JP3616297B2 - Manufacturing method of semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a semiconductor device in which a conductive film for wiring such as tungsten is embedded in a hole of a semiconductor substrate or an insulating substrate to form a plug or embedded wiring in a manufacturing process of a semiconductor integrated circuit.
[0002]
[Prior art]
(First conventional technology)
As illustrated in FIG. 12, an oxide film 22 is deposited as an insulating film on the semiconductor substrate 21 by 1 μm, and then the oxide film 22 is subjected to lithography and dry etching to form, for example, a hole 23 having a diameter of 0.3 μm (FIG. 12 ( a)).
[0003]
Next, a laminated film of titanium and titanium nitride is sequentially deposited as a first conductive film 24 on the oxide film 22 including the holes 23 by sputtering (FIG. 12B).
[0004]
Next, 400 nm of tungsten is deposited as the second conductive film 25 by the CVD method (FIG. 12C).
[0005]
Next, using a chlorine-based gas, tungsten other than in the hole 23 is completely removed by etching to leave a tungsten plug 26 in the hole 23 (FIG. 12D). A certain amount of titanium nitride / titanium remains. At this time, tungsten in the hole 23 is dug by 70 nm or more.
[0006]
This digging is called plug recess. Titanium nitride / titanium has a lower etching rate than tungsten. Therefore, when the titanium nitride / titanium is to be removed, the tungsten in the hole 23 is significantly dug down.
[0007]
On the other hand, when titanium nitride / titanium remains, it can be removed by dry etching in the next wiring formation process. However, if tungsten remains, it cannot be removed. For the above reasons, tungsten other than in the hole 23 is completely removed by etching and stopped with titanium nitride / titanium.
[0008]
Next, the wiring material 28 is deposited by sputtering (FIG. 12E). The wiring material is aluminum with a slight addition of copper. Due to the plug recess, the wiring material becomes thinner at that portion.
[0009]
Next, lithography is performed to form wiring 29 by simultaneously removing the wiring material and titanium nitride / titanium by dry etching (FIG. 12F). (Second conventional technology)
As illustrated in FIG. 13, an oxide film 22 is deposited as an insulating film on the semiconductor substrate 21 by 1 μm, and then the oxide film 22 is subjected to lithography and dry etching to form, for example, a hole 23 having a diameter of 0.3 μm (FIG. 13 ( a)).
[0010]
Next, a laminated film of titanium and titanium nitride is sequentially deposited as a first conductive film 24 on the oxide film 22 including the holes 23 by sputtering (FIG. 13B).
[0011]
Next, 400 nm of tungsten is deposited as the second conductive film 25 by the CVD method (FIG. 13C).
[0012]
Next, using a general tungsten polishing slurry comprising silica or alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as oxidizing agents, and a polishing pad comprising urethane foam or nonwoven fabric, for example, polishing. Under polishing conditions such as a pressure of 5 psi, a platen rotation speed of 60 rpm, and a slurry flow rate of 200 ml / min, tungsten / titanium nitride / titanium is completely removed except in the hole 23, leaving a tungsten plug 26 in the hole 23 (FIG. 13 (d)).
[0013]
Next, cleaning after polishing with ammonia or hydrofluoric acid is performed, and the wiring material 28 is deposited by sputtering (FIG. 13E). The wiring material is aluminum with a slight addition of copper. Since the plug recess is 20 nm, the wiring material is flat.
[0014]
Next, lithography is performed, and the wiring material is removed by dry etching to form the wiring 29 (FIG. 13F).
(Third conventional technology)
As illustrated in FIG. 14, an oxide film 22 is deposited as an insulating film on the semiconductor substrate 21 by 1 μm, and then the oxide film 22 is subjected to lithography and dry etching to form, for example, a hole 23 having a diameter of 0.3 μm (FIG. 14 ( a)).
[0015]
Next, a laminated film of titanium and titanium nitride is sequentially deposited as a first conductive film 24 on the oxide film 22 including the holes 23 by sputtering (FIG. 14B).
[0016]
Next, 400 nm of tungsten is deposited as the second conductive film 25 by the CVD method (FIG. 14C).
[0017]
Next, using a general tungsten polishing slurry comprising silica or alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as oxidizing agents, and a polishing pad comprising foamed urethane or nonwoven fabric, for example, polishing. Tungsten / titanium nitride / titanium is completely removed outside the hole 23 under polishing conditions such as a pressure of 5 psi, a platen rotational speed of 60 rpm, and a slurry flow rate of 200 ml / min (FIG. 14D), or tungsten is removed. Completely removed and a certain amount of titanium / titanium remains, leaving the tungsten plug 26 in the hole 23. In this case, the tungsten plug recess is about 20 nm.
[0018]
Next, second polishing is performed with a general slurry for polishing an oxide film composed of silica as abrasive particles and ammonium hydroxide or potassium hydroxide as a pH adjuster (FIG. 14 (e)). The second polishing may be neutral or acidic in addition to the alkaline solution described above. By this second polishing, it is possible to remove scratches (called scratches) on the surface of the oxide film generated because alumina particles were used during the first polishing. In the second polishing, tungsten is hardly polished, so that there is almost no plug recess or, conversely, a convex state.
[0019]
Next, cleaning after polishing such as ammonia or hydrofluoric acid is performed, and the wiring material 28 is deposited by sputtering (FIG. 14F). The wiring material is aluminum with a slight addition of copper. The wiring material is flat because there is almost no plug recess or the convex state.
[0020]
Next, lithography is performed, and the wiring material is removed by dry etching to form the wiring 29 (FIG. 14G).
(Fourth conventional technology)
As shown in FIG. 15, an oxide film 22 is deposited as an insulating film on the semiconductor substrate 21 by 1 μm, and then the oxide film 22 is subjected to lithography and dry etching to form, for example, a hole 23 having a diameter of 0.3 μm (FIG. 15 ( a)).
[0021]
Next, a laminated film of titanium and titanium nitride is sequentially deposited as a first conductive film 24 on the oxide film 22 including the holes 23 by sputtering to a thickness of 50 nm and 20 nm, respectively (FIG. 15B).
[0022]
Next, 400 nm of tungsten is deposited by CVD as the second conductive film 25 (FIG. 15C).
[0023]
Next, using a chlorine-based gas, tungsten other than in the hole 23 is completely removed by etching to leave a tungsten plug 26 in the hole 23 (FIG. 15D). A certain amount of titanium nitride / titanium remains. At this time, the plug recess is 70 nm or more.
[0024]
Next, using a general oxide film polishing slurry consisting of silica as abrasive particles and ammonium hydroxide or potassium hydroxide as a pH adjuster, and a polishing pad made of foamed urethane or nonwoven fabric, for example, a polishing pressure of 5 psi, The remaining titanium nitride / titanium is completely removed except in the hole 23 under polishing conditions such as a platen rotational speed of 60 rpm and a slurry flow rate of 200 ml / min (FIG. 15E). In this polishing, since tungsten is hardly polished, the plug recess becomes small. The second polishing may be neutral or acidic in addition to the alkaline solution described above. Further, it may be called a general slurry for polishing tungsten (silica or alumina as abrasive particles, hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent).
[0025]
Next, cleaning after polishing with ammonia or hydrofluoric acid is performed, and the wiring material 28 is deposited by sputtering (FIG. 15F). The wiring material is aluminum with a slight addition of copper. Since there is almost no plug recess, the wiring material is flat.
[0026]
Next, lithography is performed, and the wiring material is removed by dry etching to form the wiring 29 (FIG. 15G).
(Fifth conventional technology)
As illustrated in FIG. 16, an oxide film 22 is deposited as an insulating film on the semiconductor substrate 21 by 1 μm, and then the oxide film 22 is subjected to lithography and dry etching to form, for example, a hole 23 having a diameter of 0.3 μm (FIG. 16 ( a)).
[0027]
Next, a laminated film of titanium and titanium nitride is sequentially deposited as a first conductive film 24 on the oxide film 22 including the holes 23 by sputtering (FIG. 16B).
[0028]
Next, 400 nm of tungsten is deposited as the second conductive film 25 by the CVD method (FIG. 16C).
[0029]
Next, a chlorine-based gas is used, and tungsten other than in the hole 23 is etched away halfway (FIG. 16D). There is also a technique using polishing.
[0030]
Next, for example, using a general tungsten polishing slurry composed of alumina or silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and a polishing pad made of foamed urethane or non-woven fabric, for example, polishing The remaining tungsten / titanium nitride / titanium is completely removed outside the hole 23 under polishing conditions such as a pressure of 5 psi, a platen rotation speed of 60 rpm, and a slurry flow rate of 200 ml / min. (FIG. 16 (e)). The plug recess is about 20 nm.
[0031]
Next, cleaning after polishing with ammonia or hydrofluoric acid is performed, and the wiring material 28 is deposited by sputtering (FIG. 16F). The wiring material is aluminum with a slight addition of copper. Since there is almost no plug recess, the wiring material is flat.
[0032]
Next, lithography is performed, and the wiring material is removed by dry etching to form the wiring 29 (FIG. 16G).
[0033]
[Problems to be solved by the invention]
However, in the first conventional technique, when dry etching is stopped with titanium nitride or titanium, foreign matter (called etching residue) is formed, which cannot be completely removed by normal brush scrubber cleaning, and the wiring yield is reduced. There is a problem. In addition, there is a problem that the plug recess is large, and the wiring on the plug becomes thin at that portion, the resistance increases, and the reliability of the wiring decreases.
[0034]
The second conventional technique is a method for improving the first conventional technique. However, when the tungsten / titanium nitride / titanium other than in the hole is completely removed by polishing, the polishing rate within the substrate surface is reduced. Due to the non-uniformity, when the oxide film is completely exposed in the region where the polishing rate is low, the oxide region is shaved for a long time in the fast region, which causes a problem that the film thickness of the oxide film increases.
[0035]
The third, fourth, and fifth conventional techniques also have a problem that the oxide film is reduced because the oxide film is basically cut away.
[0036]
Accordingly, an object of the present invention is to provide a method for manufacturing a semiconductor device capable of suppressing a reduction in the thickness of an oxide film.
[0037]
[Means for Solving the Problems]
In order to achieve the above object, titanium nitride and titanium are not completely removed by polishing except in the hole. The reduction of the oxide film due to polishing becomes remarkable because the above-described titanium nitride and titanium are forcibly removed completely. Even if titanium nitride or titanium remains, there is no problem because the wiring material can be deposited and removed at the time of subsequent patterning (lithography and dry etching).
[0038]
Hereinafter, the configuration and operation of each claim will be described in detail.
[0039]
The method for manufacturing a semiconductor device according to claim 1, the step of depositing an insulating film on a substrate, the step of forming an opening in the insulating film, the step of depositing a first conductive film on the insulating film, Depositing a second conductive film on the first conductive film, completely removing the second conductive film other than in the opening by dry etching and leaving a certain amount of the first conductive film, and in the opening Except for removing a certain amount of the first conductive film remaining by polishing, a step of depositing a wiring material on the entire surface of the substrate, and removing excess wiring material and the first conductive film by dry etching. Forming a wiring.
[0040]
According to this method, the second conductive film other than in the opening is completely removed by dry etching, and a certain amount of the first conductive film remains, and then a certain amount of the first conductive film remains outside the opening. After removing a small amount of the film by polishing, a wiring material is deposited on the entire surface of the substrate, so that a short circuit between wirings due to etching residues can be suppressed and the yield can be improved. Further, the plug recess can be slightly reduced, and the reliability of the wiring can be improved. Furthermore, since polishing is stopped in the middle of the first conductive film, scratches do not occur on the surface of the insulating film, and the yield of wiring can be improved. Since the insulating film does not decrease, multilayer wiring as designed can be realized.
[0041]
The method for manufacturing a semiconductor device according to claim 2 is the method for manufacturing a semiconductor device according to claim 1, wherein the polishing is performed by using alumina or silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent. It is performed by the slurry which becomes.
[0042]
According to this method, the polishing is performed with a slurry of alumina or silica as the abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as the oxidizing agent, so that the first conductive film is made of titanium nitride or titanium. In this case, since the first conductive film is polished, the plug recess can be reduced. Etching residues can also be removed without problems. This slurry is common for tungsten polishing.
[0043]
The method for manufacturing a semiconductor device according to claim 3 is the method for manufacturing a semiconductor device according to claim 1, wherein the polishing is performed with a slurry comprising silica as abrasive particles and ammonium hydroxide or potassium hydroxide as a pH adjuster. It is performed.
[0044]
According to this method, the polishing is performed in a slurry comprising silica as abrasive particles and ammonium hydroxide or potassium hydroxide as a pH adjuster, so that the first conductive film is made of titanium nitride, titanium, or second In the case where the conductive film is tungsten, the first conductive film is polished, but the second conductive film is not polished at all. Therefore, the plug recess can be further reduced. Etching residues can also be removed without problems. This slurry is generally used for polishing an oxide film.
[0045]
According to a fourth aspect of the present invention, there is provided a semiconductor device manufacturing method comprising: depositing an insulating film on a substrate; forming an opening in the insulating film; depositing a first conductive film on the insulating film; Depositing a second conductive film on the first conductive film, completely removing the second conductive film other than in the opening by dry etching and leaving a certain amount of the first conductive film, and in the opening Polishing the first conductive film remaining in a certain amount with a slurry consisting of a liquid that does not chemically react with the first and second conductive films and abrasive particles, and a wiring material over the entire surface of the substrate And a step of forming wiring by removing excess wiring material and the first conductive film by dry etching.
[0046]
According to this method, the second conductive film other than in the opening is completely removed by dry etching, and a certain amount of the first conductive film remains, and then a certain amount of the first conductive film remains outside the opening. After the conductive film is polished with a slurry consisting of a liquid that does not react chemically with the first and second conductive films and abrasive particles, a wiring material is deposited on the entire surface of the substrate. Can be suppressed and the yield can be improved. The slurry is basically composed of abrasive particles and water, and handling of the slurry is simple and there are few problems with respect to contamination. Since the first and second conductive films are hardly polished, it is not necessary to control the polishing amount, and the polishing is simple. Since the insulating film does not decrease, multilayer wiring as designed can be realized.
[0047]
A method for manufacturing a semiconductor device according to a fifth aspect is the method for manufacturing a semiconductor device according to the fourth aspect, wherein the abrasive particles are silica, cerium oxide, or alumina.
[0048]
According to this method, since the abrasive particles are silica, cerium oxide, or alumina, they are generally handled abrasive particles and are easily available.
[0049]
The method of manufacturing a semiconductor device according to claim 6, the step of depositing an insulating film on a substrate, the step of forming an opening in the insulating film, the step of depositing a first conductive film on the insulating film, Depositing a second conductive film on the first conductive film, completely removing the second conductive film other than in the opening by dry etching and leaving a certain amount of the first conductive film, and in the opening In other than the above, a step of polishing only by flowing water into the first conductive film remaining in a certain amount, a step of depositing a wiring material on the entire surface of the substrate, an excess wiring material and the first conductive film by dry etching And forming a wiring.
[0050]
According to this method, the second conductive film other than in the opening is completely removed by dry etching and a certain amount of the first conductive film remains, and then a certain amount of the first conductive film remains outside the opening. After polishing the conductive film by flowing only water, the wiring material is deposited on the entire surface of the substrate, so that the etching residue can be reduced to some extent and the short circuit between wirings can be reduced. There is almost no consumable cost, and post-cleaning is easy. Since the insulating film does not decrease, multilayer wiring as designed can be realized.
[0051]
The method of manufacturing a semiconductor device according to claim 7 includes: a step of depositing an insulating film on the substrate; a step of forming an opening in the insulating film; a step of depositing a first conductive film on the insulating film; Depositing a second conductive film on one conductive film, removing a certain amount of the second conductive film other than in the opening by dry etching, and completely removing the second conductive film other than in the opening by polishing. Removing a predetermined amount of the first conductive film, depositing a wiring material on the entire surface of the substrate, and forming a wiring by removing the excess wiring material and the first conductive film by dry etching. including.
[0052]
According to this method, a certain amount of the second conductive film other than in the opening is removed by dry etching, and then the second conductive film other than in the opening is completely removed by polishing and the first conductive film is fixed. Since the wiring material is deposited on the entire surface of the substrate after the removal of the amount, even if the insulating film is exposed in a part of the substrate surface, the film loss can be suppressed to be small. Plug recesses can be kept small. Since the insulating film does not decrease, multilayer wiring as designed can be realized.
[0053]
The method of manufacturing a semiconductor device according to claim 8 includes: a step of depositing an insulating film on the substrate; a step of forming an opening in the insulating film; a step of depositing a first conductive film on the insulating film; A step of depositing a second conductive film on one conductive film, a step of completely removing the second conductive film except for the inside of the opening by polishing, and removing a certain amount of the first conductive film, and a substrate. The method includes a step of depositing a wiring material over the entire surface and a step of forming wiring by removing excess wiring material and the first conductive film by dry etching.
[0054]
According to this method, the second conductive film other than the inside of the opening is completely removed by polishing, and after a certain amount of the first conductive film is removed, the wiring material is deposited on the entire surface of the substrate. Even if the insulating film is exposed in a part of the surface, the reduction of the film can be kept small. There is almost no plug recess. Since the insulating film does not decrease, multilayer wiring as designed can be realized.
[0055]
A method of manufacturing a semiconductor device according to claim 9 is the method of manufacturing a semiconductor device according to claim 7 or 8, wherein the polishing is alumina or silica as abrasive particles, and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent. It is performed by the slurry which consists of these.
[0056]
According to this method, polishing is performed in a slurry comprising alumina or silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and this slurry is generally used for tungsten polishing. It is easy to obtain.
[0057]
The method for manufacturing a semiconductor device according to claim 10, the step of depositing an insulating film on a substrate, the step of forming an opening in the insulating film, the step of depositing a first conductive film on the insulating film, A step of depositing a second conductive film on the first conductive film, and a step of completely removing the second conductive film other than the inside of the opening and removing a certain amount of the first conductive film by the first polishing. A step of removing the first conductive film except for the inside of the opening by the second polishing, a step of depositing a wiring material on the entire surface of the substrate, and removing the excess wiring material and the first conductive film by dry etching. Forming a wiring.
[0058]
According to this method, the second conductive film except for the inside of the opening is completely removed by the first polishing, and a certain amount of the first conductive film is removed, and then the second polishing is used to remove the second conductive film except for the inside of the opening. Since the wiring material is deposited on the entire surface of the substrate after removing the first conductive film, there is an advantage that the advantages of the first and second polishing can be used. Since the insulating film does not decrease, multilayer wiring as designed can be realized.
[0059]
The method for manufacturing a semiconductor device according to claim 11 is the method for manufacturing a semiconductor device according to claim 10, wherein the first polishing includes alumina as abrasive particles, hydrogen peroxide, iron nitrate, or potassium iodate as an oxidizing agent. And the second polishing is performed in a second slurry comprising silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent. And
[0060]
According to this method, the first polishing is performed with a first slurry composed of alumina as abrasive particles and hydrogen peroxide, iron nitrate, or potassium iodate as an oxidizing agent, and the second polishing is polished. Since it is performed in the second slurry comprising silica as particles and hydrogen peroxide, iron nitrate or potassium iodate as oxidizer, even if the insulating film is exposed in a part of the substrate surface, Less is. Moreover, it is easy to remove abrasive particles by washing. Further, in the case of silica particles, a load is applied to the polishing apparatus.
[0061]
The method for manufacturing a semiconductor device according to claim 12 is the method for manufacturing a semiconductor device according to claim 10, wherein the first polishing is made of iron nitrate or potassium iodate as an oxidizing agent and alumina or silica as polishing particles. The first polishing is performed, and the second polishing is performed with a second slurry made of hydrogen peroxide as an oxidizing agent and alumina or silica as polishing particles.
[0062]
According to this method, the first polishing is performed with a first slurry composed of iron nitrate or potassium iodate as an oxidizing agent and alumina or silica as an abrasive particle, and the second polishing is performed as an oxidizing agent. Since it is carried out in a second slurry comprising hydrogen peroxide and alumina or silica as abrasive particles, iron and potassium contamination on the surface of the first conductive film can be removed. Moreover, the expansion of the void in the plug can be suppressed.
[0063]
The method of manufacturing a semiconductor device according to claim 13 is the method of manufacturing a semiconductor device according to claim 10, wherein the first polishing is performed by using silica or alumina as abrasive particles and hydrogen peroxide, iron nitrate or iodic acid as an oxidizing agent. It is performed in a first slurry composed of potassium, and the second polishing is performed in a second slurry composed of silica as abrasive particles and ammonium hydroxide or potassium hydroxide as a pH adjuster. And
[0064]
According to this method, the first polishing is performed with a first slurry composed of silica or alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and the second polishing is performed. Since the second slurry is composed of silica as abrasive particles and ammonium hydroxide or potassium hydroxide as a pH adjuster, the plug polishing is further reduced by the second polishing when the second conductive film is tungsten. Can be made. Further, when alumina is used for the first polishing, scratches can be reduced by the second polishing. Further, when iron nitrate or potassium iodate is used for the first polishing and ammonium hydroxide is used for the second polishing, contamination can be reduced.
[0065]
15. The method for manufacturing a semiconductor device according to claim 14, wherein a step of depositing an insulating film on the substrate, a step of forming an opening in the insulating film, a step of depositing a first conductive film on the insulating film, Opening by first polishing with a first slurry comprising a step of depositing a second conductive film on one conductive film, alumina as polishing particles, and hydrogen peroxide, iron nitrate or potassium iodate as oxidizing agents. The step of removing a certain amount of the second conductive film other than the inside of the opening, and the second polishing by the second slurry comprising silica as the abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as the oxidizing agent, the inside of the opening A step of completely removing the second conductive film other than the first conductive film and removing a certain amount of the first conductive film, a step of depositing a wiring material on the entire surface of the substrate, and an extra wiring material and the first conductive film by dry etching The And forming a removed by Shi wiring.
[0066]
According to this method, a predetermined amount of the second conductive film other than the inside of the opening is formed by the first polishing with the first slurry comprising alumina as the abrasive particles and hydrogen peroxide, iron nitrate, or potassium iodate as the oxidizing agent. Then, the second conductive film other than the inside of the opening is completely removed by the second polishing with the second slurry comprising silica as the abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as the oxidizing agent. In addition, since the wiring material is deposited on the entire surface of the substrate after removing a certain amount of the first conductive film, even if the insulating film is exposed in a part of the surface of the substrate, the method according to claim 11 Can be reduced. Moreover, it is easy to remove abrasive particles by washing. Further, in the case of silica, a load is applied to the polishing apparatus, but since it is not used for a long time, the operation of the apparatus is not hindered. Since the insulating film does not decrease, multilayer wiring as designed can be realized.
[0067]
16. The method of manufacturing a semiconductor device according to claim 15, wherein a step of depositing an insulating film on the substrate, a step of forming an opening in the insulating film, a step of depositing a first conductive film on the insulating film, A step of depositing a second conductive film on the first conductive film, a step of removing a predetermined amount of the second conductive film other than the inside of the opening by the first polishing, and a step of removing the second conductive film other than the inside of the opening by the second polishing. A step of completely removing the second conductive film and the first conductive film, a step of depositing a wiring material on the entire surface of the substrate, and a step of forming wiring by removing the excess wiring material and the first conductive film by dry etching. Including.
Here, the first polishing is performed with a first slurry composed of alumina as abrasive particles and hydrogen peroxide, iron nitrate, or potassium iodate as an oxidizing agent, and the second polishing is silica as abrasive particles. And a second slurry composed of hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent.
[0068]
According to this method, the first polishing removes a certain amount of the second conductive film outside the opening, and then the second polishing removes the second conductive film and the first conductive film outside the opening by the second polishing. Since the wiring material is deposited on the entire surface of the substrate after complete removal, there is an advantage that the advantages of the first and second polishing can be used. However, the insulation film is greatly reduced.
Further, the first polishing is performed with a first slurry comprising alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidant, and the second polishing is performed with silica as abrasive particles. Since the second slurry is made of hydrogen peroxide, iron nitrate, or potassium iodate as an oxidizing agent, many scratches are not generated on the surface of the insulating film. However, there are more than the method of Claims 11 and 14. Moreover, it is easy to remove abrasive particles by washing. Further, in the case of silica, a load is applied to the polishing apparatus, but since it is not used for a long time, the operation of the apparatus is not hindered.
[0071]
Claim16The manufacturing method of the semiconductor device described includes a step of depositing an insulating film on a substrate, a step of forming an opening in the insulating film, a step of depositing a first conductive film on the insulating film, and a first conductive A step of depositing a second conductive film on the film, a step of completely removing the second conductive film other than in the opening by the first polishing, and removing a certain amount of the first conductive film; 2 to completely remove the first conductive film except for the inside of the opening, to deposit the wiring material on the entire surface of the substrate, and to remove the excess wiring material and the first conductive film by dry etching. Forming the step.
Here, the first polishing is performed with a first slurry composed of alumina as abrasive particles and hydrogen peroxide, iron nitrate, or potassium iodate as an oxidizing agent, and the second polishing is silica as abrasive particles. And a second slurry composed of hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent.
[0072]
According to this method, the second conductive film except for the inside of the opening is completely removed by the first polishing, and a certain amount of the first conductive film is removed, and then the second polishing is used for the parts other than the inside of the opening. Since the wiring material is deposited on the entire surface of the substrate after the first conductive film is completely removed, there is an advantage that the advantages of the first and second polishing can be used. However, as in the method of the fifteenth aspect, the film thickness of the insulating film is large.
Further, the first polishing is performed with a first slurry comprising alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidant, and the second polishing is performed with silica as abrasive particles. Since the second slurry is made of hydrogen peroxide, iron nitrate, or potassium iodate as an oxidizing agent, many scratches are not generated on the surface of the insulating film. However, it is more than the case of the method of Claim 15. Moreover, it is easy to remove abrasive particles by washing. Further, in the case of silica, although a load is applied to the polishing apparatus, since it is used only for a short time, the operation of the apparatus is not hindered.
[0077]
Claim17The method of manufacturing a semiconductor device according to claim 1, 4, 6, 7, 8, 10, 14, 15, or16In the semiconductor device manufacturing method described above, the first conductive film is a stacked film of titanium and titanium nitride, and the second conductive film is tungsten.
[0078]
According to this method, since the first conductive film is a laminated film of titanium and titanium nitride and the second conductive film is tungsten, the present invention is effective for forming a tungsten plug that connects multilayer wiring such as aluminum.
[0081]
DETAILED DESCRIPTION OF THE INVENTION
(First Embodiment: Claim 15,17Corresponding to)
Hereinafter, a method of manufacturing a semiconductor device according to the first embodiment of the present invention will be described with reference to FIGS.
[0082]
An oxide film 12 of 1 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, eg, CVD, and a hole 13 having a diameter of, eg, 0.3 μm is formed by lithography and dry etching. The bottom of the hole 13 is connected to a substrate or wiring (FIG. 1 (a)). Note that being connected to the substrate means a hole (contact hole) connecting the transistor and the first wiring. Being connected to the wiring means a hole (via hole) connecting the upper and lower wirings. The same applies to the following embodiments.
[0083]
Next, as the first conductive film 14, 20 nm of titanium and 50 nm of titanium nitride are deposited, for example, by sputtering (FIG. 1B).
[0084]
Next, 400 nm of tungsten is deposited as the second conductive film 15 by, eg, CVD (FIG. 1C).
[0085]
When the method by chemical mechanical polishing is applied to the removal of the first or second conductive film 14 or 15, alumina or silica is used as abrasive particles in a polishing agent (slurry), and hydrogen peroxide is used as an oxidizing agent. It is conceivable to use iron nitrate, potassium iodate, etc., but the combination of the abrasive particles and the oxidizing agent in the slurry has advantages and disadvantages.
[0086]
Focusing on the abrasive particles, alumina tends to cause scratches on the surface of the oxide film and is difficult to remove by cleaning after polishing. Silica has a large resistance during polishing, and may vibrate depending on the apparatus. In that case, it is better to avoid polishing tungsten for several minutes (it is possible for a short time).
[0087]
When attention is paid to the oxidizing agent, since hydrogen peroxide dissolves tungsten, the joint portion of tungsten in the hole 13 spreads. Iron nitrate and potassium iodate have problems with iron and potassium contamination. Therefore, the selection of the abrasive particles and the oxidizing agent is determined by judging the above items.
[0088]
The joint of tungsten in the hole 13 is generated when tungsten is deposited in the hole 13 by CVD. When tungsten is deposited by CVD, the film thickness of tungsten increases in the same manner in any part of the inner surface of the hole 13, so that the space in the hole 13 is gradually narrowed, and the space in the hole 13 is finally reduced. It becomes a joint.
[0089]
In addition to the abrasive particles and the oxidant, the slurry contains a dispersant for dispersing the abrasive particles in the slurry, a material that makes the oxide film difficult to polish, a pH adjuster, and the like. In polishing a metal film, it is necessary to first oxidize the metal, and the optimum pH is determined accordingly.
[0090]
Next, tungsten other than the inside of the hole 13 is polished halfway with a slurry made of alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent (FIG. 1 (d)). Alternatively, polishing is performed until the oxide film is not partially exposed. The polishing pad used here is, for example, urethane foam, and the polishing pressure is 3 psi and the platen rotation speed is about 30 rpm. The reason why the alumina particles are used is to eliminate the vibration of the polishing apparatus. There is no recess when the first polishing is stopped in the middle of tungsten.
[0091]
Next, a second polishing is performed so that tungsten and titanium nitride / titanium are completely removed except in the hole 13 in a slurry composed of silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent. The tungsten plug 16 is left in the hole 13 (FIG. 1E). The polishing conditions for the second polishing are the same as those for the first polishing. For example, a urethane pad is used as the polishing pad, the polishing pressure is 3 psi, and the rotation speed of the platen is about 30 rpm. The plug recess is about 20 nm.
[0092]
In order to completely remove titanium nitride / titanium from the first polishing rate variation and the second polishing rate variation within the substrate surface, the reduction of the oxide film 12 in the region where the polishing rate is large is remarkable. Become. This is also related to the fact that the tungsten film thickness varies within the substrate surface after the first polishing (due to variations in the first polishing rate). In this case, the reduction of the oxide film is about 150 nm, and when the above plug recess 20 nm is added thereto, the tungsten plug is reduced by about 170 nm. However, in this embodiment, although there is no effect on the reduction of the oxide film, the polishing apparatus in the slurry does not place a load on the polishing apparatus by properly using the polishing particles in the first polishing and the second polishing. It is effective in that scratches hardly occur.
[0093]
Next, although not shown, cleaning after polishing such as ammonia or hydrofluoric acid is performed, and a wiring material 18 is deposited on the entire surface of the substrate (FIG. 1 (f)). Wiring in an extra region is performed by lithography and dry etching. The material is removed at a time to form the wiring 19 (FIG. 1 (g)). The wiring material is an alloy of aluminum and copper. Since the plug recess is about 20 nm, the wiring on the plug is flat.
(Second Embodiment: Claims)16, 17Corresponding to)
Hereinafter, a method for manufacturing a semiconductor device according to the second embodiment of the present invention will be described with reference to FIGS.
[0094]
An oxide film 12 of 1 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, eg, CVD, and a hole 13 having a diameter of, eg, 0.3 μm is formed by lithography and dry etching. The bottom of the hole 13 is connected to a substrate or wiring (FIG. 2A).
[0095]
Next, as the first conductive film 14, 20 nm of titanium and 50 nm of titanium nitride are deposited by sputtering, for example (FIG. 2B).
[0096]
Next, 400 nm of tungsten is deposited as the second conductive film 15 by, eg, CVD (FIG. 2C).
[0097]
Next, tungsten other than in the hole 13 is completely removed with a slurry of alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and titanium nitride / titanium is left to some extent. (FIG. 2 (d)). Within the substrate surface, there may be a portion where the oxide film is partially exposed. The polishing pad used here is, for example, urethane foam, and the polishing pressure is 3 psi and the platen rotation speed is about 30 rpm. The reason why the alumina particles are used is to eliminate the vibration of the polishing apparatus. The plug recess is about 20 nm.
[0098]
Next, a second polishing is performed so that the titanium nitride / titanium is completely removed except in the hole 13 in a slurry composed of silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidant, The tungsten plug 16 is left in the hole 13 (FIG. 2E). The polishing conditions for the second polishing are the same as those for the first polishing. For example, a urethane pad is used as the polishing pad, the polishing pressure is 3 psi, and the rotation speed of the platen is about 30 rpm. The plug recess is about 20 nm.
[0099]
In order to completely remove titanium nitride / titanium from the first polishing rate variation and the second polishing rate variation in the substrate surface, the oxide film in the region having a high polishing rate is reduced. The decrease in the oxide film is suppressed to about 150 nm.
[0100]
Therefore, in this embodiment, the polishing apparatus is not burdened by properly using the abrasive particles in the slurry, and the polishing time of the second polishing is shorter than that of the first embodiment, so that the oxidation time is reduced. The reduction of the film thickness is suppressed, and the reduction of tungsten is about 120 nm, and the expansion of the tungsten joint in the plug can be further reduced. However, there is a possibility that a part of the oxide film is exposed by the first polishing, and scratches may enter. This scratch is reduced by the second polishing, but it is more than the sixth embodiment described later. .
[0101]
Next, although not shown, cleaning after polishing such as ammonia or hydrofluoric acid is performed, and a wiring material 18 is deposited on the entire surface of the substrate (FIG. 2 (f)). Wiring in an extra region is performed by lithography and dry etching. The material is removed at a time to form the wiring 19 (FIG. 2 (g)). The wiring material is an alloy of aluminum and copper. Since the plug recess is about 20 nm, the wiring on the plug is flat.
(Third embodiment: Claim 6,17Corresponding to)
A method for manufacturing a semiconductor device according to the third embodiment of the present invention will be described below. This will be described with reference to FIGS.
[0102]
An oxide film 12 of 1 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, eg, CVD, and a hole 13 having a diameter of 0.3 μm, for example, is formed by lithography and dry etching. The bottom of the hole 13 is connected to a substrate or wiring (FIG. 3A).
[0103]
Next, as the first conductive film 14, 20 nm of titanium and 50 nm of titanium nitride are deposited by sputtering, for example (FIG. 3B).
[0104]
Next, 400 nm of tungsten is deposited as the second conductive film 15 by, eg, CVD (FIG. 3C).
[0105]
Next, tungsten other than in the hole 13 is completely removed by dry etching, and titanium nitride / titanium is left to some extent, and the tungsten plug 16 is left in the hole 13 (FIG. 3D). The dependency of the etching rate on the substrate surface is larger toward the outer periphery of the substrate, and the film thickness of titanium nitride / titanium is reduced. Etching residue 17 is generated on the titanium nitride or titanium surface. In the case of dry etching, there is a mechanism for monitoring atoms in the etching chamber, and when a titanium-based material is detected during etching, the etching is terminated.
[0106]
Next, the titanium nitride or titanium surface is pressed against the polishing pad while flowing water. The polishing pad used here is, for example, urethane foam, and the polishing pressure is 3 psi and the platen rotation speed is about 30 rpm. This process is called water polishing. Thereby, the etching residue which cannot be removed by normal brush scrubber cleaning can be mechanically removed. As for the plug recess, 70 nm generated when tungsten is dry-etched remains as it is (FIG. 3E). However, since titanium nitride and titanium are not polished at all, there is no reduction in the thickness of the oxide film.
[0107]
Next, although not shown, cleaning with ammonia, hydrofluoric acid or the like is performed, and a wiring material 18 is deposited on the entire surface of the substrate (FIG. 3 (f)). Titanium / titanium is removed at a time to form a wiring 19 (FIG. 3G). The wiring material is an alloy of aluminum and copper. Since the plug recess is about 70 nm, there is no improvement in wiring resistance and reliability as compared with the conventional etching only method, but the etching residue is reduced and the yield is improved.
(Fourth embodiment: claims 4, 5,17Corresponding to)
A method for manufacturing a semiconductor device according to the fourth embodiment of the present invention will be described below with reference to FIGS.
[0108]
An oxide film 12 of 1 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, eg, CVD, and a hole 13 having a diameter of 0.3 μm, for example, is formed by lithography and dry etching. The bottom of the hole 13 is connected to a substrate or wiring (FIG. 3A).
[0109]
Next, as the first conductive film 14, 20 nm of titanium and 50 nm of titanium nitride are deposited by sputtering, for example (FIG. 3B).
[0110]
Next, 400 nm of tungsten is deposited as the second conductive film 15 by, eg, CVD (FIG. 3C).
[0111]
Next, tungsten other than in the hole 13 is completely removed by dry etching, and titanium nitride / titanium is left to some extent, and the tungsten plug 16 is left in the hole 13 (FIG. 3D). The dependency of the etching rate on the substrate surface is larger toward the outer periphery of the substrate, and the film thickness of titanium nitride / titanium is reduced. Etching residue 17 is generated on the titanium nitride or titanium surface.
[0112]
Next, the surface of titanium nitride or titanium is polished with a liquid in which silica, alumina, cerium oxide, or the like is contained in the water as abrasive particles. Since there is no chemical reaction, titanium nitride and titanium are hardly polished, but the etching residue is mechanically removed. As for the plug recess, about 70 nm generated when the tungsten is dry-etched remains as it is (FIG. 3E). However, since titanium nitride and titanium are hardly polished, there is no reduction in the thickness of the oxide film. Furthermore, since the etching residue 17 can be completely removed as compared with the third embodiment, the yield is improved. The polishing pad used here is, for example, urethane foam, and the polishing pressure is 3 psi and the platen rotation speed is about 30 rpm.
[0113]
Next, although not shown, cleaning with ammonia, hydrofluoric acid or the like is performed, and a wiring material 18 is deposited on the entire surface of the substrate (FIG. 3 (f)). Titanium / titanium is removed at a time to form a wiring 19 (FIG. 3G). The wiring material is an alloy of aluminum and copper. Since the plug recess remains at about 70 nm, the wiring resistance and reliability are not improved as compared with the conventional etching only method, but the etching residue is reduced and the yield is improved.
[0114]
Actually, abrasive particles are not evenly dispersed with water alone. This embodiment also includes a case where a dispersing agent that does not chemically react with titanium nitride or titanium and tungsten is used to disperse the abrasive particles in the liquid.
(Fifth embodiment: claims 1, 2, 3,17Corresponding to)
A semiconductor device manufacturing method according to the fifth embodiment of the present invention will be described below with reference to FIGS. 4 (a) to 4 (g) and FIGS. 5 (a) to 5 (g).
[0115]
An oxide film 12 of 1 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, eg, CVD, and a hole 13 having a diameter of, eg, 0.3 μm is formed by lithography and dry etching. The bottom of the hole is connected to a substrate or wiring (FIG. 4A).
[0116]
Next, as the first conductive film 14, 20 nm of titanium and 50 nm of titanium nitride are deposited by sputtering, for example (FIG. 4B).
[0117]
Next, 400 nm of tungsten is deposited as the second conductive film 15 by, eg, CVD (FIG. 4C).
[0118]
Next, tungsten other than the inside of the hole 13 is completely removed by dry etching, and titanium nitride / titanium is left to some extent to leave a tungsten plug 16 in the hole 13 (FIG. 4D). The dependency of the etching rate on the substrate surface is larger toward the outer periphery of the substrate, and the film thickness of titanium nitride / titanium is reduced. Etching residue 17 is generated on the titanium nitride or titanium surface.
[0119]
Next, a small amount of the remaining titanium nitride / titanium is polished with a slurry of silica or alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and titanium nitride / titanium. Is intentionally left (FIG. 4E). For example, a urethane foam-based polishing pad is used, and the polishing pressure is 3 psi and the surface plate rotation speed is about 30 rpm. Etching residue is removed by performing a small amount of polishing.
[0120]
By the way, it is ideal that the same amount of titanium nitride / titanium remains in the surface of the substrate, but in fact, due to the in-plane non-uniformity of the tungsten etching rate and the in-plane non-uniformity of the polishing rate, There is a possibility that the oxide film is exposed in a certain part of the substrate surface and the film thickness of the oxide film may be reduced. However, since the process is not a complete removal of titanium nitride / titanium, the film thickness does not decrease so much. Since the plug recess is about 70 nm or more in the third and fourth embodiments, the titanium nitride / titanium is slightly polished by polishing with a slurry containing an oxidizing agent as in the present embodiment. It can be reduced to about 50 nm.
[0121]
Next, although not shown in the figure, cleaning with ammonium hydroxide, hydrofluoric acid, or the like is performed, and a wiring material 18 is deposited on the entire surface of the substrate (FIG. 4F), and wiring material in an extra region is obtained by lithography and dry etching. Then, the titanium nitride / titanium is removed at a time to form a wiring 19 (FIG. 4G). The wiring material is an alloy of aluminum and copper. Since the plug recess is about 50 nm, the waviness of the wiring on the plug is alleviated, the resistance of the wiring is not increased, and the reliability can be improved.
[0122]
Next, a case where a general slurry for polishing an oxide film composed of silica as abrasive particles and ammonia or potassium hydroxide as a pH adjuster is used will be described (see FIG. 5). The process up to (d) of FIG. 5 is the same as that of FIG. This slurry is a general slurry for polishing an oxide film, and tungsten in the holes 13 is not polished at all. Therefore, the plug recess is reduced to about 40 nm as compared with the case of polishing with the slurry containing the oxidizing agent shown in FIG. 4 (FIG. 5E). The steps after polishing are the same as those shown in FIGS. 4F and 4G (FIGS. 5F and 5G). Since the plug recess is small, the waviness of the wiring is further relaxed, and the reliability of the wiring is further improved. Even when this slurry is used, due to in-plane non-uniformity of the tungsten etching rate and the polishing rate, there is a possibility that the oxide film is exposed in a certain region in the substrate surface and the oxide film is reduced. The rate of titanium nitride is about 0.3 times that of the oxide film, and the rate of titanium is about 0.5 times. In other words, it is necessary to pay attention to the region where the oxide film is exposed because the rate of reduction of the oxide film increases. The pH may be neutral or acidic instead of alkali.
(Sixth embodiment: Claim 7,17Corresponding to)
Hereinafter, a method for fabricating a semiconductor device according to the sixth embodiment of the present invention will be described with reference to FIGS.
[0123]
An oxide film 12 of 1 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, eg, CVD, and a hole 13 having a diameter of, eg, 0.3 μm is formed by lithography and dry etching. The bottom of the hole 13 is connected to a substrate or wiring (FIG. 6A).
[0124]
Next, as the first conductive film 14, 20 nm of titanium and 50 nm of titanium nitride are deposited by sputtering, for example (FIG. 6B).
[0125]
Next, 400 nm of tungsten is deposited as the second conductive film 15 by, eg, CVD (FIG. 6C).
[0126]
Next, tungsten other than in the hole 13 is removed halfway by dry etching (FIG. 6D). Dry etching is performed up to a point where plug recesses do not occur remarkably. For example, 300 nm is etched to leave 100 nm. The reason why the etching is performed in such a large amount is that a recess due to etching is likely to occur at a joint (seam) at the time of deposition of tungsten, and the recess is avoided.
[0127]
Next, polishing is performed using polishing particles made of silica or alumina as polishing particles and hydrogen peroxide, iron nitrate, potassium iodate, or the like as an oxidizing agent to completely remove tungsten other than in the holes 13 and perform nitriding Titanium / titanium is left to some extent to leave a tungsten plug 16 in the hole 13 (FIG. 6E). Ideally, the same amount of titanium nitride / titanium should remain in the substrate surface. However, in reality, the substrate surface is caused by the in-plane non-uniformity of tungsten etching rate and in-plane non-uniformity of polishing rate. There is a possibility that the oxide film is exposed in a certain part of the inside, and the film thickness of the oxide film may be reduced. However, since the process is not a complete removal of titanium nitride / titanium, the film thickness does not increase so much.
[0128]
The polishing pad used here is, for example, urethane foam, and the polishing pressure is 3 psi and the platen rotation speed is about 30 rpm. When the slurry is used, the polishing rate of titanium nitride is 1 time or more than the polishing rate of tungsten, so it is somewhat difficult to leave titanium nitride, but the polishing rate of titanium is 0.5 times or less. Therefore, it is possible to leave titanium to some extent. In this way, by removing the tungsten by dry etching without stopping it completely, the plug recess is reduced to about 30 nm by polishing with the recess slightly generated by dry etching.
[0129]
Next, although not shown, cleaning with ammonia, hydrofluoric acid or the like is performed, and a wiring material 18 is deposited on the entire surface of the substrate (FIG. 6 (f)). Titanium / titanium is removed at a time to form the wiring 19 (FIG. 6G). The wiring material is an alloy of aluminum and copper. Since the plug recess is about 30 nm, the wiring on the plug becomes flat and the reliability is improved.
(Seventh Embodiment: Claim 14,17Corresponding to)
Hereinafter, a method for fabricating a semiconductor device according to the seventh embodiment of the present invention will be described with reference to FIGS.
[0130]
An oxide film 12 of 1 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, eg, CVD, and a hole 13 having a diameter of, eg, 0.3 μm is formed by lithography and dry etching. The bottom of the hole is connected to a substrate or wiring (FIG. 7A).
[0131]
Next, as the first conductive film 14, 20 nm of titanium and 50 nm of titanium nitride are deposited by sputtering, for example (FIG. 7B).
[0132]
Next, 400 nm of tungsten is deposited as the second conductive film 15 by, eg, CVD (FIG. 7C).
[0133]
Next, tungsten other than in the hole 13 is polished halfway with a slurry made of alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent (FIG. 7 (d)). Alternatively, polishing is performed until the oxide film is not partially exposed. The polishing pad used here is, for example, urethane foam, and the polishing pressure is 3 psi and the platen rotation speed is about 30 rpm. The polishing in this step removes most of the tungsten, so that the polishing time becomes long, and there is a concern about the vibration of the polishing apparatus when silica is used as the abrasive particles. Therefore, there is an effect of suppressing vibration by using alumina particles having low resistance during polishing.
[0134]
Next, second polishing is performed so that titanium nitride / titanium is left to some extent in a slurry of silica as abrasive particles and hydrogen peroxide, iron nitrate, or potassium iodate as an oxidant, and tungsten in the holes 13 is obtained. The plug 16 is left (FIG. 7E). The polishing conditions for the second polishing are the same as those for the first polishing. For example, a urethane pad is used as the polishing pad, the polishing pressure is 3 psi, and the rotation speed of the platen is about 30 rpm. The plug recess is about 20 nm. By using silica particles, even if the surface of the oxide film is exposed, scratches hardly occur, and removal of the abrasive particles is facilitated in the next cleaning step. In addition, since the polishing time is short, the polishing apparatus does not vibrate.
[0135]
Next, although not shown, cleaning after polishing such as ammonia or hydrofluoric acid is performed, and a wiring material 18 is deposited on the entire surface of the substrate (FIG. 7F). Wiring in an extra region is performed by lithography and dry etching. The material and titanium nitride / titanium are removed at a time to form the wiring 19 (FIG. 7G). The wiring material is an alloy of aluminum and copper. In the embodiment of the present invention, the plug recess can be suppressed to about 20 nm as compared with the fourth embodiment, so that the wiring on the plug is flat.
(Eighth embodiment: claims 8, 9,17Corresponding to)
A semiconductor device manufacturing method according to the eighth embodiment of the present invention will be described below with reference to FIGS.
[0136]
An oxide film 12 of 1 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, eg, CVD, and a hole 13 having a diameter of, eg, 0.3 μm is formed by lithography and dry etching. The bottom of the hole 13 is connected to a substrate or wiring (FIG. 8A).
[0137]
Next, as the first conductive film 14, 20 nm of titanium and 50 nm of titanium nitride are deposited by, for example, sputtering (FIG. 8B).
[0138]
Next, 400 nm of tungsten is deposited as the second conductive film 15 by, eg, CVD (FIG. 8C).
[0139]
Next, polishing is performed using silica or alumina as the abrasive particles and abrasive particles made of hydrogen peroxide, iron nitrate, potassium iodate or the like as the oxidant to completely remove tungsten other than in the holes 13 and nitride Titanium / titanium is left to some extent, and the tungsten plug 16 is left in the hole 13 (FIG. 8D). Ideally, the same amount of titanium nitride / titanium should remain in the substrate plane, but in reality, due to the in-plane nonuniformity of the polishing rate, the oxide film is exposed in a certain part of the substrate surface, and the oxide film Although film loss may occur, it is not a process that completely removes titanium nitride / titanium, so the film loss is not so great. The polishing pad used here is, for example, urethane foam, and the polishing pressure is 3 psi and the platen rotation speed is about 30 rpm. When the slurry is used, the polishing rate of titanium nitride is 1 or more times higher than the polishing rate of tungsten, so it is somewhat difficult to leave titanium nitride, but the polishing rate of titanium is about 0.5 times higher. Since it is as follows, it is possible to leave titanium to some extent. The plug recess is about 20 nm generated by polishing.
[0140]
Next, although not shown, cleaning with ammonia, hydrofluoric acid or the like is performed, and a wiring material 18 is deposited on the entire surface of the substrate (FIG. 8 (e)). Titanium / titanium is removed at a time to form a wiring 19 (FIG. 8F). The wiring material is, for example, titanium nitride / titanium / aluminum and copper alloy / titanium nitride / titanium in order from the top. Since the plug recess is about 20 nm, the wiring on the plug is flat.
[0141]
Each of the combinations of the abrasive particles and the oxidizing agent in the slurry has advantages and disadvantages. Focusing on the abrasive particles, alumina tends to cause scratches on the surface of the oxide film and is difficult to remove by cleaning after polishing. Silica has a large resistance during polishing, and may vibrate depending on the apparatus. In that case, it is better to avoid polishing tungsten for several minutes (it is possible for a short time).
[0142]
When attention is paid to the oxidizing agent, since hydrogen peroxide dissolves tungsten, the joint portion of tungsten in the hole 13 spreads. Iron nitrate and potassium iodate have problems with iron and potassium contamination. Therefore, the selection of the abrasive particles and the oxidizing agent is determined by judging the above items. In the case of this embodiment, since the polishing time of tungsten becomes long, it is better not to use silica particles if the polishing apparatus vibrates.
[0143]
In the embodiment of the present invention, as in the seventh embodiment, since polishing is performed from a state where tungsten is deposited, the influence of non-uniformity of the polishing rate within the substrate surface acts, and the seventh embodiment The same amount of oxide film is reduced. The advantage of this embodiment is that the step of thinning tungsten by dry etching, polishing, etc. can be eliminated outside the hole 13, so that tungsten can be removed in one step, and the production cost can be greatly reduced. .
(Reference example)
Less than,Manufacturing method of semiconductor deviceReference exampleWill be described with reference to FIGS. In this embodiment, in the formation of the embedded wiring, the wiring material is removed by forming the embedded wiring on the conductive film deposited on the insulating film, and then removing the unnecessary conductive film by dry etching. The purpose is to form a buried wiring without almost reducing the thickness.
[0144]
An oxide film 12 of 1.0 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, for example, a CVD method, and a hole 32 and a trench 31 are formed by lithography and dry etching. The bottom of the hole 32 is connected to a substrate or wiring (FIG. 9A).
[0145]
Next, as the conductive film 33, 35 nm of tantalum nitride and 150 nm of copper are deposited by sputtering, for example (FIG. 9B).
[0146]
Next, 1000 nm of copper is grown as the wiring material 34 by plating using the copper on the conductive film 33 as a seed crystal (FIG. 9C).
[0147]
Next, copper other than in the trench 31 is completely removed with a slurry composed of alumina or silica as abrasive particles and hydrogen peroxide as an oxidant, and tantalum nitride is left to some extent to leave the hole 32 and in the trench 31. The copper embedded wiring 35 is left inside (FIG. 9D). Since the polishing rate of tantalum nitride is about 0.02 times that of copper, tantalum nitride is hardly polished and only copper can be easily polished. In this case, since there is almost no reduction in the oxide film portion, the reduction in the copper wiring film thickness is about 50 nm.
[0148]
Next, tantalum nitride other than the inside of the wiring is removed by lithography and dry etching using the same mask as that used for forming the wiring (FIG. 9E).
[0149]
BookReference exampleThus, the buried wiring 35 can be formed with almost no decrease in the oxide film portion.
(No.9(Corresponding to claims 10, 11, 12, 13, and 17)
Hereinafter, the present invention9A method of manufacturing a semiconductor device according to the embodiment will be described with reference to FIGS. 10 (a) to 10 (g) and FIGS. 11 (a) to 11 (g). The purpose of this embodiment is to reduce scratches by slightly polishing after the tungsten removing step in the eighth embodiment.
[0150]
An oxide film 12 of 1 μm is deposited as an insulating film on the semiconductor or insulating substrate 11 by, eg, CVD, and a hole 13 having a diameter of 0.3 μm, for example, is formed by lithography and dry etching. The bottom of the hole 13 is connected to a substrate or wiring (FIG. 10A).
[0151]
Next, as the first conductive film 14, 20 nm of titanium and 50 nm of titanium nitride are deposited, for example, by sputtering (FIG. 10B).
[0152]
Next, 400 nm of tungsten is deposited as the second conductive film 15 by, eg, CVD (FIG. 10C).
[0153]
Next, tungsten other than the inside of the hole 13 is completely removed with a slurry made of alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and titanium nitride / titanium is intentionally left to some extent, The tungsten plug 16 is left in the hole 13 (FIG. 10D). Alumina was selected as the abrasive particles because of concern about vibration of the polishing apparatus. Ideally, the same amount of titanium nitride / titanium remains in the substrate surface, but in reality, due to the in-plane non-uniformity of the polishing rate described above, an oxide film is exposed in a portion of the substrate surface, and oxidation Although film reduction may occur, the film reduction is not so great because it is not a process that completely removes titanium nitride / titanium. The polishing pad used here is, for example, urethane foam, and the polishing pressure is 3 psi and the platen rotation speed is about 30 rpm. When the slurry is used, the polishing rate of titanium nitride is 1 or more times higher than the polishing rate of tungsten, so it is somewhat difficult to leave titanium nitride, but the polishing rate of titanium is about 0.5 times higher. Since it is as follows, it is possible to leave titanium. In particular, iron nitrate is the easiest to stop with titanium (polishing rate is about 0.2 times). The plug recess is about 20 nm.
[0154]
Since the above-mentioned slurry uses alumina, it is difficult to remove it by post-cleaning, and scratches are likely to enter at portions where the oxide film is exposed. Therefore, a small amount of second polishing is performed with a slurry composed of silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as oxidizing agents (FIG. 10 (e)), and the remaining alumina particles are dropped. If more scratches are generated, the portion is smoothed. The plug recess is also about 20 nm.
[0155]
Next, although not shown, cleaning after polishing such as ammonia or hydrofluoric acid is performed, and a wiring material 18 is deposited on the entire surface of the substrate (FIG. 10F). Wiring in an extra region is performed by lithography and dry etching. The material and titanium nitride / titanium are removed at a time to form the wiring 19 (FIG. 10G). The wiring material is an alloy of aluminum and copper. Since the plug recess is about 20 nm, the wiring on the plug is flat.
[0156]
The first polishing is performed with a slurry of iron nitrate or potassium iodate as an oxidant and alumina or silica as an abrasive particle, and the second polishing is hydrogen peroxide as an oxidant and alumina as an abrasive particle. Or the method performed with the slurry which consists of silicas is also mentioned. The main purpose of this method is to reduce the spread of tungsten joints in the plug and to reduce contamination. Hydrogen peroxide has the effect of expanding the joint, but this is not a problem because the polishing time of the second polishing is short.
[0157]
Further, the first polishing is performed with a slurry of alumina or silica as polishing particles, hydrogen peroxide, iron nitrate, or potassium iodate as an oxidizing agent, and the second polishing is performed with silica as polishing particles and pH adjustment. There is a technique performed in a slurry comprising ammonium hydroxide or potassium hydroxide as an agent. This process flow will be described with reference to FIG.
[0158]
Since FIGS. 11A to 11C are the same as FIGS. 10A to 10C, the description thereof will be omitted, and the description will be made from FIG. 11D.
[0159]
Tungsten other than in the hole 13 is completely removed with a slurry made of alumina or silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and titanium nitride / titanium is intentionally left to some extent. The tungsten plug 13 is left in 13 (FIG. 11D). The polishing pad used here is, for example, urethane foam, and the polishing pressure is 3 psi and the platen rotation speed is about 30 rpm. When the slurry is used, the polishing rate of titanium nitride is 1 or more times that of tungsten, so it is somewhat difficult to leave titanium nitride, but the polishing rate of titanium is about 0.5 times. Since it is as follows, it is possible to leave titanium. The plug recess is about 20 nm.
[0160]
Next, a small amount of polishing so that titanium nitride / titanium remains to some extent in a slurry generally composed of silica as abrasive particles and ammonium hydroxide or potassium hydroxide as a pH adjuster and generally used for polishing an oxide film. Is performed (FIG. 11E). In this slurry, tungsten is not polished at all, so there is almost no plug recess or a convex state. However, since the rate of titanium nitride is about 0.3 times and the rate of titanium is about 0.5 times the oxide film polishing rate, the oxide film reduction rate increases in the region where the oxide film is exposed. Therefore, attention is necessary. The pH may be neutral or acidic instead of alkali. When alumina particles are used for the first polishing, the second polishing is effective in reducing scratches and removing alumina particles. Further, when iron nitrate or potassium iodate is used for the first polishing, the second polishing is effective in removing contamination.
[0161]
Next, although not shown, cleaning after polishing such as ammonia or hydrofluoric acid is performed, and a wiring material obtained by adding a little copper to aluminum is deposited on the entire surface of the substrate (FIG. 11F), and lithography and dry etching are performed. Then, the wiring material and the titanium nitride / titanium in the excess region are removed at a time to form a wiring (FIG. 11G). The wiring material is an alloy of aluminum and copper. Since there is almost no plug recess or is in a convex state, the wiring on the plug becomes flat and the reliability of the wiring is improved.
[0162]
【The invention's effect】
According to the method of manufacturing a semiconductor device of the first aspect, the yield can be improved and the reliability of the wiring can be improved as compared with the conventional tungsten plug formation using only etching. Further, the reduction in the thickness of the insulating film can be reduced as compared with the conventional tungsten plug formation using polishing.
[0163]
According to the method for manufacturing a semiconductor device according to claim 2, the method according to claim 1 can be achieved by using an existing tungsten polishing slurry.
[0164]
According to the method for manufacturing a semiconductor device according to the third aspect, the method according to the first aspect can be achieved with the existing slurry for polishing an oxide film.
[0165]
According to the semiconductor device manufacturing method of the fourth aspect, the yield can be improved as compared with the conventional tungsten plug formation using only etching.
[0166]
According to the semiconductor device manufacturing method of the fifth aspect, the method of the fourth aspect can be achieved with the existing abrasive particles.
[0167]
According to the semiconductor device manufacturing method of the sixth aspect, the yield can be improved to some extent as compared with the conventional tungsten plug formation using only etching.
[0168]
According to the semiconductor device manufacturing method of the seventh aspect, the reduction in the thickness of the insulating film can be reduced as compared with the tungsten plug formation using the conventional polishing. In addition, the load on the polishing apparatus can be reduced. Further, the yield can be improved and the reliability of the wiring can be improved as compared with the conventional tungsten plug formation using only etching.
[0169]
According to the semiconductor device manufacturing method of the eighth aspect, the reduction in the thickness of the insulating film can be reduced as compared with the tungsten plug formation using the conventional polishing.
[0170]
According to the method for manufacturing a semiconductor device according to the ninth aspect, the method according to the eighth aspect can be achieved by using an existing tungsten polishing slurry.
[0171]
According to the semiconductor device manufacturing method of the tenth aspect, the yield, reliability, device operation, and the like can be improved by using the advantages of the first and second polishing. The thickness of the insulating film can be reduced as compared with the conventional tungsten plug formation using polishing.
[0172]
According to the semiconductor device manufacturing method of the eleventh aspect, since there are few scratches and the abrasive particles can be easily removed by washing, the yield can be improved and the operation of the polishing apparatus can be improved.
[0173]
According to the semiconductor device manufacturing method of the twelfth aspect, contamination can be reduced.
[0174]
According to the semiconductor device manufacturing method of the thirteenth aspect, since the scratches are small, the yield can be improved.
[0175]
According to the method for manufacturing a semiconductor device of the fourteenth aspect, the reduction in the thickness of the insulating film can be reduced as compared with the formation of the tungsten plug using the conventional polishing. Further, scratches can be reduced as compared with the method according to claim 11, and removal of abrasive particles by post-cleaning is easy.
[0176]
According to the method for manufacturing a semiconductor device according to claim 15, by using the advantages of each of the first and second polishing, compared with conventional tungsten plug formation using polishing, yield, reliability, device operation, etc. Can be improved.Further, scratches can be reduced and the yield can be improved.
[0178]
Claim16According to the method for manufacturing a semiconductor device described above, the yield, reliability, operation of the device, and the like are improved by using the advantages of the first and second polishing as compared with the formation of the tungsten plug using the conventional polishing. be able to.Further, scratches can be reduced and the yield can be improved.
[0181]
Claim17According to the described method for manufacturing a semiconductor device, it is effective for forming a tungsten plug.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing each step of a semiconductor manufacturing apparatus according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing each step of a semiconductor manufacturing apparatus according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view showing each step of a semiconductor manufacturing apparatus according to third and fourth embodiments of the present invention.
FIG. 4 is a cross-sectional view showing each step of a semiconductor manufacturing apparatus according to a fifth embodiment of the present invention.
FIG. 5 is a cross-sectional view showing each step of a semiconductor manufacturing apparatus according to a fifth embodiment of the present invention.
FIG. 6 is a cross-sectional view showing each step of a semiconductor manufacturing apparatus according to a sixth embodiment of the present invention.
FIG. 7 is a cross-sectional view showing each step of a semiconductor manufacturing apparatus according to a seventh embodiment of the present invention.
FIG. 8 is a cross-sectional view showing each step of a semiconductor manufacturing apparatus according to an eighth embodiment of the present invention.
FIG. 9HalfConductor manufacturing equipmentReference exampleIt is sectional drawing which shows each process.
FIG. 10 shows the first of the invention9It is sectional drawing which shows each process of the semiconductor manufacturing apparatus which concerns on this embodiment.
[Fig. 11] Fig. 119It is sectional drawing which shows each process of the semiconductor manufacturing apparatus which concerns on this embodiment.
FIG. 12 is a cross-sectional view showing each step of the semiconductor manufacturing method of the first conventional technique.
FIG. 13 is a cross-sectional view showing each step of a semiconductor manufacturing method according to a second conventional technique.
FIG. 14 is a cross-sectional view showing each step of a semiconductor manufacturing method according to a third conventional technique.
FIG. 15 is a cross-sectional view showing each process of a semiconductor manufacturing method according to a fourth conventional technique.
FIG. 16 is a cross-sectional view showing each step of a semiconductor manufacturing method according to a fifth conventional technique.
[Explanation of symbols]
11 Substrate
12 Oxide film
13 holes
14 First conductive film
15 Second conductive film
16 Tungsten plug
17 Etching residue
18 Wiring material
19 Wiring
31 trench
32 holes
33 conductive film
34 Wiring material
35 Embedded wiring

Claims (17)

Depositing an insulating film on the substrate;
Forming an opening in the insulating film;
Depositing a first conductive film on the insulating film;
Depositing a second conductive film on the first conductive film;
Completely removing the second conductive film other than in the opening by dry etching and leaving a certain amount of the first conductive film;
Removing a small amount of the first conductive film remaining in a certain amount other than in the opening by polishing;
Depositing wiring material on the entire surface of the substrate;
A method of manufacturing a semiconductor device, including a step of forming wiring by removing the excess wiring material and the first conductive film by dry etching. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the polishing is performed with a slurry comprising alumina or silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as oxidizing agents. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the polishing is performed in a slurry comprising silica as abrasive particles and ammonium hydroxide or potassium hydroxide as a pH adjuster. Depositing an insulating film on the substrate;
Forming an opening in the insulating film;
Depositing a first conductive film on the insulating film;
Depositing a second conductive film on the first conductive film;
Completely removing the second conductive film other than in the opening by dry etching and leaving a certain amount of the first conductive film;
Polishing the first conductive film remaining in a certain amount other than in the opening with a slurry consisting of a liquid that does not chemically react with the first and second conductive films and abrasive particles;
Depositing wiring material on the entire surface of the substrate;
A method of manufacturing a semiconductor device, including a step of forming wiring by removing the excess wiring material and the first conductive film by dry etching. 5. The method of manufacturing a semiconductor device according to claim 4, wherein the abrasive particles are silica, cerium oxide, or alumina. Depositing an insulating film on the substrate;
Forming an opening in the insulating film;
Depositing a first conductive film on the insulating film;
Depositing a second conductive film on the first conductive film;
Completely removing the second conductive film other than in the opening by dry etching and leaving a certain amount of the first conductive film;
Polishing the first conductive film remaining in a certain amount other than in the opening by flowing only water;
Depositing wiring material on the entire surface of the substrate;
A method of manufacturing a semiconductor device, comprising: a step of forming wiring by removing the excess wiring material and the first conductive film by dry etching. Depositing an insulating film on the substrate;
Forming an opening in the insulating film;
Depositing a first conductive film on the insulating film;
Depositing a second conductive film on the first conductive film;
Removing a certain amount of the second conductive film other than in the opening by dry etching;
Completely removing the second conductive film other than in the opening by polishing and removing a certain amount of the first conductive film; and
Depositing wiring material on the entire surface of the substrate;
A method of manufacturing a semiconductor device, including a step of forming wiring by removing the excess wiring material and the first conductive film by dry etching. Depositing an insulating film on the substrate;
Forming an opening in the insulating film;
Depositing a first conductive film on the insulating film;
Depositing a second conductive film on the first conductive film;
A step of completely removing the second conductive film other than in the opening by polishing and removing a certain amount of the first conductive film;
Depositing wiring material on the entire surface of the substrate;
A method of manufacturing a semiconductor device, including a step of forming wiring by removing the excess wiring material and the first conductive film by dry etching. 9. The method of manufacturing a semiconductor device according to claim 7, wherein the polishing is performed with a slurry comprising alumina or silica as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent. Depositing an insulating film on the substrate;
Forming an opening in the insulating film;
Depositing a first conductive film on the insulating film;
Depositing a second conductive film on the first conductive film;
A step of completely removing the second conductive film except the inside of the opening by a first polishing and removing a certain amount of the first conductive film;
Removing the first conductive film except for the inside of the opening by second polishing,
Depositing wiring material on the entire surface of the substrate;
A method of manufacturing a semiconductor device, comprising: a step of forming wiring by removing the excess wiring material and the first conductive film by dry etching. The first polishing is performed with a first slurry composed of alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and the second polishing is performed with silica as an abrasive particle and oxidized. 11. The method of manufacturing a semiconductor device according to claim 10, wherein the method is performed in a second slurry comprising hydrogen peroxide, iron nitrate, or potassium iodate as an agent. The first polishing is performed with a first slurry comprising iron nitrate or potassium iodate as an oxidant and alumina or silica as an abrasive particle, and the second polishing is performed with hydrogen peroxide as an oxidant and polishing. The method for manufacturing a semiconductor device according to claim 10, wherein the method is performed in a second slurry made of alumina or silica as particles. The first polishing is performed with a first slurry composed of silica or alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and the second polishing is performed with silica as abrasive particles. The method for manufacturing a semiconductor device according to claim 10, wherein the method is performed in a second slurry comprising ammonium hydroxide or potassium hydroxide as a pH adjuster. Depositing an insulating film on the substrate;
Forming an opening in the insulating film;
Depositing a first conductive film on the insulating film;
Depositing a second conductive film on the first conductive film;
Removing a certain amount of the second conductive film other than in the opening by first polishing with a first slurry comprising alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent; ,
The second conductive film except for the inside of the opening is completely removed by the second polishing with the second slurry comprising silica as the abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as the oxidizing agent, and the Removing a certain amount of the first conductive film;
Depositing wiring material on the entire surface of the substrate;
A method of manufacturing a semiconductor device, including a step of forming wiring by removing the excess wiring material and the first conductive film by dry etching. Depositing an insulating film on the substrate;
Forming an opening in the insulating film;
Depositing a first conductive film on the insulating film;
Depositing a second conductive film on the first conductive film;
Removing a predetermined amount of the second conductive film other than in the opening by the first polishing;
A step of completely removing the second conductive film and the first conductive film other than in the opening by a second polishing;
Depositing wiring material on the entire surface of the substrate;
Removing the excess wiring material and the first conductive film by dry etching to form a wiring,
The first polishing is performed with a first slurry comprising alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and the second polishing is performed with silica as abrasive particles. A method of manufacturing a semiconductor device, wherein the method is performed in a second slurry comprising hydrogen peroxide, iron nitrate, or potassium iodate as an oxidizing agent. Depositing an insulating film on the substrate;
Forming an opening in the insulating film;
Depositing a first conductive film on the insulating film;
Depositing a second conductive film on the first conductive film;
A step of completely removing the second conductive film other than the inside of the opening by the first polishing and removing a certain amount of the first conductive film;
A step of completely removing the first conductive film other than in the opening by second polishing;
Depositing wiring material on the entire surface of the substrate;
Removing the excess wiring material and the first conductive film by dry etching to form a wiring,
The first polishing is performed with a first slurry comprising alumina as abrasive particles and hydrogen peroxide, iron nitrate or potassium iodate as an oxidizing agent, and the second polishing is performed with silica as abrasive particles. A method of manufacturing a semiconductor device, wherein the method is performed in a second slurry comprising hydrogen peroxide, iron nitrate, or potassium iodate as an oxidizing agent. 17. The semiconductor according to claim 1, wherein the first conductive film is a laminated film of titanium and titanium nitride, and the second conductive film is tungsten. Device manufacturing method.

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