JPS5856414A - Plasma vapor growth method - Google Patents

Abstract

PURPOSE:To form a carbonic silicon coating under low temperature which has less damages on the formed surface, is superior in uniformity of the film thickness and which has a high coating growth speed by diluting reactive gas with helium in a plasma vapor growth method to form carbonic silicon of non-single crystal using reactive gas consisted of a hydride or a halide which contains carbon-silicon couplings. CONSTITUTION:Electrodes 9, 10 are provided above and below a reaction furnace 25 in which substrates 1 are arranged, to apply the electric field of electromagnetic energy to the substrates in the vertical direction. Outside of these electrodes an electric furnace 5 is provided to heat the substrates 1 up to 1,100- 500 deg.C, typically 300 deg.C. Reactive gas tetraethylsilane 20 containing carbon-silicon couplings is evaporated and introduced to the reaction furnace with 100% density through a flow meter. Helium as carrier gas for the reactive gas is introduced from a tube 13, diborane as an impurity with III valence from a tube 14, phosphine as an impurity with V valence from a tube 15, and silicide gas of silane as an addition with IV valence is from a tube 16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plasma vapor phase method for forming non-single crystal silicon carbide on a formation surface using a reactive gas made of a hydride or halide having a carbon-silicon bond.

By dispersing such a reactive gas with helium instead of hydrogen, nitrogen, or argon, the present invention provides an optical system with less damage to the surface to be formed, excellent film thickness uniformity, and faster film growth rate. A silicon carbide coating having a target energy band width (hereinafter referred to as Eg) of 2 to 3 ev or more is
0, the present invention further provides for such reactive gases to be formed at low temperatures of ~400°C.
An impurity gas containing an impurity with a non-V value of ffl, such as phosphin (PR,
The object of the present invention is to form a laminate layer and an N-type layer in the order of P-N.

Conventionally, amorphous (hereinafter simply referred to as As) silicon is known as a typical example of a non-single-crystal semiconductor produced by a plasma vapor phase method. This is expected to be applied to photoelectric conversion devices such as solar cells. However, when trying to make such a device, and when trying to obtain a light emitting element with η of 4 using a quick crystal semiconductor, it was also necessary to develop a window material with a wide Eg of 2.3 to 3.5 eV. It was getting worse.

This material is silicon carbide (stxa, -, (0<x<
1)) is a typical example. However, this silicon carbide is actually decomposed into a carbide gas such as methane (0111,) and a silicide gas silane (sty) in a plasma atmosphere.
There are attempts to create this by causing a reaction. However, silicon nitride obtained by the darning method has a macroscopic value of 5
ize, -, (0<xζ1), but there are many silicon clusters and carbon clusters, making it impossible to produce homogeneous silicon carbide. For this reason, it is impossible to make the basic Xg more than 2.0eV,
In general, exactly the same 1.6 to L 8 eV L as silicon could not be obtained. In addition, it costs 2,000 kg instead of the narrow kg.
If you try to obtain more than eV, the discharge power will be 2
00 to 500W, and as a result of these reactions, the reaction surface becomes sputtered (damaged), making it completely impossible to electrically form a P/N junction and obtain desirable diode characteristics. Met.

Therefore, in the present invention, in order to eliminate this drawback, a material having a carbon-silicon bond is used as the starting material, ie, a reactive gas. That is, a hydride or halide having a carbon-silicon bond, such as tetramethylsilane (81(
13ρ (referred to as mono-TMS), tetraethylsilane (s
i (c, Q) Si (C barrel > 01. Si (c Mizue c
4s1 (the first step is to use a reactive gas such as
It is a feature of

Furthermore, in the present invention, such a reactive gas is introduced into an atmosphere where electromagnetic energy is applied and a plasma state is generated, and the a-a bond, Eli-01 bond, and 5i-0 bond are severed, so that the 01S1 defect In order to prevent hydrogen from recombining with the pair bond and forming O-H bonds and 5i-H bonds again, helium instead of hydrogen is used as the carrier gas. In that case, if other conditions are the same, TMS/He -1/'1~30 and T M
8/H-; At 1/i to YO, the growth rate of the film can be increased by 3 to 9 times K, and the uniformity of the formed film is ±6% in the film thickness when hydrogen is used. However, it was possible to reduce this to ±3%, and it was possible to obtain an extremely uniform film. This Rθ is different from active gases such as Ar, and because its molecular ratio is small and the ionization energy is the highest at 2.5 eV, there is little sputtering on the surface to be formed even if it is turned into plasma, and the P-N junction is The effect was also great for the membrane provided.

Further, when such a reactive gas is used, the reactor is heated to a pressure of 1 atm or less, particularly 0.01 to 1 atm, typically 0
, even if the electromagnetic energy is 50 W or less under a pressure of 3 to 0.6 tOrr, for example, 0.1 to 100 MHz, especially 1
3.56MHg X or 1-4GH2 especially 2.450
It is possible to form a coating in H2. Therefore, a low energy plasma OVD device could be obtained.

Furthermore, when a high-energy plasma atmosphere of 50 to 500 W is applied, the formed silicon carbide becomes microcrystalline, and as a result, in P type or N type, borosilicate or phosphorus is added by 0.5 to 0.
], 0% (here (BLH, t or PHj) / (
When the ratio of carbide silicide gas + silicide gas (expressed as a percentage) is added, the electrical conductivity is 10 to 1 at low energy.
Mof) which was 0 (acm), 10~'10 (x
cmj' was able to increase K 1 "t' by about 1000 times.

And its optical Eg is 1.6~1.8e like silicon
V but not 2.3-3.5θV typically 2.5-3.
It was possible to have 2θV. In addition, if 1 to 5 mol of diborane or phosphin is added to this, the silicon nitride (Sizc, -) is added.

0<x<0.5) has a hs@ structure in the low energy method and has an activation energy of 0.3 to 0.6 eV. In addition, in the high energy method, P or N with O, O'l ~ O, leV
It was possible to make a type of semiconductor. Furthermore, silicon carbide obtained using this high-energy method was able to have a so-called semi-amorphous (hereinafter simply referred to as 8As) structure having a microcrystalline structure with a size of 5 to 200 A. In such a SAS, the ionization rate of the P or N type impurity as an acceptor or donor was 97 to 100, and all of the added impurities could be activated.

The plasma vapor phase method of the present invention will be explained below with reference to the drawings.

FIG. 1 shows a schematic diagram of a plasma CVD apparatus using the present invention.

In FIG. 1, a substrate (1) having a surface to be formed is held by a quartz jig, and in the drawing, it has a configuration of 7 stages and 2 rows, 14 in total. Each board is 10-40mm typically 20-
The substrates are arranged with a gap of 25 mm between them, and the reactive gas is uniformly injected into the gap between the substrates by this jig.

The surface to be formed is the lower surface of the substrate, and the upper surface is covered so as not to be flush with the surface to be formed. This is the amount of reactive gas h￥,
During the reaction, the reaction products are uniformly layered and formed into a film, and during the formation of this layer, a large number of flakes (fine pieces) released from the reaction wall fly off and fall onto the upper surface of the wall due to gravity. , this is because these 7 rakes induce the generation of pinholes. For this reason, it is extremely important to set the surface to be formed on the bottom surface in consideration of mass production yield. Furthermore, in the reactor (equipment) into which this substrate (1) is inserted, electrodes (9) α
A Kt air furnace (5) is provided outside the electrodes with 0) provided above and below, and the substrate (1) is heated to 100-500°C, typically 300°O.

The reactive gas is the helium of the carrier gas, υ,■
Diborane, a valence impurity, was introduced into al, phosphine, a heptavalent impurity, was introduced into α, and silane, a silicide gas, which was an valence additive, was introduced into IQ. When using a reactive gas with TM8), jnJ! Since it is a liquid in the U state, it is stored in a stainless steel container (al), which is controlled at a predetermined temperature.

In this TMS, the nodal point is 25°C, the rotor IJ-pump (b) is evacuated through the pulp α0, and the inside of the reactor is 0.
The pressure was maintained at 01 to 10 torr. By doing this, TMEI can be vaporized at a pressure lower than 1 atm without special heating for feeding rice. Introducing this vaporized TM8 at a concentration of 100% into the reactor via a flow meter is more effective than the conventional method of bubbling the container Qρ to release the reactive gas.
It is technically important because it can be controlled to a great degree.

In practice, if the flow meter becomes clogged, lfl? At v, helium was introduced from θ.

These reactive gases were mixed with helium as a carrier gas at a predetermined ratio and introduced into the reactor. Electromagnetic energy is added between the electrodes (9) and (10), for example, at high frequency (1
3.56 MH2) is applied, and an electric field is applied in a direction that compacts the film accumulated on the surface to be formed. By doing this, the presence of voids etc. in the formed silicon carbide or silicon was reduced by utilizing the flight of the reactive gas driven by the electric field. Furthermore, in this plasma discharge, after the reactive gas passes through the mixing chamber (8) and is mixed, it is decomposed or reacted in the excitation chamber (c), and a spatial reaction is mainly performed in which reaction products are formed on the substrate. Using. The electromagnetic energy mainly used was DC high frequency from the power source (4). Of course microwave (1~4GH)
z) may also be used. In this way, 100 cc7 of He was applied as a silicon carbide coating on the surface to be formed. TMS/H
A film growth rate of 1 eoh/min could be obtained at e=20. If the carrier gas [alpha] in Fig. 1 is changed to hydrogen, even if TMS/Ht = 20 and all other conditions are the same, a film growth rate of only 25 A/min can be obtained.
Its growth rate is only about 176.

This is not only true when using helium as the carrier gas to make carbon-excess silicon carbide such as TMEI or υ silicon carbide (c/Si4/1), but also when making so-called Si X Ct-
Q It gives an extremely large shadow I, and is essential for lowering the price of the formed half-human body.

Even if the electromagnetic energy was changed from 25W to 10-200W and 10°25, 50.100.200W, a significantly higher film growth rate could be obtained using N4 and helium.

In addition, the uniformity of the formed film was less than ±2%, compared to ±5% with hydrogen dilution, which was a contributing hole when used as a semiconductor device I case. Rather than only
When hydrogen was simultaneously mixed with He to reach H,/TIL·1/IK, the film growth rate also decreased accordingly.

The present invention furthermore adds P to the silicon carbide on the substrate.
A N-joint was provided.

In other words, the longitudinal cross-sectional view is shown in Figure 2). This semiconductor (31) having a P-N structure is made of 7M8 and diborane as shown in FIG.
/TMB=1 to 5%. Then, the energy band width is 2.1 to 3. OeV, and the band width did not become as small as when 1% or more of diborane was added to silane. After forming the P-type layer in this manner, intrinsic or substantially intrinsic silicon or 7M8 is added to the silicon in the thickness direction to gradually reduce the energy content, thereby forming an intrinsic or substantially intrinsic silicon layer. Made silicon carbide or silicon as a semiconductor. In Fig. 1, 7M8 is introduced and silane is added to 5iHy'TM8.0.
~ By changing Jug from 3.5 eV to 1.8 eV by changing Cl0K, negative 0 is applied to the upper surface of a photoelectric conversion device such as a solar cell.
Using TMS as the main component and adding 0.5 to 5 moles of PHj, 81, C2, and (3) of the N board were formed in the same manner as the OA.

In (2nd figure), (3 are transparent electric shrines for the incidence of light. With such a structure, the light is NJm (30) and is not absorbed by impurities, so all of it is in one layer. Moreover, in contrast to the narrow 111g of (1), the P layer (c) and N layer (30) that sandwich it have a wide Eg, and the depletion layer generated between them has a large Eg of electron-hole pairs.
The milled rice AMI that was able to separate in the negative direction
(1 oomw/cj), a vibration efficiency of 10-12% could be achieved in a 10 m' cell.

However, if the order of this product j- is such that layer (c) is NJ';
It was very important that the first material formed was P-type silicon carbide.

FIG. 2(B) shows a light-transmitting substrate (3-Q), on whose upper surface an achievement film (32) is applied.This surface KIa
Initially, similar to 0, KP-type silicon carbide (30), engineered silicon carbide or silicon (A), and N-type silicon carbide (30) are formed. The first layer is the shore of ¥0~100OA, especially ¥50~
It is extremely thin at 200A, and making this one layer thinner is favorable for the diode characteristics obtained in addition to the electrodes (32) and (33), that is, it is important that the leakage does not occur in the opposite direction. In bonding to this P layer, the P layer may be a so-called single heterojunction with a small z similar to the first layer.By doing so, a barrier can be created especially for holes with a short lifetime. However, it was able to emit enough light. Also, the first layer is P(c)-
In 1-N-N (30), Eg generally has a W-N-W relationship and has a double heterojunction. Therefore, when current is passed in the forward direction, electron holes gather in this one layer and are shielded from each other. I was able to make it emit light. In order to increase the efficiency of this light emission, it is necessary to stack layers on the surface on which the present invention is formed.
It is important to make the first order P-1-N, and vice versa.
7X-p, some N-type impurities are mixed into one layer,
In effect, it becomes N-type. For this reason, good diode characteristics could not be obtained.

This is due to the fact that silicon carbide produced by the method of the present invention usually has an N type even though it is called intrinsic, and furthermore, the mobility of holes in one layer is 1/1000 to 1/1000 of that of electrons. It is estimated that

Furthermore, as in the present invention, in the plasma vapor phase method, TMS
Even if a carbide gas and a silicide gas were reacted instead of using a silicide carbide gas such as, the structure shown in FIG. 2(B) did not exhibit diode characteristics and no light emission was observed.

From this, it is not a sufficient condition that the material is a stoichiometric mixture of carbon and silicon, and it is extremely important that carbon and silicon are sufficiently bonded. This is about 8000 when you compare the infrared absorption spectrum with Le 1! In the method of the present invention, a broad absorption ranging from 600 to 10,000 m' was obtained with a peak at n', and the presence of other bonds was extremely small, which clearly demonstrated that the 5i-Ci bond was sufficiently formed. .

[Brief explanation of the drawing]

FIG. 1 shows an apparatus for producing silicon carbide using the plasma vapor phase method of the present invention. FIG. 2 is a vertical sectional view of a semiconductor device obtained by the method of the present invention. patent author

Claims (1)

[Claims] 1. By introducing a reactive gas consisting of a hydride or halide having a carbon-silicon bond into a plasma atmosphere maintained at 1 atmosphere or less and causing it to decompose and react,
A step of forming a film having a P-N structure made of silicon carbide or a combination of silicon carbide and silicon on a surface to be formed, a silicon carbide having a sculptural conductivity type, and an intrinsic or substantially intrinsic conductivity type. A step of forming a silicon carbide film or a film mainly composed of silicon, and a step of simultaneously introducing an impurity gas having a V-valent impurity after this step to form silicon carbide having an N-type and S-electrode type. A plasma vapor phase method characterized in that a P-N junction is formed on a substrate by forming a P-N junction on a substrate.