JP2717239B2 - Coating method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for producing a vapor phase reactive coating. 2. Description of the Related Art Conventionally, in a CVD apparatus such as a PCVD apparatus, since the pressure of a reaction system is as high as 0.01 to 10 torr, only RP is used in an exhaust system and the like, and a higher degree of vacuum is generated. It was impossible at all to provide a TP or the like to make it work.
However, the present inventor has found that in such a PCVD apparatus, the exhaust system is
With only RP, this RP makes a discontinuous rotation, so that the atmosphere (especially oxygen) from the exhaust system at atmospheric pressure in contact with the air flows backward, and a part of this atmosphere mixes with the oil. It was found that re-vaporization caused a backflow into the reaction vessel. Further, for this reason, oxygen is mixed into the film formed by the backflow. For example, when a silicon film is formed, oxygen is mixed into the film at a concentration of 3 × 10 ^{19 to} 2.5 × 10 ²⁰ cm ^-3 . . For this reason, hydrogen or fluorine is added to such a film, so that what should be a silicon semiconductor can be called lower silicon oxide. The present invention aims to prevent such disadvantages. [0003] The present invention relates to the formation of a non-oxide film when forming a film using a reactive gas, the gas phase using a turbo molecular pump in an exhaust system. The reaction (hereinafter referred to as CVD)
The present invention relates to a gas phase reaction apparatus for controlling the concentration of oxygen in a coating to 5 × 10 ¹⁸ cm ⁻³ or less and a method for producing a coating using the apparatus. [0004] In the present invention, in the production of a non-oxygen or non-oxide coating, to prevent backflow of the atmosphere from the exhaust system,
Oil rotary rotary pump, mechanical booster
Instead of using only a discontinuous rotary type rough vacuum pump such as a pump (hereinafter simply referred to as a rotary pump or RP), a continuous exhaust type composite molecular pump or turbo molecular pump (hereinafter simply referred to as a turbo molecular pump). Molecular pump or TP)
Is interposed between the reaction vessel and the vacuum pump to prevent backflow of the atmosphere from the exhaust system. When the non-oxide film of the present invention, for example, non-single-crystal silicon is formed using silane (SinH _{2n + 2} n> 1) as a reactive gas, the amount of oxygen in the film is 5 × 10 5 ¹⁸
The purpose of the present invention is to prevent the backflow of the atmosphere from the exhaust system in order to make it equal to or less than cm ^−3, preferably 1 × 10 ¹⁸ cm ⁻³ or less. According to the present invention, the exhaust system is interposed between the reaction chamber and the VP via a valve for adjusting the pressure during the reaction, so that the reaction chamber has a plasma gas phase reaction (PCVD) in a pressure range of 0.05 to 10 torr. ), Photo CVD (Photo CVD) or a combination of these methods (hereinafter simply referred to as CVD method)
A film is formed using a pressure adjusting valve (control
(Also called a valve or butterfly valve). For this reason, the backflow of the oil component from the RP and
The purpose is to form a high-quality non-oxide film by preventing the backflow of air mixed with oil during RP rotation. Further, according to the present invention, when the reaction vessel is evacuated before performing the gas phase reaction, the TP can be connected to the reaction vessel with a large-diameter pipe, and the TP can be further connected to the reaction vessel. . Therefore, the pressure inside the reaction vessel can be made 3 × 10 ⁻⁸ torr or lower (3 × 10 ⁻⁸ to 1 × 10 ⁻¹⁰ torr) using the same TP. In other words, the device of the present invention evacuates the reaction vessel to 10 ^-8 torr or less and CV
The pressure of 0.01 to 10 torr required for film formation by the method D was made possible by using the same TP, in addition to controlling the backflow of oxygen. The present invention further relates to a plasma CVD apparatus in which a plurality of reaction chambers are connected to each other to form a film as a semiconductor, and a P-type non-single-crystal semiconductor, an I-type non-single-crystal semiconductor and an N-type A single crystal semiconductor is stacked on a substrate,
The present invention relates to an apparatus and a method for manufacturing a semiconductor device forming a PIN junction. Further, the present invention provides a TP
And a pressure regulating valve is provided between TP and RP. That is, if the pressure regulating valve is
And the inner diameter of this valve is generally 1 to 2 inches. Therefore, even if this valve is fully opened, the conductance at this valve portion is low, and it takes a long time even if the inside of the reaction vessel is kept at a background level (3 × 10 ⁻⁸ torr or less). In addition, this valve
When the diameter is as large as 10 inches, there is a disadvantage that the pressure cannot be adjusted with sufficient accuracy. [0009] The present invention eliminates these disadvantages, and is intended to reduce
A compound molecular pump that can be evacuated even at 01 to 10 torr is used as the TP, and a pressure control valve is provided between TP and RP, and pressure control is performed for both the inside of the TP and the reaction vessel. It is. Hereinafter, a case where a PIN junction is provided in the gas phase reaction apparatus of the present invention by a plasma CVD apparatus will be described. FIG. 1 shows an outline of the apparatus according to the present invention. That is, a doping system (50) for introducing a reactive gas, a reaction vessel
(51) and an exhaust system (52). The reaction vessel has a semiconductor layer formed as a double reaction vessel type having a reaction space in which an inner surface is formed by an insulator, and additionally, a P-type semiconductor (system I in the drawing) and an I-type semiconductor (system III in the drawing). FIG. 1 shows a multi-chamber type CVD apparatus, particularly a PCVD apparatus, in which respective reaction vessels are connected via a separation unit (system II in the drawing) when a junction is formed on a substrate by laminating with a N-type semiconductor. It is in the proposal as shown. According to the present invention, a non-single-crystal semiconductor layer to which hydrogen or a halogen element is added is used to form a semiconductor layer having a P, I, and N-type conductivity type having a low recombination center density, In addition to forming a PIN junction, it prevents each semiconductor layer from mixing impurities from other adjacent semiconductor layers and deteriorating the junction characteristics. And to a plasma gas phase reaction for performing continuous production without forming an interlayer insulator by oxidizing a part of a semiconductor. Further, the present invention relates to a so-called mass production system in which a multi-chamber plasma reaction method in which a number of such reaction vessels are independently connected in each reaction, in which a large number of substrates are simultaneously increased in film growth rate at a time. . In the present invention, the distance is 10 to 50 in the electrode direction.
cm e.g. 20 cm and width 15-120 cm e.g. 30
cm substrate (10 pieces of 15 cm × 30 cm per batch) was used.
In FIG. 1, a means (50) for introducing a reactive gas and an exhaust means
(52), these are provided with a supply nozzle and an exhaust nozzle,
A pair of electrodes (6
1), (51) or (62), (52) and reactive gas supply nozzle
(17), (18) and exhaust nozzles (17 '), (18') were provided.
That is, a structure in which the outside of the electrode is wrapped with a hood insulator (38), (3)
9 '). In order to confine the reaction space between the hoods, the outer periphery was surrounded by insulators (38) and (38 '). Although not shown, an opening / closing door is provided before and after the reaction vessel, and a substrate heating means such as a halogen lamp is provided on the inner surface of the door. This drawing shows a PIN junction, PI
P-junction, NIN-junction or PINPIN ... PIN-junction, etc. are applied to the semiconductor on the substrate by using semiconductor layers of different conductivity type or different materials, but with different main components or stoichiometric ratios of the semiconductors to be formed. This is an apparatus for automatically and continuously forming a multilayer in which semiconductor layers are stacked without being affected (mixed) by a semiconductor layer formed in a previous step. The drawing shows a part of a plurality of reaction systems constituting a PIN junction. That is, a multi-chamber system having two (I, II) of three reaction systems formed by stacking P, I and N type semiconductor layers, and further having a first spare chamber and a buffer chamber (II) for transfer. 1 shows an example of a plasma gas phase reaction apparatus. The system I, II, III in the drawing has two reaction vessels (101), (103) and a buffer chamber (102),
Separation sections (44), (45), (46) and (47) are provided between the respective reaction vessels. This device has a first spare room (10
0), and two substrates (1) each having two surfaces to be formed were inserted from the door (42) to two surfaces of the substrate holder (2). Then, insert this holder (3) into the outer frame jig (only
8), (38 ')). That is, the substrate having the surface on which the film is to be formed is in contact with the substrate holder (2) on the back side on which no film is formed, and the two substrates and the substrate holder are used as one holder (3) for 6 cm ± 0.5 cm.
It was planted in an insulating outer frame jig with a gap of m. As a result, 10 15 cm × 30 cm substrates could be simultaneously formed. Thus, the reaction space (6), (8), 55cm in height, 40cm in depth, and 40cm in width, is surrounded by insulators (39), (39 ') on the upper and lower sides, and the outer peripheral jig is on the side periphery (38) , (38 ') enclosed in an electrically insulating material. The first preliminary chamber (100) was evacuated by the RP (35) through the TP (86) and the stop valve (71). this
As the TP, a compound molecular pump TG550 manufactured by Osaka Vacuum was used. This compound molecular pump has a constant speed of 400 rps (rotation speed per second), and N ₂ and SiH ₄ have a pumping speed of 500 l / s.
Furthermore, exhaust at 0.01 to 10 torr is possible, and 10 torr at 10 torr
Evacuation of liter / sec is possible. In particular, in the case of 0.1 to 1 torr generally used for a gas phase reaction, 450 liter / sec.
Exhaust of up to 440 liters / sec is possible. In the present invention, the rotation speed of the TP is made variable. Therefore, even when the reaction vessel was at atmospheric pressure, the rotation speed of the TP was lowered to a fixed value of 100 to 200 rps, and the rotation was continued. And TP was not damaged. Therefore, the reaction vessel valved RP at atmospheric pressure
With (71) open, vacuum evacuation was achieved while driving vacuum evacuation by the TP. As a result, the TP prevents the oil component from flowing backward from the RP, and the substrate surface is not contaminated with the oil component. Thereafter, the inner diameters of the pressure adjusting valve (72) and the gate valve (85) are made the same as the inner diameter of the TP (using a VG150 or JIS B2290 vacuum flange), and the gate valve (8) is used.
5) Fully opened, 3 × 10 ^-8 by TP (also using TG550)
A reaction vessel (10
A gate valve (44) (opening 35 cm × 30 cm) for separation from 1) was opened, and the substrate held by the outer frame jig (38) was transferred. For example, the substrate is moved from the preliminary chamber (100) to the first reaction vessel (101), and the substrate is moved to the first reaction vessel (101) by closing the gate valve (44). At this time, the substrate (1) and the like held in the first reaction vessel (101) are stored in the buffer chamber (10) in advance or simultaneously.
2), the jig and the substrate (2) held in the buffer chamber (102) are stored in the second reaction vessel (103), and the substrate held in the second reaction vessel (103) is stored in the second reaction vessel (103). Buffer room
Although not shown in (104), the substrate and the jig in the third reaction chamber are provided with a gate valve in the second preliminary chamber on the outlet side.
(45), (46), and (47) are opened and moved. After this, the gate valve (4
4), (45), (46) and (47) were closed. The case where the P-type semiconductor layer is formed by the PCVD method in the first reaction vessel (101) in the system I will be described below.
The reaction system I (including the reaction vessel (101)) was 0.01 to 10 torr, preferably 0.01 to 1 torr, for example, 0.1 torr. That is, the pressure regulating valve (72) is closed, and the reaction vessel and the TP (87), (10
The pressure in 1) is 0.01 to 10 torr, especially 0.05 to 1 torr. This degree of vacuum is controlled by controlling the opening and closing of the pressure regulating valve (72) below the TP (87), and the rotation speed of the TP is set to 100 rps. Let me. The reason why the rotation speed of the TP was reduced was that the pressure control of the pressure regulating valve was easily performed by reducing the compression ratio of the TP from a constant of 10 ⁷ to 10 ⁸ to 10 ² to 10 ³ . Since the present invention operates this continuous exhaust TP, it is possible to prevent, for the first time, the reverse diffusion of the polymerized oil of the RP (36) and the reverse flow of the exhaust air impregnated in the oil, particularly oxygen. did it. The reactive gas was supplied from the system I doping system (50). That is, silane (SinH _{2n + 2} n) purified as silicide gas (24) and further filled in a stainless steel cylinder
≧ 1 Especially SiH ₄ or Si ₂ H ₆ ) Silicon fluoride (SiF ₄ or Si
F ₂₎ was used. Here, an ultra-high-purity silane (purity 99.99%, water and oxygenates of 0.1 PPM or less), which is easy to handle, was used. In order to form SixC _1-x (0 <x <1) according to the present embodiment, methyl carbide (56) having a Si 予 め C bond in advance, ie, MMS (H Si (CH ₃ ) ₃ ), was used as the carbide gas (25). ) Or DMS
(Dimethylsilane (SiH ₂ (CH ₃ ) ₂ purity 99.99%) was used. For silicon carbide (Si _x C _{1 -x} 0 <x <1), P
Boron as an impurity of the type was added to the above-mentioned monosilane in 0.5%.
% Together with silane from a cylinder (24) mixed to a concentration of 10%. If necessary, hydrogen (purity of 7 N or more) or nitrogen (purity of 7 N or more) was supplied from (23) when the pressure in the reaction chamber was set to atmospheric pressure. Each of these reactive gases is flow meter (33)
And a valve (32), a reactive gas was supplied from a supply nozzle (17) to a reaction space (6) via a negative electrode (61) of a high frequency power supply (14). The reactive gas was supplied into a cylindrical space (6) surrounded by a holder (38), and a film was formed on a substrate (1) constituting this space. Further, electric energy, for example, high-frequency energy (14) of 13.56 MHz was applied between the negative electrode (61) and the positive electrode (51) to cause a plasma reaction, thereby forming a film of the reaction product on the substrate. The substrate was heated to 100 to 400 ° C., for example, 200 ° C. by the same means as the infrared heaters placed before and after the reaction vessel (103) shown in FIG. This infrared heater is a near infrared halogen lamp (constant emission wavelength 1 to 3 μm) heater or a far infrared ceramic heater (emission wavelength 8 to 25 μm).
And the cylindrical space surrounded by the holder in the reaction vessel was set at 210 ± 10 ° C., preferably within ± 5 ° C. Thereafter, as described above, the above-described reactive gas was introduced into the container, and a high-frequency energy (14) was further supplied to 5 to 100 W, for example, 20 W to cause a plasma reaction.
Thus, the P-type semiconductor layer has B ₂ H ₆ / SiH ₄ = 0.5%, MS / (Si
H ₄ + MS) = 20%, the average thickness of this reaction system I was 30
It was formed as a thin film having a thickness of about 300 mm, for example, about 200 mm. Eg = 2.15eVσ = 1 × 10 ^{-6 to} 3 × 10 ^-5 (Ωcm) ^-1
Met. Substrate is a conductor substrate (stainless steel, titanium, aluminum, other metals), semiconductor (silicon, germanium), insulator (glass, organic thin film) or composite substrate (glass or translucent organic resin) A conductive film such as tin oxide or ITO to which fluorine is added, which is a conductive film, or a two-layer film in which SnO ₂ is formed on ITO
Was used. In this example, a composite substrate was used. Thus, a plasma gas phase reaction was performed for 1 to 5 minutes to form a silicon carbide film to which boron as a P-type impurity was added to a thickness of about 200 °. Further, the gate (45) was opened on the substrate on which the first semiconductor layer was formed, and the substrate was moved to the buffer chamber (102) according to the above-described operation sequence, and the gate (45) was closed. The buffer chamber (102) is previously evacuated to 10 ^-8 torr or less, for example, 4 × 10 ^-10 torr by a cryopump (88). This substrate was placed in a reaction vessel maintained at 3 × 10 ⁻⁸ torr or less by TP (89) as in System III.
6) It was relocated after opening and closing. That is, the reaction system II in FIG.
In I, ultra-high-purity monosilane or disilane is added as a semiconductor reactive gas (water or silicon oxide, the concentration of oxide gas is 0.1 PPM or less) (28), and boron of 10 ¹⁷ cm ^-3 or less is added. 0.5 to 0.5 depending on hydrogen, silane, etc.
B ₂ H ₆ diluted to 30 PPM was supplied from (27), and a carrier gas was supplied from (26) as needed. After reacting in the reaction vessel, the reactive gas reaches the TP (89) via the gate valve (84), and further reaches the control valve (74) and the RP (34). 7000 mm thick
SiH ₄ 60cc / min, film formation rate 2.52.5 / sec, substrate (20cm
20 sheets of × 60 cm, total area 24000 cm ² ) and pressure 0.1 torr. When Si ₂ H ₆ was used, the film formation rate was 28 ° / sec. Thus, in the first reaction chamber, the P-type semiconductor layer was formed by the plasma vapor phase method, and then the I-type semiconductor layer was formed by the PCVD method to form a PI junction. After being formed to a thickness of about 7000 mm by the system III, the substrate is transferred to the next buffer chamber (102) according to the above-described operation, and further transferred to the next reaction chamber, and subjected to the same PCVD process. A type semiconductor layer was formed. This N-type semiconductor layer was supplied in the same manner as in system I by supplying silane with a phosphine of PH ₃ / SiH ₄ = 1.0% and hydrogen of a carrier gas at SiH ₄ / H ₂ = 20% by PCVD. To form a polycrystalline semiconductor layer having an N-type microcrystalline or fibrous structure with a thickness of about 500 mm, and furthermore, Si _x C _{1 on the} upper surface of which silicon carbide is set to MS / (SiH ₄ + MS) = 0.2. _-x (0
It is formed by laminating N-type semiconductor layers represented by <x <1) to a thickness of 10 to 200 mm, for example, a thickness of 50 mm. Other reactors are the same as in system I. After such a step, a 100-1500 mm thick ITO is further placed on the substrate formed by forming a PIN junction outside the second preparatory chamber, and a reflective or sublimable metal electrode such as an aluminum electrode is further placed thereon. Was formed to a thickness of about 1 μm by a vacuum evaporation method, and a (ITO + SnO ₂ ) front electrode {(PIN semiconductor)} (back electrode) was formed on a glass substrate. Its characteristic as a photoelectric conversion device is 8
AM1 (100mW / 100mW /
NEDO on a 40 cm x 60 cm glass substrate integrated as a hybrid type with intrinsic efficiency characteristics under the condition of cm ² )
In the panel, 5.7% was obtained with an effective efficiency. As a result, the open circuit voltage of one element is 0.85 to 0.85.
0.9V (0.87 ± 0.02V), but short circuit current is 18 ± 2 mA
/ Cm ^2, and the FF is as large as 0.60 to 0.70, and its variation is small within the panel and within the batch. Thus, it has been found that the method of the present invention is extremely effective industrially. FIG. 2 shows the result of measurement of the concentration distribution of oxygen and carbon impurities in a semiconductor by SIMS (using Cameca 3F) in the PIN type photoelectric conversion device manufactured by the present invention and the conventional method. The drawing shows aluminum {ITO} back electrode (9
4), N-type semiconductor (93), I-type semiconductor (92), P-type semiconductor (9
1) shows a tin oxide translucent conductive film (90) on a substrate. In the conventional exhaust system using only the RP pump, carbon is curved because the continuous exhaust system TP is not used.
(95), oxygen contained a high concentration of impurities as shown in curve (96). Especially for oxygen, 5 × 10 ¹⁹ to 2 × 10 ²⁰ cm ^-3
Had in the type semiconductor (92). The drawing is 5 × 10 ¹⁹ cm ^-3
Of oxygen. In addition, the carbon had 5 × 10 ¹⁹ to 4 × 10 ²⁰ cm ^-3 due to the backflow of the oil component from the oil rotary pump. The drawing is for a case having 1 × 10 ²⁰ cm ⁻³ . On the other hand, in the exhaust system as shown in the present invention, the carbon concentration is 1%.
It has from × 10 ^{17 to} 5 × 10 ¹⁸ cm ^-3 , and generally contains only 1 × 10 ¹⁸ cm ^-3 or less. In addition, oxygen is 5 × 10 ¹⁸ cm ⁻³ or less, generally 1 × 10 ¹⁸ cm ⁻³ or less, and FIG. 2 shows 2 × 10 ¹⁸ cm ^−3.
The case of is shown. [0030] In FIG. 2, Aruminyu back electrode (94) - arm has oxygen 3~6 × 10 ²⁰ cm ^-3. For this reason, this oxygen is used for SIMS (secondary ion analysis) (Kameka 3F
It is considered that in the measurement, the background oxygen was used, and the oxygen in the N-type semiconductor (93) was 10 ¹⁸ to 10 ²⁰ cm ⁻³ . Oxygen impurities in the P-type semiconductor and oxide impurities such as water components in the MS are contained in the P-type semiconductor. The starting material is purified in the same manner as silane to obtain oxygen or oxide of 0.1 PPM or less to further reduce the oxygen concentration. The possibility of lowering can be estimated. Regarding the types of semiconductors to be formed, not only Si but also other group IV Ge, Si _x C _1-x (0 <x <1), Si _x
Ge _1-x (0 <x <1), Si _x Sn _1-x (0 <x <1) Even if it is a single layer or a multilayer, besides these, GaAs, GaAlAs,
It goes without saying that non-oxygenated compounds such as compound semiconductors such as BP and CdS may be used. The present invention has shown the PCVD method in a multi-chamber system using three reaction vessels. However, this was used as one reaction vessel, where silicon nitride was converted to silane (Si
It is effective to form the film by a PCVD reaction between H ₄ or Si ₂ H ₆ ) and ammonia (NH ₃ ). Also the MS and Si ₂ H ₆ by the optical CVD method and the reaction of one reactive example system I of the present invention B ₂
The TP and pressure regulating valve of the simultaneously present invention also possible to perform H ₆ mixed be used for the exhaust system is effective. Further, according to the present invention, a single reaction vessel
₄ and PCVD reaction with SiH _4, MoCl _5, WF ₅ or Ti by reaction thereof with _{silicide, TiSi 2, Mo, MoSi 2} , W, equally effective in the production of non-oxygenates coating such as WSi ₂ is there. In the present invention,
The separation section may omit the system II and simply use only the gate valve. It goes without saying that the plasma CVD apparatus of the present invention can be applied to a single-chamber or multi-chamber system having another structure. Further, the embodiment of the present invention is a multi-chamber system shown in FIG.
VD method was supplied. However, if necessary, part or all of this can be performed by photo-CVD without plasma or LT CVD (HOMO CVD).
), Or a reduced pressure CVD method may be used to form the composite coating. [0034]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an outline of an apparatus for producing a coating for a plasma vapor phase reaction for carrying out the present invention. FIG. 2 shows the distribution of impurities in a semiconductor device manufactured according to the present invention and a conventional method.

Continuation of front page    (72) Inventor Minoru Miyazaki               7-21-21 Kitakarasuyama, Setagaya-ku, Tokyo               Semiconductor Energy Laboratory Co., Ltd.                (56) References JP-A-57-44786 (JP, A)                 JP-A-59-16328 (JP, A)                 JP-A-57-49082 (JP, A)                 JP-A-56-151287 (JP, A)

Claims (1)

(57) [Claims] T is placed on a substrate placed in a reaction chamber maintained under reduced pressure.
In forming a non-oxygenated film such as i, TiSi ₂ , Mo, MoSi ₂ , W, WSi ₂ by a CVD method, the reaction chamber is evacuated to a relatively high vacuum and then a reactive gas is introduced into the reaction chamber. Means for forming a reaction product on the substrate,
After the reaction, an exhaust means for exhausting unnecessary reaction products during the reaction to a relatively low vacuum is provided , and by a continuous exhaust type compound molecular pump arranged in series via a valve on the reaction chamber side of the exhaust means. The unnecessary reaction product is exhausted, and the valve is
It is characterized by lowering the compression ratio of the serial composite molecular pump
Film formation method. 2. Oite the film forming method according to claim 1, CVD method a plasma CVD method, optical CVD method, LTCVD method (HO
MOCVD) and reduced pressure CVD.
Coating method.