JPS63239930A - Deposited film forming apparatus by microwave plasma cvd method - Google Patents

Abstract

PURPOSE:To improve a depositing speed, to simplify the control of film forming conditions, to achieve the mass production of the films and, at the same, time, to make it possible to form a deposited film having excellent characteristics with good reproducibility, by forming at least a part of a closed microwave path with an exciting space and introducing means. CONSTITUTION:The following parts are provided in this apparatus: a depositing space 101 for forming a deposited film; exciting spaces 105, 106 for exciting a precursor or/and an active seeds, which are to become a materials for forming the deposited film with microwave energy; and introducing means 103, 104 for introducing the precursor and the active species into the depositing space 101. In this deposited film forming apparatus, the exciting space 101 and the introducing means 103, 104 form at least a part of a closed microwave path. For example, a microwave is propagated from a rectangular waveguide 110 and distributed through a directional distributer 111. The microwaves are introduced into the exciting spaces 105, 106. The precursor and the active layer, which are excited in the exciting spaces 105, 106 through the introducing pipes 103, 104, are introduced into the depositing space 101.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a deposited film forming apparatus, and particularly to a deposited film forming apparatus for forming a deposited film forming a semiconductor device such as a thin film transistor, a photovoltaic device, or a photoconductive member for electrophotography. Wave plasma CVD method (
Hereinafter, this will be referred to as the "MW-P CVD method." ) relates to a forming device.

[Description of prior art]

For example, the amorphous silicon film (hereinafter referred to as A-3i film) that constitutes the photoelectric conversion layer of a photovoltaic element can be formed using vacuum evaporation, plasma CVD, CVD, reactive sputtering, ion beam Rating method, optical CVD
Generally, plasma CVD methods are widely used and commercialized.

The reaction process in forming an A-3t-based deposited film by the plasma CVD method is considerably more complicated than that of the conventional CVD method, and the reaction mechanism is also unclear in many aspects. In addition, there are many formation parameters for the deposited film (e.g., substrate temperature, flow rate and ratio of introduced gas, pressure during formation, high frequency electrode, electrode structure, reaction vessel structure, pumping speed, plasma generation method, etc.). However, sometimes the plasma becomes unstable, which often has a significant effect on the deposited film. Furthermore, it is necessary to select parameters unique to each device, making it difficult to generalize manufacturing conditions.

For this reason, A-5 formed by plasma CVD method
The t-based deposited film must exhibit satisfactory characteristics in terms of electrical and optical properties, fatigue characteristics during repeated use, use environment characteristics, and productivity and mass production, including uniformity and reproducibility. was difficult.

However, in order to improve the performance of semiconductor devices such as photovoltaic elements, A-3i constituting the semiconductor device must be
It is essential to improve the overall properties of deposited films.

As mentioned above, in forming the A-3L deposited film, it is strongly desired to develop a forming apparatus that can be mass-produced with a low-cost apparatus while maintaining its practically usable characteristics and uniformity.

These things are similar to other deposited films, such as silicon nitride films,
The same can be said of silicon carbide films and silicon oxide films.

[Object of the Invention] It is an object of the present invention to provide a functional device using the MW-PCVD method that can solve the problems of the conventional device described above and meet the above-mentioned demands.

[Structure of the invention]

The present invention achieves the above-mentioned objects of the present invention, and an apparatus using the MW-PCVD method according to the present invention includes a deposition space for forming a salt m film and a precursor serving as a raw material for forming the deposited film. or/and an excitation space for exciting active species with microwave energy, and an introduction means for introducing the precursor and the active species into the deposition space, wherein the excitation space and the introduction means are It is characterized in that it forms at least a part of a closed microwave path.

According to the device of the present invention, since the excitation space and the introducing means form at least a part of a closed microwave path,
Since the microwave for exciting the precursor and/or the active species propagates around the closed microwave path,
In addition to the excitation space for exciting the precursors and/or active species, it is possible to reduce or eliminate dark places where microwave energy is consumed. therefore,
Since it becomes possible to efficiently excite the precursor and/or the active species, the deposition rate can be increased and a deposited film can be formed with good mass productivity.

Further, since the microwave for exciting the precursor and/or the active species propagates around the closed microwave path, it is possible to reduce or eliminate the number of locations where the microwave is reflected. Therefore, the propagation characteristics of the microwave are good and stable, so the precursor and/or active species can be excited stably,
As a result, it has become possible to form a deposited film with good characteristics with good reproducibility.

Note that the "precursor" in the present invention refers to a substance that can serve as a raw material for a deposited film to be formed, but is completely or almost incapable of forming a deposited film in its current energy state.

In addition, "active species" means to cause a chemical interaction with the precursor to give energy to the precursor, for example, or to chemically react with the precursor to form a deposited film of the precursor. refers to something that plays a role in making things possible. Therefore, the active species may contain constituent elements constituting the deposited film to be formed, or may not contain such constituent elements.

In the present invention, the raw material gas for producing the precursor is as follows:
A silicon atom having a highly electron-withdrawing atom or atomic group, or a polar group bonded to the silicon atom is used. As such, for example, 5i6Xz+tB (n-1,2
,3・=,X-F,C1゜Br, I), (SiXx)
n (n≧3.X-F, C1°Br, r), 5iaHX
t++-+ (n" 1+ 2+ 3"'+X=F
, C12,Br,I)+5InHzXza(n-1
, 2,3-, X-F, C1, Br, r), and the like.

Specifically, for example, SiF4. (SiFg)s, (SiF
z)6゜(SiFg)n, 5izF6.5iHFz
, SiH*Fz.

5iC1a, (SiC1g)@, 5IBrt, (
Examples include those in a gaseous state or those that can be easily gasified, such as SiBrz)s. Also, 5iHz(ChHs)t
, 5IHz(CN)t, etc. may also be used depending on the purpose of use of the deposited film to be formed.

However, the above-mentioned materials may be used as they are as precursors, or may be made into precursors by applying decomposition energy such as heat, light, discharge, or microwaves.

In the present invention, the raw material for generating active species is H
,,StH,,5tHzF,5iHs,CI,5iHs
Br.

In addition to 5iHzl, rare gases such as He+Ne and Ar may be used.

In the present invention, the active species are not only activated by energy such as electric discharge, light, heat, microwaves, etc., or a combination thereof, but also may be generated by contact with or addition of a catalyst.

Hereinafter, the contents of the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic diagram of a first embodiment of a deposited film forming apparatus according to the present invention.

In the figure, a deposition space 101 is evacuated by an exhaust system (not shown) via an exhaust pipe 102 and can be maintained at a desired pressure. An introduction pipe 1 connected to the deposition space
03 and 104, excitation spaces 105 and 10
6, the excited precursors and active species are deposited in the deposition space 1.
01. Using the precursor and/or active species introduced in this way as raw materials, a deposited film is formed on the substrate 10B for forming a deposited film held in the substrate holder 107 arranged in the deposition space 101. . Note that the substrate holder 107 is provided with a heater 109 for heating the substrate, and it is possible to maintain the substrate 108 at an arbitrary temperature.

Next, propagation of microwaves used to excite precursors and/or active species will be explained in detail.

Microwaves generated by a microwave oscillator (not shown) propagate through a rectangular waveguide 110 and reach a directional distributor 111. The microwave is distributed by a directional distributor and the excitation space! Introduced in 05 and 106. In the excitation spaces 105 and 106, the introduction pipe 1
The precursors and active species introduced through -03 and 104 are excited by microwaves, and part or all of the precursors and/or active species become plasma.

Therefore, the introduction pipe 103 and/or 104 becomes a microwave waveguide.

Therefore, after the microwaves that have reached the excitation space 105 described above propagate to the excitation space 106 via the introduction tubes 103 and/or 104, some of them are radiated into the deposition space 101, and the other part is emitted into the rectangular guide. It is radiated to the wave tube 112. The microwave radiated into the deposition space 101 is transmitted to the antenna 11.
3, propagates to the antenna 115 via the coaxial line 114, is excited into the rectangular waveguide 116 by the antenna 115, and reaches the directional coupler 111 via the waveguide 116. . Furthermore, the microwave radiated to the rectangular waveguide 112 is transmitted to the antenna 1 via the waveguide 116.
After being received by the antenna 16, the wave propagates to the antenna 113 via the coaxial line 114, and is transmitted to the deposition space 1 by the antenna 113.
01 and the introduction tube 103 or/and 104
and propagates into the excitation space 106 via.

In this way, the excitation spaces 105 and 106 and the introduction means IQ3
or/and 104 forms a part of a closed microwave path, and the microwave emitted by the microwave oscillator (not shown) propagates around the closed microwave path. .

Using such a deposited film forming apparatus, a deposited film was formed in the following manner. Here, a case will be described in which a flat glass substrate is used as the base 108 and an A-3i film is formed as the deposited film.

5IFa is supplied as a precursor raw material gas to the introduction pipe 103 at a flow rate of 5 Qsces, and Hl is supplied as an active species raw material gas to the introduction pipe 104 at a flow rate of 50 seconds,
A precursor and an active species were generated by excitation with microwaves having a frequency of 2.45 GHz, and introduced into the deposition space 101. At this time, the substrate heating heater 109
The temperature of the substrate 108 was maintained at 250°C. Thus 30
The A-3i film with a thickness of 1.5 μm was deposited on the substrate 1.
08.

On the formed A-3ipJ, a comb shape/
Forms an electric beam, 2.2 x 101 photon/c
When the dark conductivity and bright conductivity were measured by irradiation with a He-Ne laser of
'.

(0cm)-', fp=7.3X10-"<0cm)-
It was found that it had good photoconductivity.

FIG. 2 is a schematic diagram of another embodiment of the deposited film forming apparatus according to the present invention. However, for members that are functionally the same as in the first embodiment, the last two digits are the same.
The explanation will be simplified.

The figure shows antennas 113 and 1 in the first embodiment.
15 and coaxial line 114, an alumina window 217
This is a schematic diagram of a deposited film forming apparatus similar to that shown in FIG. 1, except that a rectangular waveguide 216 is directly connected to the window. The microwave generated by the wave oscillator passes through the rectangular waveguide 2
10 , distributed by directional distributor 211 and introduced into excitation spaces 205 and 206 .

In the excitation spaces 205 and 206, the introduction pipe 203
The precursors and/or active species introduced through 204 are excited by microwaves, and part or all of the precursors and/or active species become plasma. Therefore, the introduction tube 203 and/or 204 becomes a microwave waveguide.

Therefore, the microwaves that have reached the excitation space 205 are transferred to the excitation space 205 through the introduction tube 203 and/or 204.
After propagating to 06, a part is radiated to the deposition space 201,
The other part is radiated to the rectangular waveguide 212. The microwave radiated into the deposition space 201 is transmitted through the alumina window 2.
17 into a rectangular waveguide 216 and reaches the directional coupler 211 via the waveguide 16. Furthermore, the microwave radiated to the rectangular waveguide 212 is transmitted to the waveguide 216.
After propagating, it is radiated into the deposition space 101 through the alumina window 217, and is emitted into the inlet pipe 203 or/and 20.
4 into the excitation space 206.

In this way, the excitation spaces 205 and 206 and the introducing means 203
and/or 204 form a part of a closed microwave path, and the microwave emitted by the microwave oscillator (not shown) propagates around the closed microwave path.

Using this example with such a structure, an A-5i film with a thickness of 1.5 μm was deposited on the glass substrate 2 under the same conditions as in the first embodiment.
08.

On the formed A-3j film, comb shapes A are formed at intervals of 0.2f1.
n! Form ii pole, 2.2 x 1014 photo
When the dark conductivity and bright conductivity were measured by irradiation with n/- He-Ne laser, they were σa -7,4xl, respectively.
O-"(Ωam)-', σp-5.2X10-'(0c
It was found that it had a good photoconductivity of m)-'.

FIG. 3 is a schematic diagram of still another embodiment of the deposited film forming apparatus according to the present invention. However, the first and second
Components that are functionally the same as those in the embodiment are given the same numbers in the last two digits, and the description will be simplified.

In this device, microwaves emitted by a microwave oscillator (not shown) are transmitted to a movable stub tuner 318.
and is introduced into the excitation space 305.

In the excitation space 305, the introduction pipes 303 and 304
The precursor and active species introduced through the microwave are excited by microwaves, and part or all of the precursor and/or active species become plasma. For this reason, the introduction pipe 3
03 and/or 304 are microwave waveguides.

Therefore, after the microwaves that have reached the excitation space 305 described above propagate to the excitation space 306 via the introduction tubes 303 and/or 304, some of them are radiated into the deposition space 301, and the other part is emitted into the rectangular guide. It is radiated to the wave tube 312. The microwave radiated into the deposition space 301 is radiated into the rectangular waveguide 316 through the alumina window 317 and reaches the excitation space 306 through the rectangular waveguide 312 . Furthermore, the microwave radiated to the rectangular waveguide 312 is transmitted to the waveguide 316.
After propagating, it is radiated into the deposition space 301 through the alumina window 317, and is emitted into the inlet pipe 303 or/and 30.
4 into the excitation space 306.

In this way, the excitation space 306 and the introducing means 303 or/and
and 304 form a part of a closed microwave path, and the microwave emitted by the microwave oscillator (not shown) propagates around the closed microwave path.

A case will be described in which a 13i film is formed using such a deposited film forming apparatus as follows.

SiF4 is flowed into the introduction pipe 303 as a precursor source gas f
In addition to supplying t1ooscc-, H! and Ar are respectively flowed into the introduction pipe 304.
The precursors and active species were supplied at 50 sccm and 200 sccs and activated by microwaves at a frequency of 2.45 GHz, respectively, and introduced into the deposition space 301. At this time, the temperature of the substrate 308 was maintained at 250° C. by the substrate heating heater 309. Deposition was carried out in this manner for 45 minutes to a thickness of 2. An A-3t film of O77m was formed on the substrate 308.

On the formed A-3t film, comb-shaped AI electrodes with a spacing of 0.2 f1 were formed, and 2.2 x 101 photon/
When irradiated with cd He-Ne laser and measured the dark conductivity and bright conductivity, each cd = 3. I
XIO"(Ωam)-', σp=4.2xlo-'(
It was found that it had a good photoconductivity of 9)-1.

〔Effect of the invention〕

As described above in detail, the deposited film forming apparatus according to the present invention includes an excitation space for exciting a precursor and/or an active species, which is a raw material for deposited film formation, by microwave energy, and By making the introduction means for introducing the active species into the deposition space at least part of a closed microwave path, the propagation characteristics of the microwave for exciting the precursor and/or the active species are stabilized. , Therefore, it became possible to stably excite the precursor and/or the active species.

In addition, as mentioned earlier, microwaves propagate in a circular manner through a closed microwave path that includes the excitation space and the introducing means, so that the loss of microwave energy is reduced or eliminated, resulting in It has become possible to efficiently excite precursors and/or active species for film formation.

As described above, according to the deposited film forming apparatus according to the present invention, a deposited film with good properties can be reproduced while improving the deposition rate, simplifying the management of film forming conditions, and mass producing films. It has become possible to form the structure with good properties.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 3 are schematic diagrams of embodiments of a deposited film forming apparatus according to the present invention. 101.201,301. ...Deposition space, 102゜2
02.302...Exhaust pipe, 103,203,303・
...Introduction pipe, 104,204,304...Introduction pipe, 1
05°205.305...excitation space, 106,206
, 306... excitation space, 107, 207, 307...
・Substrate holding part, 108.208,308...Base, 1
09,209゜309...Heater for heating the substrate, 11
0,210°310... rectangular waveguide, 111,211
...Directional coupler, 112,212.312...Rectangular waveguide, 113...Antenna, 114...Coaxial line, 115...Antenna, 116,216,316...
...Rectangular waveguide, 217°317...Alumina window,
318...Movable squib tuner. Figure 1 Figure 2

Claims (1)

[Claims] a deposition space for forming a deposited film; an excitation space for exciting a precursor and/or an active species as a raw material for forming the deposited film with microwave energy; A deposited film forming apparatus using a microwave plasma CVD method, wherein the excitation space and the introducing means form at least a part of a closed microwave path. .