on the photomask MA, the photomask alignment marks may be located between the die.

The device shown can be used in at least one of the following modes: 1. In the stepping mode, the mask table MT and the substrate table WT remain substantially fixed, while the entire pattern of the radiation beam is transmitted at a time (ie, a single static exposure) Project on a target part C. Then, the substrate table WT is displaced in the X and/or Y directions to expose different target portions C. In step mode, the maximum size of the exposure field is limited to the size of the target portion C imaged in a single static exposure.

2. In the scanning mode, the reticle stage MT and the substrate stage WT are scanned simultaneously, and the pattern transmitted to the radiation beam is projected on a target portion C (ie, a single dynamic exposure). The speed and direction of the substrate table WT relative to the mask table MT are determined by the (de)magnification and image reversal characteristics of the projection system PL. In scanning mode, the maximum size of the exposure field limits the width of the target portion (in the non-scanning direction) in a single dynamic exposure, but the length of the scanning motion determines the height of the target portion (in the scanning direction).

3. In another mode, the photomask table MT basically maintains a programmable patterning device fixedly and moves or scans the substrate table WT, while the pattern transmitted to the radiation beam is projected on a target portion C. In this mode, a pulse radiation source is generally used, and the programmable patterning device is updated as needed between successive radiation pulses after each movement of the substrate table WT or during scanning. This mode of operation can be applied to maskless lithography, which utilizes a programmable patterning device, such as the type of programmable mirror array described above.

Combinations and/or variations of the above modes can also be used, or completely different usage modes can be used.

Another immersion lithography solution with a regional liquid supply system is shown in Figure 4. The liquid is supplied by two groove-shaped inlets IN on both sides of the projection system PL, and is discharged by a plurality of separate outlets OUT arranged radially outside the inlet IN. The inlet IN and the outlet OUT can be arranged in a plate with a central hole, and the projection beam is projected through the hole. The liquid is supplied by a groove-shaped inlet IN on one side of the projection system PL and discharged by a plurality of separate outlets OUT on the other side of the projection system PL, so that a thin film flow can be generated between the projection system PL and the substrate W. Which combination of inlet IN and outlet OUT is selected for use may depend on the moving direction of the substrate W (the other combination of inlet IN and outlet OUT is invalid).

Another immersion lithography solution has been proposed, which has an area liquid supply system with the purpose of providing a closed element of the liquid supply system that extends along at least a part of the boundary of the space between the last element of the projection system and the substrate table. This solution is shown in Figure 5. The projection system of the closing element relative to the XY plane is essentially fixed, although there is a certain relative movement in the Z direction (in the direction of the optical axis). A closure is formed between the closure element and the surface of the substrate.

Referring to FIG. 5, the solution reservoir 10 forms a non-contact closure of the substrate around the image field of the projection system to limit the liquid filling the space between the surface of the substrate and the final element of the projection system. The solution reservoir is formed by the closing element 12 located at the bottom of the projection system PL and around it. The liquid is introduced below the projection system and in the closing element 12. The closing element 12 extends slightly above the last element of the projection system, and the liquid level rises above the last element to provide liquid cushioning. The closing element 12 has an inner ring, which in one embodiment is at the upper end, closely conforms to the shape of the projection system or its final element, and may be round. At the bottom, the inner ring closely conforms to the shape of the image field, such as a rectangle, although this need not be the case.

The liquid is confined in the solution reservoir by the airtight 16 between the bottom of the closing element 12 and the surface of the substrate W. Airtightness is formed by gas such as air or synthetic air, but in one embodiment, high-pressure nitrogen (N₂) Or another inert gas is provided to the gap between the closing element 12 and the substrate through the inlet 15 and is released through the first outlet 14. The overpressure of the gas inlet 15, the vacuum level of the first outlet 14, and the geometry of the gap are appropriately arranged so that the high-speed gas flows inward to restrict the liquid. This system is disclosed in US Patent Application No. 10/705,783, the content of which is incorporated herein by reference.

The inventor understands that some coverage errors of the immersion lithography projection device are caused by thermal effects, especially the cooling of the substrate, which is caused by the evaporation of the remaining immersion liquid, such as water, remaining on the target part after exposure to the immersion liquid. The present invention understands that these errors are not only dependent on location, like some other system coverage errors in lithography devices, but also dependent on the exposure history of the substrate, that is, the route (path and direction) and speed during the previous exposure.

In addition, the inventor understands that these errors also depend on the materials used during substrate processing. Those skilled in the art will understand that the pattern is a resist layer written on the substrate. The thermal conductivity depends on the resist layer used. Those skilled in the art will understand that these resist layers are applied in many processes with a top coat. The evaporation of the immersion liquid (such as water) depends on the top coat used. Therefore, the calibration of the lithography device can be regarded as the calibration of the lithography device for a lithography process, or the calibration of the lithography device for a specific process layer.

The dependence of the coverage error in the exposure history of the substrate can be confirmed by Figures 6 and 7, which show experimental data obtained from finite element analysis and simulation of thermal effects. In particular, FIG. 6 shows the coverage error data caused by the thermal effect caused by the substrate cooling, which is caused by the substrate channel under the liquid supply system, especially because the remaining immersion liquid such as water evaporates from the substrate after printing a target portion. The results of the simulation of a normal bending scan of this data are shown in Figure 8, starting from the bottom left side of the wafer. A set of similar data obtained to simulate a reverse bending scan is shown in Figure 9, starting from the top right side of the wafer and then following the same route in the reverse direction. Figure 7 shows the results of subtracting these two sets of data, from which significant changes can be seen to allow the identification and thus correction of wafer cooling-related coverage errors respectively.

The following conclusions can be drawn from Fig. 7: by obtaining coverage error data from scanning when executed in the opposite direction, the coverage error caused by the thermal effect and the dependence of the exposure history can be identified, and thus it can be separated from other systems and random errors. The calibration of the device can then be performed using only systematic errors, thereby increasing accuracy.

Those familiar with the art will understand that in addition to simulation data, measurement data can also be used to explain the present invention. It will also be understood that the reverse bending scan can also be easily performed under normal conditions. The programming of the curved scan in the lithography device is the same as the reverse curved scan.

The flowchart of the method according to the present invention is shown in FIG. 10. Expose (S1) the first substrate with the first set of test structures during the first test exposure sequence, and at the same time proceed along the first route and profile according to the first speed. The test structure is a coverage sensitive mark (coverage mark). The measurement (S2) test structure (in other words, measurement coverage) to obtain the first set of position data (in this case, position error data). Then use the second route which is equal to the first route but advances in reverse (in other words a different speed profile), and expose (S3) the second set of test structures during the second test exposure sequence, preferably the same as the first set, to On the same substrate. Then measure (S4) the second set of structures to obtain the second set of error data.

In a particular embodiment, the first test structure is printed in a predetermined order, and the first row (bottom) is printed, such as printing subsequent rows from left to right and alternating directions to form a so-called curved pattern.

In the scanner, it is a lithography device in which each target part is printed, while scanning the substrate and pattern relative to the projection lens, scanning the continuous target part in the opposite direction, because it needs to scan at full speed at the beginning of each scan, and It is necessary to stop between the target parts and reverse the mask (if used). Therefore, additional back and forth movement of the substrate is applied on the curved path. For clarity, this movement has been omitted in Figures 8 and 9.

As for the target parts of the exposure of the second group of test structures, the same scanning direction can be used for the corresponding target parts of the first group of test structures. This ensures the same cooling effect of the inner target part to facilitate the isolation of the overall (entire substrate) cooling effect. Alternatively, the scanning direction between the first and second test structures can be reversed for each target part, which can be the reverse of the entire curve or not. Various combinations of the exposure sequence and scanning direction are changed to perform multiple sets of measurements, which can achieve isolation and thus compensate for the various forms of area and overall cooling effect.

The route used for the second set of test structures is reversed, which means it follows the same path but in the opposite direction (the time is reversed, in other words the route is the same but the speed profile is different), it is a mirror image of the first route in the vertical plane of the substrate, or It rotates around the central axis through the substrate, or a combination of these. In these examples, it is preferable that the advancing speed of the second route is the same as that of the first route.

Those who are familiar with this art will know that the first route and the second route can be made exactly the same and proceed in the same direction, but at different speeds. That is, the speed of the route will be regarded as the speed profile. For example, the speed profile corresponding to the second route is half of the speed profile corresponding to the first route. Or, the substrate is suspended in several situations during the second route. For example, this can be applied when it is desired to conduct heat energy along the surface of the substrate through the substrate layer. The heat conduction through the resist layer affects the temperature of part of the substrate. This can be explained by the middle target part, the adjacent target part to the left of the middle target part, and the adjacent target part to the right of the middle target part. The positions of all three target parts are known. Then cool the rightmost part of the target because the liquid evaporates on its surface. Heat conduction also cools the intermediate target part. By cooling, the middle target part is reduced. This means that the position of the leftmost target part changes from its known position, which will cause coverage errors when illuminating the left target part.

The greater the distance between the first target portion and the second target portion on the substrate, the longer it takes for the heat energy of the first target portion to transfer to the second target portion. At its top, the effect at larger distances is less, because the thermal energy will be conducted through a larger part of the substrate, and thus will diffuse to a larger part of the substrate.

The exposure and measurement of the first and second groups of test structures can occur in either sequence, and if measurement is performed with independent tools or at a measurement station of a two-stage device, the measurement and exposure can be performed in parallel. The first and second test structures can be exposed and measured multiple times on the same or different substrates, and the average result is the effect of reducing random errors.

Then process the first and second error data S5 to obtain the third set of error data, which can be used in calibration S6 of the device before performing production exposure S7. The processing of the first and second data sets to obtain the third data set can be a simple subtraction of the two data sets or a more complex calculation depending on the exact form of the desired thermal coverage error.

In another embodiment of the present invention, the thermal conductivity of the first substrate during the first test exposure sequence is different from the thermal conductivity of the second substrate during the second test exposure sequence. By changing the process parameter values of the process, it is applied to the two resist layers, that is, the resist layer different from the first substrate can be supplied to the second substrate. The parameters that generally change are the thickness of the resist layer and the conductivity of the resist layer material. The resist layers are applied to the first and second substrates by a coating process called spin coating. The process parameters of this process are, for example, the material used, the viscosity of the resist material, the rotation speed of the substrate, the coating temperature during application, and the curing time.

In an embodiment of the present invention, a lithography device is used to print the first set of test structures on the first substrate during the first test exposure sequence. During the second test exposure sequence, a lithography device is used to print a second set of test structures on the second substrate. The second test exposure sequence is equal to the first test exposure sequence, that is, the route, speed profile, and heat in the two test exposure sequences. The load profiles are all equal. However, the heat dissipation characteristics of the first substrate are different from the heat dissipation characteristics of the second substrate. This can be achieved by applying different top coats. The top coat is a coating on the substrate through which radiation passes to reach the resist layer, which is the photoactive layer. The top coat is applied by the coating process. The process parameters of this process are, for example, the material used, the viscosity of the top coating material, the coating temperature during application, and the curing time. The heat dissipation characteristics of the top coating (and the substrate) can be changed by changing one or more process parameters.

In an embodiment of the present invention, a lithography device is used to print the first set of test structures on the first substrate during the first test exposure sequence. Follow the first route and the first velocity profile during the first test exposure sequence. During the second test exposure sequence, a lithography device is used to print a second set of test structures on the second substrate, and the first route and the first velocity profile are also followed during the second test exposure sequence. However, the temperature of the immersion liquid during the first route is higher than during the second route (for example, 0.1 to 0.01 degrees Celsius higher), in other words, follow a different thermal load profile. Therefore, the substrate is cooled less during the evaporation of the immersion liquid after the first test exposure sequence than during the evaporation of the immersion liquid after the second test exposure sequence. This is because less heat is required to evaporate a higher temperature liquid from the substrate than to evaporate a colder liquid. In other words, the thermal energy used during the evaporation of liquid from the substrate after the second test exposure sequence is greater. Measure and subtract the coverage errors after the first and second test exposure sequences. It also calculates the difference in thermal energy used after the first and second test exposure sequences. By dividing the subtracted coverage error by the thermal energy difference, the derivative of the coverage error with respect to the thermal energy can be calculated. By multiplying the estimated total thermal energy required to evaporate all the liquid from the substrate by the derivative, an estimate of the total coverage error can be obtained, which is caused by the evaporation of the liquid. Of course, other models of the relationship between overlay error and evaporation can be used, or more complex models can be used, including other thermal effects, such as heat conduction through the resist layer.

Those who are familiar with this technique will understand that the test structure is also an alignment mark. When printing the registration mark, it has the desired printing position. By subtracting the desired printing position (in other words, previous information) from a measurement position, a coverage error can be determined. Therefore, the position measurement of the alignment mark can be used to obtain the first set of error data, and in the same way, the second set of error data can be obtained. It will also be understood that a measured alignment mark position, which corresponds to the first expected printing position of a second set of test structures, is also directly subtracted from a measured alignment mark position, which corresponds to the first expected printing position of the first set of test structures Location. From this result, the coverage errors related to wafer cooling can be identified and corrected.

In European Patent Application No. 03257072.3, the concept of a double or two-stage immersion lithography device is disclosed. This device is equipped with two tables to support a substrate. When there is no immersion liquid, use one at the first position to perform level measurement, and when there is immersion liquid, use one at the second position to perform exposure. Or, when there is immersion liquid, one unit is used to perform level measurement at the first position, and when there is no immersion liquid, one unit is used to perform exposure at the second position. Or, the immersion lithography device has only one table. This method is also applied to non-immersion lithography devices.

Those who are familiar with this art will know that the printing of the first set of test structures (S1) can be performed on the first lithography projection device, the second set of test structures can be printed (S3) using the second lithography projection device, and the actual calibration (S6) Applied to the third lithography projection device or a series of projection devices. In this example, first calibrate the coverage difference between different lithography projection devices, and different lithography projection devices are preferably of the same brand or type.

Those familiar with the art will understand that different embodiments have different advantages. Use one and the same lithography projection device to print the first set of test structures and the second set of test structures instead of printing on two different lithography projection devices. The advantage is the difference between the machine and the machine, such as two lithography The difference in uncalibrated coverage between the projection devices is not important. The advantage of calibrating the lithographic projection devices actually used to print the first and second sets of test structures is that the difference between machines is not important. The advantage of using one and the same substrate for printing the first and second sets of test structures is that for multiple substrates, the area expansion characteristics of one substrate are equal. In these substrates, the area expansion characteristics are mainly determined by the substrate material. , Does not depend on the layer above it. This layer with the reference mark is the first layer below the second layer, in which the first set of test structures will be printed. After reading the position of the first group of test structures, the second group of test structures is printed on the third layer. Alternatively, remove the second layer before applying the third layer. When the performance of the lithography device changes (drifts) over time, the advantage is that two different substrates are used and the first and second sets of test structures are printed directly to each other. Accordingly, the time difference between the two sets of test structures is smaller than when one and the same substrate is used to print the first and second sets of test structures, so the influence of drift is minimized.

Although the lithography device for manufacturing IC has been used as a specific reference here, it should be understood that the lithography device described herein can have other applications, such as manufacturing integrated optical systems for guiding and detecting memory in the magnetic field. Patterns, flat panel displays, liquid crystal displays (LCD), thin film magnetic heads, etc. Those familiar with the art will understand that in the content of these alternative applications, any use of the noun "wafer" or "die" in this article is regarded as synonymous with the more general noun "substrate" or "target part", respectively. In, for example, a track (a tool that generally applies a resist layer to a substrate and develops the exposed resist), a metrology tool, and/or an inspection tool, the substrate referred to herein is processed before or after exposure . As long as applicable, the present invention can also be applied to these and other substrate processing tools. In addition, the substrate can be processed more than once, for example to produce a multilayer IC, so that the term substrate used herein can also refer to a substrate that already contains multiple processing layers.

The terms "radiation" and "beam" as used herein include all types of electromagnetic radiation, including ultraviolet (UV) radiation (such as those having or approximately having a wavelength of 365, 248, 193, 157, or 126 nm).

The term "lens", as long as it is applicable, can refer to a variety of different optical components, including any one or a combination of refractive and reflective optical components.

Although the characteristic embodiments of the present invention have been described, it will be understood that the present invention can be implemented in ways other than those described above. For example, as long as appropriate, the present invention can be implemented as a computer program that contains one or more strings of machine-readable instructions that describe the above-mentioned method, or a data storage medium (such as semiconductor memory, magnetic disk or CD) contains this computer program.

The present invention can be applied to any immersion lithography device, especially, but not limited to, the above-mentioned types. The immersion liquid used in the device has different compositions according to the desired characteristics and wavelength of the exposure radiation used. For the 193 nm exposure wavelength, the purest water or water-based components can be used, so the immersion liquid can be used. It is sometimes called water and water-related terms such as hydrophilicity, hydrophobia, humidity, etc. However, it will be understood that the embodiments of the present invention can be used for other types of liquids, and in this case a term related to water should be considered to be replaced with equivalent terms related to the immersion liquid used.

The foregoing description is intended to be illustrative and not restrictive. Therefore, those who are familiar with this technique will understand that various improvements can be made to the present invention without violating the scope of the attached patent application.

The present invention can be summarized in the following points: 1. A method of calibrating a lithography projection device, the device having a projection system, the method comprising: printing a first set of test structures on a substrate, the substrate being opposed to the A first route of the projection system advances to realize the printing of the first set of test structures; a second set of test structures is printed on a substrate, and the substrate advances in a second route relative to the projection system to realize the first set of test structures. For the printing of two sets of test structures, the second route is different from the first route; measure the position error in the first set of test structures to obtain a first set of position error data; measure the position in the second set of test structures Error to obtain a second set of position error data; calculate a third set of position error data from the first and second sets of position error data; and use the third set of position error data to calibrate the lithographic projection device.

2. The method as summarized in 1, wherein the first and second test structures are printed in a series of target parts, which are arranged in a plurality of rows on the substrate, and the target parts are printed in a preset order. The first test structures are printed, and the second test structures are printed by printing the target parts in one order, the order is opposite to the preset order.

3. The method as summarized in 2, wherein each target part is printed by scanning the substrate in a different scanning direction relative to the projection system, the direction of one target part is different from the direction of another target part, and for each target The same scanning direction is partially used to print the first and second test structures.

4. The method as summarized in 2, wherein each target portion is printed by scanning the substrate in a different scanning direction relative to the projection system, the direction of one target portion is different from the direction of another target portion, and for each target The opposite scanning direction is partially used to print the first and second test structures.

5. As summarized in 3, the method also includes printing a third set of test structures on each target part in one order, the order is opposite to the preset order, and using multiple individual scanning directions, which is the opposite of printing The scanning directions of the first and second sets of test structures.

6. The method as in summary 1, wherein the first route includes a curved path along which the first substrate advances in a first direction, and the second route includes the curved path along which the second substrate follows The path advances in a second direction opposite to the first direction.

7. The method as in summary 1, wherein the second route is substantially the same as a mirror image of the first route.

8. The method as in summary 1, wherein the second route is substantially the same as the 180 degree rotation of the first route.

9. The method as in summary 1, wherein calculating the third set of position error data includes obtaining a difference between the first set of position error data and the second set of position error data.

10. The method as summarized in 1, wherein the printing of the first and second sets of test structures and the measurement of the position error therein are repeated multiple times to obtain the first and second sets of position error data.

11. The method as in summary 1, wherein the first and second test structures are printed on the same substrate.

12. The method as in summary 1, wherein the first and second test structures are printed on different substrates.

13. The method as in summary 1, wherein the lithographic projection device is an immersion type.

14. The method as summarized in 1, wherein the first and second sets of position error data are multiple sets of coverage error data.

15. A method for manufacturing a device using a lithography projection, the lithography projection having a projection system, the method comprising: calibrating the lithography projection device by: printing a first set of test structures on a substrate, the substrate Advancing in a first route relative to the projection system to achieve the printing of the first set of test structures; printing a second set of test structures on a substrate, the substrate advancing in a second route relative to the projection system To realize the printing of the second set of test structures, the second route is different from the first route; measure the position error in the first set of test structures to obtain a first set of position error data; measure the second set of tests Position error in the structure to obtain a second set of position error data; calculate a third set of position error data from the first and second sets of position error data; use the third set of position error data to calibrate the lithographic projection device And using the lithography device to print device patterns on multiple substrates.

16. The method of summarizing 15, wherein the first and second test structures are printed in a series of target parts, which are arranged in a plurality of rows on the substrate, and the target parts are printed in a preset order. The first test structures are printed, and the second test structures are printed by printing the target parts in one order, the order is opposite to the preset order.

17. The method as summarized in 16, wherein each target part is printed by scanning the substrate in a different scanning direction relative to the projection system, the direction of one target part is different from the direction of another target part, and for each target The same scanning direction is partially used to print the first and second test structures.

18. The method as summarized in 16, wherein each target portion is printed by scanning the substrate in a different scanning direction relative to the projection system, the direction of one target portion is different from the direction of another target portion, and for each target The opposite scanning direction is partially used to print the first and second test structures.

19. As summarized in 17, the method also includes printing a third set of test structures on each target part in one order, the order is opposite to the preset order, and the use of multiple individual scanning directions, which is the opposite of printing The scanning directions of the first and second sets of test structures.

20. The method of summarizing 15, wherein calculating the third set of position error data includes obtaining a difference between the first set of position error data and the second set of position error data.

21. The method of summarizing 15, wherein the printing of the first and second sets of test structures and the measurement of the position error therein are repeated multiple times to obtain the first and second sets of position error data.

22. The method of summary 15, wherein the first and second test structures are printed on the same substrate.

23. The method of summary 15, wherein the first and second test structures are printed on different substrates.

24. The method as summarized in 15, wherein the lithographic projection device is an immersion type.

25. The method as summarized in 15, wherein the first and second sets of position error data are multiple sets of coverage error data.

<p>10. . . Solution library</p><p>12. . . Closure element</p><p>14. . . First exit</p><p>15. . . Gas inlet</p><p>16. . . airtight</p><p>AD. . . Adjuster</p><p>BD. . . Beam delivery system</p><p>C. . . Target part</p><p>CO. . . Condenser</p><p>IH. . . Immersion hood</p><p>IF. . . Position sensor</p><p>IL. . . Lighting system</p><p>IN. . . Integrator</p><p>M1, M2. . . Mask alignment mark</p><p>MA. . . Patterning device</p><p>MT. . . supporting structure</p><p>P1, P2. . . Substrate alignment mark</p><p>PB. . . Radiation beam</p><p>PM. . . First locator</p><p>PL. . . Projection system</p><p>PW. . . Second locator</p><p>SO. . . Radiation source</p><p>S1. . . Expose the first substrate with normal bending</p><p>S2. . . Measure the first substrate</p><p>S3. . . Expose the second substrate with reverse bending</p><p>S4. . . Measure the second substrate</p><p>S5. . . Process the first and second coverage data</p><p>S6. . . calibration</p><p>S7. . . Production exposure</p><p>W. . . Substrate</p><p>WT. . . Substrate table</p>

Figure 1 illustrates a lithography device that can be used in an embodiment of the present invention; Figures 2 and 3 illustrate a liquid supply system used in a lithography projection device; Figure 4 illustrates a lithography device used in a lithography projection device Another liquid supply system; Figure 5 shows another liquid supply system used in a lithographic projection device; Figure 6 shows a first set of coverage error data obtained by implementing an embodiment of the present invention; Figure 7 shows the implementation The third set of coverage error data obtained by an embodiment of the present invention; FIG. 8 shows a normal curved path; FIG. 9 shows a curved path proceeding in the opposite direction; and FIG. 10 is a flowchart of the method according to the present invention.