JPS61276976A - Method and apparatus for producing high quality thin film containing silicon by thermal cvd method using species in intermediate state - Google Patents

Abstract

PURPOSE:To obtain a high quality thin film contg. silicon, almost free from defects and undergoing no damage by plasma by thermally decomposing a gaseous mixture of species in an intermediate state such as SiF2 with decomposed species obtd. by bringing H2, SiH4 or the like into contact with a catalyst. CONSTITUTION:H2, SiH4, Si2H6, NH3 or N2O6 is brought into contact with a catalyst such as a platinum catalyst to obtain the decomposed species by a thermal reaction, a plasma reaction or a photoreaction. A gaseous starting material contg. a gaseous mixture of the decomposed species with the species in an intermediate state such as SiF2 or SiF as the principal component is thermally decomposed to deposit a thin film.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method and apparatus for producing a silicon-containing high-quality thin film, and in particular, for producing a silicon-containing high-quality thin film by thermal CVD using an intermediate material. METHODS AND APPARATUS.

(Prior Art) Amorphous semiconductor thin films such as amorphous silicon are currently formed by discharging and decomposing silane or the like. Therefore, when various amorphous semiconductor films are stacked in multiple layers to form a solar cell or the like, the interface between - and the like suffers plasma damage due to discharge, which puts a limit on the improvement of its properties. As a way to solve this problem, attempts have been made to form an amorphous semiconductor through a photochemical reaction, but there are also problems with the method of introducing light into the film deposition area and the light source itself.

On the other hand, in the production of semiconductor technology such as MO8) transistors, it is desired to develop a technology for forming high-quality insulating films at low temperatures. For this reason, insulating film deposition methods using plasma reactions or photoreactions are being considered, but these methods also have the same problems as the more advanced amorphous semiconductor thin film manufacturing methods.

(Problems to be Solved by the Invention) The starting point of the present invention is the idea that in order to solve the problems of the prior art, it would be better to use the thermal CVI method. ing. That is, if
Thermal CVD of amorphous semiconductors with high photosensitivity, etc.
If it could be produced by a method, not only would the film deposition equipment be simpler and cheaper, but the film deposition itself would be cheaper. Furthermore, if a high-quality insulating film can be formed by thermal CVD at a low temperature including room temperature, it will be an ideal method for forming an insulating film that does not cause damage to the semiconductor device itself.

Therefore, the present invention forms high-quality silicon-containing thin films such as amorphous semiconductor thin films such as amorphous silicon and insulating films such as silicon nitride using only thermal CVD without using plasma reactions or photoreactions. It is an object of the present invention to provide a method and apparatus.

(Means for Solving the Problems) The method of the present invention uses species in an intermediate state that does not exist in nature, especially silicon di7fluoride SiF, which has an unusually long lifespan among them.
2 or hydrogen fluoride SiF is used, and hydrogen H2 is added to it.
) Thermal CVD, in which pyrolysis, plasma decomposition species, or photodecomposition species such as silane SI H4, disilane Si2H6, ammonia NH3, and hydrazine N2H4 are mixed, and a material gas containing this mixed gas as the main component is pyrolyzed and deposited. The present invention relates to a thin film forming method characterized by forming a high quality thin film containing silicon, such as an amorphous semiconductor thin film such as amorphous silicon or an insulating film such as silicon nitride, by a method.

In the method of the present invention, silicon difluoride, 5in2
or as a fragment thereof, fluorinated silicon SiF
is solid silicon and silicon tetrafluoride SiF4 at 90%
It is produced by chemical reaction at temperatures above 0°C. In addition, silicon difluoride SiF2 etc. is silicon hexafluoride Si2F6 etc.Sim F'2m+2 (m =
1.2.3...) or a molecule in which part of the fluorine in the molecule is replaced with hydrogen, such as 5iF2H2, is decomposed by thermal reaction, plasma reaction, or light reaction. It can also be obtained by

In the method of the present invention, these silicon difluoride Si
F2 or silicon fluoride 5IFe, hydrogen H2) silane SiH, disilane Si2H6, ammonia N T
T5 or hydrazine N2H1, etc. is mixed with a species decomposed by thermal reaction, plasma reaction, or photoreaction, and the mixed gas is deposited by thermal decomposition (so-called thermal chemical) on the entire substrate.
Vaper T)position (CVD)). At this time, silicon difluoride S
Intermediate state species such as iF2 or decomposition of hydrogen horses! Even when plasma reactions are used to generate various decomposed species such as 4 (hydrogen atoms), after they are transported onto the substrate surface, the substrate surface is damaged by being exposed to plasma and high-energy sources. The key point of the invention is that a silicon-containing thin film can be subjected to thermal CVI on a substrate without being subjected to thermal CVI.

The amorphous semiconductor thin film formed is made of amorphous silicon, amorphous silicon carbide, amorphous silicon germanium, or a fluorine-containing substance thereof, and also includes thin films made of microcrystallized or polycrystalline materials.

In addition, the insulating film to be formed contains silicon such as silicon nitride, silicon oxide, or stolen silicon oxide, but these films also contain 7 atoms or hydrogen or both at the same time. In some cases.

The temperature of the substrate when depositing a thin film is above room temperature, and especially when forming an amorphous semiconductor thin film, the temperature of the substrate is
It is desirable that the temperature is in the range of 0°C to 400°C.

As a method for generating decomposition species, there is a method in which hydrogen, silane, disilane, ammonia, or hydrazine, etc. are brought into full contact during a thermal catalytic reaction of incandescent or red-hot tungsten, platinum, or palladium.

The apparatus of the present invention includes an intermediate state seed generation section, a film deposition section equipped with a heating device that communicates with the intermediate state seed generation section and accommodates a substrate therein and heats it to a predetermined temperature, and an intermediate state 111m generation section. and a decomposition species generation part provided in the gas passage between the introduction part and the substrate heating part or near the membrane deposition part; It consists of

An example of the decomposition species generating section is a metal heater that causes a thermal catalytic reaction, such as tungsten, platinum, or palladium.

(Example) Next, an example of the method and apparatus for manufacturing a silicon-containing film of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows one example of the method of the present invention and 1. This figure shows an outline of an apparatus that generates hydrogen decomposition species, that is, hydrogen atoms, through a thermal catalytic reaction, and forms amorphous silicon using a mixed gas of silicon difluoride and hydrogen atoms. This device includes an intermediate state species generating section 1 consisting of a highly heat-resistant tube 5 such as a quartz tube that connects solid silicon 6 and an electric furnace 3 for completely heating the highly heat-resistant tube, and a substrate 8 housed therein. The second type of quartz tube etc.
A high heat resistant tube 7 and a second electric furnace 4 which heats the substrate f through the heating tube to a predetermined temperature
a film deposition part g consisting of a film deposition part g, a raw material gas inlet 9 for decomposition extraction of hydrogen etc. provided near the connection part between the outlet of the first high heat resistant tube 5 and the inlet of the second high heat resistant tube 70; It mainly consists of a tungsten heater 10 provided in the gas passage between the inlet 9 and the heating section of the substrate or near the substrate 8.

Silicon tetrafluoride SiF4 is introduced into a quartz tube or high temperature tube 5 filled with solid silicon 6.

At that time, the tube 5 is heated to 900°C or higher and 1200°C in the electric furnace 3.
It is heated to around 10°C, where silicon difluoride, SiF2, etc. are produced through a chemical reaction. The generated silicon difluoride SiF2 is immediately transferred to the film deposition area? will be introduced to In the film deposition section, the substrate 8 is kept warm at a set position by an electric furnace 4. Furthermore, hydrogen H2 is also simultaneously introduced into the film deposition section 2 from the decomposition and packaging raw material gas inlet 9.

After being introduced, the hydrogen 112 comes into contact with the tungsten heater 10 placed on the gas introduction side of the film deposition section 2 or near the substrate 8, and is decomposed into hydrogen atoms by a thermal catalytic reaction. Rl, platinum, palladium, etc. are used as metals that can support this thermal catalytic reaction. -fL'-C, the hydrogen atoms and silicon niphnoide SiF2 are transported onto the substrate 8, and amorphous silicon is formed. At this time, the board m I
When l&j is between 150°C and 400°C, amorphous silicon with good photosensitivity is produced, and in particular, when the substrate variation is between 200°C and 350°C, the photosensitivity becomes great.

FIG. 2 V1, t-vt flow in the tungsten heater 10,
Also, the film formation rate of amorphous silicon is shown as a function of the temperature of the tungsten heater 10 at that time as measured by the pyrometer. As the tungsten heater's flow rate increases, the W44% ratio of hydrogen increases by -L, and the film forming rate increases accordingly. In the case of Honsochi,
The film formation rate can be improved to at least 47X/sec'.

Figure 3 shows photoconductor Δσ4, dark conductivity σd, photosensitivity change Δσ, /σd? of the deposited amorphous silicon as a function of tungsten heater toughness. Here, the photoconductivity Δσ is 100 mW/crF? It was measured using AM-1 light.

When the tungsten heater current is 8A or less, the photosensitivity Δσ,
/σd reaches 106, and the photosensitivity 1 in amorphous silicon made by the conventional discharge decomposition method is 10'.
It can be seen that amorphous silicon of higher quality than that of 105 is formed. In addition, the spin density corresponding to defects due to dangling bonds in silicon determined by ESR measurement of this amorphous silicon is 10150
m-S, which is lower than the typical M 10 "am"" in amorphous silicon made by conventional discharge decomposition methods.

When the tungsten heater current is increased, the film formation rate is increased by 1 Fi as shown in FIG. 2, but tungsten is mixed into the film and the film quality is deteriorated. For example, if the heater current is 13A,
As much as 0 pPm of tungsten is mixed in. When the heater current is 6 A, it is suppressed to 9 pl)m or less. This metal contamination (1) can be prevented by using a metal that causes a thermal catalytic reaction at low temperatures, such as platinum.

In addition, among the symbols representing the film forming conditions shown in FIGS. 2 and 3, F R (G), T8, and Pg are respectively,
Gas G flow rate (sect), substrate variation (°C), gas pressure (
'rorr).

(Effects of the Invention) The silicon-containing thin film produced by the method and apparatus of the present invention is not damaged by plasma etc.
As shown above using amorphous silicon as an example, it has low defects and high quality. Therefore, when the formed thin film is an amorphous semiconductor such as amorphous silicon, amorphous silicon carbide, or amorphous silicon germanium, highly efficient solar cells,
Can be used in electrophotographic photoreceptors, thin film transistors, image pickup tubes, etc. In addition, when the formed thin film is an insulating thin film such as troubled silicon or silicon oxide, the gate insulating film of the transistor and the field insulating film 11 may be affected by local oxidation (L o e a ) in the field insulating film and the integrated circuit.
It can be used as a dense silicon film for masks used in 10xidization, LOGO8) technology. When the present invention is applied to electronic devices such as transistors and integrated circuits, a great advantage of the present invention is that insulating films such as silicon nitride and silicon oxide can be formed by low-temperature thermal CVD.

The present invention relates not only to the formation of amorphous semiconductors or their microcrystalline or multicrystalline thin films, but also to the formation of silicon-containing insulating films, and has an extremely large and wide-ranging impact on industry.

Note that the generation of decomposed species by thermal decomposition in the method of the present invention is not limited to the method using a catalytic reaction as in the above-mentioned example. In addition to thermal decomposition, decomposition can also be caused by decomposition by plasma reaction, decomposition by photoreaction, etc.

(one

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an example of the apparatus according to the present invention, Fig. 2 is a graph of a characteristic curve showing the relationship between heater current and the growth rate, and Fig. 3 is a characteristic curve of the heater current and the thin film formed. It is a graph showing photoconductivity Δσ9, dark conductivity σd, and photosensitivity change Δσp/σd as examples.

Claims (10)

[Claims] (1) Seeds in which hydrogen H_2, silane S_iH_4, disilane S_i_2H_6, ammonia NH_3 or hydrazine N_2H_6 are decomposed into intermediate state seeds such as silicon difluoride S_iF_2 and silicon monofluoride S_iF by thermal reaction, plasma reaction or photo reaction. 1. A method for producing a silicon-containing thin film, the method comprising forming a silicon-containing thin film by thermally decomposing and depositing a material gas containing this mixed gas as a main component. (2) In claim 1, the silicon-containing thin film to be formed is amorphous silicon, fluorine-containing amorphous silicon, amorphous silicon carbide, fluorine-containing amorphous silicon carbide, amorphous silicon germanium, fluorine-containing amorphous silicon germanium, etc. A method for producing a silicon-containing thin film, characterized in that the amorphous semiconductor thin film is a microcrystalline or polycrystalline film. (3) The method for manufacturing a silicon-containing thin film according to claim 1, wherein the silicon-containing thin film formed is an insulating thin film of silicon nitride, silicon oxide, silicon nitride, or the like. (4) The silicon-containing thin film formed in claim 1 is an insulating film of silicon nitride, silicon oxide, silicon nitride oxide, etc., and this insulating film contains fluorine, hydrogen, or both. A method for producing a silicon-containing thin film, characterized by: (5) A method for producing a silicon-containing thin film according to any one of claims 1 to 3, characterized in that the thermal decomposition temperature during deposition of the thin film is room temperature or higher. (6) In any one of claims 1 to 5, the thermal decomposition temperature when depositing the thin film is from 150°C to 4°C.
A method for producing a silicon-containing thin film, characterized in that the temperature is in the range of 00°C. (7) In any one of claims 1 to 6, hydrogen H_2, silane S_iH_4, disilane S_i_2H_6, ammonia NH_3 or hydrazine N_2H_4 is added to a metal that causes a thermal catalytic reaction such as incandescent or red-hot tungsten, platinum or palladium. A method for producing a silicon-containing thin film, characterized in that decomposed species are generated by contacting the silicon-containing thin film. (8) In any one of claims 1 to 7, the thin film is deposited only by thermal decomposition without exposing the surface of the thin film deposition substrate to plasma or high-energy light when depositing the thin film. A method for producing a silicon-containing thin film characterized by: (9) An intermediate state species generation section, a film deposition section that communicates with the intermediate state species generation section and includes a heating device that accommodates a substrate therein and heats it to a predetermined temperature, an intermediate state species generation section, and film deposition. The decomposition species source gas introduction section is provided near the connection part of the part, and the decomposition species generation part is provided in the gas passage between this introduction part and the substrate heating part or near the film deposition part. An apparatus for manufacturing a silicon-containing thin film, which is characterized by: (10) The device for manufacturing a silicon-containing thin film according to claim 9, wherein the decomposition species generating section is comprised of a heater made of a metal that causes a thermal decomposition reaction, such as tungsten, platinum, or palladium.