JPH06267870A - Method and device for forming deposit film - Google Patents

Abstract

PURPOSE:To mass-produce a III-V compound semiconductor film having excellent electrical characteristics and a large area at a relatively low temperature by reducing the adhesion of the film to members on the outside of a discharge vessel so as to prolong the maintenance interval of the vessel and enlarging the exhaust conductance from the vessel, and then, reducing the leakage of microwaves from the vessel and generating plasma in the vessel by efficiently utilizing energy. CONSTITUTION:A discharging space is formed of a discharge vessel 105 and substrate 107 and a film is formed by applying a DC voltage across at least part of the vessel 105 so that the vessel 105 can become the positive side against the substrate 107. In addition, a louver is fitted to the exhaust port of the vessel. Or, the gaseous raw material of a III-V semiconductor is subjected to microwave energy which is smaller than that required for completely decomposing the gaseous raw material under a pressure of <=50mTorr and, at the same time, to high-frequency energy larger than the microwave energy while the gaseous raw material is introduced into the vessel 105.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a microwave plasma C
The present invention relates to a deposited film forming method and apparatus by the VD method.

[0002]

2. Description of the Related Art Hydrogenated amorphous silicon (a-Si (H)) and hydrogenated amorphous silicon carbide (a-SiC (H)) are used as materials for solar cells, photovoltaic elements, photosensitive drums for copying machines, etc. The amorphous semiconductor deposited film has been put to practical use. As a method for depositing such an amorphous semiconductor film, a high frequency plasma CVD method has been put into practical use in the past. In this high-frequency plasma CVD method, when a high frequency of 13.56 MHz is used when the degree of vacuum is on the order of 1 Pa, only low-ionization plasma with an electron density of about 10 ¹⁰ pieces / cm ³ is generated, and the use efficiency of the source gas is high. There is a problem that the deposition rate is low and slow.

On the other hand, in the microwave plasma CVD method, for example, when a microwave of 2.45 GHz is used, the electron density is up to 7 × 10 ^{11 under the} same degree of vacuum.
Since highly ionized plasma of about 1 piece / cm ³ is generated, the utilization efficiency of the source gas and the deposition rate are significantly improved.

For depositing a-Si (H), for example, silane (S
iH ₄ ) gas is used, but in general, in the plasma decomposition reaction of SiH ₄ gas, SiH ₂ + H ₂ (2.1 eV), SiH ₃ + H (4.1
eV), Si + H ₂ (4.4 eV), SiH + H ₂ + H
A reaction such as (5.9 eV) occurs, and as a result, neutral radical species, or charged particles such as ionic species and electrons are generated. Among these decomposition products, under the condition of a vacuum degree of about 1 Pa, neutral radical species are generated in the seed due to inelastic collision of electrons and molecules, and the radical generation amount in plasma is SiH ₂ ^* , SiH ₃ The order is ^* , Si ^* , and SiH ^* . Of these neutral radical species, Si ^* and SiH ^* contribute to the formation of a good quality a-Si (H) film.
If there are many high-order silicon particles such as ₂ ^* and SiH ₃ ^* ,
The deposited film becomes a polymer having a high hydrogen content and becomes a low quality amorphous silicon film having a high defect density in the film.

The amorphous silicon film formed by the microwave plasma CVD method is formed at a higher speed and has a higher quality as compared with the film formed by the high frequency plasma CVD method. Seed (S
This is because a large amount of i ^* , SiH ^* ) is produced.

More recently, compound semiconductors of Group III and Group V of the periodic table (so-called III-V group semiconductors) have attracted attention. This III-V group semiconductor contains, for example, GaAs or InP and is applied to a diode, a transistor, a laser oscillation element, or the like. Conventionally, III-V group compound semiconductors are, for example, molecular beam epitaxy (MBE) method, metalorganic thermal decomposition (MO-CVD) method, halide CVD method,
It was formed by the liquid phase epitaxial growth (LPE) method (edited by Kiyoshi Takahashi, "Molecular Beam Epitaxy Technology", Industrial Research Committee). In addition, II by plasma CVD method
For the formation of IV compound semiconductors, see Leiber J, Bra.
"Growth" by users A, Heinecke H, Lueth H, Balk P
of GaAs and InP on Si using plasma stimulated MOCV
D ", J. Cryst. Growth, Vol. 96, No. 3, p. 483 (1989)
It is described in.

FIG. 18 shows a conventional microwave plasma CV.
It is a schematic diagram which shows the structural example of D apparatus. Vacuum container 901
Is connected to an exhaust pump (not shown) via an exhaust pipe 909. An applicator 902 is attached to the upper surface of the vacuum container 901 via a microwave introduction window 903. The substrate 907 on which the deposited film is formed is held in the vacuum container 901 by a substrate holder 906 having a heater 910 inside. Then, a raw material gas introduction pipe 904 for introducing the raw material gas into the vacuum container 901.
Are attached to the vacuum container 901.

Then, film formation by the microwave plasma CVD method is performed as follows. First, the inside of the vacuum container 901 is evacuated to a predetermined degree of vacuum by an exhaust pump (not shown), and the substrate 9 is heated by the heater 910 as necessary.
While heating 07, the raw material gas is introduced into the vacuum container 901 through the raw material gas introduction pipe 904. At the same time, an applicator 902 from a microwave power source (not shown)
And microwave energy is supplied into the vacuum container 901 through the microwave introduction window 903 to generate plasma discharge in the vacuum container 901. As a result, the source gas is decomposed and a deposition film 908 is formed on the base 907.

In the microwave plasma CVD method, it is an important condition to generate stable microwave plasma. Therefore, a further discharge container is provided inside the vacuum container,
The generation of microwave plasma is localized in this discharge vessel. In this case, it is necessary to efficiently store microwaves in the discharge vessel. If the microwave leakage from the discharge container is large, the microwave energy density may not increase and the discharge may not occur, or the discharge may occur outside the discharge container.
Therefore, the discharge vessel must be structured so that microwaves do not leak to the outside.

The discharge vessel is provided with an exhaust means for exhausting the raw material gas. The exhaust means is generally provided as an opening in the discharge vessel. This opening must have an exhaust conductance that can maintain a predetermined degree of vacuum inside the discharge vessel, and must be shaped so that microwave leakage is small.

By the way, a part of radical species or ionic species decomposed and produced by microwave energy is discharged to the outside of the discharge vessel through the opening which is the above-mentioned exhaust means, and a member (for example, an exhaust pipe or a valve) outside the discharge vessel is discharged. ) To form a deposited film. This accumulated film peels off as the thickness increases and adheres to the sealing surface of the valve, causing valve open / close failure, or mixes with pump oil to deteriorate the oil and reduce the pump's exhaust capacity. May cause.
Therefore, in order to prevent such troubles from occurring, it is necessary to regularly perform dry etching and mechanical maintenance in the vacuum container. Particularly, in a microwave plasma CVD apparatus using a roll-to-roll method or the like for continuously mass-producing a deposited film, since the film formation is continuously performed for a long time, this trouble is likely to occur. Further, dry etching in the vacuum container may cause contamination by etching residues and by-products due to the reaction between the wall material and the etchant, and it is necessary to remove the peeling film pieces accumulated in the exhaust pipe. There are problems that it is difficult and that the film formation time is restricted by performing etching.

[0012]

In the conventional microwave plasma CVD method, since a large amount of high-order neutral radical species are simultaneously produced, there is a problem that a low-quality portion is mixed in the deposited film. there were. Furthermore, since the microwave frequency is high during microwave discharge, the charged particles generated by the decomposition of the source gas that have a relatively large mass (heavy mass charged particles) can follow the vibration of the electric field due to the microwave. Instead, it is almost stationary in plasma. Therefore, these heavy mass charged particles cannot have enough kinetic energy to collide with source gas molecules to generate new neutral radical particles, and the generation of neutral radical particles is directly excited by microwaves. , Or only due to the collision of lightly charged particles such as electrons. Therefore, there is a problem that not all of the generated charged particles are effectively used for film formation.

Further, in the conventional microwave plasma CVD method, as described above, there is a problem to reduce the amount of radical species or ionic species flowing out from the discharge vessel to the outside, and dry cleaning for maintenance. It is desired to reduce the number of etchings and the like to lengthen the maintenance interval.

When a group III-V compound semiconductor is produced,
Conventional MBE method, MO-CVD method, halide CVD method,
In the LPE method, the substrate has to be heated to a high temperature of 500 ° C. or higher during the deposition, which causes a problem that impurities may be mixed from the inside of the deposition apparatus. In addition, since the substrate temperature during film deposition is high, the material of the members used to configure the deposition apparatus is limited to quartz glass, which can withstand high temperatures, and is not suitable for industrial mass production and large film area. It was unsuitable. In addition, normal plasma C
When the III-V group compound semiconductor film is formed by the VD method, there is a problem that a secondary gas phase reaction is likely to occur and the deposited compound semiconductor does not have sufficient electric characteristics.

An object of the present invention is that the generated charged particles as a whole contribute to film formation, film adhesion to members outside the discharge vessel is reduced, maintenance is simplified, and a maintenance interval can be extended. Provided is a method and apparatus for forming a deposited film by the CVD method, which has a large exhaust conductance from the discharge vessel, little leakage of microwaves to the outside of the discharge vessel, and can efficiently generate plasma in the discharge vessel. A method and apparatus for forming a deposited film are provided, and a large area III-V excellent in electrical characteristics is provided.
It is an object of the present invention to provide a deposited film forming method and apparatus capable of mass-producing group compound semiconductor films at a lower temperature than conventional ones.

[0016]

According to a first aspect of the present invention, there is provided a deposited film forming method according to a microwave plasma CVD method for forming a deposited film on a substrate held in a vacuum container. At least a part of the discharge vessel such that a discharge space in which microwave energy is introduced is formed by the discharge vessel provided inside and made of a conductive member, and the discharge vessel is positive with respect to the base body. A deposited film is formed on the substrate while applying a DC voltage to the substrate.

The deposited film forming apparatus of the second invention is a deposited film forming apparatus by a microwave plasma CVD method for forming a deposited film on a substrate held in a vacuum container, wherein the substrate is provided in the vacuum container. A discharge vessel that is electrically insulated from the discharge vessel and that is made of a conductive member; and a voltage applying unit that applies a positive DC voltage to at least a part of the discharge vessel. Defined by the substrate and the discharge vessel.

The deposited film forming method of the third invention is a method for forming a deposited film by a microwave plasma CVD method for forming a deposited film on a substrate held in a vacuum container, the opening being provided in the vacuum container. A discharge vessel composed of a louver at least a part of which is made of a conductive member is used, microwave energy is introduced into the discharge vessel to generate microwave plasma, and a deposited film is formed on the substrate.

The deposited film forming apparatus of the fourth invention is a deposited film forming apparatus by a microwave plasma CVD method for forming a deposited film on a substrate held in a vacuum container, the deposited film forming apparatus being provided in the vacuum container, A discharge vessel surrounding a discharge space in which microwave energy is introduced to form a deposited film and plasma is generated, and a louver made of a conductive member is formed in at least a part of an opening provided in the discharge vessel. Has been done.

The deposited film forming method of the fifth aspect of the present invention is to form a deposited film of a group III group V compound semiconductor of the periodic table on a substrate held in a vacuum container by a microwave plasma CVD method. In the method, while introducing a raw material gas of the compound semiconductor into the vacuum vessel, a microwave energy smaller than a microwave energy required for 100% decomposition of the raw material gas is applied to the raw material gas at an internal pressure of 50 mTorr or less. At the same time, the high-frequency energy larger than the applied microwave energy is applied to the source gas.

The deposited film forming apparatus according to the sixth aspect of the present invention forms a deposited film of a group III group V compound semiconductor of the periodic table on a substrate held in a vacuum chamber by a microwave plasma CVD method. In the apparatus, gas introducing means for introducing the raw material gas of the compound semiconductor into the vacuum container, microwave introducing means for introducing microwave energy into the vacuum container, and high frequency for introducing high frequency energy into the vacuum container. A microwave energy smaller than the microwave energy required to decompose 100% of the raw material gas at an internal pressure of 50 mTorr or less, and causes the raw material gas to act on the microwave energy at the same time. A deposited film is formed on the substrate by causing a large amount of high frequency energy to act on the source gas.

[0022]

In the first and second aspects of the invention, since a positive DC voltage is applied to the discharge vessel, a DC electric field is formed between the discharge vessel and the substrate so as to cross the discharge space, that is, plasma. This accelerates the movement of particularly heavy mass charged particles in the plasma, promotes the decomposition of high-order neutral radical species, and forms a high-quality deposited film (for example, an amorphous silicon film). Here, if the applied DC voltage value is changed to adjust the electric field strength, for example, when depositing an amorphous silicon film, Si ^* or SiH ^* and higher-order neutral radical species (SiH ₂ ^* , SiH ₃ ^{*) are used.} It is possible to obtain a deposited film having a required film quality. Further, by measuring the direct current flowing through the discharge vessel and controlling the applied direct current voltage so that the direct current value becomes constant, the deposition rate can be kept stable for a long time.

In the third and fourth aspects of the invention, since the louver is provided in the opening of the discharge vessel, the microwave does not leak to the outside through this opening, and the microwave energy can be efficiently stored in the discharge vessel. You can

It is preferable that a plurality of louvers are provided in the opening, which is the exhaust means, and that a plurality of partition plates are provided vertically to the louvers. At this time, it is preferable that the longer one of the distance between the louvers and the distance between the partition plates be shorter than 1/2 of the microwave wavelength. That is, by lowering the microwave frequency below the cutoff frequency of the waveguide when the prismatic cylinder surrounded by the louver and the partition plate is regarded as the waveguide, The propagation of microwaves is prevented.

Further, the inclination angle and the arrangement of the louver may be set so that the inside and the outside of the discharge vessel cannot be seen from each other. The arrangement here also includes the spacing between the plurality of louvers. By setting the inclination angle and the arrangement of the louvers in this way, formation of a deposited film outside the discharge vessel can be suppressed. It is desirable that the distance between the louvers be 5 cm or less and the inclination angle be around 45 degrees. The depth of the louvers may be the same as or slightly longer than the distance between the louvers.

In the third and fourth aspects of the invention, the pressure inside the discharge vessel is set to 1 to 100 mTorr to form a deposited film on the substrate. In this pressure range, H, H ₂ , SiH,
The mean free path of gas molecules such as SiH ₂ , SiH ₃ , and He is several centimeters to several tens of centimeters, and molecules flying in the direction of the louver from inside the discharge vessel efficiently collide with and adhere to the louver. . Therefore, it is possible to significantly reduce the formation of the deposited film on the member outside the discharge vessel. By inclining the louver downward toward the inside of the discharge vessel, it is possible to prevent the film thickly deposited on the louver from peeling off and scattering outside the discharge vessel.

In the fifth and sixth aspects of the present invention, microwave energy and radio frequency (RF) energy are simultaneously acted on the source gas, so that the periodicity table of excellent film quality III
This is based on the finding that the present inventors have found that a deposited film of a Group V group compound semiconductor is formed. The details of the deposition mechanism of the compound semiconductor here are unclear, but the selection of the optimum active species by microwave energy and the promotion of the surface reaction on the substrate surface result in the deposition of a semiconductor film with excellent electrical properties. it is conceivable that.
That is, by decomposing the raw material gas with energy lower than the microwave energy required to decompose 100% of the raw material gas for forming the deposited film, it is possible to select an active species that is unlikely to cause a gas phase reaction, and to determine the degree of vacuum in the deposition chamber. Is high (the internal pressure is low), so that the gas phase reaction can be further suppressed.

RF energy is introduced into the deposition chamber at the same time as microwave energy. RF energy makes little contribution to the decomposition of the source gas and changes the spatial distribution of electrons and ions in the plasma formed by microwaves. When RF energy is applied, a potential difference is generated between the plasma and the substrate due to the synergistic effect of electrons and ions in the plasma, unlike when DC energy is applied. Since this potential difference is due to the synergistic effect described above, abnormal discharge such as spark is unlikely to occur, and stable plasma can be maintained even during deposition for several tens of hours. Also, due to this potential difference, an electric field is generated in which the plasma side is positive and the substrate side is negative, so that the cations in the plasma are accelerated toward the substrate and promote the relaxation reaction for forming the deposited film of active species on the substrate surface. It is supposed to do. As a result, a high quality epitaxial film is considered to be formed.

Periodic table suitable for the fifth and sixth inventions
Examples of the compound containing a Group III or Group V element include the following.

Examples of the Al compound include AlCl ₃ and AlBr.
₃ , AlI ₃ , Al (CH ₃ ) ₂ Cl, Al (CH ₃ ) ₃ , Al (OC
_{H 3) 3, Al (CH} 3) Cl 2, Al (C 2 H 5) 3, Al (OC
_{2 H 5) 3, Al (} i-C 4 H 9) 3, Al (i-C 3 H 7) 3, Al (C 3
H _{7) 3,} such as Al (OC ₄ H _{9) 3} and the like.

As the Ga compound, GaCl₃, GaI₃,
GaBr₃, Ga (OCH₃)₃, Ga (OC₂H_Five)₃, Ga (OC
₃H₇)₃, Ga (OC_FourH₉)₃, Ga (CH₃)₃, Ga₂H₆, Ga
H (C ₂H_Five)₂, Ga (OC₂H_Five) (C₂H_Five)₂Etc.
It

As the In compound, In (CH ₃ ) ₃ , In
_{(C 3 H 7) 3,} In (C 4 H 9) 3 and the like.

As the P compound, PF ₃ , PF ₅ , PCl ₃ ,
PCl ₅ , PBr ₃ , PBr ₅ , P (CH ₃ ) ₃ , P (C ₂ H ₅ ) ₃ , P
_{(C 3 H 7) 3,} P (C 4 H 9) 3, P (OCH 3) 3, P (OC 2 H 5) 3,
P (OC ₃ H ₇ ) ₃ , P (OC ₄ H ₉ ) ₃ , PSF ₃ , PSCl ₃ , P
(SCN) ₃ , P ₂ H ₄ , PH _{3 and the} like.

As compounds include AsH ₃ , AsCl ₃ ,
_{AsBr 3, As (OCH 3)} 3, As (OC 2 H 5) 3, As (OC
₃ H ₇ ) ₃ , As (OC ₄ H ₉ ) ₃ , As (C ₂ H ₅ ) ₃ , As (C ₆ H ₅ ) ₃
And so on.

As the Sb compound, SbF ₃ , SbF ₅ , S
bCl ₃ , SbCl ₅ , SbBr ₃ , Sb (OCH ₃ ) ₃ , Sb (O
_{C 2 H 5) 3, Sb} (OC 3 H 7) 3, Sb (OC 4 H 9) 3, Sb (CH
₃ ) ₃ , Sb (C ₃ H ₇ ) ₃ , Sb (C ₄ H ₉ ) _{3 and the} like.

When a III-V group compound semiconductor is formed using these compounds, a multi-element compound semiconductor may be formed by using a plurality of these compounds.

Examples of the dopant for the III-V group compound semiconductor include the following.

As the n-type dopant, Si, Ge, S
n, Te, Se, S, O and the like can be mentioned.

Specifically, a gas containing Si atoms and capable of being gasified
As a compound, SiH_Four, Si₂H₆, SiF_Four, SiFH₃,
SiF₂H₂, SiF₃H, Si₃H₈, SiD_Four, SiHD₃, S
iH ₂D₂, SiH₃D, SuFD₃, SiF₂D₂, Si₂D₃H
₃And so on.

Specific examples of the gasifiable compound containing Ge atoms include GeH ₄ , GeD ₄ , GeF ₄ , GeFH ₃ ,
GeF ₂ H ₂ , GeF ₃ H, GeHD ₃ , GeH ₂ D ₂ , GeH ₃
D, GeH ₆ , GeD _{6 and the} like can be mentioned.

Specific examples of the gasifiable compound containing Sn atom include SnH ₄ , and Sn as an organometallic compound.
_{(CH 3) 4, Sn (} C 2 H 5) 2, Sn (C 2 H 5) 4, Sn (n-C 4 H
₉ ) ₃ , SnH (n-C ₄ H ₉ ) _{3 and the} like.

Specific examples of the gasifiable compound containing Te atoms include organometallic compounds such as Te (CH ₃ ) ₂ and Te (C ₂ H ₅ ) ₃ .

Specific examples of the Se-containing atomizable compound include SeF ₄ , SeF ₆ , Se ₂ Cl ₂ and SeC.
l ₄ , H ₂ Se, Se (CH ₃ ) ₂ , Se (C ₂ H ₅ ) _{2 and the} like.

Specific examples of the gasifiable compound containing S atom include SF ₄ , SF ₆ , S ₂ Cl ₂ , SCl ₂ and SC.
l ₄ , S ₂ Br ₂ , H ₂ S and the like.

Specific examples of the gasifiable compound containing an oxygen atom include O ₂ , H ₂ O, CO ₂ , NO, N ₂ O and NO ₂ .

As the p-type dopant, C, Be, Mg, Z
n, Cd, Li, Au, Mn, Ag, Pb, Co, Ni, Cu, F
e, Cr and the like.

Specific examples of the gasifiable compound containing a carbon atom include CH ₄ , CD ₄ , C _n H _{2n + 2} (n is an integer), C
_Examples include _n H _2n (n is an integer), C ₂ H ₂ , C ₆ H _{6 and the} like.

Specific examples of the gasifiable compound containing Be atom include Be (CH ₃ ) ₂ , Be (C ₃ H ₇ ) ₂ and Be (C
₄ H ₉ ) _{2 and the} like.

Specific examples of the gasifiable compound containing Mg atoms include MgCH ₃ Cl, MgCH ₃ Br and MgC.
_{2 H 5 Br, MgC 3 H} 7 Cl, and the like MgC ₄ H ₉ Cl.

Specific examples of the gasifiable compound containing Zn atoms include Zn (CH ₃ ) ₂ and Zn (C ₂ H ₅ ) ₂ .

Cd, Li, Au, Mn, Ag, Pb, C
Suitable examples of the gasifiable compound containing o, Ni, Cu, Fe and Cr atoms include organometallic compounds having groups such as CH ₃ and C ₂ H _{5 of} these elements.

The preferable doping amount of these dopants is 0.01 to 10%.

Next, application of the compound semiconductor deposited film formed by the fifth and sixth inventions will be described.

FIG. 16 is a schematic sectional view of a photovoltaic device using this compound semiconductor. This photovoltaic element includes a substrate (base) 801, a back electrode 802, a first semiconductor layer 80.
3 and the second semiconductor layer 804, the comb-shaped collector electrode 806, the antireflection layer 805, and the like.

Material Suitable for Substrate 801 of This Photovoltaic Device
InAs, GaAs, In _1-xGa_xAs, Ga
_1-xAl_xExamples include As and the like. The substrate 801 is n
Type or p-type doped to have low resistance
Is preferred.

First and second semiconductor layers 803 and 804
Are deposited according to the fifth and sixth inventions. First
The semiconductor layer 803 is preferably of the same semiconductor type (conductivity type) as the substrate 201, and preferably has a layer thickness of 0.2 to 100 μm. The second semiconductor layer 804 is the first semiconductor layer 8
It is preferably a semiconductor type different from 03, and 0.2 to 1
A layer thickness of 00 μm is preferred.

The material of the back electrode 802 is Al, C
Suitable examples include r, Cu, Ag, Au, Pt, and Ni. In order to collect the photoexcited carriers efficiently, the layer thickness of the back electrode 802 is preferably in the range of 500Å to 10 μm. As a method of depositing the back surface electrode 802, resistance heating, electron beam vacuum evaporation method, sputtering method, or the like is suitable. Further, in order to improve the ohmic property between the back surface electrode 802 and the substrate 801, after the deposition of the back surface electrode 801, a laser, a tungsten lamp,
Use a halogen lamp or the like for 20 minutes or less
It is preferred to anneal at a temperature of 0-500 ° C.

The material of the antireflection layer 805 is Zn
O, SnO ₂ , In ₂ O ₃ , ITO, TiO ₂ , CdO, Cd ₂ S
Preferred examples include nO ₄ , Bi ₂ O ₃ , MoO ₃ , and Na _x WO ₃ . Suitable methods for depositing the antireflection layer 805 include vacuum vapor deposition, sputtering, CVD, spraying, spin-on, and dip methods. The thickness of the antireflection layer 805 depends on the refractive index of the material forming the antireflection layer, but is 5
It is preferable that the thickness is about 00Å to 10 μm.

As the comb-shaped collector electrode 806, Al, Cu,
A single layer of Cr, Ag, Au, Ni, etc. or a laminate of a plurality of layers is suitable. The layer thickness of the comb-shaped collector electrode 806 is preferably about 500 Å to 10 μm. Suitable methods for depositing the comb-shaped collector electrode 806 include resistance heating, electron beam vacuum evaporation method, and sputtering method.

FIG. 17 shows a MESFET (Metal-semicondu) using a compound semiconductor film according to the fifth and sixth inventions.
ctor Field Effect Transistor, metal-semiconductor field effect transistor). This MESF
In ET, first to fourth semiconductor layers 852 to 855 are sequentially stacked on a substrate (base body) 851, and a source electrode 85 is further provided.
6, gate electrode 857, drain electrode 858, protective layer 8
59 and the like are provided. Each semiconductor layer 8
52 to 855 are deposited by the fifth and sixth inventions.

Suitable materials for the substrate 851 of this MESFET are InAs, GaAs, In _1-x Ga _x As, G.
a _1-x Al _x As and the like. The substrate 851 is
Those that are effectively insulating layers are preferred. Therefore, an n-type dopant or a p-type dopant may be added to the substrate 851 as appropriate.

As the first semiconductor layer 852 formed on the substrate 851, a semiconductor whose lattice constant is substantially the same as that of the substrate 851 is suitable, and homoepitaxial (epitaxial growth of the same kind of material) is particularly suitable. . It is suitable that the first semiconductor layer 852 be a semiconductor film to which no dopant is added, or an intrinsic semiconductor film. Further, the layer thickness of the first semiconductor layer 852 is preferably 0.1 to 10 μm.

The second formed on the first semiconductor layer 852
The semiconductor layer 853 is preferably a semiconductor whose lattice constant is substantially the same as that of the first semiconductor layer 852, and is particularly preferably homoepitaxy. The second semiconductor layer 853 is n
Type semiconductor film is suitable, and the second semiconductor layer 85
The layer thickness of 3 is preferably 0.05 to 3 μm.

Third formed on second semiconductor layer 853
The semiconductor layer 854 is preferably made of a semiconductor whose lattice constant is substantially the same as that of the second semiconductor layer 853, and is particularly preferably homoepitaxy. The third semiconductor layer 854 is n
It is desirable to use a ⁺ type semiconductor film. Further, it is suitable that the layer thickness of the third semiconductor layer 854 is 0.05 to 3 μm.

The fourth formed on the third semiconductor layer 854
As the semiconductor layer 855, a semiconductor layer having a lattice constant substantially equal to that of the third semiconductor layer 854 is suitable, and homoepitaxiality is particularly suitable. The fourth semiconductor layer 855 is n
^{A +} type semiconductor film is preferable, and the fourth semiconductor layer 8
The concentration of the dopant contained in 55 is preferably higher than that in the third semiconductor layer 854. Further, the thickness of the fourth semiconductor layer 855 is preferably 0.005 to 0.1 μm.

Metals and alloys can be used for the source electrode 856, the drain electrode 857 and the gate electrode 858. As a metal electrode, Al, Au, Cr, Ni, C
u, Ag, Pt and the like are included. In addition, as an alloy, In ₂
Examples thereof include O ₃ , SnO ₂ , AlSi, AlGe, AuGe, and NiCr. Further, each of the electrodes 856 to 858 may be composed of a multilayer film of these metals and alloys. Each electrode 85
The layer thickness of 6 to 858 is preferably about 500 Å to 10 μm. As a method for depositing each of the electrodes 856 to 858, resistance heating, electron beam vacuum evaporation method, sputtering method, or the like is suitable. Also, each electrode 856-858
In order to improve the ohmic properties of the semiconductor layers 852 to 855, after depositing the electrodes 856 to 858, a laser, a tungsten lamp, a halogen lamp, or the like is used, and the temperature is 200 to 500 ° C. for 5 minutes or less. Annealing at temperature is preferred.

[0067]

Embodiments of the present invention will now be described with reference to the drawings.

<< First Embodiment >> (Embodiment 1-1) FIG. 1 is a schematic view showing a structure of a deposited film forming apparatus by a microwave plasma CVD method according to a first embodiment of the present invention. A discharge container 105 for forming a discharge space is provided inside the vacuum container 101 connected to a vacuum pump (not shown) via an exhaust pipe 111. The discharge container 105 is a container having a substantially rectangular parallelepiped shape, which is made of a conductive member and has an open upper surface. Discharge vessel 105
On the side wall of the exhaust pipe 111 side of the vehicle
6 is provided, and an applicator 102 is attached to a side wall opposite to the side wall via a microwave introduction window 103. The other end of the applicator 102 is connected to a microwave power source (not shown). Discharge vessel 10
A raw material gas introduction pipe 104 for introducing the raw material gas into the discharge vessel 105 is attached to the lower surface of 5.

The substrate 107 on which the deposited film is formed is held so as to cover the opening on the upper surface of the discharge container 105, and a heater 108 for heating the substrate 107 is provided. The discharge container 105 is a vacuum container 1 via an insulator 110.
01, a variable DC power supply 109 for applying a DC voltage to the discharge container 105 is provided outside the vacuum container 101. The insulator 110 includes the discharge vessel 105,
It is for electrically insulating the vacuum container 101, the ground, and the base 105.

When a deposited film is formed on the surface of the substrate 107 by using this deposited film forming apparatus, first, the inside of the vacuum container 101 is evacuated to a predetermined vacuum degree via the exhaust pipe 111, and the heater 108 of the substrate 107 is evacuated. Heating. Next, the source gas is introduced into the discharge vessel 105 through the source gas introduction tube 104, and a positive DC voltage is applied to the discharge vessel 105 by the variable DC power source 109. Further, a microwave is generated by a microwave power source (not shown), and this microwave is supplied into the discharge container 105 through the applicator 102 and the microwave introduction window 103.

As a result, microwave discharge occurs in the discharge vessel 5, plasma is generated and the source gas is decomposed, and a deposited film is formed on the surface of the substrate 107. At this time, since a positive DC voltage is applied to the discharge vessel 105, the heavy mass charged particles in the plasma also have sufficient kinetic energy. In the case of forming an amorphous silicon film, generation of radical particles in plasma, particularly generation of low-order silicon particles from high-order silicon particles is promoted, and a high-quality amorphous silicon film is deposited on the surface of the substrate 107. To be done.

By appropriately adjusting the DC voltage applied to the discharge vessel 105 and changing the magnitude of the DC electric field in the plasma, the composition of the radical species generated is changed and a deposited film having a desired film quality is obtained. be able to. Further, by monitoring the DC current flowing from the variable DC power supply 109 to the discharge vessel 105 and controlling the DC voltage applied so that this current becomes constant, the deposition rate stabilizes at a constant value for a long time.

(Embodiment 1-2) FIG. 2 is a schematic diagram showing another structure of the deposited film forming apparatus by the microwave plasma CVD method according to the first embodiment of the present invention. This deposited film forming apparatus is different from that shown in Example 1-1 in that a rectangular horn type discharge vessel is used and a deposited film is formed on a film-shaped substrate.

Inside the vacuum container 130, which is connected to a vacuum pump (not shown) via the exhaust pipe 132, a rectangular horn-shaped discharge container 134 made of a conductive material is provided.
It is attached to the vacuum container 130 via 39. The opening surface as the horn of the discharge container 134 is provided with the exhaust pipe 141.
The film-shaped base 136 is arranged so as to cover the opening surface. Both ends of the base 136 are
The base 136 is supported by a base holder 140 for feeding and winding the base 136. A heater 137 for heating the base 136 is provided. On the other hand, an applicator 131 is attached to the base side of the discharge vessel 134 as a horn via a microwave introduction window 132. The other end of the applicator 131 is connected to a microwave power source (not shown). Further, the discharge vessel 134 is provided with a source gas introduction pipe 133 for introducing a source gas into the discharge vessel 134. Further, a variable DC power supply 138 for applying a positive DC voltage to the discharge container 134 is provided.

The formation of the deposited film on the surface of the substrate 136 by this deposited film forming apparatus is the same as that of the above-mentioned Example 1-1 except that the film-shaped substrate 136 is wound by the substrate holder 140. is there. By continuously winding the base 136, a deposited film is continuously formed on the surface of the long film-shaped base 136.

In this deposited film forming apparatus, the discharge vessel 134
Since it is a horn type, there is an advantage that impedance matching to microwaves can be easily performed.

<Second Embodiment> (Embodiment 2-1) Next, a deposited film forming apparatus by a microwave plasma CVD method according to a second embodiment of the present invention will be described with reference to FIG.

The deposited film forming apparatus 200 shown in FIG. 3 comprises a substantially rectangular parallelepiped vacuum container 201 and a discharge container 202 provided in the vacuum container 201. Vacuum container 20
Both 1 and the discharge vessel 202 are made of metal and are grounded. Long strip-shaped substrate 203 on which a deposited film is formed
Passes through the gas gate 204 attached to the left side of the vacuum container 201 in the figure, that is, the side wall on the carry-in side.
01, is penetrated through the discharge vessel 202, and is discharged to the outside of the vacuum vessel 201 through the gas gate 205 attached to the right side of the vacuum vessel 201 in the drawing, that is, the side wall on the carry-out side. Each gas gate 204,20
Gate gas supply pipes 206 and 207 for supplying gate gas are connected to the column 5, respectively. Substrate 203
Is configured to continuously move from a substrate delivery container (not shown) connected to the carry-in side gas gate 204 to a substrate winding container (not shown) connected to the carry-out side gas gate 205. There is. Further, the vacuum container 201 has an exhaust pipe 2 for directly exhausting the vacuum container 201.
09 is attached through an exhaust port 208, and the exhaust pipe 209 is connected to an exhaust means (not shown) such as a vacuum pump.

The discharge vessel 202 cooperates with the base body 203 to create a space (discharge space 2) in which microwave plasma discharge occurs.
It is for surrounding 10). This discharge vessel 20
An applicator 216 is attached to the substrate 2 in parallel with the base body 203 penetrating the discharge vessel 202 at a right angle to the moving direction of the base body 203. The applicator 216 is for introducing microwave energy into the discharge vessel 202, and has the other end of the waveguide 217, one end of which is connected to a microwave power source (not shown). Further, the attachment site of the applicator 216 to the discharge vessel 202 is
Each is a microwave introduction window (not shown) made of a material that transmits microwaves. A gas discharger 214 that discharges the source gas is attached to the bottom wall of the discharge vessel 202. The surface of the gas discharger 214 is provided with a large number of gas discharge holes for discharging the source gas.
The gas discharger 214 is attached to one end of a gas supply pipe 215 connected to a source gas supply source (not shown) such as a gas cylinder.

Further, the discharge port 202 is provided in the discharge vessel 202.
1 is the surface facing the applicator 216 (the discharge vessel 20
Of the two side surfaces, it is provided on the surface close to the exhaust pipe 209). The exhaust port 211 is provided with a plurality of louvers 212 in order to prevent outflow of active gas species that may form a deposited film on an external member of the discharge vessel 202.
Further, in order to prevent microwave leakage, the louver 212 has a plurality of partition plates 213 perpendicular to the louver 212.
Is attached. Each louver 212 is inclined downward toward the inside of the discharge vessel 202. The louvers 212 are selected in terms of inclination angle, spacing, depth, etc. so that the inside and outside of the discharge vessel 202 cannot be overlooked. The longer one of the distance between the louvers 212 and the distance between the partition plates 213 is set to be shorter than 1/2 of the wavelength of the microwave used.

A large number of infrared lamp heaters 218 and the radiant heat from these infrared lamp heaters 218 are efficiently provided in a portion of the discharge container 202 which is located on the opposite side of the gas discharger 214 with the strip-shaped base body 203 interposed therebetween. A lamp house 219 for concentrating on the base body 203 is provided. Further, a thermocouple 220 for monitoring the temperature of the base body 203 heated by the infrared lamp heater 218 is provided so as to be in contact with the base body 203.

The substrate 203 penetrating the discharge vessel 202 is
The discharge container 202 is introduced into the discharge container 202 through an opening provided in a side wall on the carry-in side (the left side in the drawing) and discharged from an opening provided in a side wall on the carry-out side (the right side in the drawing).

Next, the operation of the deposited film forming apparatus 200 will be described.

First, a substrate delivery container (not shown) connected to a gas gate 204 on the carry-in side so as to penetrate through the deposited film forming apparatus 200, and a substrate winding container (not shown) connected to a gas gate 205 on the carry-out side. ), The belt-shaped substrate 203 is stretched, and the inside of the vacuum container 201 and the discharge container 202 is evacuated to a vacuum through each exhaust pipe 209. When the predetermined degree of vacuum is reached, each gate gas supply pipe 206, 2
Gate gas is supplied to each gas gate 204, 205 from 07. The gate gas is mainly exhausted from the exhaust pipe 209 of the vacuum container 201. Further, a substrate feeding means (not shown) provided in the substrate feeding container
And the substrate winding means (not shown) provided in the substrate winding container are operated to continuously move the substrate 203 from the substrate delivery container toward the substrate winding container.

Then, while monitoring the output of the thermocouple 220, the infrared lamp heater 218 is operated to heat the substrate 203 to a predetermined temperature. And
The source gas is supplied from the source gas supply pipe 215 to the gas discharger 214 and discharged into the discharge vessel 202. In addition, the microwave power is applied to the applicator 216 via the waveguide 217.
Apply to.

By doing so, the discharge vessel 20
Since the raw material gas is released into the discharge space 210 (the space surrounded by the base body 203 and the part of the discharge container 202 on the applicator side 216) inside the discharge space 210, microwave power is applied to the applicator 216. In the space 210, microwave glow discharge occurs, the source gas is decomposed by the plasma, and a deposited film is formed on the base body 203. At this time, the gas generated by decomposition of the raw material gas and the unreacted raw material gas are discharged through the exhaust port 211.
02 is discharged outside. The gas contains radical molecules and ionic molecules. However, by setting the interval between the louvers 212 to be shorter than the mean free path of these molecules, these radicals and ions can be absorbed by the louvers 212. Crash into and deactivate. Therefore, these radicals and ions do not leak outside the discharge container 202. The distance between the louvers 212 and the partition plate 21
Since the longer one of the three mutual intervals is set to be shorter than 1/2 of the wavelength of the microwave used, the microwave energy is transmitted through the gap between the louvers 212 to the outside of the discharge vessel 202. It does not leak. As a result, the density of microwave energy in the discharge vessel 202 is increased, a good quality film is deposited on the substrate 203, and the deposition film is prevented from adhering to the outside of the discharge vessel 202.

Next, a continuous deposited film forming apparatus 300 incorporating the deposited film forming apparatus shown in FIG. 3 will be described with reference to FIG. This continuous deposited film forming apparatus 300 is suitable for forming a semiconductor element having a pin junction on a belt-shaped substrate 203, and includes a substrate delivery container 351 and a first substrate delivery container 351.
The impurity layer forming vacuum container 361, the intrinsic layer forming vacuum container 301, the second impurity layer forming vacuum container 371, and the substrate winding container 381 of four gas gates 204, 205, 2
04 and 205 are connected in series. Gate gas supply pipes 206 and 207 for supplying gate gas to the gas gates 204 and 205, respectively.
Are connected.

The substrate delivery container 351 is for accommodating the substrate 203 and delivering it to the substrate winding container 381, and is equipped with a bobbin 352 on which the substrate 203 is wound. In addition, the substrate delivery container 35
1, an exhaust pipe 354 connected to an exhaust means (not shown) such as a pump is attached, and a throttle valve 355 for controlling the pressure in the substrate delivery container 351 is provided in the middle of the exhaust pipe 354. Has been. Bobbin 3
A substrate delivery mechanism (not shown) for delivering the base body 203 is connected to 52. Further, a transport roller 353 for transporting the base body 203 is provided.

Vacuum container for forming first and second impurity layers 36
1, 371 have the same structure and are for forming a p-type or n-type semiconductor layer, respectively. The structure is the same as that of the deposited film forming apparatus 200 shown in FIG. A throttle valve 212 for pressure adjustment is provided in the middle of the exhaust pipe 209.

The intrinsic layer forming vacuum vessel 301 is based on the deposited film forming apparatus shown in FIG. 3 and is partially modified as shown below. Vacuum container 3 for forming intrinsic layer
A plurality of applicators 316 are installed in parallel with the strip-shaped substrate 203 penetrating the discharge vessel 302 in 01 and along the moving direction of the substrate 203. Each applicator 316 is connected to the other end of a waveguide (not shown) whose one end is connected to a microwave power source (not shown). Further, a plurality of gas dischargers 314 that discharge the raw material gas are attached to the bottom wall of the discharge vessel 302. Gas ejector 31
The surface of 4 is provided with a gas release hole for releasing the source gas. The gas discharger 314 is a gas supply pipe 3 connected to a source gas supply source (not shown) such as a gas cylinder.
One end of 15 is attached. Each gas discharger 314
The amount of gas supplied from the discharge vessel 302 to the discharge vessel 302 can be independently adjusted.

Further, in the discharge vessel 302, rod-shaped bias electrodes 330 are provided parallel to the base body 203, perpendicular to the moving direction of the base body 203 (in the width direction), and on each central axis of the applicator 316. A bias voltage can be applied from a DC or AC (low frequency to high frequency) bias power supply (not shown) outside the intrinsic layer forming vacuum container 301.

The intrinsic layer forming vacuum container 301 includes:
An exhaust pipe 309 communicating with an exhaust pump (not shown) is connected, and a throttle valve 3 is provided in the middle of the exhaust pipe 309.
21 is provided. Further, an infrared lamp heater 318 for heating the base body 203, a lamp house 319,
The provision of the thermocouple 320 for measuring the temperature of the substrate 203 is the same as in the case of the above-described deposited film forming apparatus. Further, an exhaust port is provided on the side wall of the discharge vessel 302 so as to face the applicators 316, and the exhaust port has the louver 31 as in the case described above.
2 and a partition plate 313 are attached.

The substrate winding container 381 is for winding the substrate 203 on which the deposited film is formed, and has the same structure as the substrate feeding container 351. However, in order to wind the base body 203, a base body winding mechanism (not shown) is connected to the bobbin 352.

Next, the operation of the continuous deposited film forming apparatus 300 will be described focusing on the case of forming a semiconductor element having a pin junction.

First, the strip-shaped substrate 203 is stretched from the substrate delivery container 351 toward the substrate winding container 381. Subsequently, the substrate delivery container 351, each of the impurity layer forming vacuum containers 361 and 371, and the intrinsic layer forming vacuum container 30.
1. The substrate winding container 381 is evacuated, and when a predetermined degree of vacuum is reached, gate gas is supplied to the gas gates 204 and 205.

Next, each impurity layer forming vacuum container 361,
A raw material gas for forming a p-type or n-type semiconductor layer is supplied to 371 respectively, and an intrinsic layer forming vacuum container 3 is formed.
01 is supplied with a source gas for forming an i-type semiconductor layer, and further, each impurity layer forming vacuum vessel 361, 371,
By supplying microwave power to the intrinsic layer forming vacuum container 301 to start moving the substrate 203 from the substrate delivery container 351 toward the substrate winding container 381,
Plasma is generated in each of the impurity layer forming vacuum vessels 361 and 371 and the intrinsic layer forming vacuum vessel 301, and a deposited film is formed on the substrate 203. The base body 203 is the first
Since it is continuously moved to the impurity layer forming vacuum container 361, the intrinsic layer forming vacuum container 301, and the second impurity layer forming vacuum container 371, a semiconductor element having a pin junction is formed on the base body 203. Will be done.

(Embodiment 2-2) In the discharge vessel, the exhaust port provided with the louver and the applicator do not necessarily have to be opposed to each other. In order to obtain the above, the position of the exhaust port and the configuration / arrangement of the louver can be appropriately selected.

Continuous deposited film forming apparatus 400 shown in FIG.
Is different from the intrinsic layer forming vacuum vessel 301 of the continuous deposited film forming apparatus 300 shown in FIG.
It has been replaced with.

This intrinsic layer forming vacuum vessel 401 is substantially the same as the intrinsic layer forming vacuum vessel 301 shown in FIG. 4, but differs in the position of the exhaust port of the discharge vessel 402. That is, the exhaust port of the discharge vessel 402 is the base 203.
Are provided on both end surfaces with respect to the moving direction of. Similar to the case described above, the exhaust port is provided with a plurality of louvers 412 and a plurality of partition plates 413 to diffuse active species, which cause formation of a deposited film, to the outside of the discharge vessel 402, as well as microwaves and plasma. To prevent the leak.

The operation of the continuous deposited film forming apparatus 400 is as follows.
This is the same as the continuous deposited film forming apparatus 300 shown in FIG.
However, the discharge container 402 of the intrinsic layer forming vacuum container 401
In the inside, since the source gas flows in a direction parallel to the moving direction of the substrate 203, the film forming conditions can be changed depending on the position in the moving direction of the substrate 203, and the deposited layer (eg, intrinsic semiconductor layer) to be formed. It is also possible to generate a composition distribution in the film thickness direction.

(Embodiment 2-3) In FIG. 6, the deposited film forming apparatus as shown in FIG. 3 is connected, and the substrate on which the deposited film is formed is transported between the deposited film forming apparatuses by the load lock method. The configuration of the deposited film separation forming apparatus 450 thus configured is shown.

The deposited film separation / forming apparatus 450 includes a substrate loading chamber 451, a first impurity film forming chamber 452, an intrinsic film forming chamber 453, a second impurity film forming chamber 454, and a substrate unloading chamber 4.
55 is provided in series, and each of these chambers 451
.About.455, separated by gate valves 456-459, respectively. First and second impurity film forming chamber 4
52, 454 and the intrinsic film forming chamber 453 have the same configuration, and a discharge vessel 462 is provided inside. That is, each of the forming chambers 452 to 454 is connected to an exhaust pipe 461 that communicates with an exhaust pump (not shown), and a throttle valve 466 for adjusting the internal pressure of each chamber is provided in the middle of each exhaust pipe 461. There is. In each of the forming chambers 452 to 454, an infrared lamp heater 471 for heating the base body 481, a lamp house 472, and a thermocouple 47 for measuring the temperature of the base body 481.
3 is provided. Each discharge vessel 462 is similar to the discharge vessel 202 shown in FIG.
5 is provided on the bottom wall, and an applicator 476 connected to a microwave power source (not shown) via a waveguide (not shown) is provided on the side wall.
A side wall of the discharge container 462 facing the applicator 476 is an exhaust port, and a plurality of louvers 477 and a plurality of partition plates 478 are attached to the exhaust port. The configuration and arrangement of the louver 477 and the partition plate 478 are the same as those in the above-described Embodiments 2-1 and 2-2.

The base body 481 on which the deposited film is formed is fixed to the base body holder 480 and then carried in and installed in the base body carry-in chamber 451. And the base holder 48
0 and the substrate 481 are opened from the substrate loading chamber 451 to the first impurity film forming chamber 452, the intrinsic film forming chamber 453, and the second impurity film forming chamber by sequentially opening the gate valves 456 to 459. The film is sequentially moved to 454 to form a deposited film. After the formation of the deposited film is completed, the substrate holder 480 and the substrate 48 are
1 can be moved to the substrate unloading chamber 458 by the transfer device.

Further, exhaust pipes 463 for directly exhausting these chambers are attached to the substrate loading chamber 451 and the substrate unloading chamber 455, respectively.
It is connected to an exhaust means (not shown) such as a vacuum pump via a throttle valve 464 so that the internal pressure can be controlled.

Next, the formation of a deposited film using this deposited film separation forming apparatus 450 will be described.

After fixing the base body 481 to the base body holder 480, these are installed in the base body carry-in chamber 451. Substrate carry-in chamber 451, each forming chamber 452 to 454, substrate carry-out chamber 4
55 is a pump (not shown) for each exhaust pipe 461, 463
Evacuate to vacuum through. When the specified vacuum level is reached,
The gate valve 456 is opened, and the substrate holder 480 on which the substrate 481 is mounted is moved to the first impurity film forming chamber 452 by a transfer device (not shown). Subsequently, in the forming chamber 452, the infrared lamp heater 471 is operated while the output of the thermocouple 473 is monitored, so that the substrate 481 is heated to a predetermined temperature. And
The raw material gas is supplied from the gas introduction pipe 475 to the gas discharger 474. Also, microwave power is applied to the applicator 476 via a waveguide (not shown).

By doing so, the discharge container 46
2, the substrate holder 480, the applicator 47
6. The source gas is released into a space (discharge space) surrounded by the wall of the discharge vessel 462 and the louver 477, and microwave glow discharge is generated in the discharge space to decompose the source gas to decompose the base 481. Deposited film on top (first
Impurity film) is formed. When the deposited film is formed to a desired film thickness, the supply of microwave power is stopped and the discharge is stopped. Further, the supply of the source gas is stopped and the inside of the first impurity film formation chamber 452 is evacuated to a high vacuum.

Next, the gate valve 457 is opened, and the substrate holder 480 having the substrate 481 mounted thereon is moved from the first impurity film forming chamber 452 to the intrinsic film forming chamber 453 by a transfer device (not shown). After closing the gate valve 457, a deposited film made of an intrinsic film is formed by the same procedure as in the first impurity film forming chamber 452 described above.

Further, similarly, a second impurity film is formed in the second impurity film forming chamber 454.

After the formation of the second impurity film, the second impurity film forming chamber 454 is evacuated to a high vacuum, the gate valve 459 is opened, and the substrate holder 480 with the substrate 481 is unloaded by a transfer device (not shown). Move to chamber 485 and close gate valve 459 again. After cooling the substrate 481 in the substrate unloading chamber 455, the substrate unloading chamber 455 was leaked to the atmosphere, and the deposited film was laminated over three layers (first impurity film, intrinsic film, and second impurity film). By taking out the substrate 481, one deposition film forming operation is completed.

Next, the result of the experiment actually carried out with respect to the second embodiment will be described.

(Experimental Example 2-1) Using the deposited film forming apparatus 200 shown in FIG. 3, a substrate feed container (not shown) and a substrate take-up container (not shown) are respectively attached to the gas gate 204 on the loading side and the gas gate 205 on the unloading side. (Not shown). The strip-shaped substrate 20 is provided in the substrate delivery container and the substrate winding container.
A substrate feeding mechanism (not shown) for feeding 3 and the substrate 20
A substrate winding mechanism (not shown) for winding 3 is provided, respectively.

First, a strip-shaped substrate 203 (width 20 cm × length 200 m × thickness 0.125 mm) made of stainless steel (SUS304BA) was thoroughly degreased and washed, and the substrate 203 was wound around a bobbin (not formed). (Illustration) was attached, the substrate 203 was passed through the gas gate 204 on the loading side, the deposited film forming apparatus 200, and the gas gate 205 on the unloading side to the substrate winding container, and the tension was adjusted so that the substrate 203 did not sag. Then, each of the substrate delivery container (not shown), the vacuum container 201, and the substrate winding container (not shown) is roughly drawn by a mechanical booster pump / rotary pump (not shown), and 5 × by an oil diffusion pump (not shown). An oil diffusion pump (not shown) connected to the exhaust pipe 209 after exhausting to a high vacuum of 10 ^-6 Torr or less
While operating, the raw material gas for forming the deposited film was introduced into the discharge vessel 202 from the gas discharger 214. At the same time, from each gate gas supply pipe 206, 207 to each gas gate 20
4,205, the gate gas flow rate is 30
0 sccm of H ₂ gas is supplied, and the gate gas is exhausted through an exhaust pipe 209 directly connected to the vacuum container 201, a substrate delivery container (not shown) and a substrate winding container (not shown). I chose When the pressure inside the discharge vessel 202 becomes stable, a frequency of 2.45 is supplied from a microwave power source (not shown) through the waveguide 217 and the applicator 216.
A microwave of GHz was introduced into the discharge vessel 202.

As a result, microwave glow discharge occurred in the discharge space 210 and plasma was generated. 1 as it is
The discharge was maintained over time. After the discharge was completed, the film thickness deposited on the stainless steel piece behind the substrate and the louver 212 (outside the discharge vessel) was measured to calculate the film formation rate.

Next, the size of the louver 212 or the film forming conditions (discharge vessel pressure) was changed to form a deposited film by the same procedure. The shapes of the louver 212 and the partition plate 213 installed at the exhaust port of the discharge vessel 202 were designated as shown in FIG. In the experiment, the dimensions shown in FIG. 7 and the pressure inside the discharge vessel 202 were set variously. In the experiment, the stability of discharge was investigated. The results are shown in Table 1.

[0116]

[Table 1]

From the results shown in Table 1, in order to suppress the microwave leakage and to generate and maintain a stable discharge, the interval P between the louvers 212 and the interval l (lowercase letter L) between the partition plates 213 are set to It has been found that it is desirable to set the wavelength to 1/10 or less.

(Experimental Example 2-2) The shape of the louver 212 in which the amount of deposited film formed on a member outside the discharge vessel was small was examined by using the same apparatus as in Experimental Example 2-1 and following the same operation procedure. As shown in FIG. 7, a stainless piece 290 was installed at the center of the rear surface of the louver 212 at a distance of 10 cm, and the amount (thickness) of the deposited film formed on this stainless piece was compared to evaluate. The experimental conditions and results are shown in Table 2.

[0119]

[Table 2]

According to the results of the experiment, the deposition rate of the film formed on the member outside the discharge space is about 1/10 by setting the louver shape condition (x> 0) such that the opposite side cannot be seen through the louver from the front of the louver. It turns out that it can be suppressed to.

(Experimental Example 2-3) A semiconductor element having a pin junction was formed on the strip-shaped substrate 203 by the above-mentioned procedure by the continuous deposited film forming apparatus 300 shown in FIG. This semiconductor device has an n-type layer with a thickness of 200Å and a thickness of 2 on a substrate.
A 000 Å i-type layer and a 200 Å-thick p-type layer are sequentially laminated, and a transparent electrode and a comb-shaped current collecting electrode are further provided on the p-type layer.

SUS430BA (stainless steel) on bobbin
One roll (200 m) of a substrate composed of (width 20 cm × length 200 m × thickness 0.125 mm) was wound to form a continuous film. After the film formation by one roll, the discharge container was removed, the film adhering to the film was removed and cleaned, and the film was attached to the apparatus again. One roll of the substrate 200 m was attached to the substrate delivery container 351 again, and film formation was performed according to the above procedure.
By the above procedure, the film formation of the substrate was repeated every 200 m per roll. Table 3 shows the conditions for forming the pin layer. For comparison, a punching board (opening φ5 mm, opening ratio 50%) was attached to the exhaust port instead of the louver, and the film forming cycle was repeated every 200 m per roll by the same procedure. The substrate transport speed was 1.3 m / min. Therefore, the film formation time for one roll (200 m) is about 2 hours and 30 minutes.

[0123]

[Table 3]

As a result, when the louver is used, 10
Almost no peeling of the film adhering to the outer member of the film-forming container was observed after the 0-roll film formation, and mixing of the peeled film pieces into the pump oil was not observed. Moreover, the peeled film pieces did not adhere to the sealing surface of the valve in the middle of the exhaust pipe up to the pump and deteriorate the sealing performance of the valve (internal leakage). After 100 rolls of film formation, maintenance such as cleaning of the outside of the discharge vessel was not necessary.

On the other hand, when a punching board is used, a valve sealing failure (internal leak) occurs after 20 rolls of film formation, and when 40 rolls of film are formed, it is considered that deterioration of the diffusion pump oil is the cause of exhaust performance. Has occurred. At the end of 10-roll film formation, peeling of the film already attached to the member outside the discharge vessel was observed. At the end of film formation for 50 rolls, a large number of peeling film pieces of 2-3 mm square or less were mixed in the diffusion pump oil.

An upper electrode was attached to the pin deposited film manufactured in Experimental Example 2-3 to evaluate the performance as a photovoltaic element. Processed into a large number of solar cell modules with an area of 20 cm x 20 cm and an AM value of 1.5 with an energy density of 100 mW / cm ²
Characteristic evaluation was performed using the pseudo sunlight. A photovoltaic conversion efficiency of 8.0% or more was obtained for both the solar cell modules formed from the deposited films of the first roll and the 100th roll of film formation.

From the results of Experimental Example 2-3, it was found that by using the louver, stable film formation can be performed for a long period of time and the maintenance cycle can be significantly extended.

<< Third Embodiment >> Next, a third embodiment of the present invention will be described. Here, a deposition film forming apparatus suitable for depositing a group III group V compound semiconductor film of the periodic table by a microwave plasma CVD method will be described.

(Example 3-1) FIG. 8 is a table III of the periodic table.
It is a figure which shows the structural example of the deposited film forming apparatus suitable for depositing a group V group compound semiconductor film. This deposited film forming device
It is a microwave plasma CVD apparatus that causes radio frequency (RF) energy to act on a source gas at the same time as microwave energy, and is roughly composed of a deposition apparatus 500 and a source gas supply apparatus 520.

The deposition apparatus 500 has a deposition chamber 501 connected to an exhaust device (not shown) via a conductance valve 507, and the auxiliary valve 50 is provided in this deposition chamber 501.
8, a leak valve 509, and a vacuum gauge 516 are provided. A waveguide 510 is attached to the bottom wall of the deposition chamber 501 via a dielectric window 502. The other end of the waveguide 510 is connected to a microwave power source (not shown). The base 504 on which the compound semiconductor film is formed is a deposition chamber 501.
A heater 505 for heating the substrate 504 is provided therein. A shutter 513 is provided between the base body 504 and the dielectric window 502. The shutter 513 is a shutter rod 514.
It can be opened and closed by operating.
Further, a bias rod 512 is provided in a substantially central portion of the space between the base body 504 and the dielectric window 502. The bias rod 512 is supplied with a high frequency wave from an RF (high frequency) power source 511 outside the deposition chamber 501. Bias is applied.

On the other hand, the source gas supply device 520 communicates with the deposition chamber 501 via the auxiliary valve 508. This source gas supply device mixes a liquid source filled in the liquid cylinders 571 to 573 and a gas source filled in the cylinders 574 to 576, respectively, and mixes the source gas with the source gas in the deposition chamber 501.
And has mass flow controllers 521 to 526 and valves 541 to 562.
Further, a constant temperature bath 580 for heating and vaporizing the liquid source is provided corresponding to each of the liquid cylinders 571 to 573. Further, pressure regulators 563 to 565 are provided corresponding to the respective cylinders 574 to 576.
Also, a hydrogen purifier 581 is provided corresponding to the cylinder 576 for hydrogen gas. The source gas refining apparatus 520 shown here is often used for manufacturing compound semiconductors and the like, and its configuration is apparent to those skilled in the art.

Next, a procedure for forming a deposited film using this deposited film forming apparatus will be described.

First, the deposition chamber 501 is leak valve 509.
After leaking to atmospheric pressure, the deposition chamber 501 is opened and the substrate 504 for forming a deposited film is set. Next, the deposition chamber 501 is closed, a roughing valve (not shown) is opened to exhaust the inside of the deposition chamber 501, and when a predetermined pressure is reached, the roughing valve is closed and the conductance valve 507 is opened. When the pump behind the conductance valve 507 is a turbo molecular pump, the internal pressure in the deposition chamber 501 is reduced to 10 ⁻⁵ Torr or less. When the pump behind the conductance valve 507 is an oil diffusion pump, the inside of the deposition chamber 501 is not sufficiently pulled up by the pump because there is back diffusion of oil.

That is, the pressure in the deposition chamber 501 is 10 ⁻³ To.
If it becomes less than or equal to rr, an inert gas such as H ₂ or He, Ar, Ne is fed from the source gas supply device 520 to the deposition chamber 50.
1, and the pressure in the deposition chamber 501 is maintained on the order of 10 ⁻³ Torr and maintained for 10 minutes. When the oxygen and nitrogen in the deposition chamber 501 are sufficiently exhausted, H ₂ and H
Gas such as e, Ar, Ne is introduced so that the pressure is 1 to 10 mTorr. Then, the substrate 504 is heated by the heater 505 to a desired substrate temperature in the range of 25 ° C to 600 ° C.
If the temperature of the substrate 504 reaches the desired temperature, the above H ₂ , H
Gases such as e, Ar, and Ne are stopped, and while these gases are exhausted, the raw material gas for forming the deposited film is introduced into the deposition chamber 501 from the raw material gas supply device 520 at a desired flow rate through the auxiliary valve 508. .

The raw material (liquid source) which is liquid at room temperature is packed in liquid cylinders 571 to 573 or the like and heated in a constant temperature tank 580 to a temperature at which a sufficient flow rate as a raw material gas is obtained, or the liquid cylinders 571 to 573 are heated in a constant temperature tank 580. While keeping warm, H ₂ ,
It is preferable that a gas such as He, Ar, or Ne be used as a carrier gas to bubble in the liquid cylinders 571 to 573, and the raw material is introduced into the deposition chamber 501 together with the carrier gas at a predetermined flow rate. In this way, the raw material gas for forming the deposited film is introduced into the deposition chamber 501, and the internal pressure in the deposition chamber 501 during film formation is adjusted by the conductance valve 507 so as to be a desired internal pressure in the range of 1 to 50 mTorr.

When the internal pressure stabilizes at a desired pressure, microwave energy is introduced from a microwave power source (not shown) into the deposition chamber 501 through the waveguide 510 and the dielectric window 502 to generate microwave plasma. Let Deposition chamber 50
The microwave energy to be introduced into the chamber 1 is the deposition chamber 501.
The microwave energy is lower than the microwave energy required for 100% decomposition of the raw material gas, although it depends on the type and flow rate of the raw material gas introduced therein. At the same time, RF energy is also introduced from the RF power source 511 into the deposition chamber 501 via the bias rod 512.

A preferable range of microwave energy is about 0.02 to 1 W / cm ³ . A preferable frequency range of microwaves is 0.5 to 10 GHz, and a frequency around 2.45 GHz is particularly suitable.

Further, in order to form a deposited film with reproducibility and to form a deposited film over several hours to several tens of hours, stability of microwave frequency is very important. The frequency variation is preferably within ± 2%. Further, the ripple of the microwave is preferably within ± 2%.

The RF energy that is input into the deposition chamber 501 at the same time as the microwave energy is a very important factor in combination with the microwave energy.
The preferred range of RF energy is 0.04 to 2
W / cm ³ .

A preferable frequency range of the RF energy is 1 to 100 MHz, and the frequency fluctuation is ±
It is preferably within 2% and the waveform of the RF energy is smooth (similar to a sine wave).

Thus, microwave energy is introduced from the waveguide 510 into the deposition chamber 501 via the dielectric window 502, and at the same time RF energy is introduced into the deposition chamber 501 from the bias power source 511 via the bias rod 512. , Decompose the raw material gas for a desired time in such a state,
A deposited film having a desired layer thickness is formed on the substrate 504. After that, the input of microwave energy and RF energy is stopped, the inside of the deposition chamber 501 is evacuated, and H ₂ , He, Ar, N
After sufficiently purging with a gas such as e, Kr, or Xe, the substrate 504 on which the semiconductor film is deposited is taken out from the deposition chamber 501.

A DC voltage may be applied to the bias rod 512 in addition to the RF energy. As for the polarity of the DC voltage, it is preferable to apply the voltage so that the bias rod 512 becomes positive. And a preferable range of the DC voltage is 10 to 300V.

The following is a detailed description of the case where a GaAs (gallium arsenide) solar cell having the structure shown in FIG. 16 is produced by an experimental example, but the present invention is not limited to this.

(Experimental Example 3-1) First, semiconductor layers of n-type and p-type GaAs crystals were formed on an n-type GaAs substrate by the deposited film forming apparatus shown in FIG.

Liquid cylinders 571 to 573 and cylinders 574 to 576 in FIG. 8 are sealed with a raw material gas for preparing a GaAs solar cell and a liquid, and the liquid cylinders 571 to 573 are respectively at room temperature and Liquid trimethylgallium at normal pressure [Ga (CH ₃ ) ₃ , abbreviated as TMG]
(Purity 99.999%) cylinder, liquid diethyl zinc [Zn (C ₂ H ₅ ) ₂ , abbreviated as DEZ] at normal temperature and pressure] (Purity 99.
999%) cylinder, liquid trimethylaluminum [Al (CH ₃ ) ₃ , TMA, abbreviated as TMA] at room temperature and pressure (purity 99.
(999%). Each liquid cylinder 571-57
No. 3 is stored in a constant temperature bath 580 so that bubbling can be performed. On the other hand, the cylinder 574-
576 is arsine [AsH ₃ ] gas (purity 9
9.999%) cylinder, hydrogen selenide [H ₂ Se] gas (purity 99.999%) cylinder, H ₂ gas (purity 99.999%)
It was a cylinder.

AsH ₃ is filled up to the valve 559, H ₂ Se gas is filled up to the valve 560, and hydrogen which has passed through the hydrogen purifier 581 is filled inside the other gas pipes. Moreover, the pressure of each gas is the pressure regulator 563-56.
The secondary pressure of No. 5 is adjusted to 2.0 Kg / cm ² .

The n-type GaAs substrate (base 504) is Bridgm.
It was produced by the an method, and the surface of which was inclined by 2 to 3 ° from the <110> plane was used. First, the substrate 504 is formed by using ammonia water (NH ₄ OH): hydrogen peroxide water (H
₂ O ₂ ): water (H ₂ O) = 20: 7: 1000 for 30 seconds, and immediately thereafter, the deposition apparatus 5 of FIG.
It is placed in the heating chamber 050 and is closely attached to the heater 505, and the deposition chamber 5
It was confirmed that the leak valve 509 of 01 was closed, and the inside of the deposition chamber 501 was evacuated by a vacuum pump (not shown). When the reading of the vacuum gauge 506 becomes about 1 × 10 ⁻⁴ Torr, the auxiliary valve 508 and the valves 544 and 545 are opened,
When the reading of the vacuum gauge 506 became about 1 × 10 ⁻⁴ Torr again, the valves 544 and 545 were closed and the valves 559 and 560 were closed.
Was opened, AsH ₃ and H ₂ Se were introduced into the mass flow controllers 524 and 525, and the valves 559 and 560 were closed. Further, the constant temperature bath 580 of the liquid cylinders 571 to 573 is
It is controlled by the temperature at which bubbling is possible.

After the preparation for film formation was completed as described above, n-type and p-type GaAs crystal semiconductor layers were formed on the substrate 504.

As the first semiconductor layer 803 (FIG. 16), n
Valves 541, 542, 546, 5 are used to form the mold layer.
Gradually open 50,551,556,557,561,562
K, each mass flow controller 521,522,526
Than H₂Gas flow rate is 100sccm and 100scc respectively
It was set to flow at m and 300 sccm. Deposition chamber 501
Conductance bar so that the internal pressure becomes 30 mTorr
The position of the base 504 (n-type substrate) is adjusted by the knob 507.
Set the heater 505 so that the temperature is 480 ° C,
When the substrate 504 is sufficiently heated, the valves 544, 5
Open 45, 547, 553 gradually and close valve 550.
It was At this time, each mass flow controller 521,52
4,525,526, H respectively₂Gas flow is 500s
ccm, AsH ₃Gas flow rate is 100 sccm, H₂Se gas flow rate
Is 1 sccm, H₂Set the gas flow rate to 500 sccm
did. At this time, pass through the mass flow controller 521
H₂Bubbling the inside of the liquid cylinder 571 with gas
In the deposition chamber 501 by Ga (CH₃)₃Gas is about 100sc
The temperature of the thermostat 580 is preset so that
Oita. The pressure in the deposition chamber 501 will be 20 mTorr.
While looking at the vacuum gauge 506, the conductance valve 50
The opening of 7 was adjusted.

Next, the power of a microwave power source (not shown) is set to 0.25 W / cm ³ , and microwave power is introduced into the deposition chamber 501 through the waveguide 510 and the dielectric window 502 to cause glow discharge. Raise the radio frequency (RF) power supply 51
The power of 1 is set to 0.40 W / cm ³ , and the bias rod 51
2 was applied. The shutter 513 is opened, the production of the n-type layer on the n-type substrate (base 504) is started, and the layer thickness is 4.0 μm.
When the n-type layer is prepared, the shutter 513 is closed,
The microwave power source and the RF power source were turned off, and the production of the n-type layer was completed. Valves 544, 545, 547, 553, 55
Closing 9,560, Ga (CH ₃ ) ₃ , AsH ₃ , H ₂ Se
The respective gases of No. 2) were stopped from flowing into the deposition chamber 501, the valves 550 and 551 were opened, and the H ₂ gas was sufficiently flowed into the deposition chamber 501.

As the second semiconductor layer 804 (FIG. 16), p
To prepare the mold layer, the heater 505 is set so that the substrate temperature is 450 ° C., and when sufficiently heated, the valves 542, 544, 547, 548, 553, 554, 559.
Gradually open, then close valves 550 and 551 to
Gases of a (CH ₃ ) ₃ , AsH ₃ , and Zn (C ₂ H ₅ ) ₂ were made to flow into the deposition chamber 101. At this time, the mass flow controllers 521, 522, 524, and 526 were set to flow H ₂ gas 500 sccm, H ₂ gas 25 sccm, AsH ₃ gas 100 sccm, and H ₂ gas 475 sccm, respectively. At this time, the mass flow controllers 521, 52
By bubbling the insides of the liquid cylinders 571 and 572 with H ₂ gas that has passed through No. ₂ , Ga (CH ₃ ) _{3 is} introduced into the deposition chamber 501.
The temperature of the thermostat 580 was preset so that about 100 sccm of gas and about 5 sccm of Zn (C ₂ H ₅ ) ₂ gas were introduced. The opening of the conductance valve 507 was adjusted while observing the vacuum gauge 506 so that the pressure in the deposition chamber 501 was 20 mTorr.

After confirming that the shutter 513 is closed, the power of the microwave power source (not shown) is set to 0.25 W /
cm ³ is set, microwave power is introduced into the deposition chamber 501 through the waveguide 510 and the dielectric window 502 to cause glow discharge, and the RF power source 511 is turned on.
An RF bias of 0.40 W / cm ³ was applied to the bias rod 512, and the shutter 513 was opened. p on the n-type layer
When the production of the mold layer was started and the layer thickness reached 1.2 μm, the shutter 513 was closed and the microwave power source and RF power source 5
11 and the heater power source (not shown) were turned off to complete the production of the p-type layer. Valves 544, 547, 548, 553,
By closing 554 and 559, Ga (CH ₃ ) ₃ and Zn (C
₂ H ₅ ) ₂ and AsH ₃ gas were stopped from flowing into the deposition chamber 501, the valves 550 and 551 were opened, and H ₂ gas was kept flowing into the deposition chamber 501.

When the substrate 504 has cooled to room temperature, all valves are closed, the leak valve 509 is opened, and the deposition chamber 5 is opened.
The inside of 01 leaked to atmospheric pressure.

Next, a comb-shaped collector electrode 806 made of an alloy of gold (Au) and zinc (Zn) was vapor-deposited on the p-type layer by the resistance heating vacuum vapor deposition apparatus shown in FIG.

First, the resistance heating vacuum vapor deposition apparatus shown in FIG. 10 will be described. A vacuum gauge 608, a valve 610, and a leak valve 612 are installed in a deposition chamber 601 connected to an exhaust pump (not shown) via a conductance valve 609.
Is attached. The valve 610 is connected to a source gas supply means such as a gas cylinder (not shown) via a mass flow controller 611. A vapor deposition source 604, which is a raw material for the deposited film, is provided in the deposition chamber 601, and is heated by a heater 605. The heater 605 is driven by an AC power source 606 outside the deposition chamber 601. On the other hand, the substrate 602 on which the deposited film is formed is held in the deposition chamber 601 so as to face the vapor deposition source 604. The substrate 602 is adapted to be heated by the substrate heater 603.
Are driven by an AC power supply 613 outside the deposition chamber 601. Further, a shutter 607 for controlling vapor deposition on the substrate 402 by opening and closing is provided in the deposition chamber 601.

First, a mask 620 for a comb-shaped collector electrode as shown in FIG. 9 was placed on the surface of the p-type layer, and the back surface of the substrate was brought into close contact with the substrate heater 603. As the vapor deposition source 604, a granular vapor deposition source of 99% pure Au—Zn alloy was used. The inside of the deposition chamber 601 was evacuated by a vacuum pump (not shown), and when the reading of the vacuum gauge 608 became about 1 × 10 ⁻⁶ Torr, AC
The power source 606 was operated, the evaporation source was heated and evaporated, and after 5 minutes, the shutter 607 was opened to start the production of the comb-shaped collector electrode on the n-type layer, and when the layer thickness became 1.0 μm. The shutter 607 was closed, the AC power source 606 was turned off, and the vacuum deposition was completed.

Next, the inside of the deposition chamber 601 is evacuated by a vacuum pump (not shown), and the reading of the vacuum gauge 608 is about 1 × 10 ⁻⁶ To.
When rr is reached, the valve 610 is opened, and N ₂ gas is introduced from a nitrogen gas (purity 99.999%) cylinder (not shown).
The mass flow controller 611 adjusted the flow rate to 200 sccm.

The heater 603 was set so that the temperature of the substrate 602 became 300 ° C., and alloying treatment was performed for 1 minute. Immediately turn off the AC power supply 613 and turn off the valve 6
10. Close the conductance valve 609 and open the leak valve 612 when the substrate temperature drops to room temperature.
The inside of the deposition chamber 601 leaked to atmospheric pressure.

Next, using a photomask similar to the mask 620 for the comb-shaped current collecting electrode shown in FIG. 9, the second semiconductor layer is formed by the photolithography process which is usually performed.
The cross-sectional shape shown in FIG. At this time the second
The semiconductor layer 804 was etched to a thickness of 1.2 μm in the lower region of the comb-shaped collector electrode 806 and 0.6 μm in the other regions.

Next, using the deposited film forming apparatus shown in FIG. 8, an antireflection layer 805 made of non-single-crystal silicon nitride was formed on the p-type layer and the comb-shaped collector electrode 806.

First, the cylinders 574 and 575 were replaced with monosilane [SiH ₄ ] (purity 99.999%) cylinders and ammonia [NH ₃ ] (purity 99.999%) cylinders, up to valves 559 and 560, respectively. The raw material gas is introduced, and the secondary pressure of the pressure regulators 563 and 564 is 2.0 kg / c.
It was set to m ² . The manufacturing procedure was the same as that for manufacturing the GaAs crystal layer. The above substrate was placed in the deposition chamber 501, and the back surface was brought into close contact with the heater 505.
After confirming that the leak valve 509 of the deposition chamber 501 is closed, the deposition chamber 501 is evacuated by a vacuum pump (not shown), and when the reading of the vacuum gauge 506 becomes about 1 × 10 ⁻⁴ Torr, an auxiliary valve. 508 and valves 544 and 545 are opened, and when the reading of the vacuum gauge 506 becomes about 1 × 10 ⁻⁴ Torr again, the valves 544 and 545 are closed and the valves 559 and 5
Open 60 and mass flow controller 524,525
Introduce SiH ₄ and NH ₃ respectively into the valve 559,
560 was closed. This completes the preparation for film formation.

To form a non-single-crystal silicon nitride layer as the antireflection layer 805, the valves 546, 561 and 562 are gradually opened and the H _{2 of the} mass flow controller 526 is set to H _2.
The gas flow rate was set to be 300 sccm. Deposition chamber 5
The conductance valve 107 is adjusted so that the pressure in 01 becomes 10 mTorr, the heater 505 is set so that the temperature of the substrate 504 becomes 300 ° C., and when sufficiently heated, the valves 544, 545, 559 and 560 are gradually increased. The mass flow controllers 524, 525 and 526 were set so that the flow rate of SiH ₄ gas was 5 sccm, the flow rate of NH ₃ gas was 10 sccm, and the flow rate of H ₂ gas was 800 sccm at this time. Conductance valve 507 while watching vacuum gauge 506 so that the pressure in deposition chamber 501 becomes 20 mTorr.
Adjusted the opening. Confirm that the shutter 513 is closed, and set the power of the microwave power source (not shown) to 0.2.
The waveguide 510 and the dielectric window 5 are set to 0 W / cm ^3.
Microwave power was introduced into the deposition chamber 501 through 02, glow discharge was generated, the RF power supply 511 was turned on, an RF bias of 0.30 W / cm ³ power was applied to the bias rod 512, and the shutter 513 was opened. . A non-single-crystal silicon nitride layer was formed on the p-type layer and the comb-shaped collector electrode, and the shutter 5 was pressed when the layer thickness became 0.07 μm.
13, the microwave power source, the RF power source 512, and the heater power source were turned off, and the preparation of the antireflection layer made of single crystal silicon nitride was completed.

The valves 544, 545, 559 and 560 were closed to stop the SiH ₄ gas and NH ₃ gas from flowing into the deposition chamber 501. Further, the valves 546 and 561 are opened and H ₂ gas is continuously flown into the deposition chamber 501. When the temperature of the substrate is lowered to room temperature, the valves 546 and 561 and the auxiliary valve 508 are closed, and the leak valve 509 is opened. 501 leaked.

Next, a back surface electrode 80 made of an alloy of gold (Au), germanium (Ge) and nickel (Ni) is formed on the back surface of the substrate.
2 was vapor-deposited with the resistance heating vacuum vapor deposition apparatus of FIG. The procedure was the same as when the comb-shaped collector electrode was produced.

First, the substrate was mounted in the deposition chamber 601 so that the surface on the side where the antireflection layer 805 was formed was in close contact with the substrate heater 603. The inside of the deposition chamber 601 was evacuated by a vacuum pump (not shown), and the reading of the vacuum gauge 608 was about 1 × 1.
When it reaches 0 ^-6 Torr, activate the AC power supply 606,
The evaporation source 604 is heated and evaporated, and after 5 minutes, the shutter 607 is opened to start the production of the backside electrode on the n-type GaAs substrate, and when the layer thickness becomes 1.0 μm, the shutter 607 is closed and the AC power supply is turned on. The operation of 606 was stopped and the vacuum deposition was completed. Next, the inside of the deposition chamber 601 is evacuated by a vacuum pump (not shown), and the reading of the vacuum gauge 608 is about 1
The valve 610 was opened at the time of × 10 ^-6 Torr, H ₂ gas was flown from a hydrogen gas (purity 99.999%) cylinder (not shown), and the mass flow controller 611 changed the flow rate to 20.
It was set to 0 sccm. The substrate heater 603 was set so that the substrate temperature was 300 ° C., and alloying treatment was performed for 1 minute. Immediately turn off the AC power supply 613,
The valve 610 and the conductance valve 609 are closed, and when the substrate temperature drops to room temperature, the leak valve 612
Then, the inside of the deposition chamber 601 was leaked to the atmospheric pressure.

With the above operation, the fabrication of the GaAs crystal solar cell was completed.

(Comparative Experimental Example 3-1) Microwave power and R applied when forming the p-type layer as the second semiconductor layer.
The F power was changed variously, and other conditions were the same as in Experimental Example 3-1, and a GaAs crystal solar cell was manufactured. Figure 11
Shows the relationship between the microwave power and the deposition rate at this time. When the microwave power is 0.32 W / cm ³ or more, the deposition rate does not increase.
(CH ₃ ) ₃ gas, AsH ₃ gas, Zn (C ₂ H ₅ ) ₂ gas
It was found to be decomposed by 0%.

The photoelectric conversion efficiency η (photovoltaic power of the solar cell / incident light energy per unit time) of the solar cell when irradiated with AM1.0 (100 mW / cm ² ) light was measured and found to be microwave power. Depending on the RF power, FIG.
It changed as shown in. The curve in this figure is a plot of microwave power and RF power when the same photoelectric conversion efficiency is obtained. In the figure, the photoelectric conversion efficiency is represented by a relative value with the photoelectric conversion efficiency of the solar cell of Experimental Example 3-1 being 1.

As can be seen from the figure, the microwave power is G
1 a (CH ₃ ) ₃ gas, AsH ₃ gas, Zn (C ₂ H ₅ ) ₂ gas
It was found that the photoelectric conversion efficiency η is significantly improved when the microwave power is 0.3% W / cm ³ or less that is decomposed by 00% and the RF power is higher than the microwave power.

(Comparative Experimental Example 3-2) Microwave power and R applied when forming the n-type layer as the first semiconductor layer.
The F power was variously changed, and the other conditions were the same as in Experimental Example 3-1, and a GaAs crystal solar cell was produced. Microwave power was 0.32 W / c as in Comparative Experimental Example 3-1.
When m ³ or more, the deposition rate did not increase, and Ga (CH ₃ ) ₃ gas, AsH ₃ gas, H ₂ Se, which are raw material gases, were generated by this electric power.
It was found that the gas was 100% decomposed. AM
When the photoelectric conversion efficiency η of the solar cell when irradiated with 1.0 light was measured, the same result as in Comparative Experimental Example 3-1 was obtained. That is, the microwave power is Ga (CH ₃ ) ₃ gas, A
When the microwave power (0.32 W / cm ³ ) or less that decomposes 100% of sH ₃ gas and H ₂ Se gas and the RF power is higher than the microwave power, the photoelectric conversion efficiency η is significantly improved. I understood.

(Comparative Experimental Example 3-3) When forming the n-type layer in Experimental Example 3-1, the flow rate of the source gas introduced into the deposition chamber 501 was set to 200 sccm for Ga (CH ₃ ) ₃ gas and 200 s for AsH ₃ gas.
The temperature of the mass flow controller and the constant temperature bath were adjusted so that the flow rate of ccm, H ₂ Se gas was ₂ sccm, and the total flow rate of H ₂ gas was 2000 sccm. Other conditions were the same as in Comparative Experimental Example 3-1, and the microwave power and the RF power were changed variously to fabricate a GaAs crystal solar cell. When the microwave power is 0.51 W / cm ³ or more, the deposition rate does not increase, and this power causes Ga (CH ₃ ) ₃ gas, A
It was found that the sH ₃ gas and the H ₂ Se gas were 100% decomposed. When the photoelectric conversion efficiency η of the solar cell when irradiated with AM1.0 light was measured, the result was similar to that of Comparative Experimental Example 3-1. That is, the microwave power is Ga
If the microwave power (0.32 W / cm ³ ) or less that decomposes 100% of (CH ₃ ) ₃ gas, AsH ₃ gas, and H ₂ Se gas, and the RF power is higher than the microwave power, the photoelectric conversion efficiency η is large. It turned out that it has improved.

(Comparative Experimental Example 3-4) When forming the p-type layer in Experimental Example 3-1, the substrate temperature was set at 350 ° C. and the flow rate of the source gas introduced into the deposition chamber 501 was Ga (CH ₃ ). ₃ gas 5
0 sccm, Zn (C ₂ H ₅ ) ₂ gas 2.5 sccm, AsH ₃ gas 5
The temperature of the mass flow controller and the constant temperature bath were adjusted so that the total H ₂ gas flow rate was 0 sccm and 1000 sccm. Other conditions were the same as in Comparative Experimental Example 3-1, and microwave power and RF power were variously changed to fabricate a GaAs crystal solar cell as shown in FIG. When the relationship between the microwave power and the deposition rate was examined in the same manner as in Comparative Experimental Example 3-1, the deposition rate did not increase when the microwave power was 0.18 W / cm ³ or more, and Ga, which was the source gas at this power, was used. It was found that the (CH ₃ ) ₃ gas, Zn (C ₂ H ₅ ) ₂ gas, and AsH ₃ gas were 100% decomposed. When the photoelectric conversion efficiency η of the solar cell when irradiated with AM1.0 light was measured, the result showed the same tendency as in Comparative Experimental Example 1. That is, the microwave power is Ga (CH ₃ ) ₃ gas, Z
When microwave power (0.18 W / cm ³ ) or less for 100% decomposition of n (C ₂ H ₅ ) ₂ gas and AsH ₃ gas and RF power is higher than microwave power, photoelectric conversion efficiency η is significantly improved. I found out that

(Comparative Experimental Example 3-5) When the p-type layer was formed in Experimental Example 3-1, the pressure was variously changed from 5 mTorr to 200 mTorr, and the other conditions were the same as in Experimental Example 3-1. A GaAs crystal solar cell as shown in 1 was manufactured. When the photoelectric conversion efficiency η of the solar cell when irradiated with AM1.0 light was measured, the results shown in FIG. 13 were obtained, and it was found that the photoelectric conversion efficiency was significantly reduced when the pressure was 50 mTorr or more. .

(Comparative Experimental Example 3-6) When forming the n-type layer in Experimental Example 3-1, the pressure was variously changed from 5 mTorr to 200 mTorr, and the other conditions were the same as in Experimental Example 3-1. A GaAs crystal solar cell as shown in 1 was manufactured. When the photoelectric conversion efficiency η of the solar cell when irradiated with AM1.0 light was measured, the result was similar to that shown in FIG.
It was found that the photoelectric conversion efficiency was significantly reduced when the pressure was 50 mTorr or more.

Experimental Example 3-1, Comparative Experimental Examples 3-1 to 3-6
Table 4 collectively shows the manufacturing conditions of the GaAs crystal semiconductor layer in.

[0176]

[Table 4]

As described above, Experimental Example 3-1, Comparative Experimental Examples 3-1 to 3-1
As shown in 3-6, it was found that when the pressure was 50 mTorr or less, a good solar cell was produced without depending on the source gas flow rate and the substrate temperature.

(Experimental Example 3-2) In Experimental Example 3-1, the n-type layer,
A GaAs solar cell was produced under the same conditions as in Experimental Example 3-1 except that the substrate temperature when forming the p-type layer was changed to 550 ° C.

(Comparative Example 3-1) Microwave power required to decompose 100% of the raw material gas was the minimum power (in this case, 0.32).
A GaAs solar cell was manufactured under the conventional manufacturing conditions of W / cm ³ ) or less and microwave power> RF power. That is, when forming the n-type layer, the microwave power was 0.16 W / cm ³ , the RF power was 0.10 W / cm ^3, and the other conditions were the same as in Experimental Example 3-2.

The photoelectric conversion efficiency of these solar cells was determined by the same method as in Comparative Experimental Example 3-1, and Experimental Example 3-2 based on the present invention was about 1. It turned out to be three times better.

(Comparative Example 3-2) The minimum power at which microwave power can decompose 100% of the raw material gas (0.32 in this case).
A GaAs solar cell was manufactured under the conventional manufacturing conditions of W / cm ³ ) or more and microwave power> RF power. That is, when forming the n-type layer, the microwave power was 0.40 W / cm ³ , the RF power was 0.10 W / cm ³ , and the other conditions were the same as in Experimental Example 3-2.

The photoelectric conversion efficiency of these solar cells was determined using the same method as in Comparative Experimental Example 3-1, and Experimental Example 3-2 according to the present invention was about 1. It turned out to be seven times better.

(Comparative Example 3-3) The minimum power at which microwave power can decompose 100% of the raw material gas (in this case, 0.32).
A GaAs solar cell was manufactured under the conventional manufacturing conditions of W / cm ³ ) or more and microwave power> RF power. That is, when forming the n-type layer, microwave power and 0.40 W / cm ^3, RF power 0.50 W / cm ^3, the other conditions were the same as in Experimental Example 3-2.

The photoelectric conversion efficiencies of these solar cells were determined by the same method as in Comparative Experimental Example 3-1, and Experimental Example 3 based on the present invention was about 1.
It turned out to be three times better.

(Comparative Example 3-4) MOC which is a conventional method
A GaAs solar cell as shown in FIG. 16 was produced by the VD (Metal Organic Chemical Vapor Deposition) method.

FIG. 14 is a diagram showing a deposition apparatus by the MOCVD method used here. This deposition apparatus is configured so that it can be connected to the source gas supply device 520 of the deposited film forming apparatus shown in FIG. 8, and is made of quartz and has a cylindrical tubular deposition chamber 651.
have. The deposition chamber 651 is connected to a vacuum pump (not shown) via a conductance valve 657. Further, an auxiliary valve 658, a leak valve 659, and a vacuum gauge 666 are attached to the deposition chamber 651, and the other end of the auxiliary valve 658 is connected to the above-mentioned source gas supply device 520. The substrate 653 on which the deposited film is formed is held by a substrate holder 652 made of graphite and arranged inside the deposition chamber 651. The surface of the substrate holder 652 is covered with silicon carbide (SiC). Further, in order to heat the substrate 653 and the like, a high frequency heater 655 is provided along the outer peripheral surface of the deposition chamber 651.
Is provided.

First, the n-type GaAs substrate 653 is brought into close contact with the substrate holder 652, it is confirmed that the leak valve 659 and the auxiliary valve 658 are closed, the conductance valve 657 is fully opened, and a vacuum pump (not shown) is used. The inside of the deposition chamber 651 was evacuated. Vacuum gauge reading is 1 × 1
When 0 ^-6 Torr is reached, H
_Two gases were introduced into the deposition chamber to complete the preparation for film formation.

As the first semiconductor layer 803 (FIG. 16), n
To prepare the mold layer, the pressure in the deposition chamber 651 is 30 Torr.
The high-frequency heater 655 is set so that the temperature of the substrate 653 is 550 ° C. when the conductance valve 657 is adjusted so that the temperature of the substrate 653 is sufficiently heated, and the valves 544, 545, 547, and 553 are gradually heated. Opened and closed valve 550. At this time, in each of the mass flow controllers 521, 524, 525, 526, the H ₂ gas flow rate is 500 sccm and AsH ₃
Gas flow rate is 1000sccm, H ₂ Se gas flow rate is 1sccm,
The H ₂ gas flow rate was set to 500 sccm. At this time, by bubbling the inside of the liquid cylinder with H ₂ gas passing through the mass flow controllers 521 and 522,
The thermostat 580 was set in advance so that the Ga (CH ₃ ) ₃ gas flowed into the deposition 651 at about 100 sccm. Deposition chamber 6
The pressure inside 51 was adjusted to 30 Torr by adjusting the opening of the conductance valve 657 while watching the vacuum gauge 666.
The source gas reacted in the gas phase, and an n-type GaAs layer started to grow on the substrate. When the layer thickness reaches 4.0 μm, the valves 544, 545, 547, 553, 559, 560 are closed, and Ga (CH ₃ ) ₃ gas, AsH ₃ gas, and H ₂ Se gas flow into the deposition chamber 651. Then, the production of the n-type layer was completed. The valves 550 and 551 were opened, and H ₂ gas was kept flowing sufficiently into the deposition chamber 651.

P is used as the second semiconductor layer 804 (FIG. 16).
Valves 542, 544, 547, 5 are used to make the mold layers.
48, 553, 554, 559 are gradually opened, and then valves 550, 551 are closed to allow Ga (CH ₃ ) ₃ gas, AsH ₃ gas and Zn (C ₂ H ₅ ) ₂ gas to flow into the deposition chamber 651. It was At this time, each mass flow controller 521,5
22, 524 and 526 were set so that the H ₂ gas flow rate was 500 sccm, the H ₂ gas flow rate was 25 sccm, the AsH ₃ gas flow rate was 1000 sccm, and the H ₂ gas flow rate was 475 sccm. At this time, the mass flow controller 52
Liquid cylinder 571,572 with H ₂ gas passing through 1,522
The inside of the deposition chamber 651 is filled with Ga by bubbling the inside.
The constant temperature bath 580 was set in advance so that (CH ₃ ) ₃ gas was introduced at about 100 sccm and Zn (C ₂ H ₅ ) ₂ gas was introduced at about 5 sccm. The opening of the conductance valve 657 was adjusted while observing the vacuum gauge 666 so that the pressure in the deposition chamber 651 was 20 mTorr. The source gas reacted in the gas phase, and a p-type GaAs layer started to grow on the n-type layer. Layer thickness is 1.2 μm
When it became, valves 544, 547, 548, 553,
554 and 559 are closed, and Ga (CH ₃ ) ₃ gas and Zn (C ₂
The H ₅ ) ₂ gas and AsH ₃ gas were stopped flowing into the deposition chamber 651, and the production of the p-type layer was completed. The high-frequency heater power source (not shown) was turned off, the valves 550 and 551 were opened, and H ₂ gas was kept flowing into the deposition chamber 651.

When the substrate had cooled to room temperature, all valves were closed and the leak valve 659 was opened to leak the inside of the deposition chamber 651.

Then, in the same manner as in Experimental Example 3-1, the comb-shaped collector electrode was prepared, the second semiconductor layer was etched, the antireflection layer was prepared, and the back surface electrode was prepared.

The photoelectric conversion efficiencies of these solar cells were determined using the same method as in Comparative Experimental Example 3-1, and Experimental Example 3-2 based on the present invention was about 1.
It turned out to be twice as good.

Table 5 collectively shows the conditions for manufacturing the semiconductor layers of Experimental Example 3-2 and Comparative Examples 3-1 to -4. From the above measurement results, it was found that the solar cell manufactured by using the method of the present invention has excellent characteristics as compared with the conventional solar cell.

[0194]

[Table 5]

(Experimental Example 3-3) Using the deposited film forming apparatus shown in FIG. 8, a GaAs crystal solar cell having a heterojunction and having the structure shown in FIG. 16 was produced.

A p-type single crystal GaAs substrate is used as the substrate 801, and a layer thickness of 5. is formed as the first semiconductor layer 803 on the substrate.
A p-type GaAs crystal layer having a thickness of 0 μm is formed, and an n-type Al _0.2 G layer having a thickness of 0.75 μm is formed thereon as a second semiconductor layer 804.
a _0.3 As crystal layer was formed. Next, as in Experimental Example 3-1, a comb-shaped collector electrode 806 was formed using the mask for the comb-shaped collector electrode in FIG. 9, and a back surface electrode 802 was formed on the back surface of the substrate. Next, the second semiconductor layer 804 was formed into a cross-sectional shape as shown in FIG. 16 by using the photolithography process as in Experimental Example 3-1. At this time, in the lower region of the comb-shaped collector electrode 806, the layer thickness of the second semiconductor layer 804 is 0.75 μm.
m, and 0.15 μm in the light incident region. Next, the antireflection layer 805 was also formed in the same manner as in Experimental Example 3-1.

The p-type layer which is the first semiconductor layer 803 was formed under the same conditions as in Experimental Example 3-1, but the second semiconductor layer 8 was formed.
Deposition of 04 a is n-type layer was performed microwave power, RF power, respectively 0.30 W / cm ^3, and 0.40 W / cm ^3. When the n-type layer was formed in the same manner as in Comparative Experimental Example 3-1, the minimum microwave power capable of decomposing the source gas by 100% was examined, and it was found to be 0.35 W / cm ³ .

(Comparative Example 3-5) When forming an n-type layer,
According to the conventional manufacturing condition that the microwave power is less than the minimum power (0.35 W / cm ^{3 in} this case) capable of decomposing the raw material gas 100%, and the microwave power> RF power,
A GaAs solar cell having a heterojunction similar to that in Experimental Example 3-3 was produced. That is, when forming the n-type layer, the microwave power is 0.25 W / cm ³ , and the RF power is 0.10 W.
/ Cm ^3, and other conditions were the same as in Experimental Example 3-3.

The photoelectric conversion efficiency of these solar cells was determined by the same method as in Comparative Experimental Example 3-1, and Experimental Example 3-3 according to the present invention was about 1. It turned out to be twice as good.

(Comparative Example 3-6) When preparing an n-type layer,
According to the conventional manufacturing conditions that the microwave power is the minimum power (0.35 W / cm ^{3 in} this case) capable of decomposing the raw material gas 100% and the microwave power> RF power,
A GaAs solar cell having a heterojunction similar to that in Experimental Example 3-3 was produced. That is, when forming the n-type layer, the microwave power is 0.40 W / cm ³ , and the RF power is 0.10 W.
/ Cm ^3, and other conditions were the same as in Experimental Example 3-3.

The photoelectric conversion efficiencies of these solar cells were determined by using the same method as in Comparative Experimental Example 3-1, and Experimental Example 3-3 according to the present invention was about 1. It turned out to be 6 times better.

(Comparative Example 3-7) When manufacturing an n-type layer,
According to the conventional manufacturing conditions that the microwave power is the minimum power (0.35 W / cm ^{3 in} this case) capable of decomposing the raw material gas 100% and the microwave power> RF power,
A GaAs solar cell having a heterojunction similar to that in Experimental Example 3-3 was produced. That is, when forming the n-type layer, the microwave power is 0.40 W / cm ³ , and the RF power is 0.50 W.
/ Cm ^3, and other conditions were the same as in Experimental Example 3-3.

The photoelectric conversion efficiencies of these solar cells were determined using the same method as in Comparative Experimental Example 3-1, and Experimental Example 3-3 according to the present invention was about 1. It turned out to be twice as good.

The manufacturing conditions and photoelectric conversion efficiency of the semiconductor layers of Experimental Example 3-3 and Comparative Examples 3-5 to 3-7 are summarized in Table 5 above.

From the above measurement results, it was found that the solar cell produced by the method of the present invention has excellent characteristics as compared with the conventional solar cell.

(Experimental example 3-4) The MESFET shown in FIG. 17 was produced using the deposited film forming apparatus shown in FIG.

As the substrate 851, a semi-insulating single crystal GaAs substrate doped with chromium (Cr) [plane orientation: (10
0)] was used. The first semiconductor layer 8 is formed on the substrate 851.
A non-doped GaAs crystal layer having a layer thickness of 2.0 μm is formed as 52, and an n-type GaAs crystal layer having a layer thickness of 0.3 μm is formed as a second semiconductor layer 853 on the third semiconductor layer. N-type Al _{0.2 with a} layer thickness of 0.2 μm as 854
A Ga _0.8 As crystal layer was formed, and an n-type GaAs crystal layer having a layer thickness of 0.02 μm was formed thereon as a fourth semiconductor layer 855.

Next, the substrate on which each semiconductor layer was formed was taken out from the deposited film forming apparatus of FIG. 8, and the active region was subjected to mesa structure (trapezoidal) structure etching by using a normal photolithography process. Then, on the fourth semiconductor layer 855, as shown in FIG.
A source electrode 856 and a drain electrode 858 made of an alloy of gold (Au) and germanium (Ge) were formed by using the resistance heating vacuum vapor deposition apparatus. First, the vapor deposition source 604 is Au-
A granular deposition source of Ge alloy (purity 99%) was exchanged, and a layer thickness of 5 was formed on the fourth semiconductor layer 855 in the same manner as in Experimental Example 3-1.
A metal electrode layer having a thickness of μm is formed, alloying treatment is performed at 300 ° C. for 1 minute in an H ₂ atmosphere, and a source electrode 856 and a drain electrode 858 having the structure of FIG. 17 are completed by using a normal photolithography process. .

Next, using the same method and conditions as those for the antireflection layer in Experimental Example 3-1, a layer thickness of 6.0 was formed on the source electrode 856, the drain electrode 858 and the fourth semiconductor layer 855.
A protective layer 859 made of non-single-crystal silicon nitride having a thickness of μm was formed, and a structure shown in FIG. 17 was formed by using a normal photolithography process.

Next, in order to open a hole for the gate electrode, an etching solution having a dilution ratio of KI: I ₂ : H ₂ O = 7: 7: 180 (weight ratio) was used, and a second n-type GaAs crystal was used. With respect to the semiconductor layer 853, the third semiconductor layer 854 made of n-type Al _0.2 Ga _0.8 As crystal and the fourth semiconductor layer 855 made of n-type GaAs crystal were selectively etched.

Next, a gate electrode 857 made of aluminum (Al) was produced. First, the protective layer 859 and the source electrode 8
56, a resist is applied on the drain electrode 858, and the vapor deposition source 604 is made of Al by the same method as in Experimental Example 3-1.
Replace with a granular evaporation source (purity 99.9%), layer thickness 6.0 μm
A metal electrode layer made of Al is formed, and the structure shown in FIG. 17 is formed by using a lift-off process.
57 was completed.

As described above, MESFET made of GaAs crystal
Has been completed. Table 6 shows the manufacturing conditions of each semiconductor layer.

[0213]

[Table 6]

(Comparative Example 3-8) MOC which is a conventional method
Some MESFETs shown in FIG. 17 were manufactured by using the VD method. That is, a semiconductor layer of MESFET was manufactured using the same manufacturing procedure and manufacturing method as in Comparative Example 3-4, and mesa-shaped etching was performed using the same procedure and manufacturing conditions as in Experimental Example 3-4 to form a protective layer. And each electrode was produced.

[0215] Next, fabricated by MESFET drain voltage - drain current (V _DS -I _D) gate voltage characteristics (V _GS) measured dependence, mutual conductance g
_{m (= △ I D / △} V GS, I D: the drain current, V _GS: gate voltage) was determined. The one having the largest mutual conductance g _m was set as a representative of Comparative Example 3-8. Table 6 shows the manufacturing conditions of each semiconductor layer.

Comparing the transconductance g _m between Experimental Example 3-4 and Comparative Example 3-8, Experimental Example 3-8 is about 1.2 times larger than Comparative Example 3-8 and is excellent in low noise. I found out. From the above measurement results, it was found that the FET manufactured by using the method of the present invention had excellent characteristics as compared with the conventional FET.

(Experimental example 3-5) An InP crystal solar cell was manufactured using the deposited film forming apparatus shown in FIG. Figure 15
FIG. 3 is a schematic cross-sectional view showing the configuration of this InP solar cell. That is, in this solar cell, the back electrode 886 is formed on one surface of the substrate (base) 881, the first and second semiconductor layers 882 and 883 are sequentially laminated on the other surface, and the third electrode is further patterned. A semiconductor layer 884 and a comb-shaped collector electrode 885 are formed, and these semiconductor layers 882 are formed.
~ 884 and the comb-shaped collecting electrode 885,
An antireflection layer 887 is provided.

First, the creation procedure will be described. The device shown in FIG.
Al (C₂H_Five)₂Liquid bottle
Indium [In (CH₃)₃, TMI]
(Purity of 99.9%)₂H_Five)₂Liquid cylinder
Triethyl zinc salt [Zn (C ₂H_Five)₃, TEZ]
Replace with liquid cylinder, H₂Se gas cylinder with hydrogen sulfide
"H₂S "gas (purity 99.999%) and exchange
Sphinh "PH₃Gas (purity 99.999%) cylinder and machine
Sflow controller is newly connected.

An n-type single crystal InP substrate is used as the substrate 881, and a layer thickness of 4.0 is formed as the first semiconductor layer 882 on the substrate.
An n-type InP crystal layer with a thickness of 0.75 μm was formed on the n-type InP crystal layer as a second semiconductor layer 883. The thickness of the third semiconductor layer 884 is 0.5 μm.
A p-type In _x Ga _1-x As (x = 0.53) crystal layer of m was formed.

Next, a comb-shaped collector electrode 885 is formed on the third semiconductor layer 884 by using the mask as shown in FIG.
As an alloy of gold (Au) and zinc (Zn) (Au-Zn)
Was vapor-deposited. In the resistance heating vapor deposition apparatus of FIG. 10, the vapor deposition source 604 was replaced with the above alloy (purity 99%), and Experimental Example 3
Vacuum deposition was started by the same procedure and method as in No. 1, and a comb-shaped collector electrode 885 having a layer thickness of 0.3 μm was produced.

Next, gold (Au) and tin are used as the back surface electrode 886.
An alloy (Au—Sn) composed of (Sn) was deposited on the back surface of the substrate 851. In the apparatus of FIG. 10, the vapor deposition source 604 was replaced with the above alloy (purity 99%), vacuum vapor deposition was started by the same procedure and the same method as in Experimental Example 3-1, and a back electrode having a layer thickness of 0.6 μm was used. 886 was produced.

Then, alloying treatment is performed in the same manner as in Experimental Example 3-1.
It was carried out at 00 ° C. for 1 minute. Then, similarly to Experimental Example 3-3, the photolithography process was used to form the semiconductor layer into a mesa-shaped (trapezoidal) structure as shown in FIG.

Next, a layer made of antimony oxide (Sb ₂ O ₃ ) was formed as an antireflection layer 887 on the comb-shaped collector electrode 885 and the third semiconductor layer 884. In the apparatus of FIG. 10, the vapor deposition source 604 was replaced with antimony (purity 99.999%). The deposition chamber 601 was evacuated by a vacuum pump (not shown), and when the reading of the vacuum gauge 658 was about 1 × 10 ^-6 Torr, oxygen gas (purity 99.999%) cylinder (not shown) was used to remove O ₂ gas. The mass flow controller 611 is set so that the flow rate is 100 sccm, and the deposition chamber 601
Conductance valve 6 so that the pressure in the chamber becomes 5 mTorr
Adjusted at 09. Turn on the AC power, dissolve the vapor deposition source 604, open the shutter after 5 minutes, layer thickness 0.75 μm
The antireflection layer 887 of No. 1 was formed.

Table 7 shows the conditions for manufacturing each semiconductor layer.

[0225]

[Table 7]

(Comparative Example 3-9) MOC which is a conventional method
Several InP solar cells shown in FIG. 15 were produced by using the VD method. Each semiconductor layer constituting the InP solar cell is formed by using the same manufacturing procedure and manufacturing method as in Comparative Example 3-4,
Further, the comb-shaped collector electrode 885 and the back surface electrode 886 were formed using the same procedure and manufacturing conditions as in Experimental Example 3-5 to form a mesa structure, and further an antireflection layer 887 was provided.

The photoelectric conversion efficiency was measured by the same method as in Comparative Experimental Example 3-1, and the one showing the largest value was represented as Comparative Example 3-9. The manufacturing conditions of each semiconductor layer in Table 7 are shown. Furthermore, when the photoelectric conversion efficiencies of the solar cell of Experimental Example 3-5 and the solar cell of Comparative Example 3-8 were measured, it was about 1.1 times larger in Experimental Example 3-5 than in Comparative Example 3-9.

From the above measurement results, it was found that the InP solar cell produced by the method of the present invention has excellent characteristics as compared with the InP solar cell produced by the conventional method.

[0229]

According to the invention described in claims 1 to 5, a discharge vessel made of a conductive member is used, and a positive DC voltage is applied to at least a part of the discharge vessel, so that the weight of plasma in plasma is increased. There is an effect that the movement of the mass-charged particles is promoted and a higher quality deposited film can be stably obtained for a long time.

In the invention described in claims 6 to 12, by providing the louver at the opening of the discharge vessel, it is possible to prevent leakage of microwaves and plasma or active species to the outside of the discharge vessel. There is an effect that stable plasma can be generated in the discharge vessel by effectively utilizing the above. Further, since formation of a deposited film on the outside of the discharge vessel is prevented, there is an effect that the maintenance work can be simplified and the maintenance cycle can be extended. In the invention described in claims 13 and 14, the microwave energy and the high frequency energy are simultaneously acted on the raw material gas, and conditions are set for the intensities of both of these energies, whereby a III-V group compound semiconductor excellent in electrical characteristics is provided. There is an effect that the film can be produced at a temperature lower than that of the conventional one and by a method suitable for more industrial production and larger area.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a deposited film forming apparatus of Example 1-1.

FIG. 2 is a schematic diagram showing a configuration of a deposited film forming apparatus of Example 1-2.

FIG. 3 is a schematic diagram showing a configuration of a deposited film forming apparatus of Example 2-1.

4 is a schematic diagram showing a configuration of a continuous deposited film forming apparatus incorporating the deposited film forming apparatus shown in FIG.

FIG. 5 is a schematic diagram showing a configuration of a continuous deposited film forming apparatus of Example 2-2.

FIG. 6 is a schematic diagram showing the configuration of a deposited film separation / forming apparatus of Example 2-3.

7A and 7B are diagrams showing a dimensional relationship between a louver and a partition plate, FIG. 7A is a perspective view, and FIG. 7B is a sectional view taken along a plane parallel to the partition plate.

FIG. 8 is a schematic diagram showing a configuration of a deposited film forming apparatus of Example 3-1.

FIG. 9 is a plan view of a mask for forming a comb-shaped collector electrode.

FIG. 10 is a schematic diagram showing a configuration of a resistance heating vacuum vapor deposition apparatus.

FIG. 11 is a characteristic diagram showing the relationship between microwave power and deposition rate.

FIG. 12 is a characteristic diagram showing the relationship between microwave power, RF power, and photoelectric conversion efficiency.

FIG. 13 is a characteristic diagram showing a relationship between pressure and photoelectric conversion efficiency when forming a deposited film.

FIG. 14 is a schematic diagram showing a deposited film forming apparatus by MOCVD.

FIG. 15 is a schematic cross-sectional view showing the structure of an InP solar cell.

FIG. 16 is a schematic cross-sectional view showing the structure of a photovoltaic element made of a III-V group compound semiconductor.

FIG. 17 is a MESFET made of a III-V group compound semiconductor.
It is a schematic cross-sectional view showing the configuration of.

FIG. 18 is a schematic view showing a configuration of a conventional deposited film forming apparatus using a microwave plasma CVD method.

[Explanation of symbols]

 101,130,201 Vacuum vessel 102,131,216,316 Applicator 104,133 Raw material gas introduction tube 105,134,202,302,402 Discharge vessel 107,136,203,481,504 Base 109,138 Variable DC power supply 110,139 Insulator 200 Deposited film forming device 204,205 Gas gate 212,312,412 Louver 213,313,413 Partition plate 215,315 Gas supply pipe 300,400 Continuous deposited film forming device 301,401 Vacuum container for forming intrinsic layer 351 Substrate Delivery Container 361 First Impurity Layer Forming Vacuum Container 371 Second Impurity Layer Forming Vacuum Container 381 Substrate Winding Container 450 Deposition Film Separation Apparatus 451 Substrate Loading Room 452 First Impurity Film Formation Chamber 453 Intrinsic Film Formation chamber 454 Second impurity film formation chamber 455 Substrate unloading chamber 45 ～459 gate valve 500 deposition apparatus 501 deposition chamber 510 waveguide 511 RF power 520 source gas supply unit

Front page continued (72) Inventor Megumi Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Toshimitsu Kariya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masafumi Sano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Ryo Hayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Invention Person Masahiko Tonogaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Shotaro Okabe 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasushi Fujioka Tokyo 3-30-2 Shimomaruko, Ota-ku, Canon Inc. Canon Inc. (72) Inventor Akira Sakai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Nao Yoshiri, Ota Ward, Tokyo Shimomaruko 3-30-2 Canon Inc.

Claims (14)

[Claims] 1. A deposition film forming method by a microwave plasma CVD method for forming a deposition film on a substrate held in a vacuum container, comprising: a discharge container made of a conductive member provided in the vacuum container; and the substrate. By forming a discharge space into which microwave energy is introduced, while applying a DC voltage to at least a part of the discharge container so that the discharge container is positive with respect to the substrate,
A method for forming a deposited film, comprising forming a deposited film on the substrate. 2. The deposited film forming method according to claim 1, wherein the deposited film is formed while changing the DC voltage applied to the discharge vessel to adjust the DC electric field strength in the discharge vessel. 3. The method for forming a deposited film according to claim 1, wherein the magnitude of the direct current passing through the discharge vessel is changed by adjusting the direct current voltage applied to the discharge vessel. 4. A deposition film forming apparatus using a microwave plasma CVD method for forming a deposition film on a substrate held in a vacuum container, the deposition film forming device being provided in the vacuum container and electrically insulated from the substrate. A discharge vessel made of a conductive member, and a voltage applying means for applying a positive DC voltage to at least a part of the discharge vessel, a discharge space into which microwave energy is introduced is defined by the base body and the discharge vessel. A deposited film forming apparatus characterized by being defined. 5. The deposited film forming apparatus according to claim 4, wherein the DC voltage value generated by the voltage applying means is variable. 6. A deposition film forming method by a microwave plasma CVD method for forming a deposition film on a substrate held in a vacuum container, wherein at least a part of an opening provided in the vacuum container is made of a conductive member. A method for forming a deposited film, which comprises using a discharge vessel composed of a louver, introducing microwave energy into the discharge vessel to generate microwave plasma, and forming a deposited film on the substrate. 7. A deposition film forming apparatus by a microwave plasma CVD method for forming a deposition film on a substrate held in a vacuum container, the microwave being provided in the vacuum container for forming the deposition film. A deposition having a discharge vessel surrounding a discharge space in which energy is introduced to generate plasma, and a louver made of a conductive member is formed in at least a part of an opening provided in the discharge vessel. Membrane forming container. 8. The deposited film forming container according to claim 7, wherein the louver is inclined downward toward the inside of the discharge container. 9. The deposited film forming apparatus according to claim 7, wherein a plurality of partition plates perpendicular to the louver are provided on the louver. 10. The deposited film forming apparatus according to claim 7, wherein the louver has an inclination angle and an arrangement so that the inside and the outside of the discharge vessel cannot be seen from each other. 11. A plurality of louvers, wherein the length of the longer one of the intervals between the louvers and the intervals between partition plates is shorter than 1/2 of the wavelength of the microwave used.
The deposited film forming apparatus according to claim 9. 12. The internal pressure of the discharge vessel during the deposition film formation is 1
The deposited film forming apparatus according to claim 7, which has a mTorr or more and 50 mTorr or less. 13. A method of forming a deposited film by a microwave plasma CVD method for forming a deposited film of a group III group V compound semiconductor of the periodic table on a substrate held in a vacuum container, wherein a source gas of the compound semiconductor is used. While introducing into the vacuum vessel, microwave energy smaller than the microwave energy required to decompose 100% of the raw material gas is applied to the raw material gas at an internal pressure of 50 mTorr or less, and at the same time, the applied microwave is used. A method for forming a deposited film, characterized in that high-frequency energy larger than wave energy is caused to act on the source gas. 14. A deposition film forming apparatus by a microwave plasma CVD method for forming a deposition film of a group III group V compound semiconductor of the periodic table on a substrate held in a vacuum container, wherein a source gas of the compound semiconductor is used. 50 mTorr or less, comprising: a gas introducing unit that introduces into the vacuum container, a microwave introducing unit that introduces microwave energy into the vacuum container, and a high frequency introducing unit that introduces high frequency energy into the vacuum container. With the internal pressure of, the microwave energy smaller than the microwave energy required for 100% decomposition of the raw material gas is applied to the raw material gas, and at the same time, the high frequency energy larger than the applied microwave energy is applied to the raw material gas. A deposited film forming apparatus, characterized in that a deposited film is formed on the substrate by acting.