JPS63222424A - Method and apparatus for forming deposited film - Google Patents

Abstract

PURPOSE:To stabilize microwaves and to decrease plasma, which intrudes into a depositing space, by providing a structure wherein activating chambers are formed so that resonant frequencies are provided for the microwaves for activating a precoursor and active species and the outer parts are formed of conductive networks. CONSTITUTION:Raw material gases A and B are introduced through pipes 1 and 2 and made to be a precoursor and active species in activating spaces 3 and 4. The precoursor and the active seeds are introduced into a depositing chamber 7, in which a substrate 8 is provided, through conductive networks 5 and 6. The spaces 3 and 4 are surrounded with waveguides 12 and 13 having termination parts 10 and 11 for adjusting resonant frequencies and cylindrical water-cooling applicators 14 and 15. Microwaves are introduced from microwave oscillators 16 and 17 through pipes 12 and 13. When plasma is yielded in the spaces 3 and 4, the resonant frequencies are fluctuated. Then the termination parts 10 and 11 are moved so as to correct the fluctuations, and the microwave discharge is stabilized. The networks 5 and 6 prevent the intrusion of the plasma into the chamber 7 and damage on the deposited film.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to amorphous (microcrystalline) functional films, particularly those used in semiconductor devices, photosensitive devices for electrophotography, line sensors for image input, imaging devices, etc. The present invention relates to a method suitable for forming a deposited film in a non-monocrystalline state such as a polycrystalline state (including cases where the deposited film exhibits a phase), and a deposited film forming apparatus.

[Conventional technology]

For example, to form an amorphous silicon film (hereinafter referred to as a-8i film), vacuum evaporation method 2 plasma CVD method,
CVD method 2 Reactive sintering method 9 Ion derating method, photo-CVD method, etc. have been tried, but plasma CVD method is generally widely used.

It has been corporatized.

However, the photoelectric conversion layer composed of A-8T has poor electrical and optical properties, fatigue properties during repeated use, use environment properties, and productivity and mass production, including uniformity and reproducibility. There is room for further improvement of the overall characteristics.

On the other hand, in order to develop a photoelectric conversion layer made of a-St that has electrical and optical properties that fully satisfy various uses, it is currently considered best to form it by plasma CVD.

However, in the case of photovoltaic elements, it is now necessary to achieve mass production with high reproducibility by satisfying the requirements of large area, uniformity of film thickness, and uniformity of film quality. In this respect, in the formation of A-8T photoelectric conversion using the conventional plasma CVD method, a large amount of capital investment is required for mass production equipment, and the management items for mass production are also complicated. Problems that need to be improved in the future include narrow management tolerances and delicate equipment adjustments.

On the other hand, the conventional technique using the normal CVD method requires high temperatures and has not been able to provide a deposited film with practically usable characteristics.

As mentioned above, in the formation of an A-81 photoelectric conversion layer, there is a strong desire to develop a formation method and apparatus that can be mass-produced using low-cost equipment while maintaining its practical characteristics and uniformity.

These things are not limited to the case of the above-mentioned a-8t film, but also apply to non-monocrystalline, single-crystalline, etc. silicon films such as polycrystalline, and non-single-crystalline and monocrystalline silicon films constituting other photoelectric conversion layers. The same applies to crystalline films such as silicon nitride films, silicon carbide films, and silicon oxide films.

For the above reasons, multiple gases are introduced into the deposition space, and some of them are injected with light and heat in advance.

HR-C is activated by energy such as plasma and forms a deposited film on the base button placed in the film forming space.
The VD method has been proposed. (Unexamined Japanese Patent Publication No. 60-41047) According to this HR-CVD method, a precursor for forming a deposited film generated from a gas and active species such as H (hydrogen radicals) are used, including when forming an a-8i film. A method is used in which an 8-81 film is formed on a substrate by bringing the substrate into contact with the substrate. Among other things, the advantage of this method is that the degree of microcrystalline phase, which is a form of amorphous, can be changed depending on the concentration of H*.
Furthermore, low-temperature film formation of polycrystalline silicon becomes possible.

Methods for forming the precursors and active species include activation using energy such as light, heat, and plasma, but the activation efficiency of the precursors and active species with respect to the introduced energy, or the generation Excitation by microwave discharge is superior in terms of the utilization efficiency of precursors and active species, and the difficulty of injecting funtaminic acid.

However, when the present inventors investigated the HR-CVD method using microwave discharge, the following drawbacks became clear. That is, the microwave discharge is not stable depending on the shape of the deposition space and the material of the wall surface.

Problems remain with film deposition rates and reproducibility in electrical and optical properties.

Furthermore, the plasma generated in the activation space.

It invades the deposition space, damages the surface of the deposited film, and deteriorates the properties of the deposited film.

[Problem that the invention seeks to solve]

The present invention solves the conventional problems and stabilizes the microwave discharge, thereby improving the reproducibility of the electrical and optical properties of the deposited film and reducing the invasion of plasma that damages the surface of the deposited film. By making the deposited film electrically
The object of the present invention is to provide a deposited film forming method and a deposited film forming apparatus that can improve the optical characteristics and further improve the deposition rate of the deposited film with the aid of thermal excitation.

[Means for solving problems]

The method for forming a deposited film provided by the present invention is to form a deposited film on a substrate by activating a raw material gas and bringing it into contact with a precursor used for forming a deposited film and an active 11 that chemically reacts with the precursor. A deposited film forming method for forming a deposited film having a resonant frequency with respect to the microwave used for activating part or all of the precursor and/or the active species, and at least a portion of the outer circumference of which is a conductive network. A deposited film is formed by communicating the activation space formed by the method with a deposition space for accommodating a substrate and forming a deposited film via at least a portion of the conductive network.

Further, the deposited film forming apparatus provided by the present invention includes an activation chamber that activates a source gas to generate a precursor used for forming a deposited film and an active species that chemically reacts with the precursor; A deposited film forming apparatus having a deposition chamber for forming a deposited film on a substrate by bringing a precursor and an active species into contact with each other, a microorganism used for activating some or all of the precursor and the active species. An activation chamber having a resonant frequency with respect to waves and having at least a portion of its outer envelope formed by an electrically conductive mesh is in communication with the deposition chamber via at least a portion of the electrically conductive mesh. do.

〔Example〕

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

FIG. 1 is a schematic diagram showing the outline of one structural example of a deposited film forming apparatus according to the present invention.

In Figure 1, pipe 1 and pipe 2 are filled with raw material gas and B, respectively.
is introduced and activated into precursors and active species for forming a deposited film in the activation spaces 3 and 4, respectively.

From the outlets of the tubes 1 and 2, the precursor and active species are introduced into the deposition chamber 7 through conductive nets (hereinafter simply referred to as nets) 5 and 6f. A substrate 8 with its deposition surface facing the discharge port is supported by a substrate holder 9 in the deposition chamber γ.

The activation spaces 3 and 4 are surrounded by waveguides 12 and 13 with terminations 10 and 11 for resonant frequency adjustment, cylindrical water-cooled applicators 14 and 15, and a microwave oscillator 16 and Microwaves are introduced from 17 through waveguides 12 and 13, respectively. Microwave (2450±
50 MHz) to resonate within a certain space, a standing wave must be generated within that space. In general, the tube wavelength varies depending on the shape of the space and the propagation mode of the microwave, so these effects must be taken into consideration when designing the activation space.

Also, when plasma is generated within the activation space.

Its resonant frequency fluctuates. This variation can be corrected by moving the terminations 10 and 11.

The nets 5 and 6 are also provided with heaters 18 and 19, respectively, which heat the nets to prevent deposition on the nets and their surroundings, as well as to prevent the accumulation of particles on the nets that reach the nets without being activated. The gas thermally decomposes the gas and improves the activation efficiency of precursors and active species relative to the input flow rate.

The temperature of the screen should be 200℃ to prevent the deposited film from being deposited on the screen.
℃ or above, more preferably 80℃ for thermal decomposition of residual gas
The temperature is set between 0°C and 1600°C.

In order for the net not to transmit microwaves, the largest opening of the conductor constituting the net should have a cutoff frequency for microwaves.

The net used in the present invention is one that is conductive, has a shielding effect against microwaves, is not attacked by generated plasma, and does not react with source gases, precursors, and active species.

The structure of the net is not limited to a combination of linear materials, but it can also be made of one or more holes (
It may be a plate (for example, nine-inch metal) having orifices distributed over a portion or the whole, or one or more tubes.

The material for the net is a metal with the above characteristics.

For example, stainless steel, nickel, aluminum, etc.
Alternatively, nonmetallic materials such as ceramics coated with metal or glass may be used.

Moreover, the net is not limited to one stage, but may be provided in multiple stages, in which case the structure and material of each stage may be different.

The heater for heating the net is not limited to being provided separately from the net; the net itself may be used as a heating element by using a material such as tungsten.

In addition, a thermometer such as a thermocouple may be provided to control the temperature of the screen, and a cooling lid such as water-cooled lid may be provided around the screen.

Note that quartz is suitable as the material for the tubes 1 and 2. Since quartz is a material with low dielectric loss, heat generation is not a problem. As such a material, other than quartz, polytetrafluoroethylene or the like can also be used.

In FIG. 1, reference numeral 20 denotes an exhaust port for evacuating the inside of the deposition chamber 7, and is connected to a suitable evacuation means.

The raw materials A and B are determined by the film to be deposited on the substrate 8, but when forming an a-8t photoconductive layer,
The source gases for generating active species in the activation space 3 include H2, SiH4, SiH, F, SiH, and CI.

In addition to S i Hs B r , S i H3I, etc.
Examples include rare gases such as Ha, Ne, and Ar.

On the other hand, as the raw material gas for producing the precursor, one in which an atom or atomic group with high electron-withdrawing property, or a polar group is bonded to a silicon atom is used.

For example, 5lnX2n+2 (n=1,2,3...,X=F,C
I, Br1I) #(Six2)n (n≧3.X=F
, CI, Br, I)S'n"zn+1(
n==1e2*3・-mX=F, Ct, Br, I).

5inH2x2n (n=1, 2p3..., X=p,
CI, Br, I), etc.

Specifically, for example, 5IH4, (SiF2)51.
(sir2)6°(SiF2)4.512F6. Si
Examples include those in a gaseous state or those that can be easily gasified, such as HF3.5in2F2.5tC14 (SiCl2)5°5iBr4- (StBr2)5. Also, Si horse (C10 horse)2.

5IH2(CN)2 and the like may also be used depending on the intended use of the deposited film to be formed.

Using such a deposited film forming apparatus according to the present invention, one embodiment of the deposited film forming method according to the present invention will be specifically described below. Here, a case will be described in which an a-81 film is formed as the deposited film.

Example 1 First, in FIG. 1, the distance L1 between the base 8 and the end (a) of the tube 1 is 70 tm, the distance t2 between the base 8 and the end (b) of the tube 2 is 70 m, and the distance L1 between the base 8 and the end (b) of the tube 2 is 70 m. Both outputs are 1
50W, meshes made of stainless steel are used for both meshes 5 and 6, and S[4
508CCM, H2 as raw material gas B 40SCC
M and Ar 'x 300 SCCM were introduced respectively, and the internal pressure'! : It was set at 0.50 Torr.

The nets 5 and 6 are heated to 1200° C. by tungsten heaters 20 and 21, and the source gases A and B are activated in the excitation spaces 3 and 4 by direct excitation by microwaves and the heat of the nets.

Then, from the tube 1, a precursor for forming an a-Si deposited film is supplied.

Activated species are introduced into the film forming space 7 from the tubes 2, and a chemical reaction between the two causes a substrate 8 to have good photoconductive properties.
-A Sl film was formed. The deposition rate at this time is 6X/s
In this embodiment, the activation spaces 3 and 4 are surrounded by a stainless steel outer wall having a cylindrical shape with an inner diameter of 80 fins and a length of 138 n in order to satisfy the above-mentioned resonance conditions.

Plasma is easily generated and the distance between the terminals 10 and 11 is about 10 m.
No significant change was observed in the discharge even after moving. From this, it seems that the resonance peak in the presence of plasma is a rather broad one.

For comparison, a-8t film deposition was performed without nets 5 and 6. In this case, the shape of the deposition space 7.

Due to the position and shape of the substrate 8, the discharge in the excitation spaces 3 and 4 was unstable and had poor reproducibility. Furthermore, the plasma enters the deposition space 7 and reaches the substrate 8, damaging the surface of the deposited film, leading to deterioration of the photoconductive properties of the deposited film. /as
They varied from e, to 3X/see.

As is clear from this comparative example, by using the nets 5 and 6, the discharge is stabilized, the plasma is prevented from entering the deposition space, and the precursor and active species are The excitation efficiency is improved, and as a result,
The deposited film has better photoconductive properties than conventional ones, depending on the shape of the deposition space and the position of the substrate.

Regardless of the shape, it could be formed with good reproducibility and at a higher deposition rate.

Furthermore, when only thermal excitation by a heating element was used to activate the precursor and active species, the temperature of the heating element had to be raised to 11,600° C. in order to obtain excitation efficiency equivalent to that of this example. In comparison, in this example, the temperature of the net is 12
The temperature is low, such as 00° C., and the amount of contamination generated is suppressed to a low level, and as a result, the photoconductive properties of the deposited film are further improved.

Embodiment 2 FIG. 2 is a schematic diagram showing the outline of another example of the structure of the deposited film forming apparatus according to the present invention.

The same elements as in FIG. 1 are denoted by the same reference numerals. In this example, source gases A and B are introduced into the inner cylinder 1 and outer cylinder 2 of a coaxial double cylinder made of quartz, respectively, and are activated in the same way. In the space 3, a deposited film is formed on the substrate 8 placed in the deposition chamber 7 by being excited by the microwave 12 and the heat of the net 5 provided at the end of the quartz outer cylinder.

In FIG. 2, the distance t between the base 8 and the end (a) of the inner cylinder 1
,=60txx, distance t between the base 8 and the end of the outer cylinder 2, ,=
300 cycles, the output of the microwave 18 was set to 150 W, a mesh made of tungsten was used as the mesh 5, and SiF4'i 30 SCCM was used as the raw material gas A.

The raw material is 20 H2 as B, 25 SCCM and Ar.
Each was introduced at 0 SCCM, and the internal pressure k was 0.30 Torr.
It was set to Further, the temperature of the screen was raised to 800°C.

In the case of this embodiment, the net 5 made of tungsten acts as a catalyst and increases the efficiency of producing H* radicals as active strains from the raw material B. As a result, the temperature of the net can be kept low and contamination can be reduced. was reduced, and an a-8l deposited film with good photoconductive properties could be formed.

For comparison, when deposition was carried out without using the net 5, A-81 was deposited near the outlet of the outer cylinder 2, and it peeled off during film formation and the A-81 deposited film on the substrate 8 was removed. This caused a pinhole. Furthermore, the deposition rate was also lower than that of this example.

In this embodiment, tungsten is used as the material for the net 5 having a catalytic effect, but materials having similar effects, such as vanadium, f-latina, etc. may also be used.

Embodiment 3 FIG. 3 is a schematic diagram showing the outline of another example of the structure of the deposited film forming apparatus according to the present invention.

In FIG. 3, the activation spaces 3 and 4 surrounded by stainless steel have terminations 10 and 11 for adjusting the resonant frequency and have the same elements as in FIG. A and B are introduced through orifices 22 and 231 having a cutoff frequency for microwaves, and microwaves 12 and 13 are introduced through quartz windows 24 and 25, respectively, and the excited precursors and active species are introduced here. is introduced into the deposition space through the nets 5 and 6, and forms a deposited film on the substrate 8 by a chemical reaction.

In the case of this embodiment, since the standing waves of the microwaves 12 and 13 are excited over a wide range, the excitation efficiency does not vary depending on the position of the quartz cylinder as in the conventional example. As a result, the deposition rate of the deposited film and the reproducibility of the film quality were improved.

〔Effect of the invention〕

As explained in detail above, the deposited film forming method and deposited film forming apparatus according to the present invention can stabilize microwaves regardless of the shape of the deposition space and the position and shape of the substrate, and can prevent plasma entering the deposition space. By reducing the It makes it possible to easily achieve mass production.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are schematic diagrams each showing a schematic configuration of a configuration example of a deposited film forming apparatus according to the present invention. 1.2...tube, 3,4...excitation space, 5,6...
Conductive net, 7... Film forming space, 8... Substrate, 9...
・Substrate holder, 10.11... Termination part for adjusting resonance frequency, 12°13... Waveguide, 14.15... Water-cooled applicator. 16.17...Microwave oscillator, 18.19...
Heater, 20... Exhaust port, 22.23... Oriswiss, 24.25... Quartz window. Agent Patent Attorney Jo Taira Yamashita Figure 3

Claims (3)

[Claims] (1) A deposited film forming method in which a deposited film is formed on a substrate by activating a raw material gas and bringing into contact a precursor used for forming a deposited film and an active species that chemically reacts with the precursor. An activation space having a resonant frequency with respect to the microwave used for activating part or all of the precursor and/or active species and having at least a portion of the outer circumference formed by a conductive mesh is provided on the substrate. A method for forming a deposited film, the method comprising forming a deposited film by communicating with a deposition space for accommodating the conductive network through at least a portion of the conductive network. (2) The method for forming a deposited film according to claim (1), wherein at least a portion of the conductive network is heated or cooled to form the deposited film. (3) An activation chamber that activates a source gas to generate a precursor used for forming a deposited film and an active species that chemically reacts with the precursor; A deposited film forming apparatus having a deposition chamber for forming a deposited film at least one part of the outer enclosure has a resonant frequency with respect to the microwave used for activating some or all of the precursors and active species. A deposited film forming apparatus characterized in that an activation chamber, a portion of which is formed by a conductive net, communicates with a deposition chamber through at least a portion of the conductive net.