JPH03266434A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the reliability of elements by a method wherein a silicon oxide film is formed by thermally oxidizing a silicon substrate and then a polysilicon film is formed on the silicon oxide film in a chamber of same device as that forming the silicon oxide film by chemical vapor deposition process. CONSTITUTION:A gate oxide film 7 is formed by thermally oxidizing a silicon substrate 1 and then a polysilicon film 8 is formed on the gate oxide film 7 in a chamber of same device as that forming the gate oxide film 7 by chemical vapor deposition process. Through these procedures, the gate oxide film 7 is formed by thermal oxidation while the gate oxide film 7 and the polysilicon film 8 can be continuously formed in the same chamber without requiring wafer carriage so that the gate oxide film 7 in excellent film quality may be formed further enabling any foreign matter particles to be sufficiently prevented from adhering to the gap between the gate oxide film 7 and the gate electrode forming polysilicon film 8.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method of manufacturing a semiconductor device, and can be applied to a method of manufacturing a MOS transistor, etc. The present invention relates to a method for manufacturing a semiconductor device that can sufficiently suppress adhesion of foreign particles between silicon films.

Recently, in a semiconductor device manufacturing method in which a gate oxide film made of SiO2 is formed by thermal oxidation in a heat treatment furnace, and then a gate electrode made of polysilicon is formed by the CVD method in a CVD apparatus, there is no transfer from the heat treatment furnace to the CVD apparatus. When transferring wafers, the wafers are exposed to air, which causes foreign particles to adhere between the gate oxide film and the polysilicon film, resulting in a problem in that the withstand voltage of the gate oxide film deteriorates.

Therefore, there is a need for a method of manufacturing a semiconductor device that can suppress the adhesion of foreign particles between the gate oxide film and the polysilicon film and improve the breakdown voltage of the gate oxide film.

[Conventional technology]

FIGS. 4(a) to 4(g) are diagrams illustrating a conventional method of manufacturing a semiconductor device.

In this figure, 31 is a substrate made of Si or the like, 32 is 5
A silicon oxide film made of i02 etc., 33 a silicon nitride film made of Si3N4, 34 an opening formed in the silicon nitride film 33, 35 a field oxide film made of SiO□ etc., 36 a gate oxide film made of 5i02 etc. , 37
37a is a polysilicon film for forming a gate electrode, and 37a is a polysilicon film for forming a gate electrode.
38 is a resist film, 39 is a source/drain diffusion layer, 40 is a glabella insulating film made of PSG, etc., 41 is a contact hole, 42 is A1. It is a wiring layer consisting of etc.

Next, the manufacturing method will be explained.

First, as shown in FIG. 4(a), after oxidizing the substrate 31 by, for example, thermal oxidation to form a silicon oxide film 32 as an initial oxide film on the substrate 31, a silicon oxide film 32 is formed on the silicon oxide film 32 by, for example, CVD method. to Si3N.

is deposited to form a silicon nitride film 33.

Next, as shown in FIG. 4(b), the silicon nitride film 33 is selectively etched by RIE, for example, so that it remains only in the element region, and an opening 34 for forming a field oxide film is formed.
form. At this time, the silicon oxide film 3 is formed inside the opening 34.
2 is exposed.

Next, as shown in FIG. 4C, a field oxide film 35 is formed by selectively oxidizing the substrate 31 through the opening 34 using the silicon nitride film 33 as a mask using LOCO3.

Next, as shown in FIG. 4(d), after the silicon nitride film 33 is removed by wet etching with a phosphoric acid solution at about 150°C, for example, the silicon oxide film 32 is removed by wet etching with a hydrochloric acid solution, for example. to expose the substrate 31. At this time, an element region is formed.

Next, as shown in FIG. 4(e), the wafer from which the silicon oxide film 32 shown in FIG. 4(d) has been removed is set in a heat treatment furnace (not shown), and the substrate 31 is oxidized by thermal oxidation. After forming the gate oxide film 36 on the substrate 31, the wafer with the gate oxide film 36 formed thereon is transferred from the heat treatment furnace to a CVD apparatus and set therein, and a gate electrode is formed to cover the gate oxide film 36 by the CVD method. Polysilicon film 3 for
form 7.

Next, a resist is applied onto the polysilicon film 37 to form a resist film 38, and then the resist film 38 is patterned by exposure and development so that it remains only in the region on the polysilicon film 37 corresponding to the gate electrode.

Next, as shown in FIG. 4(f), the polysilicon film 37 is selectively etched by, for example, RIE using the resist film 38 as a mask to form a gate electrode 37a, and after removing the resist film 38, for example, Impurities are introduced into the substrate 31 by ion implantation using the gate electrode 37a as a mask, and source/drain diffusion layers 39 are formed by annealing.

Then, a glabellar insulating film 40 made of PSG is formed on the entire surface, and a contact hole 41 is formed in the glabellar insulating film 40 and the gate oxide film 36, and then wiring is formed to make contact with the source/drain diffusion layer 39 and the gate electrode 37a. layer 4
By forming 2, a semiconductor device as shown in FIG. 4(g) can be obtained.

Note that the above-described semiconductor device manufacturing method includes a fourth heat treatment furnace.
A wafer from which the silicon oxide film 32 shown in FIG.
In this case, the wafer having been formed is transferred from the heat treatment furnace to a CVD apparatus, and a polysilicon film 37 for forming a gate electrode is formed on the gate oxide film 36 by the CVD method. Other conventional techniques for forming polysilicon films include CVD.
A gate oxide film is formed on the substrate within the device by the CVD method, and then CVD is applied on the gate oxide film using the same CVD device.
Polysilicon films may be formed continuously by the D method.

Furthermore, a so-called multi-chamber device is used to transport the wafer between the gate oxide film forming device and the polysilicon film growing device using the CVD method so that the wafer is not exposed to air.
Another example is the case of forming a gate oxide film and a polysilicon film for forming a gate electrode.

[Problem to be solved by the invention]

However, in the conventional semiconductor device manufacturing method in which the gate oxide film 36 is formed by thermal oxidation in the heat treatment furnace described above, and then the polysilicon film 37 is formed by the CVD method in the CVD apparatus, the wafer is transferred from the heat treatment furnace to the CVD apparatus. When the wafer is transferred, the wafer is exposed to air, which causes foreign particles to adhere between the gate oxide film 36 and the polysilicon film 37, resulting in a problem in that the withstand voltage of the gate oxide film 36 deteriorates.

Furthermore, the conventional semiconductor device manufacturing method in which a gate oxide film and a polysilicon film for forming gate electrodes are successively formed by the above-mentioned CVD method solves the problem of particle adhesion better than the case where the wafer is exposed to air. Although it has the advantage that it can be formed by CVD method.

The problem is that the gate oxide film made of the above has poor film quality and lacks stability compared to a thermal oxide film. This becomes more noticeable as the film thickness becomes thinner, and is particularly unsuitable for a gate oxide film with a thickness of several + nanometers or less (several hundred angstroms or less is also acceptable).

Furthermore, in the conventional semiconductor device manufacturing method using the above-mentioned multi-chamber apparatus, the gate oxide film can be formed by thermal oxidation, so the gate oxide film can be formed more easily than in the case where the gate oxide film is formed by the above-mentioned CVD method. This method has the advantage that the film quality of the wafer can be improved, and that particle adhesion can be reduced compared to the case where the wafer is exposed to the atmosphere. However, since this method involves transporting wafers, there is a problem in that it is not sufficient to prevent particle adhesion during wafer transport.

Therefore, the present invention makes it possible to form a gate oxide film of good quality, and to sufficiently suppress the adhesion of foreign particles between the gate oxide film and the polysilicon film for gate electrode formation. An object of the present invention is to provide a method for manufacturing a semiconductor device that can improve the voltage resistance of the semiconductor device and the reliability of the device.

[Means to solve the problem]

In order to achieve the above object, the method for manufacturing a semiconductor device according to the present invention thermally oxidizes a silicon substrate to form a silicon oxide film, and then deposits the silicon oxide film in a chamber of the same device as the one in which the silicon oxide film was formed. This includes the step of forming a polysilicon film thereon by chemical vapor deposition.

In the present invention, the natural oxide film may be removed by heat-treating the silicon substrate in the apparatus and in a reducing gas atmosphere or an etching gas atmosphere before removing the silicon oxide film, in this case,
Furthermore, a silicon oxide film with good film quality can be formed, and the voltage resistance of the silicon oxide film can be further improved.

[Effect]

As shown in FIGS. 1(g) and 1(h), the present invention includes the apparatus shown in FIG. 2 in which a silicon substrate 1 is thermally oxidized to form a gate oxide film 7, and then the gate oxide film 7 is formed. A polysilicon film 8 is formed on the gate oxide film 7 by chemical vapor deposition in a chamber 17 of the same device.

In this way, the gate oxide film 7 is formed by thermal oxidation,
Since the gate oxide film 7 and the polysilicon film 8 are formed consecutively in the same chamber 17 without transporting the wafer, it is possible to form a gate oxide film of good quality, and it is possible to form a gate oxide film of good quality. It becomes possible to sufficiently suppress the adhesion of foreign particles between polysilicon films for forming gate electrodes.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

1 and 2 are diagrams for explaining one embodiment of the method for manufacturing a semiconductor device according to the present invention, FIG. 1 is a diagram for explaining the method for manufacturing one embodiment, and FIG. 2 is a diagram for explaining one embodiment. 1 is a schematic diagram showing a manufacturing apparatus.

In these figures, 1 is a substrate made of Si or the like, 2 is S
A silicon oxide film made of iO□ or the like, 3 a silicon nitride film made of Si3N, 4 an opening formed in the silicon nitride film 3, 5 a field oxide film made of 5ioz or the like,
6 is a natural oxide film made of SiO□ etc., 7 is a gate oxide film made of SiO□ etc., 8 is a polysilicon film for forming a gate electrode, 8a is a gate electrode made of polySi etc., 9 is a resist film, 10 is a Source/drain diffusion layer, 11 is PS
Glabellar insulating film made of G etc., 12 is a contact hole, 1
3 is a wiring layer made of A1 or the like, 14 is a wafer, 15 is a susceptor that supports the wafer 14, and 16 is a heater 17 which is a chamber made of quartz or the like.

Next, the manufacturing method will be explained.

The manufacturing apparatus shown in FIG. 2 is a known barrel-type epitaxial apparatus equipped with N2 gas as a reducing gas, 02 gas as a thermal oxidation gas, and 5iHa as a poly-Si growth gas.
A gas system is connected to Nt gas or Ar gas as a carrier gas, and is mainly used to reduce and remove the natural oxide film 6, form a gate oxide film by thermal oxidation, and form a polysilicon film by CVD method. It is.

First, as shown in FIG. 1(a), a silicon oxide film 2 is formed as an initial oxide film on a substrate 1 by oxidizing the substrate by, for example, thermal oxidation. Si3N4 is deposited on the silicon nitride film 3.
form.

Next, as shown in FIG. 1(b), the silicon nitride film 3 is selectively etched by, for example, RIE so that it remains only in the element region to form an opening 4 for forming a field oxide film. At this time, silicon oxide 112 is exposed within opening 4.

Next, as shown in FIG. 1(c), field oxide film 5 is formed by selectively oxidizing substrate 1 through opening 4 using LOGO 3 using silicon nitride film 3 as a mask.

Next, as shown in FIG. 1(d), the silicon nitride film 3 is removed by wet etching with a phosphoric acid solution at about 150°C, for example, and then the silicon oxide film 2 is removed by wet etching with a hydrofluoric acid solution, for example. to expose the substrate 1. At this time, an element region is formed.

Next, the wafer from which the silicon oxide film 2 has been removed is transferred from a wet etching device (not shown) into a chamber 17 of a manufacturing device shown in FIG.

At this time, the wafer is exposed to air, so the wafer is exposed to air.
), a natural oxide film 6 of about 40 layers is formed on the substrate 1.
occurs.

Next, as shown in Figure 1(e), Hz
By heat-treating the substrate 1 in a gas atmosphere, the base ll1
The natural oxide film 6 generated on I is removed. in particular,
Susceptor 1 in chamber 17 of the manufacturing apparatus shown in FIG.
The wafer 14 (the wafer shown in FIG. 1(e)) was set in the chamber 5, and the inside of the chamber 17 was replaced with N2 gas or Ar gas, and the inside of the chamber 17 was further replaced with N2 or N2 + HC4 (several percent) gas. Thereafter, the temperature is raised to 1,000 to 1,100° C. using a heater 16, and the natural oxide film 6 is reduced and removed while preheating for about 1 to 10 minutes.

Note that in the etching gas atmosphere of H, +HCf (several percent), the surface of the Si substrate 1 is also slightly etched, further improving the film quality.

Next, as shown in FIG. 1(g), the substrate 1 is heated by thermal oxidation.
A gate oxide film 7 having a thickness of, for example, 200 to 500 layers is formed on the substrate 1 by oxidizing the gate oxide. Specifically, the natural oxide film 6
After removal, thermal oxidation is performed using the apparatus shown in FIG. 2 without removing the wafer 14 from the apparatus. That is, after removing the natural oxide film 6, the chamber 1 is heated with N2 gas or Ar gas.
After replacing the inside of the chamber 17 with Oz gas, the gate oxide film 7 is formed by thermally oxidizing the substrate 1 at, for example, 1000° C. for about 5 to 10 minutes.

Next, as shown in FIG. 1(h), a film thickness of, for example, 200 mm for forming a gate electrode is formed on the gate oxide film 7 by the CVD method.
A polysilicon film 8 of 0 to 4000 layers is formed. Specifically, after forming the gate oxide film 7, the wafer 14 is not removed from the apparatus shown in FIG. 2, but CVD is performed using this apparatus. That is, after forming the gate oxide film 7, N2 gas or Ar
After replacing the inside of the chamber 17 with gas and lowering the temperature to about 900″C, further Hz gas (10 to 50 f/min) + Si
CVD by introducing H4 gas (100-300cc/min)
A polysilicon film 8 is formed by a method. Furthermore, at this time,
By introducing P into the polysilicon film 8 by simultaneously flowing PH3 gas or the like, a film with low resistivity can be formed. Next, after forming the polysilicon film 8, the inside of the chamber 17 is replaced with Nt gas or Ar gas, and the wafer 14 is
is removed from the device and moved to the next process.

Next, as shown in FIG. 1(i), after coating a resist on the polysilicon film 8 to form a resist film 9, the resist film 9 is exposed and developed to form a polysilicon film 9 corresponding to the gate electrode. Butter it so that only the top area remains.

Next, as shown in FIG. 1(j), the polysilicon film 8 is selectively etched by, for example, RIE using the resist film 9 as a mask to form a gate electrode 8a.
After removing the gate electrode 8a, the gate electrode 8a is removed by, for example, ion implantation.
Impurities are introduced into the substrate 1 using the mask as a mask, and the source/drain diffusion layer 10 is formed by annealing.

Then, after forming a glabellar insulating film 11 made of PSG on the entire surface and forming a contact hole 12 in the glabellar insulating film 11 and the gate oxide film 7, the source/drain diffusion layer 10 and the gate electrode 8a are connected via the contact hole 12. By forming the wiring layer 13 so as to make contact, a semiconductor device as shown in FIG. 1(h) can be obtained.

That is, in the above embodiment, the gate oxide film 7 is formed by thermal oxidation.
and polysilicon film 8 for gate electrode formation by CVD method.
and are successively formed in the chamber 17 of the same device shown in FIG. 2, so when forming the polysilicon film 8 on the gate oxide film 7, the wafer is not exposed to air
Moreover, the movement of transferring wafers can be eliminated.

Therefore, adhesion of foreign particles between gate oxide film 7 and polysilicon film 8 can be sufficiently suppressed. Further, since the gate oxide film 7 can be formed by thermal oxidation instead of the CVD method, the film quality can be improved. In the above embodiment, in the apparatus shown in FIG.
Since the gate oxide film 7 is formed without moving the wafer after the natural oxide film 6 is removed by the reduction action of two gases, the gate oxide film 7 with good film quality can be preferably formed. Therefore, the voltage resistance of the gate oxide film 7 can be improved, and the reliability of the device can be improved.

In the above embodiment, the case where the removal of the natural oxide film 6, the formation of the gate oxide film 7, and the formation of the polysilicon film 8 are performed using a known barrel type epitaxial device has been described, but the present invention is not limited to this. Alternatively, a known low pressure CVD apparatus as shown in FIG. 3 may be used.

[Effects of the Invention] According to the present invention, it is possible to form a gate oxide film of good quality, and to sufficiently suppress the adhesion of foreign particles between the gate oxide film and the polysilicon film for forming the gate electrode. This has the effect of improving the voltage resistance of the gate oxide film and improving the reliability of the device.

[Brief explanation of drawings]

1 and 2 are diagrams for explaining one embodiment of the method for manufacturing a semiconductor device according to the present invention, FIG. 1 is a diagram for explaining the method for manufacturing one embodiment, and FIG. 2 is a diagram for explaining one embodiment. FIG. 3 is a schematic diagram showing a manufacturing device of another embodiment, and FIG. 4 is a diagram illustrating a conventional manufacturing method. 1...Silicon substrate, 6...Natural oxide film, 7...Gate oxide film, 8...Polysilicon film, 17... Chamber 1: Silicon substrate 6: Natural oxide film Fig. 1 A diagram explaining the manufacturing method of one embodiment Fig. 1 A diagram explaining the manufacturing method of one embodiment Fig. 1 A diagram explaining the manufacturing method of one embodiment ↓ Exhaust 17: Champer Schematic diagram showing the manufacturing equipment of one embodiment Schematic diagram showing the manufacturing equipment of other embodiments

Claims (2)

[Claims] (1) The silicon substrate (1) is thermally oxidized to form a silicon oxide film (7), and then the silicon oxide film (7) is formed in a chamber (17) of the same device as that in which the silicon oxide film (7) was formed. (7) A method for manufacturing a semiconductor device, comprising the step of forming a polysilicon film (8) thereon by chemical vapor deposition. (2) Before forming the silicon oxide film (7), the silicon substrate (1) is placed in the chamber (17) of the apparatus and in a reducing gas atmosphere or an etching gas atmosphere.
2. The method of manufacturing a semiconductor device according to claim 1, further comprising the step of removing the natural oxide film (6) by heat treating the semiconductor device.