JP3128153B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device having a high-density integrated circuit, and more particularly to a method for preventing occurrence of a connection failure in a contact hole or a via hole.

[0002]

2. Description of the Related Art In recent years, high density and high integration of MOS integrated circuit devices have been advanced. For example, a dynamic RAM having a minimum size of 0.5 μm and a large capacity of 16 Mbit or more has been reported. However, as one of the issues of miniaturization, there is an improvement in microfabrication technology for electrodes and metal wiring. In particular, with respect to metal wiring represented by an aluminum alloy, miniaturization is difficult, and there are many technical problems in forming electrodes and metal wiring in a submicron pattern. This is mainly due to the instability of the connection of the aluminum alloy film in the contact hole and the occurrence of defects due to the adhesion of particles during the deposition of the aluminum alloy film and the barrier metal.

Here, a conventional method for forming electrodes of a semiconductor integrated circuit device will be described with reference to FIGS. 3 and 4. FIG.

FIGS. 3A and 3B show a method of forming an electrode of a semiconductor device using a single layer of aluminum wiring for taking out an electrode. Each part of the electrode is taken out from a diffusion layer formed on a semiconductor substrate. FIG. 4 is a partial process sectional view of the CMOS integrated circuit device showing the above. In FIG. 3A, 10
1 is a P-type silicon substrate, 102a is a silicon substrate 101
P-type well region 102b is also an N-type well region, 103 is an element isolation region made of a silicon dioxide film, 104a and 104b are gate oxide films, 105
Reference numerals a and 105b denote gate electrodes made of polysilicon;
6a is an N-type impurity diffusion layer formed in the P-type well region 102a, 106b is a P-type impurity diffusion layer formed in the N-type well region 102b, and 107 is an interlayer insulating film. In FIG. 3B, reference numeral 8 denotes the interlayer insulating film 107.
The contact hole formed in the silicon substrate is an outlet from the impurity diffusion layers 106a and 106b formed in the silicon substrate. Then, on the substrate after the opening of the contact hole 8, a titanium tungsten film 111 as a refractory metal film and an aluminum alloy film 112 are sequentially deposited by a well-known sputter deposition method. Is formed, and the metal films 111 and 11 are further formed.
2 is performed. Thereafter, a passivation film 113 is deposited to manufacture a CMOS integrated circuit device.

[0005] On the other hand, FIG. 4 shows a conventional example of a semiconductor device using two layers of aluminum wiring for taking out electrodes. In the figure, elements are formed on the main surface of the silicon substrate 101 in the same manner as in FIG. 3, but are omitted for simplification of the figure. Then, the interlayer insulating film 1 is formed on the main surface of the silicon substrate 101.
07, a first aluminum alloy film 112 as a metal film for wiring is formed thereon, and a second interlayer insulating film 1 is further formed.
14, a via hole 9 is opened, and a titanium tungsten film 115 and a second aluminum alloy film 116 are sequentially deposited thereon by a well-known sputter deposition method.

[0006]

However, the conventional method for manufacturing a semiconductor device has the following problems.

First, in the case of using one layer of aluminum wiring, after the contact hole 8 is opened, the surfaces of the diffusion layers 106a and 106b formed on the silicon substrate and the gate electrodes 105a and 105b of polysilicon are exposed. However, since these surfaces are water-repellent, if particles and the like adhere to the exposed surface during the photoresist removal and surface cleaning steps, they are difficult to remove and easily remain in the final step. Furthermore, particles and the like are likely to adhere even during the sputtering process. Then, when the above-mentioned high melting point metal or aluminum alloy film is deposited and an electrode pattern is formed in a state where the particles remain in the contact hole, the long-term reliability and the processing yield of the semiconductor device are reduced.

Also, in a semiconductor device using two-layer aluminum wiring, the aluminum alloy film in the via hole 9 is easily oxidized in the middle of the process, and since these oxide films are generally thick, static electricity easily accumulates. Particles easily adhere. Since dust in the liquid in the cleaning process is easily adsorbed in the via hole 9, when the surface of the first aluminum alloy film 112 is exposed in the via hole 9, particles in the via hole eventually adhere to this surface. Will occur. Furthermore, in order to remove the thick alumina film formed in the middle of the process on the surface of the first aluminum alloy film during the deposition of the second aluminum alloy film, rf etching using reverse sputtering is performed as a pretreatment in a vacuum chamber. However, since the oxide film is etched by the rf etching, the metal oxide-based particles generated in this step are likely to be charged with static electricity, and are likely to become a source of adhesion.

Therefore, adhesion of particles due to these steps is a major problem in improving the processing yield of semiconductor devices and long-term reliability.

The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the generation and adhesion of particles and the like accompanying the exposure of a silicon substrate surface and an aluminum alloy film surface in a semiconductor device manufacturing process. By taking such a measure, it is possible to prevent a connection failure at a contact hole or a via hole, thereby improving the processing yield and reliability of the metal wiring.

[0011]

In order to achieve the above object, a solution of the present invention is to forcibly form an extremely thin oxide film on the exposed silicon or aluminum alloy surface in a contact hole or a via hole. The semiconductor device is manufactured by a method of diffusing and eliminating the oxide film by heat treatment.

Specifically, the means of the invention of claim 1
As method for manufacturing a semi-conductor device, the interlayer insulating film covering element provided on the main surface of the semiconductor substrate, a step of contact holes toward the signal connection portion of the element,
Table of the signal connection part exposed in the contact hole
Forming a thin protective oxide film by immersing the surface in an oxidizing solution, depositing in contact with the source metal layer to oxide film for the protective place on the protective oxide film, the place of a step of depositing a wiring metal film on the original metal film , and a step of heat treatment.
Alloying the multilayer metal film by
The oxide film is obtained by a method comprising the Engineering <br/> extent to disappear reduced by the reducing metal film.

A second aspect of the present invention is that the oxidizing solution according to the first aspect of the present invention comprises the steps of: adding a mixed aqueous solution of hydrogen peroxide and ammonia water, a mixed aqueous solution of hydrogen peroxide and hydrochloric acid, sulfuric acid and hydrogen peroxide; Or fuming nitric acid.

According to a third aspect of the present invention, as shown in FIGS. 2A to 2C, a method for manufacturing a semiconductor device includes an element for covering an element provided on a main surface of a semiconductor substrate. It is assumed that a semiconductor device includes a covering interlayer insulating film, two or more metal wiring layers connected to the above-described element, and a wiring covering interlayer insulating film covering the metal wiring layer.

[0015] As a method of manufacturing a semiconductor device, a step of opening a via hole toward the metal wiring layer in a wiring coating interlayer insulating film that covers a metal wiring layer directly connected to the signal connection portion of the element is provided. And inside the via hole
Forming a thin protective oxide film by immersing the exposed surface of the above metal wiring layer is the oxidizing solution, the protection of the original metal film instead of the top of the coercive <br/> protection oxide film Contact oxide film
Depositing by, gold wiring on said reducing metal film
Depositing a Shokumaku, the multilayered metal film by a heat treatment
Alloying, and replacing the protective oxide film with the reducing metal film
By heat-treating the multilayered metal film to disappear reduced by is obtained by a method comprising the step of alloying.

According to a fourth aspect of the present invention, the oxidizing solution according to the third aspect is fuming nitric acid.

According to a fifth aspect of the present invention, there is provided a semiconductor device according to the first or third aspect, wherein the wiring metal film is a multilayer film comprising a titanium tungsten film or a titanium nitride film and an aluminum alloy film. Things.

[0018]

According to the first aspect of the present invention, after opening the contact hole, the surface of silicon or polysilicon constituting the signal connection portion in the contact hole is covered with a thin protective oxide film. Therefore, since the intermediate steps are carried out in a state where these surfaces are hydrophilic, dust in the liquid is easily removed by washing in the photo etching step, and various metal films are removed by processing such as sputtering. Particles hardly adhere to the openings even in the deposition step, and as a result, the occurrence of poor connection in the contact holes is reduced. On the other hand, the thin protective oxide film is reduced by the reducing metal in the step of alloying the multi-layered metal film by heat treatment and disappears, so that the contact resistance is well maintained.

According to a second aspect of the present invention, in the first aspect, the oxidizing aqueous solution includes a mixed aqueous solution of hydrogen peroxide and ammonia water, a mixed aqueous solution of hydrogen peroxide and hydrochloric acid, and a mixed aqueous solution of sulfuric acid and hydrogen peroxide. Alternatively, since fuming nitric acid is used, an extremely thin oxide film of about 1 nanometer is formed on the silicon or polysilicon surface of the signal connection portion of the element, and a function of suppressing particle adhesion and a function of eliminating by reduction are obtained.

According to the third aspect of the present invention, the subsequent processing proceeds with the surface of the metal wiring layer in the via hole covered with a thin protective oxide film. Therefore, the thicker natural metal oxide film generated in the middle step does not cause static electricity to be charged, and the rf etching is not required, so that the generation of oxide film-based particles that are easily attached is suppressed. In this case, the adhesion of particles and the like is reduced, the occurrence of poor connection is reduced, and the contact resistance is favorably maintained by the same operation as the first aspect of the present invention.

According to a fourth aspect of the present invention, since fuming nitric acid is used as the oxidizing aqueous solution in the third aspect of the present invention, an electrode of about 1 nanometer is formed on the surface of the aluminum alloy film constituting the surface layer of the metal wiring layer. A thin protective oxide film is formed, and a function of suppressing particle adhesion and a function of eliminating by reduction are obtained.

According to a fifth aspect of the present invention, in the first or third aspect,
In the invention of the above, since the metal film for wiring is a multilayer film composed of a titanium tungsten film or a titanium nitride film and an aluminum alloy film, a high melting point metal film is interposed between the reducing metal film and the aluminum alloy film. This reduces the contact resistance.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

First, a first embodiment relating to a semiconductor device having one layer of aluminum wiring will be described with reference to a partial structural sectional view of the CMOS integrated circuit device of FIG. FIG. 1A shows a state immediately after a contact hole is opened, and is a view corresponding to FIG. That is, on the main surface of the P-type silicon substrate 101, the P-type well region 102a and the N-type
b, an element isolation region 103 made of a silicon dioxide film is formed over the P-type well region 102a and the N-type well region 102b, and an N-type impurity is formed on the P-type well region 102a. The diffusion layer 106a has a P-type impurity diffusion layer 106b formed on the N-type well region 102b.

Further, there is provided an interlayer insulating film 107 made of a silicon dioxide film covering the surface of each part, and the interlayer insulating film 107 has an impurity diffusion layer as a signal connection part formed on the silicon substrate. Contact holes 8 are opened toward 106a and 106b, respectively.

Reference numerals 104a and 104b denote gate oxide films of an N channel portion and a P channel portion, respectively.
Reference numerals a and 105b denote gate electrodes made of polysilicon, respectively. Since these gate electrodes 105a and 105b are also signal connection portions, contact holes are opened, but are not shown in this drawing.

Next, as shown in FIG. 1B, the impurity diffusion layers 106a, 106a,
A thin protective oxide film 1 is grown on the surface of 106b.
This protective oxide film 1 is formed by photolithography.
After opening part of 07, immersion in an oxidizing solution, for example, a mixed aqueous solution of hydrogen peroxide and ammonia water, a mixed aqueous solution of hydrogen peroxide and hydrochloric acid, a mixed aqueous solution of sulfuric acid and hydrogen peroxide, or fuming nitric acid Accordingly, the surface portion of silicon is oxidized to form a thin silicon dioxide film. then,
For example, in a mixed aqueous solution of hydrogen peroxide and ammonia water, the mixing ratio of hydrogen peroxide, ammonia water, and water is 1: 1: 10.
(Volume ratio), the protective oxide film 1 is formed with a thickness of about 1 nanometer on silicon at 70 ° C. for 20 minutes. Although the protective oxide film 1 may be formed by using another acidic aqueous solution, it is desirable that the thickness be up to about 2 nanometers in consideration of disappearance later.

Further, as shown in FIG. 1C, titanium, titanium tungsten, and aluminum alloy are sequentially deposited by a sputter deposition method, and a titanium film 1 is sequentially deposited from below.
10. After depositing the titanium tungsten film 111 and the aluminum alloy film 112, an electrode pattern is formed by photolithography.

Finally, as shown in FIG. 1 (d), each metal atom is interdiffused by heating to 450 ° C. in a hydrogen atmosphere to alloy each metal film 110, 111, 112. , Passivation film 1 made of silicon nitride film
13 is deposited. At this time, the thin protective oxide film 1 in FIG. 1B is reduced by titanium and disappears when heat treatment is performed in hydrogen at 450 ° C. That is,
By interposing the titanium film 110 between the protective oxide film 1 and the titanium tungsten film 111, the thin protective oxide film 1 on the silicon surface is reduced to silicon and eliminated. In other words, up to the heat treatment step, the intermediate step is performed with the silicon surface in the contact hole 8 covered with the protective oxide film 1. If the thickness of the titanium film 110 is 30 nanometers or more, it is enough to reduce and eliminate the protective oxide film 1.

As described above, in the first embodiment, after the contact hole 8 is opened, the thin protective oxide film 1 is grown on the silicon surface exposed in the contact hole 8 while also cleaning the surface. Since the titanium film 110 is deposited and the titanium film 110 is interposed between the protective oxide film 1 and the titanium tungsten film 111, the silicon surface in the contact hole 8 is covered with the protective oxide film 1, The intermediate process can be performed in a state of being hydrophilic. Therefore, in the photolithography process, even if dust in the liquid adheres, it is easily removed by washing, and a reducing metal film such as a titanium film 110, a titanium tungsten film 111, an aluminum alloy film is formed by a treatment such as sputtering. Even in the step of depositing 112 or the like, particles hardly adhere to the opening, and the number of particles remaining in the contact hole 8 finally decreases. As a result, the occurrence of connection failure in the contact hole 8 is reduced.

On the other hand, the protective oxide film 1 is made of a titanium film 11
In the alloying step of the titanium tungsten film 111 and the aluminum alloy film 112, the resistance of titanium which has been reduced by titanium and disappeared and has absorbed oxygen has a small change in the electrical resistance value, and the contact resistance value is small. Is no different from the conventional structure. The same applies to the contact resistance value with polycrystalline silicon. Further, it is unknown whether a part of the oxidized titanium evaporates or remains after absorbing oxygen, but there is no problem at all from the resistance value and the long-term reliability evaluation of the device.

In the first embodiment, an example in which a titanium tungsten film is used has been described. However, similar effects can be obtained by using a titanium nitride film.

Next, a second embodiment of the present invention will be described. FIG. 2 shows a CMOS having two layers of aluminum wiring.
This shows the manufacturing process of the integrated circuit device, and similarly to FIG. 4 in the above-mentioned conventional example, for simplification, the element portion is omitted and only the two-layer aluminum wiring portion is shown.

First, as shown in FIG. 2A, a P-type silicon substrate 101 is covered with a first interlayer insulating film 107, similarly to FIG. On the insulating film 107, the first aluminum alloy film 1
12 and a second interlayer insulating film 114 are formed, and the second interlayer insulating film 114
Is opened, and a connection port with the first aluminum alloy film 112 is exposed.

Next, as shown in FIG. 2B, the surface of the first aluminum alloy film 112 is dipped in fuming nitric acid to oxidize the surface and simultaneously remove the organic components adhering to the surface. . By this processing, a thin protective oxide film 2 is formed on the surface of the first aluminum alloy film 112. Then, the titanium film 11 is formed by a sputter deposition method.
5. After the titanium tungsten film 116 and the aluminum alloy film 117 are successively deposited, a pattern of an electrode wiring is formed by a known photolithography method. When this is alloyed at 450 ° C. as in the first embodiment, the thin protective oxide film 2 on the first aluminum alloy film 112 is reduced and disappears.

Therefore, in the second embodiment, the first aluminum alloy film 1 serving as the electric wiring layer in the via hole 9 is formed.
In the state where the surface of the substrate 12 is covered with the thin protective oxide film 2, an intermediate step is performed. This protective oxide film 2 is less likely to generate static electricity than a naturally thick alumina oxide film generated in the middle of the process without an oxide film, and is less likely to adhere particles and the like during processing. Further, since the rf etching for removing the natural alumina oxide film is not required, there is almost no generation of alumina which is easily charged with static electricity. Therefore, the amount of attached particles can be reduced, and the occurrence of poor connection can be suppressed. In addition, in the step of alloying at 450 ° C., the protective oxide film 2 on the first aluminum alloy layer 112 is reduced and disappears, and the contact resistance is maintained well as in the first embodiment.

As in the case of the first embodiment, the same effect as that of the titanium tungsten film can be obtained by using titanium nitride as the high melting point metal film.

The surface can be oxidized with various oxidizing solutions. Particularly, in a process in which no metal is used in the hole, a mixed aqueous solution of hydrogen peroxide and ammonia water, a mixed aqueous solution of hydrogen peroxide and hydrochloric acid are used. A mixed aqueous solution of sulfuric acid and hydrogen peroxide is preferable. In a process using a metal film such as an aluminum alloy, it is possible to oxidize with fuming nitric acid.

Further, in each of the above embodiments, a titanium tungsten film 111 (or 116), which is a high melting point metal film, is deposited on the titanium film 110 (or 115) as a wiring metal film, and an aluminum Although the alloy film 112 (or 117) is deposited, the aluminum alloy film 112 (or 117) may be deposited directly on the titanium film 110 (or 115), for example, without the refractory metal film. However, by interposing the high-melting-point metal film 111 (or 116) in the middle, the contact resistance can be reduced as described above, and therefore, a remarkable effect can be exhibited.

Further, in each of the above embodiments, a metal having a reducing power other than titanium can be applied to the material forming the reducing metal film.

[0041]

According to the first aspect of the present invention, as a method of manufacturing a semiconductor device, a contact hole is opened in an interlayer insulating film toward a connection portion of an element, and a surface of the connection portion of the element exposed in the contact hole is provided. Is immersed in an oxidizing solution to form a thin protective oxide film and hydrophilize the surface, then successively deposit a reducing metal film such as titanium and a metal film for wiring, and heat-treat the alloy after forming the electrode pattern. And the thin protective oxide film is eliminated, so that the adhesion of particles in the contact holes can be suppressed and the contact resistance characteristics can be maintained favorably. , While increasing the density of the integrated circuit.

According to a second aspect of the present invention, in the first aspect, the oxidizing solution is a mixed aqueous solution of hydrogen peroxide and ammonia water, a mixed aqueous solution of hydrogen peroxide and hydrochloric acid,
Since a mixed aqueous solution of sulfuric acid and hydrogen peroxide or fuming nitric acid is used, a very thin protective oxide film can be formed on the surface of the connection portion of the element, thereby improving the effect of suppressing adhesion of particles and reducing and eliminating the protective oxide film. And the contact resistance can be improved.

According to the third aspect of the present invention, as a method of manufacturing a semiconductor device, an interlayer insulating film for element covering, two or more metal wiring layers, and an interlayer insulating film for wiring covering each metal wiring layer are provided. As a method of manufacturing a semiconductor device provided with, a via hole is opened toward a metal wiring layer in a wiring coating interlayer insulating film that covers a metal wiring layer directly connected to a signal connection portion of an element. After immersing the exposed surface of the metal wiring layer in the oxidizing solution to form a thin protective oxide film, a reducing metal film such as titanium and the next wiring metal film are successively deposited thereon, and the electrode is formed. Since the alloy is formed by heat treatment after forming the pattern, the process can be performed in a state where it is protected by a thin protective oxide film instead of a thick natural oxide film generated in an intermediate process, and thus has a multilayer metal wiring layer. About semiconductor devices It is possible to obtain the same effect as the invention of the claim 1.

According to the invention of claim 4, in the invention of claim 3, since the oxidizing solution is fuming nitric acid, an extremely thin protective oxide film can be formed on the surface of the metal wiring layer, and particles adhere. It is possible to improve the suppression effect and improve the contact resistance due to reduction and disappearance of the protective oxide film.

According to the fifth aspect of the present invention, in the first or third aspect of the present invention, the wiring metal film is a multilayer film of a titanium tungsten film or a titanium nitride film and an aluminum alloy film, so that the contact resistance characteristic is improved. Can be maintained satisfactorily, and the remarkable effects of the above inventions can be exerted.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram illustrating a method for manufacturing a semiconductor device according to a first embodiment.

FIG. 2 is a manufacturing process diagram illustrating a method for manufacturing a semiconductor device according to a second embodiment.

FIG. 3 is a manufacturing process diagram showing a conventional method for manufacturing a semiconductor device having a single-layer aluminum wiring.

FIG. 4 is a manufacturing process diagram according to a conventional method for manufacturing a semiconductor device having two-layer aluminum wiring.

[Explanation of symbols]

1, 2 protective oxide film 8 contact hole 9 via hole 101 silicon substrate 105a, 105b gate electrode (signal connection portion) 106a N-type impurity diffusion layer (signal connection portion) 106b P-type impurity diffusion layer (signal connection portion) 107 interlayer Insulating films 110, 115 Titanium film (reducing metal film) 111, 116 Titanium tungsten film (high melting point metal film) 112, 117 Aluminum alloy film 114 Second interlayer insulating film (interlayer insulating film for wiring coating)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI H01L 21/88 R (58) Investigated field (Int.Cl. ⁷ , DB name) H01L 21/28 H01L 21/285 301 H01L 21 / 768 H01L 21/283 H01L 21/3205

Claims (5)

(57) [Claims] To 1. A interlayer insulating film covering the element provided on the main surface of the semiconductor substrate, a step of contact holes toward the signal connection portion of the device, the contact holes
Forming a thin protective oxide film by immersing the surface of the signal connection portion exposed in the device in an oxidizing solution;
The protective oxidation of the original metal film instead of the top of the protective oxide film
Depositing in contact with the film, distribution on the reducing metal film
A step of depositing a wire metal film, and a heat treatment
Alloying the metal film and converting the protective oxide film to the reducing property
The method of manufacturing a semiconductor device which comprises a step of eliminating by reduction with a metal film. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the oxidizing solution is a mixed aqueous solution of hydrogen peroxide and ammonia water, a mixed aqueous solution of hydrogen peroxide and hydrochloric acid, or a mixed aqueous solution of sulfuric acid and hydrogen peroxide. A method for manufacturing a semiconductor device, wherein the method is fuming nitric acid. 3. A device for covering the interlayer insulating film covering the element provided on the main surface of the semiconductor substrate, and two or more layers of metal wiring layer connected to the element, the wiring cover for covering the metal wiring layer A method of manufacturing a semiconductor device, comprising: an interconnect insulating film for covering a metal wiring layer directly connected to a signal connection portion of the element; Opening a hole, and
In forming a thin protective oxide film by immersing the exposed surface of the above metal wiring layer is the oxidizing solution, the protection of the original metal film instead of the top of the <br/> protective oxide film Oxide film
Depositing in contact, wiring on said reducing metal film
A step of depositing a metal film and the above-described multilayer metal film by heat treatment
Alloying the protective oxide film with the reducing metal
The method of manufacturing a semiconductor device which comprises a step of alloying by heat-treating the multilayered metal film to disappear reduced by membrane. 4. The method for manufacturing a semiconductor device according to claim 3, wherein the oxidizing solution is fuming nitric acid. 5. The semiconductor manufacturing method according to claim 1, wherein the wiring metal film is a multilayer film including a titanium tungsten film or a titanium nitride film and an aluminum alloy film. Device manufacturing method.