JPS63248172A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To attain the improvement of the insulating properties of a gate oxide film and the lowering of the resistance of an impurity diffusion layer without having an adverse effect on electrical characteristics by implanting ions, using a gate electrode consisting of a polycrystalline layer, etc., as a mask, forming the gate oxide film and substituting a metal for the gate electrode in an atmosphere containing the metal. CONSTITUTION:When ions are implanted to a semiconductor substrate 101, employing a gate electrode 108 composed of a polycrystalline layer, which is shaped onto an oxide film 104 on the substrate 101 and in which oxidation-resistant films are laminated, as a mask, impurity diffusion layers 107 are formed excellently because the mask is not shaped by a metallic layer. When the side face sections of the electrode 108 are oxidized and a polycrystalline section is oxidized, oxide films 110 as excellent insulating films, at edge sections of which film thickness is ensured sufficiently, are shaped. When the oxidation-resistant films are etched and a metallic gate electrode 112 is substituted for the gate electrode in an atmosphere including a metal, a sufficiently thick resistance metallic layer 113 is formed onto impurity diffusion layers 111 at the same time, thus preparing a semiconductor device in which the improvement of the insulating properties of a gate oxide film and the lowering of the resistance of the impurity diffusion layers are attained without having an effect on electrical characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of manufacturing a semiconductor device that includes a step of attaching metal to a metal gate or a diffusion layer.

(Prior Art) In order to increase the speed of semiconductor devices, a process of attaching metal to metal gates and diffusion layers is performed.

FIG. 2 shows an example of a conventional method for manufacturing such a semiconductor device. First, as shown in Figure 2(a),
A SIO 2 is formed in a predetermined shape on a semiconductor substrate 1 made of P-type silicon using a selective oxidation method (LOCOS method) to form a field oxide film 2 . A portion surrounded by this field oxide film 2 becomes an element region 3. Next, the second
As shown in Figure (b), 5102 was heated to 10% by thermal oxidation.
The oxide film 4 is formed to a thickness of 0.0 nm, and then tungsten is deposited to a thickness of 2000 nm by sputter deposition to form a metal layer 5.

Next, as shown in FIG. 2(C), using a resist formed into a predetermined pattern by photolithography as a mask, the metal layer 5 is etched by anisotropic etching.
The oxide film 4 is etched using F solution or the like, and the resist is removed to form the gate oxide film 4' and the gate electrode 5.
′ is formed.

After that, using the gate electrode 5' as a mask, 35k e of phosphorus is added.
Ions are implanted at a density of 4.times.10.sup.13/cd using an acceleration energy of V to form a diffusion layer 6. Next, chemical energy (
S io 2 is deposited to a thickness of 2000 Å using a solar growth method, and this is further etched by anisotropic etching to obtain an oxide layer 7. Then, the gate electrode 5' and the oxide layer 7
Using arsenic as a mask with an acceleration energy of 40 keV,
Diffusion layer 8 is formed by ion implantation at a density of X 1015/cd.
form. Diffusion layers 6 and 8 formed in this way
is electrically activated by maintaining it at 900'C in a nitrogen atmosphere and performing a heat treatment for 60 minutes.

Next, as shown in FIG. 2(d), tungsten is selectively deposited by chemical vapor deposition using WFe.
A metal film 9 is formed. Thereafter, as shown in FIG. 2(e), SIO2 was grown at 5000A by chemical vapor deposition.
The oxide layer 10 is deposited to a thickness of . Further, this oxide layer 10 is etched using a resist having a predetermined pattern formed thereon by photolithography as a mask to open a contact hole 11. Next, the resist was removed, aluminum was deposited to a thickness of 4,000 wafers using the sputter evaporation method, and anisotropic etching was performed again using the resist with a predetermined pattern formed by photolithography as a mask.
A wiring layer 12 is formed.

In the manner described above, the metal wiring layer 12 is attached to the gate electrode 5' and the diffusion layer 8.

(Problems to be Solved by the Invention) However, the conventional semiconductor device manufacturing method described above has the following problems.

(1) Adversely affects the electrical characteristics of the element.

In the final ion implantation process for forming the diffusion layer 6.8, the gate voltage t! i5' is used as a mask, but since metals such as tungsten and molybdenum have poor masking properties for implanted ions, ions penetrate through the gate electrode 5' and are implanted under the gate electrode in the substrate, affecting the electrical characteristics of the device. may have an adverse effect on

(2) The insulation of the gate oxide film is low.

Generally, in devices using polysilicon as gate electrodes, an additional thermal oxidation process is performed to strengthen the electrical insulation properties of the gate oxide film, particularly the breakdown voltage at the edges. However, when high-melting point metals such as tungsten and molybdenum are used for the gate electrode, these metals have poor oxidation resistance, making it difficult to perform the thermal oxidation process. There is also a method of oxidizing, for example, using an oxidation method that uses a reduction reaction between hydrogen and tungsten oxide, but since the oxide film does not become thick on the gate electrode side at the edge of the gate oxide film, sufficient insulation is not achieved. cannot be secured.

(3) It is not possible to reduce the resistance of the impurity diffusion layer.

As shown in FIG. 2(d), an oxide layer 7 is provided to prevent short circuit between the gate electrode 5' and the diffusion layer 6.8 when forming the metal film 9. Therefore, metal film 9 is not formed under this oxide layer 7. As a result, the LDD (LlgMIy Doped Dr.
ain) structure, the electrical resistance between impurity region 6 and metal film 9 will be high. This region poses a major problem because it is the most important part for increasing the speed of the device and is the part where the resistance should be made as low as possible.

Therefore, the present invention provides a method that does not adversely affect the electrical characteristics of the element.
It is an object of the present invention to provide a method for manufacturing a semiconductor device that can improve the insulation properties of a gate oxide film and lower the resistance of an impurity diffusion layer.

[(I'4) of the invention (Means for solving the problems) (1) The first feature of the present invention is that in a method for manufacturing a semiconductor device, 11: forming an insulating film on a conductor substrate; A step of forming a polycrystalline semiconductor layer on this insulating film, a step of forming a gate electrode by patterning the polycrystalline layer, and a step of forming an impurity diffusion layer in the semiconductor substrate using this gate electrode as a mask. a step of depositing a metal on the polycrystalline layer in an atmosphere containing metal and replacing the polycrystalline with a metal to form a gate electrode made of this metal;
The point is that it has been established.

(2) The second feature of the present invention is that seven people with manufacturing capabilities for semiconductor devices form an insulating film on a semiconductor substrate, form a semiconductor polycrystalline layer on top of this insulating film, and A process of forming an oxidation-resistant layer on the polycrystalline layer, a process of forming a stacked gate electrode consisting of these two layers by patterning the polycrystalline layer and the oxidation-resistant layer, and using the stacked gate electrode as a mask. , a process of forming an impurity diffusion layer in the semiconductor substrate, a process of performing an oxidation process on the side surfaces of the stacked gate electrode, and a process of oxidizing the polycrystalline layer part of the stacked gate electrode, and etching and removing the oxidation-resistant layer. However, the present invention includes the following steps: depositing metal on the polycrystalline layer in an atmosphere containing metal, replacing the polycrystalline with metal, and forming a gate electrode made of this metal.

(3) The third feature of the present invention is that in the method of manufacturing a semiconductor device, an insulating film is formed on a semiconductor substrate, and 'P' is formed on the insulating film.
A stacked gate consisting of these two layers is formed by forming a polycrystalline conductor layer, forming an oxidation-resistant layer on the circular conductor polycrystalline layer, and patterning the polycrystalline layer and the oxidation-resistant layer. A process of forming an electrode, a process of forming an impurity diffusion layer in the semiconductor substrate using the stacked gate electrode as a mask, a process of forming a metal film on this impurity diffusion layer, and a process of etching and removing the oxidation-resistant layer. , depositing metal on the polycrystalline layer in an atmosphere containing metal, replacing the polycrystalline with metal, forming a gate electrode made of this metal, and thickening the metal film. At the point.

(Function) (1) According to the first feature of the present invention, ions are implanted into a semiconductor substrate using a gate electrode made of a polycrystalline semiconductor layer as a mask, and then implanted in an atmosphere containing metal. By depositing metal on the polycrystalline layer and replacing the polycrystalline with metal to form a gate electrode made of this metal, a sufficient masking effect can be obtained during ion implantation, and there is no negative impact on the electrical characteristics of the device. There will be nothing left to give.

(2) According to the second feature of the present invention, a laminated date electrode consisting of two layers, a polycrystalline layer and an oxidation-resistant layer, is formed on a semiconductor substrate, and the side surface of this laminated gate electrode is oxidized. By applying a process to oxidize the polycrystalline layer of the stacked gate electrode, it is possible to ensure a sufficient thickness of the gate insulating film, especially at the edges, and improve the insulation properties of the gate oxide film. Can be done.

(3) According to the third feature of the present invention, impurities are deposited on the polycrystalline layer in an atmosphere containing metal, and the polycrystal is replaced with metal, and during the process of forming a gate electrode made of this metal. Since the metal film on the diffusion layer is thickened, it is possible to reduce the resistance of the impurity diffusion layer.

(Example) The present invention will be described below based on an illustrative example. FIG. 1 is a process diagram of an embodiment of a method for manufacturing a semiconductor device according to the present invention. First, as shown in Figure 1(a), the first
A silicon oxide film is formed in a predetermined shape on a conductive type semiconductor substrate 101, for example, a P-type silicon substrate, using a selective oxidation method (LOCO5 method) to form a field oxide film 102. A portion surrounded by this field oxide film 102 becomes an element region 103.

Next, as shown in FIG. 1(b), a silicon oxide film 104 is formed to a thickness of 100A using, for example, a thermal oxidation method, and polycrystalline silicon is formed on this film to a thickness of 500A by, for example, a chemical vapor deposition method. Then, a polycrystalline layer 105 is formed. Furthermore, an oxidation-resistant film [06] such as a silicon nitride film is deposited on this to a thickness of about 200 OA.

For example, chemical vapor deposition may be used for this purpose.

Subsequently, as shown in FIG. 1C, the oxidation-resistant film 10 is etched by, for example, anisotropic etching using a resist on which a predetermined pattern has been formed by photolithography as a mask.
6 and polycrystalline layer 105 are etched to form a stacked gate electrode 108.

Next, using this stacked gate electrode 108 as a mask, for example, phosphorus is heated at a density of 4 at an acceleration energy of 351 c e V.
Ion implantation is performed at x 10 '3/cd to form a diffusion layer 107 that will become a source/drain.

Next, combustion oxidation is performed for about 10 minutes at a temperature of, for example, 850° C. to oxidize the surface as shown in FIG. 1(d). This oxidation strengthens the electrical withstand voltage at the edge portion of the stacked gate electrode 108.

After that, as shown in FIG. 1(e), after removing the silicon oxide film on the diffusion layer 107 using, for example, anisotropic etching, tungsten is grown by chemical vapor deposition using WF6. accumulate. With this deposition method, tungsten is deposited only on the upper part of the diffusion layer 107, and the metal film 109
form.

Subsequently, as shown in FIG. 1(f), a silicon oxide film is deposited to a thickness of about 3000 Å by, for example, chemical vapor deposition, and is removed by anisotropic etching to form the side surfaces of the stacked gate electrode 108. An oxide layer 110 is formed thereon. Then, using the stacked gate electrode 108 and the oxide layer 110 as a mask, ions of, for example, arsenic are implanted at a density of 5×10 15 at an acceleration energy of 40 keV to form the diffusion layer 11.
form 1. FIG. 1(r) shows the state up to this point.

Here, the laminated gate electrode 108 is partially composed of an oxidation-resistant film 106' made of silicon nitride, and its lower part is a polycrystalline layer 105' made of polycrystalline silicon. Therefore, the oxidation-resistant film 106' is removed by, for example, a chemical dry etching method.

Then, tungsten is deposited thereon by chemical vapor deposition using WF8. At this time, 5()OA
The silicon polycrystalline layer 105' having a certain thickness becomes entirely tungsten due to the reduction reaction between WF6 and silicon. If hydrogen is added to the tungsten layer during deposition, the tungsten film can be thickened to a predetermined thickness.
As shown in Figure (g), metal gate electrodes 1 and 2 made of tungsten are formed. Also, in this step, the diffusion layer 1
The tungsten metal film 109 on 11 is also thickened to become a metal layer 113.

Finally, as shown in FIG. 1(h), an oxide layer 114 is formed by depositing a silicon oxide film with a thickness of about 5,000 layers using, for example, a stoichiometric growth method, and a predetermined pattern is formed using a photolithography method. The contact hole 115 is opened by performing, for example, anisotropic etching using the resist with which it has been formed as a mask. Furthermore, after depositing aluminum of about 4000 Å on this layer by sputter deposition, for example, anisotropic etching is performed using a resist with a predetermined pattern formed by photolithography as a mask to remove metal made of aluminum. Wiring layer 1
form 16.

That's all, L D D (LlgMIy Doped Dr
ain)? Although an embodiment in which the present invention is applied to the manufacture of a transistor having a +% structure has been shown, the present invention can be similarly applied to the manufacture of a transistor that does not have an LDD structure. In this case, there is no need for ion implantation to form the diffusion layer 111 in FIG. 1(r), and there is no need to form the oxide layer 110. In addition, if tungsten is not formed on the diffusion layer and only the gate electrode is made of tungsten, as shown in FIG.
The process of forming the metal film 109 in 0) is also not necessary.

〔Effect of the invention〕

As described above, according to the present invention, after ions are implanted into a semiconductor substrate using a gate electrode made of a polycrystalline semiconductor layer as a mask, metal is deposited on the polycrystalline layer in an atmosphere containing metal. At the same time, the polycrystal is replaced with metal and the gate electrode made of this metal is formed, so that a sufficient masking effect is achieved during ion implantation, and the electrical characteristics of the device are not adversely affected.

In addition,) a laminated gate electrode consisting of two layers, a polycrystalline layer and an oxidation-resistant layer, is formed on one part of the conductor board, and an oxidation process is performed on the side surfaces of this laminated gate electrode. Since the polycrystalline layer is oxidized, a sufficient thickness of the gate insulating film, especially at the end portions, can be ensured, and the insulation properties of the gate oxide film can be improved.

Historically, metal was deposited on a polycrystalline layer in an atmosphere containing metal, the polycrystalline was replaced with metal, and the metal film in the impurity diffusion layer was thickened during the process of forming a gate electrode made of this metal. This makes it possible to reduce the resistance of the impurity diffusion layer.

In addition, as can be seen by comparing FIG. 1 (1)) and FIG. Since the level difference between the elements is reduced, the element becomes flat, and there is also the effect of suppressing the occurrence of disconnection of the wiring IA, short circuit, etc. due to the level difference of the element.

[Brief explanation of drawings]

FIG. 1 is a process diagram of a method for manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a process diagram of a conventional method for manufacturing a semiconductor device. 1... Semiconductor substrate, 2... Field oxide film, 3...
...Element region, 4...Oxide film, 4'...Gate oxide film, 5...Metal layer, 5'...Gate electrode, 6...
Impurity diffusion layer, 7... Oxide layer, 8... Impurity diffusion layer, 9... Metal film, 10... Oxide layer, 11... Contact hole, 12... Wiring layer, 101... Semiconductor substrate, 102... Field oxide film, 103... Element region, 104... Oxide film, 105... Polycrystalline layer, 1
06... Oxidation resistance 1ii, 107... Impurity diffusion layer, 108... Laminated gate electrode, 109... Metal film,
110... Oxide layer, 111... Impurity diffusion layer, 11
2... Metal gate electrode, 1] 3... Metal IA, 11
4... Oxide layer, 115... Contact hole, ]1
6...Wiring layer. (a) (e) (b)
) (f) (C)
(Q) (d) (h
) Wear 1 mouth

Claims (1)

[Claims] 1. Steps of forming an insulating film on a semiconductor substrate, forming a polycrystalline semiconductor layer on the insulating film, and forming a gate electrode by patterning the polycrystalline layer. forming an impurity diffusion layer in the semiconductor substrate using the gate electrode as a mask; depositing the metal on the polycrystalline layer in an atmosphere containing metal and replacing the polycrystalline with the metal; A method for manufacturing a semiconductor device, comprising the steps of: forming a gate electrode made of the metal. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor is silicon, the insulating film is silicon oxide, and the metal is tungsten. 3. The process of forming the gate electrode made of metal is WF_
3. The method for manufacturing a semiconductor device according to claim 2, wherein the method is carried out by a chemical vapor phase method using a chemical vapor deposition method using a chemical vapor deposition method using a chemical vapor deposition method using a chemical vapor deposition method using a chemical vapor deposition method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor deposition method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method; 4. Forming an insulating film on a semiconductor substrate, forming a semiconductor polycrystalline layer on this insulating film, and forming an oxidation-resistant layer on this semiconductor polycrystalline layer; forming a stacked gate electrode made of these two layers by patterning the oxidation-resistant layer; forming an impurity diffusion layer in the semiconductor substrate using the stacked gate electrode as a mask; oxidizing the polycrystalline layer portion of the laminated gate electrode by performing an oxidation process on the side surface of the stacked gate electrode; and removing the oxidation-resistant layer by etching the polycrystalline layer in an atmosphere containing metal. A method for manufacturing a semiconductor device, comprising the steps of depositing a metal and replacing the polycrystal with the metal to form a gate electrode made of the metal. 5. The method for manufacturing a semiconductor device according to claim 4, wherein the semiconductor is silicon, the insulating film is silicon oxide, the oxidation-resistant film is silicon nitride, and the metal is tungsten. . 6. The process of forming a gate electrode made of metal is WF_
6. The method for manufacturing a semiconductor device according to claim 5, wherein the method is carried out by a chemical vapor phase method using a chemical vapor deposition method using a chemical vapor deposition method using a chemical vapor deposition method using a chemical vapor deposition method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor deposition method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method using a chemical vapor phase method; 7. The method of manufacturing a semiconductor device according to any one of claims 4 to 6, wherein the step of oxidizing a portion of the polycrystalline layer is performed by hydrogen combustion oxidation. 8. Forming an insulating film on a semiconductor substrate, forming a semiconductor polycrystalline layer on this insulating film, and forming an oxidation-resistant layer on this semiconductor polycrystalline layer; forming a stacked gate electrode consisting of these two layers by patterning the oxidation-resistant layer; forming an impurity diffusion layer in the semiconductor substrate using the stacked gate electrode as a mask; and forming an impurity diffusion layer in the semiconductor substrate. forming a metal film thereon, etching away the oxidation-resistant layer, depositing the metal on the polycrystalline layer in an atmosphere containing the metal and replacing the polycrystal with the metal; A method for manufacturing a semiconductor device, comprising the steps of: forming a gate electrode made of metal; and increasing the thickness of the metal film. 9. The method for manufacturing a semiconductor device according to claim 8, wherein the semiconductor is silicon, the insulating film is silicon oxide, the oxidation-resistant film is silicon nitride, and the metal is tungsten. . 10. The step of forming a gate electrode made of metal is WF
10. The method of manufacturing a semiconductor device according to claim 9, wherein the method is carried out by a chemical vapor phase method using _6. 11. The method of manufacturing a semiconductor device according to claim 10, wherein the step of thickening the metal film is performed in an atmosphere containing hydrogen.