JPS5972182A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve intrinsic conversion efficiency by a method wherein the effective molecular diameter of a reactive gas is rendered not smaller than specified and P leading to the generation of recombination cores is rendered very low in concentration. CONSTITUTION:A reaction furnace 1 is provided with an external heating furnace 21, a substrate 22, a pair of electrodes 3, 3', a high frequency oscillator 2 and, for the purpose of activating and decomposing a reactive gas, with a microwave oscillator 17 and an attenuator 18. For the formation of an Si film, silane is supplied through a supply pipe 4 as a reactive gas. Diborane diluted with H, a P type impurity, is supplied through a supply pipe 5, and phospine is supplied through a supply pipe 6. Specified quantities of these gases are put into the active furnace 1 with the intermediary of gas refining means 11, 14; 12, 15; 13, 16. A molecular sieve or the like of a specified effective molecular diameter is employed to keep the effective diameter of molecules of silane etc. not smaller than specified and the concentration low of P in phospine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes an ultra-high purity semiconductor manufacturing gas with an extremely low concentration of phosphorus to produce an intrinsic or substantially The present invention relates to a photoelectric conversion device comprising an intrinsic semiconductor layer and a method for manufacturing the same.

The present invention provides a substrate or a first electrode on the substrate and a K on the electrode.
A non-single-crystal semiconductor layer having at least one P-type semiconductor layer, N-type semiconductor layer, or N-type junction
By laminating semiconductor layers independently to form a junction, it is possible to use an intrinsic or substantially intrinsic semiconductor layer, which is an active semiconductor layer that generates a photovoltaic force upon irradiation with light, in a provided semiconductor device, such as a photoelectric conversion device. (P-type impurity is 1×1
Curia (artificially mixed at a concentration of 0 to 5 x 10'cm' or at a background level) that promotes insulation or combines with P-type impurities to cause impurity scattering (contains artificially or at a background level) reduces the diffusion length of the poles, in particular, Furthermore, the phosphorus, which results in the generation of recombination centers, is preferably lower than 5X10 am, i.e., the pH in the silicide gas such as silane, from 1x10'' to 3X10 am.

The aim is to reduce the concentration to an extremely low concentration of 3 x 10 to 1 ppb.

For this purpose, the present invention provides reactive gases for semiconductors such as silicide gases such as silane, polysilane, silicon fluoride,
In addition, germanium compound gases such as germane have an effective molecular diameter of 4. This method takes advantage of the fact that it has more than copper.

That is, by using molecular seeds or zeolite with an effective molecular diameter of 2°9-4.65A, phosphorus, an impurity having an effective molecular diameter of 4°5A or less (hereinafter referred to as molecular diameter), can be purified, especially phosphorus hydride. The aim is to remove iosuhin, which is In addition, oxide gases such as ice, carbon dioxide (aqL oxygen (0,)) and carbide gases such as methane ( O striking, ethane (0, Hρ, propane (
The purpose is to adsorb and remove a, ntt, a H, OI (, atH?J).

Furthermore, in order to promote this adsorption power, the adsorbent that performs this chemical adsorption is used at room temperature to -so'c, preferably -20 to -40'.
a, and further cooled to -30±, which is the maximum adsorption capacity.
Cool the column to 10'C and increase its capacity by 5
With the aim of increasing the conversion efficiency by more than 00 times, the conversion efficiency of amorphous semiconductors, which had a conversion efficiency of only 6 to 8 cm under the condition of AMI (roomW, zc= ), was increased to 11 to 1.
The intrinsic conversion efficiency can be increased to 4.5%.

In particular, we investigated the reason why this first layer, which is the active semiconductor layer, tends to become KN-type or weakly N-type, and found that phosphides, oxides, and carbides remain in the reactive gas as impurities for N-type conversion. It turns out that the main reason for this is that. Therefore, in the present invention, the concentration of phosphorus is changed from the conventional 65X10 to 1X10 cm to 115 torr/10+
lower to lXl0"cm' or less, preferably ψ8□♂ ~
, it is characterized by lowering the Kt by X10'icm. Furthermore, the oxygen concentration is increased to the conventional 2x4x10 c
m'yop 5X10 cm-' or less preferably 1x10
As low as ~lXl0 am K, and furthermore, KO-
Carbon having a large number of 0 bonds, that is, mixed in a clasp shape, is 4×10 am or less, preferably 4×10 to 1×10 cm.
In order to reduce the density to K', the density of recombination centers in a semiconductor, for example, a silicon semiconductor, is
am or less, preferably 5×10 to 1×10 cm K.

Conventionally, since phosphorus acts as a donor type impurity in semiconductors such as single crystal silicon semiconductors, it has been thought that the lower the concentration, the better. However, since non-single-crystal silicon contains recombination centers such as hydrogen, there has been little demand for the phosphorus concentration to be as low as in single-crystal silicon. However, in the present invention, it has been found that in this non-single crystal semiconductor, the main reason is that the diffusion length of minority carriers, particularly holes, is reduced more than in a single crystal semiconductor. For this reason, the present invention incorporates impurities in the form of 7 osphine into the starting material of the phosphorus, such as silane, into a reactive gas for semiconductors, such as silane.
The aim is to lower it to K. Furthermore, as another impurity in the conventional semiconductor layer, oxygen forms local KSi→41 in a semiconductor, for example, a silicon semiconductor, and exhibits only insulating properties. However, when a few dozen oxygen molecules gather together in silicon to form a cluster, it creates electrons,
In non-single-crystal semiconductors obtained by plasma vapor phase method with addition of hydrogen or halogen elements, it is possible to create recombination centers of holes and act as a killer of minority carriers generated by light irradiation. was also found to be extremely significant. In addition, the dangling bond of oxygen also acts as an N-type donor center, so if a non-single crystal semiconductor is semi-amorphous (semi-crystalline), which has lattice strain and is more sensitive to structure than amorphous, N It turns out that it becomes a pattern.

Therefore, when considering industrial applications, it is extremely important to essentially remove phosphorus or oxygen, which would become donor centers, and create a structurally sensitive intrinsic semiconductor (Fermi level is approximately in the middle of the band width). It was important.

The present invention removes such impurities, makes hydrogen or halogen elements necessary for neutralizing silicon and recombination centers in silicon semiconductors as subcomponents, and further adds (10- 5XIOam) is added.

Conventional silane has an effective molecular diameter of just under 5'5 (4,8 to 5), and germane has an effective molecular diameter of approximately 6λ. Polysilanes such as C silane have an even larger effective molecular diameter. For example, Table 1 shows the impurities contained in the reactive gas of silane (monosilane), which has the smallest effective molecular diameter.

Table 1 Purity for epitaxial and electronics (%)
99,99 99.99 Hydrogen (P P
M) 300 3000 Nitrogen
550 Oxygen 0.11 Argon 1050 Helium 10 50 Methane 550 Ethane 0.1 0.5
Ethylene Q, 1. 0.5
Propane 0.10.5 Propylene 0.10.5 Chloride 1050 Phuoshine 0.05 0.5 Water
35 Investigating these, we found that, especially when performing this epitaxial growth, oxides and nitrides have a segregation effect during the gas phase-solid phase reaction, which reduces the specific resistance by about 1730 K in Table 1 above. It is possible to obtain a substantially intrinsic semiconductor of 100 U am or more.

However, in the plasma vapor phase method using glow discharge carried out at 100-400'O, the effect of segregation of impurities resulting from such physical purification cannot be expected.

For this reason, the impurities shown in Table 1 are mixed into the semiconductor as they are, and in particular, phosphorus decomposes from phosphin and becomes a donor impurity, and all oxygen reacts with silane to form silicon oxide reaction products. . Regarding silane itself, activation (ionization) by plasma reaction is 1-5
Therefore, the gas state is essentially about 2.
Phosphorus is concentrated 0-30 times and phosphorus in the semiconductor film is 1-3X1
0"CQuestion'It was also found that the concentration of oxygen reached 2~4X10 am.Furthermore, phosphorus was mixed into the metal constituting the cylinder at a rate of about 15 PPM, and this reacted with hydrogen during long-term storage. It was found that this compound became huonuhin, mixed into silane, and became an impurity.

For this reason, when using reactive gases for plasma vapor phase method,
It has been found experimentally that purification is extremely important when using reactive gases in the reactor.

Thus, in the present invention, the conversion efficiency is reduced to 1 at AM1.
In order to guarantee 0% or more, phosphorus is added in one layer.
It is extremely important that the oxygen concentration be below 5×10 am.

The present invention aims to improve the purity of such semiconductors.

It is shown below according to the drawings.

FIG. 1 shows an outline of the manufacturing apparatus used for manufacturing the semiconductor device Ml/i' of the present invention.

In the drawing, for the reaction furnace (1) K, external heating furnace Qυ,
A substrate (C), a pair of electrodes (3), (A), a high frequency oscillator (2) (for example, 13.56MHz or 100KH
z), to further activate and decompose reactive gases,
Microwaves with a frequency of 1GH2 or higher, e.g. 2.45GH
It has an oscillator αη of z and an attenuator α frame.

0,001 from the emitting part protected by ceramic α
: Microwaves were emitted to the reactor (1) maintained at ~10 tOrr. The entire reactor is shielded (a) to prevent radio wave interference, and the reactive gas is shielded from the substrate (a).When forming a semiconductor film on soil, the electric field of electrical energy is set parallel to the surface to be formed. ing. Further, the reactive gas is arranged so as to have a laminar flow parallel to the surface on which it is formed.

Impurities in carrier gas such as oxygen and water were reduced to 1 ppb, preferably O, and hydrogen was introduced as shown in (7). Further, as the reactive gas, for example, when a silicon film was to be formed, silane, which is a silicide gas, was introduced from (4). In addition, due to hydrogen, which is an impurity for P type, 500-5
Diborane diluted with 000 PPM K was introduced as (5), and phoschin, similarly diluted with hydrogen, was introduced as (6).

These reactive gases are supplied to the gas purifier 0υ, (141, oa
, αG, 0] A predetermined flow rate was introduced into the reactor through the 0.

) These gas purifiers use a 4.5A molecular sheep or zeolite with an effective hole diameter of 4.3 to 4.65k (typically 4.5i) on the inlet side for the reaction gas of silane (4). there was. 4.5A is 4z n, ) (A 10
．． ) (S i q),.

A porous molecular adsorbent having the molecular formula of X H,6 was used. Further, after this, a porous molecular adsorbent having a high quality name such as Molecular Sheep or Zeolite with an effective pore diameter of 2.7 to 3.3 was used. This molecular sheep or zeolite is Na(AIOρ(S i
q) A compound having the molecular formula of Z HO was used.

Furthermore, to improve the chemisorption properties of these purifiers,
-'701>'T room temperature, preferably at a temperature at which only 7 osulfur is selectively adsorbed without adsorbing silane etc. -20--
40'O, e.g. -30'O (8 l(9)
(10) Cooled by K. For diboranno diluted with hydrogen, in order to remove all of the water, 7-oshin, oxygen, etc., K 3A or 4A and 4.5
A two-stage purification was performed.

In particular, for silane, in addition to oxygen, which is an impurity that easily converts into N, phosphin lowers the concentration of silane to less than 1 ppb.
Particularly effective was the removal of AK yo-shi water and the further removal of 4,5 AK yo-9 phosphin.

The exhaust system has a needle valve (c) and a stop valve (c)
, to a vacuum pump) to exhaust air (c). Reactor □
The pressure inside is controlled by the needle valve (c) at p 0.001~
1°t Orr typically 0.05-0.15torr
was controlled.

FIG. 2 shows the characteristics obtained from the results shown in FIG. That is, the substrate temperature is 25 cf'c and the pressure inside the reactor is 0.1 torr.
When r is the light irradiation (AMl) conductivity when a non-single crystal semiconductor layer is formed to a thickness of 1 μ on a substrate, for example, glass,
It's the conductivity. In the drawings, if silane is not purified in this manner, impurities in the cylinder as described above will enter the semiconductor layer as is, and phosphorus in particular will become N-type.
Furthermore, oxygen or carbon has a sensitizing effect that makes silicon amorphous. For this reason, a photoconductivity (c) and a dark conductivity (30) were obtained. That is, in the drawing, at a high frequency output of 20-30W, the optical conductivity is 10C? cm), but at the same time, the semiconductor becomes semi-amorphous with some order. For this reason, the impurities in this semiconductor, such as phosphorus and oxygen, become donor centers and become N-type. As a result, if it is intended to be used as an intrinsic semiconductor, boron, which is the opposite impurity, should be added to a concentration of 1 to 3 x 10 am, or it should be used in a low high frequency output region of 1 to 5 W with low photoconductivity that does not become a donor. We must use the semiconductors that are made. However, in all of these, the photoelectric conductivity was 10
~10←I lowered it to the order of a C groan.

Instead of such conventional methods, the present invention provides a method in which impurities in silane are sufficiently removed after purification (α] in Figure 1) and α4), and the silane is sufficiently purified before being filled into a cylinder. It is something. By doing this, we were able to obtain the light irradiation conductivity (b) and dark conductivity (c) in Figure 2.As is clear from this figure, the photoconductivity is the same as the plasma discharge output. lXl0 at 1~IOW
(ncn), and in addition, the dark conductivity is 10 to 1o (m
ci and small.

That is, the activation energy as an intrinsic semiconductor was sufficiently large, and the Fermi level was approximately E12''eV of 91.

Further investigation of this property revealed that the film had weak crystallinity and lattice distortion in the X-ray diffraction image (observed at an angle 0.5 degrees lower than the diffraction angle of the crystal, and crystallization was obtained at 5-10 W). These are semi-amorphous structures that are intermediate between amorphous and crystalline structures.
It was something that could be called a semiconductor.

That is, an intrinsic semiconductor is produced by a plasma vapor phase method at a temperature of 100 to 30
When trying to obtain the film at 0°C, for example, 250'O, the concentration of impurities in the silane at that time tends to be 30 to 100 times higher than in simple OVD or epitaxial growth. Therefore, it is extremely important to use ultra-high purity silane in which the amount of impurities in the starting material is minimized. Thus, even at low plasma powers of 1 to 5 W,
Dark conductivity is small and photoconductivity is 16'←c of single crystal.
10~10C at the same level as m)'! It was possible to obtain the value of Lcm). When we investigated the diffusion length of minority carriers, especially holes, in a device exhibiting such electrical conductivity, we found that it was 3-20μ.
By using the conventional plasma vapor phase method, it was possible to obtain a value that is 30 times longer than that of amorphous silicon, which is 0.1-0.6μ.

In particular, the fact that such a high-quality non-single crystal semiconductor can be obtained with such a low high-frequency output is due to the present invention (when the PIN junction is gradually laminated with P layer, 1 layer, and N layer, the boundary area is defined as a plane). Therefore, when one layer is laminated on top of two layers, the discharge sputters (damages) the P layer.
This is extremely important because it can prevent the formation of a mixed layer by striking the underlying P layer.

Furthermore, in Figure 2, when microwaves of 2.45 GHz are applied, the ionization rate of the reactive gas is increased, so although the characteristics are the same, the growth rate of the film increases about 3-5 times, making it larger. I was able to do that. For example, 30c of silane
Introduced at c/l;f, 0.1 torr, high frequency plasma alone was as low as 1-3 A/sec, but in this case it was 1-3 A/sec.
It was possible to grow at a high speed of 15λ/sec.

Figure 3 shows an experiment conducted to confirm the effectiveness of the gas purifier for the purification of silane according to the present invention. The results were investigated using an Ion Micro Analyzer (MA) manufactured by Kogyo Co., Ltd. The first axis shows the electrical conductivity when irradiated with light.

This is the case when 4.541A544 was used together with the silane system, and the temperature of the column was changed from room temperature to -30'C.
The adsorption properties of jl, 3A, and 4.5A can be improved by varying up to 100%. Oxygen is 30-
When phosphorus was reduced by a factor of 100, it was also reduced proportionally.

In the figure, the conductivity (46) of the photoconductive bottom 0 without such a purification device is shown. Furthermore, by using a purification device at room temperature, it was possible to lower the concentration to 1.2XlOCm. In addition, we were able to lower this to Ohatmam K, respectively.

As a result, a photoconductivity (41) and a conductivity Ω2) were obtained. These are the cases where the high frequency output is 2W in the apparatus shown in FIG.

In order to achieve these oxygen and carbon concentrations, the phosphorus in the silane should be reduced to 1 ppb or less, and the oxygen should be added to 0.03 PPM (3
It is extremely important to keep the concentration below 0pp, especially when purifying at the above room temperature (,0'o--3o'c,
The impurity concentration of phoschin is 1 opppb (o”a)0,
'1ppb (-30°),
In addition, the oxygen (including water) impurity concentration is O, OIPPM
(0'(3), 0,003PPM (-30°b) [OmHn is O,'l'PP
I was able to lower it to M, O, OIPPM K. Further K −'100°CK, 4, 5A of the purifier,
Silane was not adsorbed on the surface of the 3A mass spectrometer, and the adsorption ability of phosphin became poor. However, the adsorption of oxygen was further improved.

Of course, in order to achieve the above-mentioned high purity, even in the reaction system shown in Fig. 1, it is important to keep the overall glue QQlBθC or less, and it is important to note that devices such as joints are also important. .

Fig. 4 shows a film formed using the manufacturing apparatus shown in Fig. 1, and drawing (A) shows a transparent conductive film (three layers,
Furthermore, KP type silicon semiconductor (SiXO+-)LO<x<1 (for example, x=0.8) or P-type silicon semiconductor (34)Kyoshi1
It was formed to a thickness of 00X. Furthermore, after this reaction system was sufficiently evacuated using a cryopump (45), the intrinsic semiconductor layer was coated with purified silane to a thickness of 0.5 μm (3
1). Furthermore, vacuuming was performed again, and an N-type semiconductor layer (31) was formed by mixing silane with phosphin at a concentration similar to that of steamed rice to a thickness of 200λ. Thereafter, known aluminum (36) was vacuum deposited.

The high frequency output was 2W and the substrate temperature was 25♂C. As a result, a conversion efficiency of 11.8% could be obtained.

In order to further improve the characteristics of this glass substrate, Fig. 4 (B
) A PIN junction photoelectric conversion device was manufactured.

In the drawing, a KPP semiconductor layer (34), an I-type semiconductor layer (03), a polycrystalline semiconductor layer (35) having an N-type fiber structure on a stainless steel substrate (32) are deposited using the apparatus shown in FIG. A transparent conductive film (43) formed to a thickness of 0.5μ and 15oi was further vacuum-deposited with ITO (indium oxide (tin oxide 0-10%)), and an auxiliary electrode (36) of aluminum was provided. Ta.

When the area is 3 x 10 cm or less, that is, 3 x 10 to 1 x 10 cm, the conversion efficiency can exceed 1 bar in the area of AMI K and IC. Also, its fill factor is O6'2(
It is now possible to obtain short circuit current of up to 20 mA/cm. The open circuit voltage is 0.86 to 0.
．． It was 93V. At this time, the oxygen concentration was also increased to 4X10"
cm' or less, the silicon semiconductor was made to look more like silicon made only of silicon, and a large improvement in characteristics was observed.

In the embodiment shown in FIG. 4(B), the N-type semiconductor layer is a polycrystalline semiconductor having a fiber structure, and
Regarding production at a low temperature of 0, it is shown in patent application No. 57-08'7801 (S57.5.24), which is the application of the present invention.

In the above explanation, a photoelectric conversion device having a P-N junction has been shown, but this can also be added to a PIN-N junction...
- It is also important to form a P/N junction and at least two junctions as an application of the present invention, and these may also be integrated on a substrate.

Furthermore, in the explanations so far, silane, particularly monosilane, has been shown as the silicide gas. However, the present invention is also effective for polysilanes such as disilane because their molecular diameter is as large as 5^.

We used Kelman (Ge)9 as a non-single crystal semiconductor, 5iXGe+->, (0<
x < 1) or only Ge can be used in the semiconductor layer included in the PIN junction.

In the above description, a photoelectric conversion device having one P-N junction was mainly explained. However, the semiconductor layer has at least one N-type or P-type junction, i.e., an insulated gate type with N (source or drain) or P (intrinsic or weak P-type channel forming region), N (drain or source), or PIF junction. Field effect semiconductor device or NIP
IN.

The present invention is also extremely effective for transistors having P-type NIP junctions.

[Brief explanation of the drawing]

FIG. 1 shows an outline of a plasma vapor phase reactor for manufacturing a semiconductor device according to the present invention. FIG. 2 shows the characteristics obtained by the present invention and the electrical characteristics of a conventional intrinsic semiconductor. FIG. 3 shows changes in electrical properties obtained by the gas purification method of the present invention. FIG. 4 shows a photoelectric conversion device of the present invention. FIG. 5 shows the initial characteristics of the photoelectric conversion device obtained from FIG. 4(B). 0 70 20 30
, '5 fifl wave, t, 6 (W) Ko 21 figure fi 31 Kunouzu procedural amendment (spontaneous) November 10, 1980 Commissioner of the Japan Patent Office Tono 1, Indication of the case 1982 Patent Application No. 182546 (Application filed on October 18, 1982) 2. Name of the invention Semiconductor device 3. Relationship with the case of the person making the amendment Patent applicant 4. Subject of the amendment 11 [1if Claims column, Details of the invention Explanation column, Drawing 5, Contents of amendment (1) The claims are amended as shown in the attached sheet. (2) Correct the statement r4.5AJ on page 3, line 16 of the specification box to "4.5 people." (3) Specification page 5 line 12 r2~4X10I8cm-Yo 5X10'''c
m-3" is "2 to 4 x 10 cm-yo to 5 x 1
Correct it to 0cm'J. (4) Specification, page 5, line 13 r I X 1016 to I X 10'4 cm-yo
Correct the statement to "1 x 101 to 1 x 104 cm - yo." (5) Page 5, line 15 of the specification: r 4
Correct as X 10" cm-3J. (6) Statement box page 5, line 16 r 4 X 10" ~ l X 10I310l3 J
The statement is corrected to [4 x 10 units ~ lXl0 2 cm-horizontal. (7) Statement box 1016-I r 2-4 X 101Bc101B J and r
2 to 4 x 1020 cm-3". (8) On page 11, line 8 of the statement box, replace “5×1018cL11-3 or less” with “5
1020 cm-3 or less”. (9) In the 9th line of page 13 of the specification box, the phrase "High quality product name" is corrected to "M product name." (10) Page 22, line 2 of the specification “■-type semiconductor layer (33) J” is replaced with “I-type semiconductor layer (
31) Correct as J. (11) Specification box page 22, lines 8 to 9, "Intrinsic semiconductor layer" [Intrinsic semiconductor layer (31) J
and correct it. (12) In the 13th line of page 22 of the specification box, amend "conversion efficiency" to "conversion efficiency". (13) On page 22, line 14 of the specification, the phrase ``fill factor'' is amended to read ``fill factor''. (14) In the 15th line of page 22, the phrase ``short circuit current'' is corrected to read ``1 short circuit current, 1 rainbow''. (15) Specification page 22, line 18 14 x 10” cm-Yo J and r 4 x 1
018 Cm-3". Correct the sentence ``Stop this'' with ``1 This is due to gravity''. (17) Figure 5 of the drawings will be corrected as attached. Claim 1 includes a substrate or a first electrode on the substrate, and a PlO on the electrode.
, a semiconductor device including a non-single crystal semiconductor having at least one NI or PIN junction, and a second electrode on the semiconductor, wherein the intrinsic or substantially intrinsic semiconductor layer constituting the junction is 5 x 10” cm-
A semiconductor device characterized by containing an impurity concentration of 3 or less. 2. In claim 1, the intrinsic or substantially intrinsic semiconductor is made of silicon or germanium doped with hydrogen or a halogen element and having a semi-amorphous or amorphous structure with lattice strain. A semiconductor device characterized by: 3. The semiconductor device according to claim 1, wherein oxygen is added to the intrinsic or substantially intrinsic semiconductor layer in an amount of 5 x 10" cm or less. 404

Claims (1)

[Claims] A semiconductor device. 2. In claim 1, the intrinsic or substantially intrinsic semiconductor is made of silicon or germanium doped with hydrogen or a halogen element and having a semi-amorphous or amorphous structure with lattice strain. A semiconductor device characterized by: 3. The semiconductor device according to claim 1, wherein oxygen is added to the intrinsic or substantially intrinsic semiconductor layer in an amount of 5×10 H1 or less.