Method for Forming Metal Line in Dual Damascene Structure

Method for Forming Metal Line in Dual Damascene Structure

1 is a schematic cross-sectional view after deposition of a copper thin film inside a conventional contact area;

2A to 2D are cross-sectional views illustrating a method of forming a metal wiring having a dual multi-machine structure according to the present invention.

3 is a schematic cross-sectional view of a copper thin film after depositing a copper thin film inside a contact region by the copper thin film deposition method of the present invention;

Explanation of symbols for the main parts of the drawing

21 : substrate 22: contact etch prevention film

23 : first insulating layer 24: trench etch prevention layer

25 : second insulating film 26: diffusion barrier film

27 : first copper thin film 28: second copper thin film

29 : metal 30 : metal diffusion prevention film

<background-art><p>The present invention relates to a method for manufacturing a metal wiring, in particular, a monovalent copper (I) precursor and A method of forming a metal wiring having a dual damascene structure in which step coverage characteristics are improved by performing a chemical vapor deposition process cyclically using a divalent copper (II) precursor at the same time .</p><p>Hereinafter, a conventional method of forming a metal wiring will be described.</p><p>A contact etch stop layer, a first insulating layer, a trench etch stop layer, and a second insulating layer are sequentially deposited on the substrate.</p><p>A trench is formed by selectively removing the second insulating layer using the trench etch stop layer as an end point.</p><p>Next, a contact region is formed by selectively removing the first insulating layer using the contact etch stop layer as an end point.</p><p>An etch stop layer is deposited on the surface of the trench and in the contact region, and the metal is buried. </p><p>In this case, the metal burying method is performed by depositing a metal on the second insulating layer sufficiently enough to fill both the trench and the contact region, and planarizing the surface of the second insulating layer as an end point.</p></background-art><tech><p>However, the conventional method of forming a metal wiring as described above has the following problems.</p><p>1 is a schematic cross-sectional view after depositing a copper thin film in a conventional contact region.</p><p>As shown in FIG. 1 , the conventional deposition of a copper thin film in a contact region is a phenomenon that occurs when the contact region is buried with a copper wire. to complete the copper wiring process of </p><p>In this case, the deposition method is a chemical vapor deposition method, and deposition is performed using a single type of copper precursor. </p><p>In general, the copper precursor is largely divided into a monovalent copper (I) precursor and a divalent copper (II) precursor, and deposition conditions are different from each other. The monovalent copper (I) precursor can be deposited at a low temperature (70 to 200° C.) and the divalent copper (II) precursor can be deposited at a high temperature (150 to 400° C.).</p><p>However, the monovalent copper (I) precursor has a problem of poor thermal stability.</p><p>In addition, although the divalent copper (II) precursor is thermally stable, it contains a large amount of impurities in the thin film, so the specific resistance of the thin film is high and deposition is possible at high temperature, so the step coverage characteristic of the thin film is poor. Therefore, as the device is highly integrated, the conventional copper thin film deposition using a divalent copper (II) precursor is difficult to obtain excellent step coverage characteristics in deep and narrow contacts and contact regions, and there is a problem in improving the reliability of the device.</p><p>That is, when the monovalent copper precursor, the divalent copper precursor, and the two-type precursor are all formed in a single type, there is a problem in that a stable metal wiring cannot be formed.</p><p>The present invention has been devised to solve the above problems, and monovalent copper (I) A method of forming a metal wiring having a dual damascene structure in which step coverage characteristics are improved by performing a chemical vapor deposition process cyclically using a precursor and a divalent copper (II) precursor at the same time It is intended to provide.</p></tech>

<p>In order to achieve the above object, the method for forming a metal wiring having a dual multi-machine structure of the present invention comprises the steps of removing an interlayer insulating film deposited on a substrate in a dual multi-machine structure to form a contact region and a trench with a lower metal wiring and depositing a diffusion barrier film in the contact region and inside the trench; depositing a first copper thin film of a monovalent copper (I) precursor on the diffusion barrier film; and depositing a copper thin film, and filling the contact region and the trench with a metal using the first and second copper thin films as seed layers.</p><p>Hereinafter, a method of forming a metal wiring having a dual multi-machine structure according to the present invention will be described in detail with reference to the accompanying drawings.</p><p>2A to 2D are cross-sectional views illustrating a method of forming a metal wiring having a dual multi-machine structure according to the present invention.</p><p>As shown in FIG. 2A , an interlayer insulating film is deposited on a substrate and selectively removed to form contact regions and trenches having a dual multi-machine structure.</p><p>This is explained in detail as follows. </p><p>First, a contact etch stop layer 22 , a first insulating layer 23 , a trench etch stop layer 24 , and a second insulating layer 25 are sequentially deposited on the substrate 21 .</p><p>A trench is formed by selectively removing the second insulating layer 25 using the trench etch stop layer 24 as an end point.</p><p>Next, using the contact etch stop layer 22 as an end point, the first insulating layer 23 is selectively removed to form a contact region.</p><p>Next, a diffusion barrier layer 26 is deposited on the surface of the contact region and the trench. The diffusion barrier layer 26 is deposited to prevent diffusion of wirings filled in the contact region and trench into an interlayer insulating layer such as the first insulating layer 23 or the second insulating layer 25 .</p><p>As shown in FIG. 2B , each monovalent copper precursor is uniformly formed as a first copper thin film 27 at a low temperature on the diffusion barrier layer 26 , and then, using the first copper thin film 27 as a seed layer, 2 A second copper thin film 28 of a false copper precursor component is deposited.</p><p>The deposition of the first and second copper thin films 27 and 28 is carried out by continuously depositing the monovalent copper precursor and the divalent copper precursor in the same reactor and controlling the internal temperature through a heater, respectively, or It proceeds by separately connecting the corresponding reactor to the copper precursor and the divalent copper precursor and controlling it in the same way.</p><p>At this time, the reactor has a pressure of 0.01 to 100 Torr, and Ar, N of 1 to 5000 sccm₂, H₂ On the diffusion barrier film 26 under the condition of a transport gas atmosphere of 2 Copper thin films 27 and 28 are deposited.</p><p>In addition, the reactor deposits the first copper thin film 27 at a temperature of 70 to 200 °C, with a thickness of 50 to 500 Angstroms, and when depositing the second copper thin film 28 at a temperature of 150 to 300 °C. Deposited to a thickness of 50 to 5000 Å by a hydrogen reduction reaction.</p><p>The reactor should be maintained at a higher temperature when depositing the second copper thin film 28 than when depositing the first copper thin film 27 . When depositing each copper thin film 27 and 28 in a separate reactor, each reactor maintains the respective deposition temperatures described above (70 to 200°C for monovalent copper precursor, 150 to 400°C for divalent copper precursor). The deposition process proceeds.</p><p>A process in which the monovalent copper precursor is deposited as a first copper thin film is expressed by chemical formula as follows.</p><p>2(HFAC)Cu(I)L -&gt; Cu + Cu(II) (HFAC)₂ + 2L</p><p>Here, L (neutral ligand) is a neutral ligand, and is a component such as VCH (VinylCycloHexane) or DMP (3,3-dimetyl-1-butane). </p><p>As described above, the monovalent copper precursor is reduced to copper and deposited on the diffusion barrier layer 26 .</p><p>A process in which the divalent copper precursor is deposited as a second copper thin film is surfaced by chemical formula as follows. </p><p>2(HFAC)Cu(II)₂+ H₂ -&gt; 2Cu + 2(HFAC)H</p><p>Similarly, a divalent copper precursor is reduced to copper and deposited on the first copper thin film 27 .</p><p>In order for each copper precursor to be reduced to copper as shown in the above formula, the process conditions of the reactor described above are required.</p><p>In this way, a uniform copper thin film is formed at a low temperature using a monovalent copper precursor, and then a second copper thin film of a divalent copper precursor component is deposited at a high temperature, thereby improving bonding strength between the copper thin films and providing excellent step coverage. A thin copper film can be obtained. In addition, since the first copper thin film acts as a seed layer of the second copper thin film, it is possible to reduce the growth incubation time of the second copper thin film.</p><p>As shown in FIG. 2C, the metal 29 is planarized using the upper surface of the second insulating film 25 as an end point to form a metal wiring 29a.</p><p>As shown in FIG. 2D , a metal diffusion barrier layer 30 is deposited on the second insulating layer 25 . </p><p>In the embodiment of the present invention shown in the drawings, the metal 29 is used as copper to reduce the contact resistance between the metal 29 and the first and second copper thin films 27 and 28 used as the seed layer. do.</p><p>The method of forming a metal wiring having a dual multi-machine structure of the present invention is a cyclic chemical vapor deposition (CVD) process using a monovalent copper precursor and a divalent copper precursor at the same time. This makes it possible to compensate for the shortcomings of each copper precursor, and to produce a thin film with excellent step coverage and excellent bonding strength.</p><p>3 is a schematic cross-sectional view of a copper thin film after depositing a copper thin film in a contact region by the copper thin film deposition method of the present invention.</p><p>When the monovalent copper precursor and the divalent copper precursor are continuously deposited as shown in FIG. 3 , a copper thin film is deposited on the inner surface of the contact with high step coverage and good bonding properties.</p><p>As described above, the method of depositing the first and second copper thin films successively separately from the method of depositing the metal wiring using the first and second copper thin films as a seed layer is repeated to fill the contact regions and trenches. There is also a way. In this case, the copper wiring (described above as a metal wiring) deposition process, which was performed as a separate process, is omitted.</p><p>The method for forming a metal wiring having a dual multi-machine structure of the present invention may be used to manufacture a copper thin film during a BEOL (Back End Of Line) process for manufacturing a semiconductor device.</p>

<p>The method for forming a metal wiring having a dual multi-machine structure of the present invention as described above has the following effects.</p><p>When forming a copper thin film as a single type of copper precursor (monovalent copper precursor, divalent copper precursor), the adhesiveness prevents the problem that the step coverage characteristic deteriorates, and by depositing the monovalent and divalent copper precursors alternately, each precursor To compensate for the problems of the copper thin film It is possible to improve the step coverage characteristics of the place where it is created.</p>