JPS60218834A - Deposited film forming method - Google Patents

Abstract

PURPOSE:To increase a film-forming rate while keeping high quality, by producing gas atmosphere of hydrogen, chain silicon halide compound, and compound containing a III-family or V-family element in a chamber including substrates and by forming each deposited film containing silicon doped with said element over the respective substrates. CONSTITUTION:Gas atmosphere of hydrogen, chain silicon halide compound expressed by a general expression: SinXmYl (X and Y represent different halogen atoms respectively, n, an integer of 1-6 and m and l each an integer of 1 or more, and m+l=2n+2), and compound containing a III-family or V-family element (impurity element) is produced in the chamber including substrates, and the compound and the hydrogen are excited and decomposed by utilizing optical energy, forming each deposition film containing silicon doped with the impurity element over the respective substrates. The resulted deposited film may be crystalline or amorphous and the combination of silicon in the film may be from oligomer to polymer state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a deposited film containing doped silicon;
In particular, the present invention relates to a method suitable for forming a deposited film of doped amorphous silicon (hereinafter referred to as a-81) or polycrystalline silicon useful as a photoconductive film, a semiconductor film, etc.

[Prior art]

Conventionally, for example, N-type and P-type a-81 deposited films were deposited using 191
It is known to form by a glow discharge deposition method or a thermal energy deposition method using H4 or 512H6 as a raw material. That is, SiH4 or Si2H6 is excited and decomposed using electrical energy or thermal energy to form a-81 on the substrate.
It is well known to form a deposited film of 100% or less and use this film for various purposes.

However, when these SiH4 and S s 2H6 are used as raw materials, in the glow discharge deposition method, the discharge energy has a large influence on the film being deposited under high output, and it is difficult to control to maintain reproducible and stable conditions. difficult. This is particularly noticeable when forming a thick deposited film over a wide area.

Also, in the thermal energy deposition method, 1. Since high temperatures are required, the substrates that can be used are limited, and the probability that useful bonded hydrogen atoms in a-8t will dissociate increases, making it difficult to obtain the desired properties. Become.

In this way, when forming a deposited film using 5IH4 and 812H6, it is difficult to ensure uniform electrical and optical properties and quality stability, and it is easy to cause disturbances on the film surface and defects in the bulk during deposition. At present, there are still problems that need to be resolved.

Therefore, in recent years, in order to solve these problems, 5in4
A light energy deposition method (photoCVD method) of a-8i using 812H6 as a raw material has been proposed and is attracting attention. According to this optical energy deposition method, the above-mentioned problems can be significantly improved due to the advantage that the A-81 deposited film can be produced at a low temperature. However, SiH4 and 5i under relatively small excitation energy such as light energy
With the optical energy deposition method that uses 2n6 as a raw material, it is not possible to expect dramatically efficient decomposition, so an improvement in the film formation rate cannot be expected, and a new problem has arisen in that there are difficulties in mass production. There is.

The present invention has been made to solve these current problems.

[Purpose of the invention]

An object of the present invention is to provide a method for forming a deposited film containing doped silicon, which can increase the film formation rate while maintaining high quality.

Another object of the present invention is that even in the case of a large area and a thick film,
An object of the present invention is to provide a method for forming a deposited film that can produce a deposited film containing high quality doped silicon while ensuring uniform electrical and optical characteristics and stability of quality.

For the above purpose, the general formula 5ifl' is
xrnYt (X and Y are each different) - log/atom, n is an integer from 1 to 6, m and t are each an integer of 1 or more υ, m + L = 2 n ' + 2. )
Forms a gaseous atmosphere of hydrogen and a chain-like silicon compound represented by the formula, a compound containing an element belonging to Group Ⅰ or Group Ⅲ of the periodic table (hereinafter referred to as an impurity element), and emits light energy. This is achieved by a deposited film forming method characterized in that the compound and hydrogen are excited and decomposed by utilizing the silicon, and a deposited film containing silicon doped with an impurity element is formed on the substrate.

[Embodiment]

The deposited film containing silicon doped with an impurity element formed by the method of the present invention may be crystalline or amorphous, and the silicon bonds in the film may be in any form from oligomers to polymers. good. Further, hydrogen atoms, halodane atoms, etc. in the raw materials may be incorporated into the structure.

Hereinafter, embodiments of the present invention will be described mainly in the case of an A-81 deposited film.

The chain no-rhodanide silicon compound of the general formula is a linear or branched chain silicon hydride compound (chain silane compound), a 7-rhodan derivative of St H, and is easy to produce (IJ) and It is a highly stable compound. In the general formula, X and Y represent different rhodane atoms selected from fluorine, chlorine, bromine and iodine, respectively. The value of n is limited to 1 to 6 because as n increases, decomposition becomes easier, but it becomes difficult to vaporize (or difficult to synthesize), and the decomposition efficiency also deteriorates.

Preferred examples of the chain halogenated silicon compounds of the general formula are:
They are listed below.

■ Compound containing F and Ct: SiFmCt4-nl (m is an integer from 1 to 3), S12F
ntCt6-m (m is an integer from 1 to 5), Si3FmCt
9-in (m is an integer from 1 to 7), 5t4pn1cz.

-,, (m is an integer of 1 to 9), ■ Compound containing F and Br: 81FmBr4-ffI (m is an integer of 1 to 3), Si2
FmBr6-m (m is an integer from 1 to 5), S15FmBr
6-m (m is an integer from 1 to 7), SlaFmBrlo-m
(m is an integer of 1 to 9), ■ Compound containing Ct and Br: SSiC4Br4-rn (m is an integer of 1 to 3), Si2C
tmBr6-m (m is an integer from 1 to 5), st, c4nn
r, m (m is an integer from 1 to 7), 514C4nBr, o-
m (m is an integer from 1 to 9), ■ F! Compounds containing: 81%I4-m (m is an integer of 1 to 3), 812FmI6
-1n (m is an integer from 1 to 5).

Among the above-mentioned compounds (1) to (2), the most preferred specific examples include the following compounds.

(1) SiF, Ct, (2) 5iF2Ct2,
(3) SIF, Ct.

(4) ss, rct5. (5) 5t2r2cz4
．． (6) 5i2FsCt3゜(7) 5s2y4c
t2. (s) 5s2y5ct, (9) 81.
F.Ct.

01) st, r6cz2. αυ5i3F, C4+ (
135iF3Br rα35iF2Br2. Q4)
5iFBr, , (1!19512FsBr, αQ
5i2F4Br2゜(lη812F, Br51 (1
1195iCt5Br, σl 5iCt2Br2.

(245iCZBr3.gl SIF, I, fi
5iF2I2゜Such compounds include PH,, P2
H4, PF.

PF5a PCl5* AsH3+ AsF3. As
F5+ ktrct5+ 5bH5*SbF5.5LH
5, BF, BCl3. BBr3. B2H6,B
4H1°.

B5H,, B5H11, B6H1゜, B6H,2,A
tC1, etc. can be mentioned. The compounds containing impurity elements may be used alone or in combination of two or more.

In the present invention, the chamber in which the silicon-containing deposited film is formed is preferably placed under reduced pressure, but the method of the present invention can also be carried out under normal pressure or increased pressure.

The excitation energy used in the present invention is limited to light energy, but the chain silicon halide compound of the general formula can be easily excited and excited by applying relatively low energy such as light energy. It has the advantage that it can be decomposed to form a high-quality silicon deposited film, and in this case, the temperature of the substrate can also be kept relatively low. In addition, excitation energy is applied uniformly or selectively to the raw material that reaches the vicinity of the substrate, but
Using light energy, it is possible to irradiate the entire substrate using an appropriate optical system to form a deposited film, or to selectively control and irradiate only desired areas to form a deposited film. It is advantageously used because it has the convenience of being able to form a deposited film by irradiating only a predetermined graphical portion using a resist or the like.

In the present invention, by forming a gaseous atmosphere of a chain silicon halide compound of the general formula, a compound containing an impurity element, and hydrogen in the chamber, hydrogen generated in the process of excitation/decomposition reaction is produced. Radicals increase the efficiency of the reaction. Moreover, hydrogen is injected into the deposited film that is formed.
It plays a role in reducing defects in the St bond structure. Furthermore, the chain halogenated silicon compound of the general formula is converted into 2X5 into SIX, 5IX2 + 5IX5 * 8 during the decomposition process.
r 812X4 r 515X4.

815X5, SiY, 5IY2.5iY5,
512Y3, 5i2Y4゜5i5Y4, 815Y5
, 5iXY, 5iXY2, 5i2XY2.

812XY, , 813XY5. st, x2y2.
Radicals such as 5t5XY4゜S l , A high-quality film with a low localized level density in which the dangling bonds of Sl are sufficiently terminated with H, X, or Y can be obtained.

Further, the chain nologonated silicon compound of the general formula is:
Although 2'8i or more may be used in combination, in this case, properties that are averaged over the film properties expected by each compound, or properties that are synergistically improved can be obtained.

The drawing is a schematic diagram showing an example of an apparatus used to form an A-81 deposited film used as a photoconductive film, a semiconductor film, etc. by the method of the present invention.

In the figure, 1 is a deposition chamber, and a desired substrate 3 is placed on a substrate support 2 inside. The base 3 may be a conductive, semiconductive, or electrically insulating base.

Numeral 4 is a heater for heating the substrate, which is supplied with electricity through a conductor 5 and generates heat. The substrate temperature is not particularly limited, but in carrying out the method of the present invention, it is preferably 50 to 15
The temperature is preferably 0°C, more preferably 100 to 150°C.

6 to 9, when using a liquid compound among the gas supply sources consisting of reeds, a chain halogenated silicon compound represented by the above general formula, and an impurity element, an appropriate vaporization device is provided. . The vaporizer may be of any type, such as a type that utilizes heating and boiling, or a type that allows a carrier gas to pass through the liquid raw material Φ, or may be of any type. In addition, the hydrogen gas remains in molecular form, and the number of gas supply sources is not limited to four, and the number of chain silicon halide compounds of the general formula used, the number of compounds containing impurity elements, the carrier gas, and the diluent gas. ,
When catalyst gas etc. are used, the presence or absence of pre-mixing of these with hydrogen gas and a compound containing impurity elements of the above general formula as raw material gases, and formation of N-type and P-type films on the same substrate. It is selected appropriately considering the convenience of the case. In the figure, to the gas supply sources 6 to 9, a is added to the branch pipes, b is the flowmeter, and C is the pressure meter that measures the pressure on the high pressure side of each flowmeter. , d or e are the loops for adjusting each gas flow rate.

Raw material gases and the like supplied from each gas supply source are mixed in the middle of the gas introduction pipe 10, and are introduced into the chamber 1 by being energized by an exhaust device (not shown). 11 is a pressure gauge for measuring the pressure of the gas introduced into the chamber 1. Further, reference numeral 12 is a gas exhaust pipe, which is connected to an exhaust device (not shown) for forcibly exhausting the pressure inside the deposition chamber 1 and the introduced gas.

13 is regulator pulp.

As an example of an excitation energy supply source used in the present invention,
Reference numeral 14 denotes a light energy generator, for example, a mercury lung, a xenon lamp, a carbon dioxide slate, an argon ion laser, an excimer laser, or the like. Note that the light energy used in the present invention is not limited to ultraviolet energy, and any wavelength range may be used as long as it can excite and decompose the source gas and deposit decomposition products. Furthermore, the present invention does not exclude the case where light energy is absorbed by the source gas or the substrate and converted into thermal energy, and the thermal energy causes excitation and decomposition of the source gas to form a deposited film. Light 15 is directed from the optical energy generator 14 to the entire substrate or a desired portion of the substrate using an appropriate optical system, and is irradiated to the raw material gas flowing in the direction of the arrow 16, causing excitation and decomposition, and causing the substrate to be heated. A deposited film of a-81 is formed on the entire surface of 3 or on a desired portion.

According to the method of the present invention, a deposited film having any thickness from a thin film to a thick film can be obtained as desired, and the film area can also be arbitrarily selected as desired. The film thickness can be controlled by conventional methods such as controlling the pressure, flow rate, concentration, etc. of the source gas, controlling the amount of excitation energy, etc.

FIG. 2 shows a PDP using a 9a-8i deposited film doped with an impurity element and produced by carrying out the method of the present invention.
FIG. 2 is a sectional view showing a typical example of an IN type diode denoise.

In the figure, 21 is a substrate, 22 and 27 are thin film electrodes, 23 is a semiconductor film, P type a-8i layer 24, ■ type a-81
It is composed of a layer 25 and an N-type a-8a layer 26. 28 is a conducting wire.

The substrate 21 is semiconductive, preferably electrically insulating. As the semiconductive substrate, for example, 81
* Examples include semiconductors such as Go.

As electrically insulating substrates, I-type polyester, polyethylene, polycarbonate, etc. Films or sheets of esters, cellulose acetate, polypropylene, polyvinyl chloride, polybase resins, glass, ceramics, paper, etc. are commonly used.

The thin film electrode 22.27 is, for example, NlCr*At+
Cr*Mo, Au, It+NbrT
a * V r Ti r Pt + Pd + In
2O,t 5n02 rITO(In2O3+ 5n0
It can be obtained by providing a thin film such as 2) on a substrate by a process such as vacuum evaporation, electron beam evaporation, or sputtering. The thickness of the electrode 22 is preferably 30 to 5
In order to make the film forming the semiconductor layer 27 of 0a-81 preferably n-type 25 or p-type 23, preferably 10'l, preferably 100 to 5x10'x, as required,
During layer formation, the layer is doped with an n-type impurity, a p-type impurity, or both impurities among impurity elements while controlling the amount thereof.

Next, the operation for manufacturing the diode shown in FIG. 2 by the method of the present invention using the apparatus shown in the first figure will be described.

The substrate 21, on which the thin film of the electrode 22 is provided, is placed on a stool 2 in the etcher 1, and the deposition chamber is evacuated through the gas exhaust pipe 12 by an exhaust device (not shown) to reduce the pressure. The atmospheric pressure in the deposition chamber under reduced pressure is preferably 5 X l 0-
It is desirable that the pressure be 5 Torr or less, more preferably 10'' Torr or less. A gas supply source 6 in which the linear silicon compound of the general formula No. 10, which is in a gaseous state, is stored in order to provide the P-type a-81 film 24 on the thin film electrode 22.
A supply source 70 in which a compound containing a P-type impurity element in a gaseous state is stored.
The pulps 9d, 7e and the pulp 9de9e of the supply source 9 in which hydrogen gas is stored are opened, and these raw material gases are mixed and fed into the deposition chamber 1. At this time, the flow rate is adjusted while measuring with the corresponding flow meters 6b, 7b, and 9b. The flow rate of the silicon dedecide gas is preferably 10 to 1000 SCCM, more preferably 20 to 1000 SCCM.
A range of 5008 CCM is preferred. The flow rate of the P-type impurity gas is determined from ()·Flow rate of silicon rhodanide gas)×(doping concentration).

However, since the amount of impurity gas mixed in is very small, controlling the flow rate is very difficult. Therefore, the impurity gas is H2
It is normally stored and used diluted with gas.

The pressure of the mixed gas in the deposition chamber 1 is preferably 10-2~
It is desirable to maintain it in the range of 100 Torr, more preferably 10 to I Torr. An optical system (not shown) is incorporated so that the substrate 3 housed in the deposition chamber 1 is irradiated with light energy generated by the operation of the light energy generator 14 .

In this way, the mixed gas flowing near the surface of the substrate 30, that is, silicon halide gas, hydrogen gas, and impurity gas, is given optical energy and is stimulated to be photoexcited and photodecomposed, resulting in the production of a-81 and a small amount of P-type impurity. Atoms are deposited onto the substrate. Decomposition products other than a-8l and undecomposed surplus raw material gas are discharged through the f gas exhaust pipe 12, while new mixed gas is supplied through the gas introduction pipe 10.

In this way, a P-type a-8i film 24 is formed.

The thickness of the P-type a-8t is preferably in the range of 100 to 10'X, preferably 300 to 2.000X.

Pulp 6d, 6a then connected to gas supply source 6, 7.9
, 7d, 7e, 9d, and 9s are all closed to stop the introduction of gas into the deposition chamber 1. After removing the gas in the deposition chamber, especially the gases other than the raw material gas of a-81, such as contaminant gas and P-type impurity gas, by operating the exhaust system (not shown), the pulp 6d16e #9d190 is opened again and the silicon halide is removed. Gas and hydrogen gas are introduced into the deposition chamber 1. Suitable flow conditions and pressure conditions in this case are the same as in the case of forming the P-type a-81 film.
That is, a summer-type a-8l film 25 is formed.

The film thickness of summer type a-81 is preferably in the range of 500 to 5 x 10'X, preferably 1000 to 10,000 x.

Next, the pulps 8d and 8e connected to the gas supply source 8 in which the N-type impurity gas is stored are opened, and the N-type impurity gas is introduced into the deposition chamber 1.

The flow rate of N-type impurity gas is determined by ()・Flow rate of silicon rhodanide gas) × (as in the case of determining the flow rate of P-type impurity gas)
doping concentration). In this way, the energy flowing near the surface of the substrate 3 is imparted,
Photoexcitation and photodecomposition are promoted, and a-8S, a decomposition product, is deposited on the substrate, and a trace amount of 4N-type impurity atoms from the decomposition product is mixed into the deposit, resulting in a 9N-type a-81 film. 25 is formed. The thickness of the N-type a-8t film 25 is preferably 100 to 10X1, preferably 300 to 2.000
A range of 1 is desirable. The thin film electrode 27 on the N-type A-81 film 25 is formed by the same method as the method for forming the thin film electrode 22. The film thickness conditions are also similar.

Specific examples of the present invention are shown below. Example 1 As the chain halogenated silicon compound of the general formula, the exemplified compound (1), (2), (7) or (8)
CPH is used as a compound containing an impurity element as a component.
3 or B2H6 and doped with P (N-type) or B (P-type) as an impurity using the apparatus shown in FIG.
An 8i deposited film was formed.

First, conductive fipsubstrate (manufactured by Corning, $705)
9) on the support stand 2, and use the exhaust device to remove the deposition chamber 1.
The inside was evacuated and the pressure was reduced to 10 Torr.

At the substrate temperature shown in Table 1, 1105 CC of a mixture of the silicon halide compound in a gaseous state and PH3 gas or B2H6 gas at a ratio of 1:5 x 10 was added.
Hydrogen gas was introduced into the deposition chamber at a flow rate of 40 SCCM (D), and the substrate was irradiated perpendicularly with a high-pressure mercury lamp at a light intensity of 200 mW/z while keeping the atmospheric pressure in the chamber at 0.1 Torr to deposit the doped a -8i film was formed.

The film formation rate was 3x/IIec.

For comparison, a similarly doped a-8i film was formed using 512H6. The film formation speed is /X/s
Next, the obtained a-81 film sample was placed in a vapor deposition tank, and a comb-shaped At gap electrode (length 2
After forming a film with a thickness of 50 μm and a width of 5 strips, the dark current was measured at an applied voltage of 10 V, and the dark conductivity σd was calculated to evaluate the a-81 film. The results are shown in Table 1.

Table 1 From Table 1, it can be seen that the a-81 film according to the present invention can obtain sufficient doping efficiency and high σd even at a low substrate temperature, compared to the case where conventional Si 2H6 is used.

Example 2 The exemplified compound (121) was prepared by using a polyimide substrate as a substrate and a chain halide silicon compound having the above general formula.

a-8i in the same manner as in Example 1, except that α floor and αQ were used.
A film was formed and σd was determined. The results are shown in Table 2.

Table 2 Example 3 The exemplified compounds (1), (2), (7), (8) as chain halogenated silicon compounds of the general formula
The PIN type diode shown in FIG. 2 was manufactured using the apparatus shown in FIG.

First, 1000) f) ITOJIE22 tM arrival location t! The lath plate 21 was placed on a support stand, and the P Mla-8t film 24 doped with B (
A film thickness of 400×) was formed. The light source and light intensity were a low pressure mercury lamp 100m Juku-2.

Next, the introduction of B2H6 gas was stopped and the pressure inside the deposition chamber was reduced to 0.
A fI fjll a-8t film 25 (II (thickness: 5000 K)) was formed using the same method as in the case of the P-type a-8i film except that the pressure was set at 5 Torr.

Then, doping with P in the same manner as in Example 1
'c11!31a-8t film 26 (film thickness 400X) was formed. The light irradiation conditions were the same as for the P type.

Further, an At electrode 27 having a thickness of 1000 mm was formed on the NIJ film by vacuum evaporation to obtain a PIN type diode.

For comparison, a PIN type diode was similarly formed using 512H6.

The IV characteristics of the thus obtained diode element (area: 1 cW12) were measured, and the rectification characteristics and photovoltaic effect were evaluated. The results are shown in Table 1.

Table 1 *1 Ratio of forward current and reverse current at voltage 1V *2
From Table 1, the η value in the current equation of the p-n junction shows that the deposited film of the present invention provides superior rectification characteristics even at low substrate temperatures, compared to the case of using the conventional 8i2H6. .

In addition, regarding light irradiation characteristics, light is introduced from the substrate side,
Light irradiation intensity AM1, (approximately 100m No. 1 door 2), conversion efficiency 81 or more, open circuit voltage 0.9 V, short circuit current 10
mA/es was obtained.

Example 4 Transparent conductive film (polyester paste) as a substrate
, PIN was obtained in the same manner as in Example 3 except that the above-mentioned exemplified compounds az, α3, (us) were used as the chain-like 710r arsenic silicon compound of the above general formula, and the light source and light intensity were a high-pressure mercury lamp of 200 mW/z. A type diode was manufactured, and the rectification ratio and η value were determined.The results are shown in Table 2.

Table 2 [Effects of the Invention] According to the present invention, a high quality silicon deposited film can be formed at a low substrate temperature and at a high film formation rate. Moreover, even when the film to be formed has a wide area and is thick, uniform electrical and optical characteristics can be obtained and quality stability can be ensured, which is an unprecedented and exceptional effect. In addition, there is no need for high-temperature heating of the substrate, which saves energy; it is possible to form a film even on substrates with poor heat resistance; low-temperature processing shortens the process; and the raw material compound can be easily synthesized. It is inexpensive, has excellent stability, and has few handling risks.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the optical energy irradiation type deposited film forming method used in the present invention. FIG. 2 is a sectional view showing the structure of a PIN diode manufactured by the method of the present invention. DESCRIPTION OF SYMBOLS 1... Deposition chamber, 2... Substrate support stand, 3... Substrate,
4...Heater, 6-9...Gas supply source, 10...
- Gas introduction pipe, 12... Gas exhaust pipe, 14... Light energy generator, 21... Substrate, 22.27...
Electrode, 24... P type a-8t film, 25 ・I type a-8
i film, 26 - N type a-81 film, 28... conductor.

Claims (1)

[Claims] General formula: 5lnXITIYt(
In the formula, X and Y are different halodane atoms, and n is 1
An integer of ~6, m and t are each an integer of 1 or more, Di'
), m+t=2 n +2. ), a compound containing an element belonging to group Ⅰ or group of the periodic table, and hydrogen by forming a gaseous atmosphere, and using light energy, the said compound and hydrogen A method for forming a deposited film, characterized in that a deposited film containing silicon doped with the element is formed on the substrate by exciting and decomposing the silicon.