WO2004017396A1

WO2004017396A1 - Method of forming insulation film on semiconductor substrate

Info

Publication number: WO2004017396A1
Application number: PCT/JP2003/010357
Authority: WO
Inventors: Toshiaki Hongoh
Original assignee: Tokyo Electron Limited
Priority date: 2002-08-14
Filing date: 2003-08-14
Publication date: 2004-02-26
Also published as: CN1682357A; KR100729989B1; AU2003255034A1; CN100380610C; JPWO2004017396A1; KR20050035883A

Abstract

A method of obtaining in a short time an insulation film capable of being obtained from an LCD-use TFT and having a large dielectric strength and a small interface-level density. A silicon substrate (101) is subjected to plasma oxidizing to form a first insulation film (102), and a second insulation film (103) is deposited on the first insulation film (102) by using plasma CVD to thereby form an insulation film.

Description

Method of forming insulating film on semiconductor substrate

The present invention relates to an insulating film of a semiconductor device, particularly a thin film transistor (τ).

F T) gate insulating film, and more particularly display such as liquid crystal display

The present invention relates to the formation of a gate oxide film of TFT for LCD.

Rice field

Background art

Insulating films are used in various semiconductor devices, and various methods such as oxidation or nitridation of semiconductor substrates, CVD (chemical vapor deposition), PVD (physical vapor deposition), and coating are used to form insulating films. Technology is used. Here, in applications where a relatively high-quality insulating film is required, for example, for the use of a gut insulating film for an integrated circuit, a modification treatment such as oxidation or nitridation by heat or plasma for modifying the underlying film is used. In applications requiring a relatively high deposition rate, such as a protective layer and a gate insulating film for an LCD, a deposition process such as CVD is often used. This is because the film quality obtained by these treatments is different, for example, the surface order density of the insulating film obtained by such a modification treatment is relatively large, for example, about 5 × ¹⁰ 1 ^Q e V— ¹ cm— ^2. small and interface state density obtained Te cowpea deposition process Unaryo of CVD is example if by 5 XI 0 ¹² e V "relatively large as ¹ · cm ² or so. Also, provided by this good UNA modification treatment The fact that the film formation rate of the film is relatively low and the film formation rate of the film obtained by the deposition process is relatively high.

In recent years, in the semiconductor device manufacturing process, A plasma processing apparatus for the film may be used. For example, in a typical microwave plasma processing apparatus, an object to be processed such as a semiconductor wafer or an LCD substrate is placed by passing a microwave of about 2.45 GHz through a slot electrode. Into the reduced pressure processing chamber. Microwaves convert these reactant gases into plasmas and radicals, which are highly active, and react with the workpiece to form a film. Here, generally, a rare gas such as argon, which promotes plasma excitation, and a reactant gas are introduced into the processing chamber.

In the case of using a plasma to form an insulating film, this reactant gas is, for example, oxygen and possibly hydrogen in an oxidation treatment of a semiconductor substrate called field oxidation, and in a CVD, tetraethyl orthosilicate (TEOS). And oxygen. In particular, in LD manufacturing, plasma CVD processing is generally performed to form a gate insulating film of a transistor. For the technology of forming these insulating films, see Japanese Patent Application Laid-Open Nos. 11-293470 and 2000-214748.

When forming a silicon dioxide insulating film using the conventional thermal oxidation method for silicon substrates, a high temperature of about 100 ° C is required, but a plasma silicon oxide film is required. Can be grown at lower temperatures than the thermal oxidation method. Therefore, it is preferable for a device that dislikes high temperature, and has characteristics such that the growth rate is large, a compressive stress film can be easily obtained, the film is dense, and the oxidation rate does not depend on the surface orientation.

Although each of the conventional insulating film formation processes has its own advantages, it does not necessarily meet the requirements of current and future film quality and deposition rates. For example, parameters representing the properties of an insulating film include a tundling bond represented by an interface state density, a dielectric strength voltage, a film density, a film forming speed, and the like. Membrane Methods and apparatus are still needed. Thus, the present invention provides a method for meeting the requirements regarding the parameters used in the evaluation of insulating films.

In the past, LCD TFT switches used amorphous silicon, and their gate oxide films were manufactured using a CVD process. However, it is considered that it is difficult to achieve the film quality required for the gate oxide film of the recently developed polysilicon and continuous grain silicon (CGS) TFT switches by CVD.

Therefore, it is conceivable to use a so-called field oxidation process for oxidizing the already deposited silicon substrate, such as plasma oxidation, to form an insulating film. However, while the deposition rate by CVD is typically greater than about 100 O A / min, the deposition rate by field oxidation is on the order of about 20 AZ min. Further, in the field oxidation, the film forming process proceeds by diffusing oxygen in the formed oxide film, so that the film forming speed becomes slower as the film thickness increases. Therefore, when field oxidation is used, the high dielectric strength required for a zero cut (eg, using a gate voltage of about 15 V or 35 V) and the corresponding relatively thick oxide film ( For example, to achieve 1,000 OA), a long-term film-forming process is required, which is not practical. Disclosure of the invention

Therefore, the present invention provides a method for obtaining an insulating film having a required film quality in a short time.

The present invention provides a method for manufacturing a semiconductor device, comprising: performing a modification process on a semiconductor substrate to form a first insulating film; and performing a deposition process for depositing a second insulating film on the first insulating film. This is a method for forming an insulating film. The insulating film on the semiconductor substrate is, in particular, a gate insulating film, more particularly, a TFT gate. Oxide film, and more particularly a TFT oxide film for a display such as an LCD.

In one embodiment of the present invention, the semiconductor substrate is a silicon substrate, such as a polysilicon substrate, a continuous grain boundary crystal silicon substrate or a single crystal silicon substrate.

In one embodiment of the present invention, both the first insulating film and the second insulating film are oxide films.

In one embodiment of the present invention, the first insulating film is an oxide film, and the second insulating film is a nitride film.

In one embodiment of the present invention, the thickness of the first insulating film is 10 to 100 A, particularly 10 to 30 °. In addition, the thickness of the first insulating film may be a thickness sufficient to satisfy the requirement on the interface between the semiconductor substrate and the first insulating film, for example, the interface between the silicon substrate and the silicon oxide.

In one embodiment of the present invention, the thickness of the second insulating film is 100 to 2,000, particularly 500 to 1, 000. Further, the thickness of the second insulating film may be a thickness that satisfies the requirements regarding the dielectric strength voltage of the insulating film including the first insulating film and the second insulating film.

In one aspect of the present invention, the interface state density between the first insulating film and the semiconductor ^{substrate, 1 0 12 e V -.} 1 · cm less than ^2, for example ^{^{1 0 12 ~ 1 0 10 e}} V "1 cm a ^{^{2 - L 0 9 e V '}} !!!: 2, preferably less than ^{1 O ^ e V- 1 · cm} 2, for example 1 0 ¹⁰ ~..

In one embodiment of the present invention, the insulation withstand voltage of an insulation film on a semiconductor substrate including a first insulation film and a second insulation film has an insulation withstand voltage suitable for a desired application. The voltage is more than 10 V, more than 20 V, or more than 30 V.

In one embodiment of the present invention, the modification treatment is a heat or plasma oxidation or nitridation treatment of the semiconductor substrate, and the deposition treatment is a CVD treatment. still This deposition process may be a PVD, coating.

In one embodiment of the present invention, the modification process is a plasma oxidation process, and the deposition process is a plasma CVD process.

In one embodiment of the present invention, the atmosphere of the plasma oxidation treatment contains a rare gas and oxygen. Here, preferably, the flow ratio of the rare gas to oxygen is 100: 3 or less. The noble gas is, for example, krypton.

In one embodiment of the present invention, the plasma CVD processing atmosphere contains oxygen and a silicon-containing gas. The Kei-containing gas, for example, a monosilane SH _4.

In one embodiment of the present invention, the average film forming rate of the first insulating film is 10 to 100 AZ minutes, particularly 10 to 50 AZ minutes, and the average film forming rate of the second insulating film is Is from 100 to 100 A / min, especially from 500 to 1.0 OA / min.

The present invention also provides a method for forming an insulating film including a first insulating film and a second insulating film on a semiconductor substrate, the method comprising: forming an average film forming rate of the first insulating film adjacent to the semiconductor substrate. And the ratio of the deposition rate of the second insulating film adjacent to the first insulating film on the opposite side of the semiconductor substrate is 1: 1, 0〇0 to 1: 1, particularly 1:10. A method for producing a method for forming an insulating film including a first insulating film and a second insulating film on a semiconductor substrate, which is 0 to 1: 10 is provided by, for example, an inductively coupled plasma (ICP) generator, Or a microwave-excited plasma generator such as a slot emission type microwave-excited plasma generator, particularly a radial line slot antenna (RLSA) microwave-excited plasma generator. The method can have any other features that can be understood from the description herein.

Other objects and further features of the present invention will be described below with reference to the accompanying drawings. It will be clarified by the preferred embodiment described. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram illustrating a process of forming an insulator film formed according to one embodiment of the present invention.

FIG. 2 is a schematic block diagram showing the structure of the RLSA microwave plasma processing apparatus used in one embodiment of the present invention.

FIG. 3 is a plan view of an antenna used in the RLSA microwave plasma processing apparatus of FIG.

FIG. 4 is a top view of a cluster tool using the plasma processing apparatus of FIG.

FIG. 5 is a diagram showing the time dependence of the film formation rate by direct oxidation of the silicon surface.

FIG. 6 is a diagram showing the deposition rate of the CVD oxide film.

In the drawings described above, the meaning of each symbol is as follows.

1 0 1 ... Silicon substrate

1 0 2… First insulating film

1 0 3… Second insulating film

2 0 0R L S A Plasma processing equipment

2 0 1… Gate valve

2 0 2… Processing room

2 0 4… susceptor-

206: vacuum pump

2 0 8 ... top plate

2 1 0… Microwave source

240, 270 ... gas supply pipe

3 0 0 ... antenna 4 0 0… Cluster tool

4 1 0… Processing system section

4 3 0… Road and lock room

4 5 0… Transportation system

4 7 0… Transfer stage

4 8 0 ... force set stage Best mode for carrying out the invention

The apparatus used in the exemplary embodiment of the present invention will be described below with reference to the accompanying drawings. In each drawing, the same reference numerals represent the same components.

FIG. 2 is a schematic block diagram of a radial line slot antenna (RLSA) plasma processing apparatus 200 capable of forming an insulating film of the present invention.

Although the present invention will be described below with reference to an RLSA plasma processing apparatus, the insulating film of the present invention can be obtained by using any apparatus other than the plasma processing apparatus. Preferably, the present invention uses a plasma processing apparatus. This is because the plasma processing apparatus can achieve film formation at a relatively low temperature and achieve good film quality. More preferably, a microwave plasma apparatus such as an RLSA plasma processing apparatus capable of generating high-density plasma, an ICP (inductively coupled) plasma apparatus, an ECR plasma apparatus, or the like is used.

The microwave plasma processing apparatus 200 of the present embodiment includes a gate pulp 201 connected to a cluster tool 400 and a susceptor on which a workpiece W such as a semiconductor wafer substrate or an LCD substrate is placed. A processing chamber 202 capable of storing 204, a vacuum pump 206 connected to the processing chamber 202, a top plate 208, a microwave source 210, and an antenna 300 And gas supply pipes 240 and 270. The control system of the plasma processing apparatus 200 is not shown.

The processing chamber 202 has a side wall and a bottom made of a conductor such as aluminum. Here, the processing chamber 202 has, for example, a cylindrical shape, but the shape is arbitrary. In the processing chamber 202, a susceptor 204 and a workpiece W are supported thereon.

The top plate 208 is a cylindrical plate-like body made of a dielectric material such as quartz-nitride aluminum that blocks the upper part of the processing chamber 202. As shown in FIG. 3, the antenna 300 has a plurality of slots 310 on a concentric circle. The antenna 300 is made of, for example, a copper plate having a thickness of 1 mm or less, and is disposed on the upper surface of the top plate 208. Each slot 310 is a substantially rectangular through hole, and adjacent slots are orthogonal to each other to form an alphabet “T” shape. The arrangement, shape, and the like of the slot 310 are determined depending on the wavelength of the microphone mouth wave generated by the microwave generation source 210, the required plasma, and the like. As the optional slow wave member 222, a predetermined material having a predetermined dielectric constant and a high thermal conductivity in order to shorten the wavelength of the microwave is selected.

The microwave source 210 is made of, for example, a magnetron, and can generate a microwave of 2.45 GHz (for example, 5 kW). The microwave then passes through the rectangular waveguide 2 11 1, the mode converter 2 12, and the circular coaxial waveguide 2 13 to reach the antenna member 300. In FIG. 2, devices such as an isolator that absorbs reflected microwaves returning to the magnetron are omitted.

The susceptor 204 can control the temperature of the processing object W in the processing chamber 202 as desired. In this case, a temperature controller (not shown) controls the temperature of the susceptor 204. The susceptor 204 The susceptor 204 can be configured to be able to move up and down in the processing chamber 202, and any technique known to those skilled in the art can be applied.

The gas supply pipes 240 and 270 are connected to a gas supply source, a pulp, a controller for a mashu opening, and the like (not shown). Here, the processing gas is directly supplied to the processing chamber 202, but it is also possible to supply the processing gas uniformly through a shower plate (not shown) at the upper part of the processing chamber 202. .

The inside of the processing chamber 202 can be maintained at a predetermined reduced pressure by the vacuum pump 206. The vacuum pump 206 uniformly evacuates the processing chamber 202 to maintain a uniform plasma density and to prevent the processing density of the workpiece W from becoming uneven due to a partial concentration of the plasma density. .

The cluster tool 400 may be a cluster tool as shown in FIG. The cluster tool 400 includes a processing system section 410 for performing processing such as film forming processing, diffusion processing, and etching processing on a wafer W as a substrate to be processed; And a transfer system unit 450 for loading and unloading wafers W from and to the wafer.

The processing system 410 is composed of a transfer chamber 4101, which can be evacuated, and four processing chambers 200A, connected via a pulp pulp 201A to 201D. In each of the champers 200 A to 200 D, the same type or different types of processing can be performed on the channel W. Further, a transfer arm 412 configured to be able to bend and extend and rotate freely is provided in the transfer chamber 411, and the processing chambers 200A to 200D and a load lock chamber to be described later are provided. Between 430 A and B and ゥヱ C W are to be delivered.

On the other hand, the transport system section 450 transports and transfers the wafer W to and from the cassette stage 480 for placing the carry cassette. And a transfer stage 470 for moving the transfer arm 471. The cassette stage 480 is provided with a container mounting table 481, and a plurality of, in the illustrated example, up to four carrier cassettes 483 can be mounted thereon. The carry cassette 483 can accommodate, for example, up to 25 wafers W at equal intervals in multiple stages.

The transfer stage 470 is provided with a guide rail 472 extending in the center thereof along the length direction, and the transfer arm 471 is slidably supported on the guide rail 472. Have been. At the other end of the transfer stage 470, an orienter 475 as a direction positioning device for positioning the wafer W is provided.

Between the processing system section 410 and the transport system section 450, two load lock chambers 430A and 430B which can be evacuated are provided.

Hereinafter, a method for manufacturing an insulating film according to the present invention will be described. FIG. 1 is a vertical cross-sectional view showing a process of manufacturing an insulator film according to one embodiment of the present invention. In FIG. 1A, a silicon substrate 101 is shown. The silicon substrate 101 may be any silicon substrate, for example, a silicon wafer, amorphous silicon, low-temperature polysilicon, continuous grain boundary crystal silicon, or the like.

By subjecting the silicon substrate shown in FIG. 1A to a modification treatment, a first insulating film 102 shown in FIG. 1B is obtained. This modification treatment may be any modification treatment such as thermal oxidation, thermal nitridation, thermal oxynitridation, plasma oxidation, plasma nitridation, and plasma oxynitridation. Therefore, the first insulating film 102 in FIG. 1B may be a so-called field oxide, nitride, or oxynitride film.

In the modification treatment for manufacturing the first insulating film, plasma acid is used. When gasification is used, a rare gas such as argon and krypton and oxygen are supplied from the processing gas supply channels 240 and 270 of the processing apparatus 100 in FIG. The processing conditions in this case include the following conditions for an 8-inch silicon wafer:

0 ₂ flow rate: 10 to 100 sccm, for example, 120 sccm Kr flow rate: 100 to 100, 00 sccm, for example, 150 sccm

Processing temperature: 100 to 500 ° C, for example, 250 ° C

Pressure: 1-1, 000 Pa, for example 90 Pa

Plasma source output: 100 to 6, 00W, for example, 2000W

By performing a deposition process on the first insulating film 102 in FIG. 1B, the second insulating film 103 in FIG. 1C is obtained. This deposition process can be any modification process such as CVD, PVD, or coating. Accordingly, the second insulating film 103 in FIG. 1 (c) may be a so-called deposition (deposited) oxide, nitride, oxynitride film, or polymer film.

When a silicon dioxide layer is formed using plasma CVD in the deposition process for manufacturing the second insulating film, argon gas is supplied from the processing gas supply paths 240 and 270 of the processing apparatus 100 in FIG. , yo Una rare gas krypton and subjected feeding the S i H ₄ or TEOS by Unakei-containing gas. Although two supply paths are shown in FIG. 2, gas can be supplied from any number of supply paths.

The processing conditions in this case include the following conditions for an 8-inch silicon wafer:

S i H ₄ flow rate: 1 to 100 sccm, for example 50 to 200 sccm

0 ₂ Flow rate: 10 ~: L 0, OOO sccm, eg 1, OOO sccm Processing temperature: 100 to 500 ° C, for example, 350 ° C

Pressure: 1 to 1, O O O Pa, for example, 10 Pa

Plasma source output: 100 to 6,000 W, for example, 2,000 W

By forming the first insulating film and the second insulating film as described above, the insulating film of the present invention is formed.

According to the method of the present invention, a unique insulating film can be obtained by a combination of a modification treatment of a semiconductor substrate and a subsequent deposition treatment.

Preferably, the method of the present invention can be obtained by adjusting properties relating to an interface obtained by a modification treatment of a semiconductor substrate and properties relating to a park obtained by a subsequent deposition treatment.

Preferably, both the modification treatment and the deposition treatment are treatments using plasma. In this case, it is preferable in terms of the reliability of the obtained depiice and the flexibility of the process as described above. Also, the film quality obtained as described above is generally preferable. Furthermore, since both the denaturation process and the deposition process are plasma processes, these processes can be performed in the same apparatus.

Preferably, the advantages of the good interface characteristics obtained by the modification treatment of the semiconductor substrate and the advantages of the rapid film formation obtained by the deposition treatment are compatible. That is, for example, the advantage of good interface characteristics obtained by the plasma oxidation treatment of the semiconductor substrate and the advantage of the high film forming rate obtained by the plasma CVD treatment are both compatible.

Preferably, the insulating film obtained by the method of the present invention as a whole has an insulation withstand voltage that can be used for a gate insulating film such as a TFT gut insulating film for LCD. Preferably, a rare gas and oxygen-containing atmosphere is used in the plasma oxidation treatment, and the flow ratio of the rare gas and oxygen is set to 100: 3 or less, which is particularly suitable for TFTs of displays such as liquid crystal displays. And make a thick silicon oxide film Still another aspect of the present invention is a method for forming an insulating film including a first insulating film and a second insulating film on a semiconductor substrate, wherein the average film forming of the first insulating film adjacent to the semiconductor substrate is performed. A ratio between the speed and an average deposition rate of the second insulating film adjacent to the first insulating film on the opposite side of the semiconductor substrate is 1: 1, 0000 to 1: 1; This is a method of forming an insulating film including a film and a second insulating film on a semiconductor substrate. In other words, in semiconductor device manufacturing, the quality of the film to be formed and the film forming speed are problematic, but by changing the film forming speed of the interface portion and the parc portion, the film quality can be adjusted and improved. It is possible to obtain a film forming rate.

Although a silicon substrate has been described here as a semiconductor substrate, the method of the present invention is not limited to a silicon substrate, and can be applied to any other semiconductor substrate to which similar processing can be applied. In addition, here, the insulating film of the present invention is formed using a plasma processing apparatus connected to a cluster apparatus. However, the present invention can be performed by an arbitrary apparatus, for example, a so-called flow process currently being studied. I think it can be applied to In this case, the rapid formation of the insulating film of the present invention is considered to provide a great benefit.

(Example) ;

Regarding the formation of the insulating film of the present invention, direct oxidation of the silicon surface with krypton and oxygen and oxide film CVD with silane and oxygen were performed. Direct oxidation of silicon surface

This test was performed on a generally available silicon wafer (8-inch wafer) using the apparatus shown in Fig. 2. Conditions for direct surface oxidation were as follows:

O ₂ flow rate: 120 sccm Kr flow rate: 1500 sccm

Processing temperature: 250 ° C

Pressure: 90 Pa

Plasma source output: 200 W

The results obtained are shown in FIG. Therefore, the deposition rate is about 20 AZ when forming a 2OA oxide film, about 12 A / min when forming a 25 A oxide film, and a 27 A oxide film is formed. It is about 9 A / min. As can be readily appreciated, the deposition rate decreases as the thickness of the formed oxide film increases. This is thought to be because oxygen atoms must diffuse the already formed oxide film in order to form the oxide film. Therefore, it is not practical to make a relatively thick insulating film, for example, a gate insulating film of LCD, only by direct oxidation of the silicon surface, because it takes a long time.

Oxide film C V D

This test was performed on a generally available silicon wafer (8-inch wafer) using the apparatus shown in Fig. 2. The conditions for forming the CVD oxide film are as follows:

S i H ₄ flow rate: 50 ~ 200 sccm

0 ₂ Flow rate: 1, OOO sccm

Processing temperature: '350 ° C

Pressure: 10 Pa

Plasma source output: 2,000W

The results obtained are shown in FIG. As shown in this figure, the deposition rate of the CVD oxide film has reached from 1,000 A / min to 4,500 A / min. This film formation rate is clearly higher than the oxide film formation rate by direct oxidation of the silicon surface. For example, a relatively thick oxide film such as an LCD gate insulating film can be used for a practical time. To make with enable.

Therefore, as shown by these experiments, the method of manufacturing an insulating film of the present invention can be applied to an insulating film of a semiconductor device, particularly a gate insulating film,

Provided is a method of forming a TFT oxide film for LCD or the like. Although the preferred embodiment of the present invention has been described above, the present invention can be variously modified and changed within the scope of the gist. Industrial applicability

As described above, the present invention provides a method for obtaining an insulating film having a desired film quality (preferably in a short time).

Claims

The scope of the claims

1. forming an insulating film on a semiconductor substrate, comprising: modifying a semiconductor substrate to form a first insulating film; and performing a deposition process of depositing a second insulating film on the first insulating film. how to.

2. The method according to claim 1, wherein the insulating film on the semiconductor substrate is a gate insulating film of a thin film transistor for a display, and the semiconductor substrate is polysilicon or continuous grain boundary crystal silicon.

3. The method according to claim 1, wherein the first insulating film is an oxide film, and the second insulating film is a nitride film.

4. interface state density between the first insulating film and the semiconductor substrate, 1 XI is 0 ¹² e V "less than ¹ · c nT ^2, the method of serial载to claim 1-3.

5. The method according to claim 1, wherein an insulation withstand voltage of the insulation film on the semiconductor substrate including the first insulation film and the second insulation film is more than 10 V.

6. The method according to any one of claims 1 to 5, wherein the modification treatment is a thermal or plasma oxidation or nitridation treatment of the semiconductor substrate, and the deposition treatment is a CVD treatment.

7. The method according to claim 1, wherein the modification treatment is a plasma oxidation treatment, and the deposition treatment is a plasma CVD treatment.

8. The method according to claim 6, wherein the atmosphere of the plasma oxidation treatment contains a rare gas and oxygen.

9. The method according to claim 8, wherein the ratio of the rare gas to oxygen is 100: 3 or less.

10. The method according to claim 8, wherein the rare gas is krypton. Method.

11. The method according to claim 7, wherein the atmosphere of the plasma CVD treatment contains a gas containing oxygen and silicon.

12. The method according to claim 6, wherein the plasma generating means is an inductively coupled plasma (ICP) generator or a radial line slot antenna (RLSA) microwave-excited plasma generator.