JP2006086369A - Wiring forming method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form wirings while protecting the surface of a wiring-metal film from a damage such as oxidation and pollution so as to make easier the flattening process of the surface thereafter. <P>SOLUTION: There is prepared a substrate W obtained by forming recesses 42 for wirings in an insulating film and covering the surface of the recesses 42 with a barrier film 44. A wiring-metal film 48 is formed on the surface of the substrate W and a wiring metal is buried in the recesses 42 for wiring. A polymer protective film 50 is formed on the surface of the wiring-metal film 48. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wiring forming method and a wiring forming apparatus, and in particular, a wiring material (metal) such as copper is placed in a fine wiring recess provided in an insulating film (interlayer insulating film) formed on a substrate such as a semiconductor wafer. The present invention relates to a wiring forming method and a wiring forming apparatus used for forming a wiring by embedding.

As a wiring formation process of a semiconductor device, a so-called damascene process in which a wiring metal is embedded in a wiring recess such as a wiring groove or a via hole provided in an insulating film is being used. In this damascene process, a concave portion for wiring is formed in an insulating film (interlayer insulating film) made of SiO ₂ , SiOF, SiOC, or a so-called low-k material on the substrate, and then the entire surface of the insulating film including the concave portion for wiring is formed. Recesses for wiring by forming a barrier film made of titanium, tantalum, tungsten, ruthenium and / or an alloy thereof, and forming a wiring metal film made of aluminum, copper, silver, gold or an alloy thereof on the surface of the barrier film This is generally performed by embedding a wiring metal therein and then removing an excess wiring metal film and barrier film formed other than the wiring recess.

  In that case, the formation of the recess for wiring is often performed by dry etching or the like, and the formation of the barrier film is often performed by a dry process such as PVD, CVD or ALD. Examples of the method for forming the wiring metal film include a wet process such as electrolytic plating or electroless plating, and a dry process such as PVD, CVD, or ALD, but formation by electrolytic plating is widely performed. When forming a wiring metal film by electrolytic plating when the conductivity of the barrier film is low, a seed film for power feeding is formed in advance on the surface of the barrier film in succession to the formation of the barrier film. Is widely practiced. The excess wiring metal film and the barrier film are generally removed by a so-called flattening method such as chemical mechanical polishing (CMP), electrolytic polishing, and composite electrolytic polishing.

  The surface of the wiring metal film formed by electroplating or the like is generally chemically active, easily oxidized, and susceptible to organic contamination from the atmosphere. Also, the surface of the wiring metal film has fine irregularities reflecting the surface shape of the substrate before forming the wiring metal film, and depending on the degree of the irregularities, the unevenness of the substrate surface cannot be eliminated even in the subsequent flattening process. Sometimes. In the formation of finer wiring of 65 nm or more, it is considered that such process fluctuation has a serious influence on the manufacture of the semiconductor device.

  Since the present invention has been made in view of the above circumstances, a wiring forming method capable of forming the wiring while protecting the surface of the wiring metal film from damage such as oxidation and contamination, and further facilitating the subsequent flattening process. And it aims at providing a wiring formation apparatus.

According to the first aspect of the present invention, there is provided a substrate in which a recess for wiring is formed in an insulating film and the surface is covered with a barrier film, a wiring metal film is formed on the surface of the substrate, and wiring is formed in the recess for wiring. A wiring formation method comprising embedding metal and forming a polymer protective film on a surface of the wiring metal film.
After forming the wiring metal film on the surface of the substrate, forming a polymer protective film on the surface of the wiring metal film, covering the surface of the wiring metal film with the polymer protective film, and protecting the wiring protective film, It is possible to prevent the wiring metal film from being deteriorated due to oxidation or the like, and to reduce the fine irregularities on the surface of the wiring metal film with the polymer protective film, thereby reducing the load of the subsequent planarization process. Further, by covering the entire surface of the wiring metal film with the polymer protective film, it is possible to prevent metal contamination of other clean substrates due to subsequent handling or the like.

The invention according to claim 2 is the wiring forming method according to claim 1, wherein the wiring metal film is formed by an electrolytic plating method, and the polymer protective film is formed by an electrodeposition method.
The polymer protective film can be formed by a CVD method, a spin coating method, or the like, but a wiring metal film is formed by an electroplating method which is a mainstream, and a polymer protective film is formed by an electrodeposition method (electrolytic process). Thus, after the wiring metal film is formed, the polymer protective film can be continuously formed on the surface of the wiring protective film.

The invention according to claim 3 is the wiring forming method according to claim 1 or 2, wherein the substrate on which the polymer protective film is formed on the surface of the wiring metal film is heat-treated.
Thus, by heat-treating, the solvent component entrained in the polymer protective film can be volatilized and the polymer protective film can be made into a continuous and complete film. Further, by adjusting the heating temperature and the heating time, the polymer protective film can be reflowed, and fine irregularities on the surface of the wiring metal film can be embedded more flatly with the polymer protective film 50.
This treatment can also be expected to have an effect of crystal growth by annealing a wiring metal film formed by electrolytic plating.

The invention according to claim 4 is characterized in that after the polymer protective film is formed on the surface of the wiring metal film, the wiring metal attached to or formed on the periphery of the substrate is etched away with a chemical solution. It is a wiring formation method in any one of Claims 1 thru | or 3.
After forming a polymer protective film on the surface of the wiring metal film and covering the wiring metal film in the device region on the substrate with the polymer protective film, the wiring metal attached to or formed on the peripheral edge of the substrate with a chemical solution By removing by etching, it is possible to prevent the device region on the substrate from being damaged by the chemical solution used for the etching process.

5. The wiring formation according to claim 1, wherein the surface of the substrate on which the polymer protective film is formed on the surface of the wiring metal film is planarized. Is the method.
By forming a polymer protective film on the surface of the wiring metal film having fine irregularities on the surface, and flattening the surface of the substrate in a state where the surface of the polymer protective film is flattened, Fine irregularities can be easily eliminated. Polymer protective films generally have low mechanical strength but strong chemical resistance. Conversely, wiring metals generally have high mechanical strength but low chemical resistance. Therefore, the surface having fine irregularities on the surface is obtained by polishing and flattening the polymer protective film and the wiring metal film using, for example, a polishing liquid whose abrasive concentration and chemical composition are adjusted so that it can be removed at the same polishing rate. As compared with the case where only the metal film is polished, planarization can be realized more easily.

  According to a sixth aspect of the present invention, there is provided an embedding device in which a wiring metal film is formed on the surface of a substrate in which a wiring recess is formed in an insulating film and the surface is covered with a barrier film, and the wiring metal is embedded in the wiring recess. And a protective film forming apparatus that forms a polymer protective film on the surface of the metal wiring film.

According to a seventh aspect of the present invention, in the wiring forming apparatus according to the sixth aspect, the embedding apparatus comprises an electrolytic plating apparatus, and the protective film forming apparatus comprises an electrodeposition apparatus.
The invention according to claim 8 is the wiring forming apparatus according to claim 6 or 7, further comprising a heat treatment apparatus for heat-treating the substrate on which the polymer protective film is formed on the surface of the wiring metal film. .

The invention according to claim 9 further includes a bevel etching apparatus for etching and removing the wiring metal deposited or formed on the peripheral edge of the substrate with a chemical solution. This is a wiring forming apparatus.
The invention according to claim 10 further comprises a flattening device for flattening the surface of the substrate on which the polymer protective film is formed on the surface of the wiring metal film. It is the wiring formation apparatus as described in.

  According to the present invention, after forming the wiring metal film on the surface of the substrate, the polymer protective film is formed on the surface of the wiring metal film, and the surface of the wiring metal film is covered with the polymer protective film. By protecting the wiring, the surface of the wiring metal film can be protected from damage such as oxidation and contamination, and the wiring can be formed while further facilitating the subsequent planarization process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this example, copper wiring made of copper is formed by embedding copper as a wiring material (metal) in a wiring recess provided on the surface of a substrate such as a semiconductor wafer. Of course, metals other than copper may be used as the wiring material.

  FIG. 1 is a plan view of a wiring forming apparatus according to an embodiment of the present invention. As shown in FIG. 1, the substrate processing apparatus includes a rectangular apparatus frame 12 in which a transfer box 10 in which a plurality of substrates such as semiconductor wafers are housed is detachable. Inside the apparatus frame 12, there are provided a load / unload station 14 and a transportable robot 16 that can move the substrate between the load / unload station 14. A pair of embedding devices 18 are arranged on both sides of the transfer robot 16 with the transfer robot 16 in the apparatus frame 12 interposed therebetween, and a cleaning / drying device 20 is further provided on one side with the transfer robot 16 in between. The bevel etching device 22 and the film thickness measuring device 24 are arranged in series, and a pair of protective film forming device 26, a heat treatment (annealing) device 30 and a polishing device 32 are arranged in series on the other side.

  Here, the device frame 12 is subjected to a light shielding process, whereby the following steps in the device frame 12 can be performed in a light-shielded state, that is, without irradiating light such as illumination light on the wiring. ing. Thus, by preventing light from being applied to the wiring, for example, it is possible to prevent a light potential difference from occurring when light is applied to a wiring made of copper, and the wiring from being corroded by this light potential difference.

  The embedding device 18 forms a copper plating film as a wiring metal film on the surface of the substrate and embeds copper as the wiring metal in the wiring recess. In this example, the embedding device 18 was previously formed on the surface of the substrate. The electroplating apparatus forms a metal film (copper plating film) on the surface of the seed film by electroplating. This embedding apparatus may be composed of other wet processing apparatuses such as an electroless plating apparatus, or dry processing apparatuses such as a PVD apparatus, a CVD apparatus, or an ALD apparatus.

  The protective film forming device 26 forms a polymer protective film that covers and protects the wiring metal film formed on the surface of the wiring metal film formed by the embedding device (electrolytic plating device) 18. In this example, an electrodeposition method is used. The electrodeposition apparatus forms a polymer film. The protective film forming apparatus may be constituted by a CVD apparatus, a spin coater, or the like.

  After forming the wiring metal film by forming the wiring metal film by the mainstream electrolytic plating and forming the polymer protective film by the electrodeposition method (electrolytic process), the polymer protective film is formed on the surface of the wiring protective film. It can be formed continuously. In this case, the substrate on which the wiring metal film is formed by electrolytic plating is pulled up from the plating solution in the plating tank and washed (rinsed) with pure water or the like to remove the plating solution remaining on the substrate. And the board | substrate which sealed the peripheral part which took the electricity contact is introduce | transduced into an electrodeposition tank, and a polymer protective film is formed in the surface of a wiring metal film by electrodeposition. The substrate after electrodeposition is washed with water and dried, and then sent to the next step.

  As a polymer capable of forming a film by an electrodeposition method, there are a cationic system and an anionic system. When an anionic polymer film is formed by an electrodeposition method, the substrate needs to be anodically polarized. When the substrate is anodically polarized in this way, the wiring metal film formed on the surface of the substrate is dissolved. Therefore, it is more preferable to cathode-polarize the substrate and electrodeposit the cationic polymer film. As such a cationic polymer, for example, a polyimide-based cationic resin (manufactured by JSR Corporation: product name EDP004) can be mentioned. When forming a cationic polymer film by electrodeposition, the protective film forming apparatus (electrodeposition apparatus) has the same configuration as the electroplating apparatus for forming a wiring protective film by replacing the electrolytic solution used. Things can be used.

  Further, when the polymer protective film is formed by the CVD method or the spin coat method, the polymer protective film is formed on the entire surface of the substrate. For this reason, when the wiring metal formed on the peripheral portion of the substrate is removed by etching, the polymer protective film formed on the peripheral portion of the substrate must be peeled off by some method prior to this etching. . On the other hand, when the polymer protective film is formed by the electrodeposition method, it is possible to prevent the polymer film from being formed on the peripheral edge of the substrate by sealing the peripheral edge of the substrate where the conductive contact is made. it can.

Next, an example of forming a copper wiring with this wiring forming apparatus will be described with further reference to FIGS.
First, as shown in FIG. 2A, a trench (recess for wiring) 42 is dry-etched in an insulating film (interlayer insulating film) 40 made of, for example, SiO ₂ , SiOF, SiOC, Low-k material or the like. A substrate W is prepared, on which a barrier film 44 is formed and a seed film 46 is formed thereon as a power feeding layer for electrolytic plating by PVD, CVD, or the like. Then, the substrate W is stored in the transport box 10, and the transport box 10 is mounted on the apparatus frame 12.

  The substrates W are taken out from the transfer box 10 one by one and loaded into the load / unload station 14. The substrate W carried into the load / unload station 14 is transported to the film thickness measuring device 24 by the transport robot 16, and the initial film thickness (the film thickness of the seed film 46) is measured by the film thickness measuring device 24. If necessary, the substrate W is inverted and conveyed to the electrolytic plating apparatus (embedding apparatus) 18.

  Then, copper plating using the seed film 46 as a power feeding layer is performed on the surface of the substrate W by the electrolytic plating apparatus 18, whereby a copper plating film (wiring metal film) is formed on the surface of the substrate W as shown in FIG. ) 48 and copper (wiring metal) is buried in the trench 42. On the surface of the copper plating film 48 thus formed, fine irregularities reflecting the irregularities on the surface of the substrate W before the copper plating film 48 is formed are formed.

  The substrate W on which the copper plating film 48 is formed is transported to the cleaning / drying device 20 by the transport robot 16, and the substrate W is cleaned with pure water and spin-dried, or the electrolytic plating device 18 has a spin-drying function. Is provided, the electrolytic plating apparatus 18 performs cleaning and spin drying (liquid draining) of the substrate W, and transports the dried substrate W to the electrodeposition apparatus (protective film forming apparatus) 26. .

  In this electrodeposition apparatus (protective film forming apparatus) 26, as in the case of the electroplating apparatus, electrodeposition with the substrate W cathode-polarized is performed, and as shown in FIG. A polymer protective film 50 made of, for example, a cationic resin is formed on the surface.

  In this way, the polymer protective film 50 is formed on the surface of the copper plating film 48, and the surface of the chemically active copper plating film 48 is covered with the polymer protective film 50 to protect the copper plating film 48. Thus, deterioration of the copper plating film 48 due to oxidation or the like can be prevented, and the flattening speed in the subsequent flattening step can be made more uniform. In addition, the surface of the polymer protective film 50 becomes flatter than the surface of the copper plating film 48, thereby relieving fine irregularities on the surface of the copper plating film 48 and reducing the load on the subsequent flattening process. can do. Furthermore, by covering the entire surface of the copper plating film 48 with the polymer protective film 50, it is possible to prevent metal contamination of other clean substrates by subsequent handling or the like.

  The film thickness of the polymer protective film 50 is not particularly limited as long as the above object can be realized. However, since the film including the polymer protective film 50 is flattened as described below, the film thickness should be 10 μm or less. preferable. Similarly, the material of the polymer protective film 50 is not particularly limited, but polyimide or the like is preferable from the viewpoint of adhesion to the wiring metal film.

  Here, the electrodeposition apparatus 26 is equipped with the electroplating apparatus 18 as a substrate holder that seals the peripheral portion where the energization contact is made, holds the substrate W, and makes contact with the electrolytic solution in the electrodeposition tank. By using a substrate having substantially the same structure as the substrate holder, it is possible to prevent the polymer protective film 50 from being formed on the peripheral edge of the substrate W.

  The substrate on which the polymer protective film 50 is formed is transported to the cleaning / drying apparatus 20 by the transport robot 16 and the substrate W is cleaned with pure water and spin-dried, or the electrodeposition apparatus 26 is provided with a spin-drying function. Is provided, the electrodeposition apparatus 26 performs cleaning and spin drying (liquid cutting) of the substrate W, and transports the dried substrate W to the heat treatment apparatus 30.

The heat treatment apparatus 30 performs heat treatment (annealing) of the substrate W. Even if the polymer protective film 50 is formed on the surface of the copper plating film 48 by the spin coat method or the electrodeposition method, it has a certain degree of protective effect, but the solvent component accompanying the polymer protective film 50 by heat treatment. The copper plating film 48 can be protected using the polymer protective film 50 as a continuous and complete film. Further, by adjusting the heating temperature and time of the heat treatment, as shown in FIG. 3A, the polymer protective film 50 is reflowed so that fine irregularities on the surface of the copper plating film 48 are removed. 50 can be embedded more flatly. By taking the substrate W in this state to the next flattening step, the flattening process becomes easier. Although the heat treatment temperature depends on the material of the polymer protective film 50, it is preferably about 200 to 300 ° C. When the polymer protective film 50 contains a large amount of solvent, the substrate is pre-baked at, for example, less than 100 ° C. Then, heat treatment is preferably performed at the above temperature.
In the case where the polymer protective film 50 is formed by the electrodeposition method, flatness may be less likely to be obtained than by the spin coating method. In this case, after the electrodeposition, a solvent is sprayed to loosen the film and then heat treatment is performed. Thus, the flatness can be further improved.

  Then, the substrate W after the heat treatment is transferred to the film thickness measuring device 24 by the transfer robot 16, and the film thickness of copper or the total film thickness of the copper and the polymer protective film 50 is measured here. The total film thickness of the copper plating film 48 or the copper plating film 48 and the polymer protective film 50 is obtained from the difference from the measurement result of the initial film thickness. Adjust. Then, the substrate W after the film thickness measurement is transferred to the bevel etching apparatus 22 by the transfer robot 16.

  In this bevel etching apparatus 22, unnecessary copper (wiring metal) deposited or attached to the bevel (edge) portion of the substrate W is etched away with a chemical solution, and the back surface of the substrate W is simultaneously cleaned with pure water or the like as necessary. Wash. Thereafter, as described above, the substrate is transferred to the cleaning / drying device 20 by the transfer robot 16, and the substrate W is cleaned with pure water and spin-dried, or the bevel etching device 22 has a spin-drying function. In the case where the bevel is etched, the substrate W is cleaned and spin-dried by the bevel etching device 22, and the dried substrate is transported to the polishing device 32.

  Copper (wiring metal) deposited or formed on the peripheral edge of the substrate W causes metal contamination on other clean substrates through contact with the substrate holder or the like. For this reason, after the copper plating film 48 is formed, etching removal is performed with a chemical solution such as an acid containing an oxidizing agent. Here, since the copper plating film 48 in the device region is covered with the polymer protective film 50 by performing this process after the polymer protective film 50 is formed, the device region is damaged by the chemical solution used for the etching process. You can avoid receiving it. Although the bevel etching process may be performed immediately after the polymer protective film 50 is formed, the polymer protective film 50 after the heat treatment has higher chemical resistance than that before the heat treatment. It is more preferable to perform this etching process later.

  When the polymer protective film is formed by the CVD method or the spin coat method, the polymer protective film is formed on the entire surface of the substrate. For this reason, it is necessary to peel off only the polymer protective film formed on the peripheral portion of the substrate by some method prior to etching and removing the copper deposited or formed on the peripheral portion of the substrate. On the other hand, when a polymer protective film is formed by electrodeposition, the periphery of the substrate is sealed to obtain a current-carrying contact, thereby preventing the polymer protective film from being formed on this part. This is preferable.

  With this polishing apparatus 32, as shown in FIG. 3B, unnecessary polymer protective film 50, copper plating film 48, seed film 46 and barrier film 44 deposited on the surface of the substrate W are polished and removed, and the substrate is removed. The surface of W is flattened, whereby a wiring 52 made of copper is formed inside the insulating film (interlayer insulating film) 40. At this time, for example, the film thickness and the finish of the substrate are inspected by a monitor, and when the end point is detected by this monitor, the polishing is finished.

  The polymer protective film 50 reflowed by heat treatment or the like relieves fine irregularities on the surface of the copper plating film 48 and gives a flatter surface. By subjecting the surface of the substrate W in this state to a flattening process by, for example, chemical mechanical polishing, fine irregularities on the surface of the copper plating film 48 can be easily eliminated. Here, for example, the polymer protective film 50 made of, for example, a cationic resin generally has low mechanical strength but high chemical resistance. On the contrary, the copper plating film 48 has high mechanical strength but low chemical resistance. Therefore, it is easier than polishing only a copper plating film (wiring metal film) having fine irregularities by polishing with a polishing liquid whose abrasive concentration and chemical composition are adjusted so that both can be removed at the same polishing rate. Flattening can be realized.

  Then, the polished substrate W is transported to the cleaning / drying device 20 by the transport robot 16, the surface of the substrate W is cleaned with a chemical solution by the cleaning / drying device 20, and further washed with pure water (rinse), Spin at high speed to spin dry. Then, the substrate after the spin drying is returned to the load / unload station 14 by the transfer robot 16, and is returned from the load anduro station 14 into the transfer book 10.

  Thus, after forming the copper plating film 48 on the surface of the substrate W, the polymer protective film 50 is formed on the surface of the copper plating film 48, and the surface of the copper plating film 48 is covered with the polymer protective film 50. By protecting the copper plating film 48, the surface of the copper plating film 48 can be protected from damage such as oxidation and contamination, and the subsequent planarization process can be facilitated to form the wiring 52.

  In addition, although the example which uses copper as a wiring material (metal) is shown, you may use aluminum, a copper alloy, silver, a silver alloy, or a gold alloy other than copper.

1 is a plan layout view of a wiring forming apparatus according to an embodiment of the present invention. It is a figure which shows in order of process until it forms the polymer protective film of the wiring formation example at the time of forming copper wiring with the wiring formation apparatus shown in FIG. It is a figure which shows after forming the polymer protective film of the example of wiring formation at the time of forming copper wiring with the wiring formation apparatus shown in FIG. It is a block diagram which shows the wiring formation example at the time of forming a copper wiring with the wiring formation apparatus shown in FIG.

Explanation of symbols

10 Transport box 12 Device frame 16 Transport robot 18 Embedding device (electroplating device)
20 Cleaning / drying device 22 Bevel etching device 24 Film thickness measuring device 26 Protective film forming device (electrodeposition device)
30 Heat treatment apparatus 32 Polishing apparatus 40 Insulating film 42 Trench (recess for wiring)
44 Barrier film 46 Seed film 48 Wiring metal film (copper plating film)
50 Polymer protective film 52 Wiring

Claims (10)

Prepare a substrate with a wiring recess in the insulating film and the surface covered with a barrier film.
Forming a wiring metal film on the surface of the substrate and embedding the wiring metal in the wiring recess;
A wiring forming method comprising forming a polymer protective film on a surface of the wiring metal film.   2. The wiring forming method according to claim 1, wherein the wiring metal film is formed by an electrolytic plating method and the polymer protective film is formed by an electrodeposition method.   3. The wiring forming method according to claim 1, wherein the substrate on which the polymer protective film is formed on the surface of the wiring metal film is heat-treated.   4. The wiring metal attached or formed on the peripheral edge of the substrate is removed by etching with a chemical after forming the polymer protective film on the surface of the wiring metal film. The wiring formation method as described.   The wiring forming method according to claim 1, wherein the surface of the substrate on which the polymer protective film is formed on the surface of the wiring metal film is planarized. An embedding device for forming a wiring recess in the insulating film and forming a wiring metal film on the surface of the substrate whose surface is covered with a barrier film and embedding the wiring metal in the wiring recess;
A wiring forming apparatus comprising a protective film forming apparatus for forming a polymer protective film on a surface of the wiring metal film.   The wiring forming apparatus according to claim 6, wherein the embedding apparatus is an electrolytic plating apparatus, and the protective film forming apparatus is an electrodeposition apparatus.   The wiring forming apparatus according to claim 6, further comprising a heat treatment apparatus for heat-treating the substrate on which the polymer protective film is formed on the surface of the wiring metal film.   9. The wiring forming apparatus according to claim 6, further comprising a bevel etching apparatus that etches and removes the wiring metal deposited or formed on the peripheral edge of the substrate with a chemical solution.   10. The wiring forming apparatus according to claim 6, further comprising a flattening device for flattening a surface of the substrate on which the polymer protective film is formed on the surface of the wiring metal film.

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