JPS60218839A - Deposited film forming method - Google Patents

Abstract

PURPOSE:To increase a film-forming rate while keeping high quality, by producing gas atmosphere of cyclic silicon hydride compound or compound being substituted by other silicon hydride radical 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 cyclic silicon hydride compound or compound being substituted by other silicon hydride radical, expressed by a general expression: SinH2n (n represents an integer of 3, 4, 5, or 6), and compound containing a III-family or V-family element (impurity element) is produced in the chamber including substrates, and these compounds are excited and decomposed by utilizing optical energy, forming each deposited film containing silicon doped with the impurity element over the respective substrates. The resulted deposition 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-8i) or polycrystalline silicon useful as a photoconductive film, a semiconductor film, etc.

[Prior art]

Conventionally, for example, Nu and P type a-8i deposited films were deposited using 5iH
It is known to be formed by a glow discharge deposition method or a thermal energy deposition method using A or 512H4 as a raw material. That is, it is well known that 5IH4 or 512H6 is excited and decomposed using electrical energy or thermal energy to form a deposited film of 5-8S on a substrate, and this film is used for various purposes.

However, when these SiH4 and 5izu6 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 the deposition to achieve reproducible and stable conditions. Especially one large area,
This is noticeable when forming a thick deposited film.

In addition, since the thermal energy deposition method requires high temperatures, the substrate to be used is destroyed and the probability that useful feed hydrogen atoms in a-8t will be released due to high temperatures is also increased. increases, making it difficult to obtain desired characteristics.

In this way, when forming a deposited film using 5IH4 and s i 2H6, uniform electrical and optical properties and quality O
At present, there are still problems that need to be solved, such as difficulty in ensuring stability and the tendency to cause disturbances on the surface of the film during deposition and defects in the bulk.

Therefore, in recent years, in order to solve these problems, 5IH4
A light energy deposition method (photoCVD method) of a-81 using Si 2H4 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-8L deposited film can be produced at a low temperature. However, in the optical energy deposition method using SiH4 and Si2H4 as raw materials under relatively small excitation energy such as optical energy,
Since dramatically more efficient decomposition cannot be expected, an improvement in film formation speed cannot be expected, and a new problem has arisen in that mass production is difficult.

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.

The above purpose is to store the general formula=S1nH in the chamber containing the substrate.
A cyclic silicon hydride compound represented by zn (in the formula, n is 3.4.5 or 6) or a compound in which the cyclic silicon hydride is replaced with another silicon hydride, and a compound represented by No.
Elements belonging to group or group (hereinafter referred to as impurity elements)
forming a gaseous atmosphere of a compound containing as a component, and using light energy to excite and decompose the compound to form a deposited film containing silicon doped with an impurity element on the substrate; This is achieved by a deposited film forming method characterized by the following.

[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 bonding of silicon in the film may be in any form from oligomers to polymers. 7. Further, hydrogen atoms, halogen 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.

Specifically, the cyclic silicon hydride compound of the general formula used in the present invention is cyclobutasilane represented by 815H4, cyclobutasilane represented by 5i4Hp, S'5
Cyclopentasilane represented by H10, and 5t6n
The cyclohexasilane represented by 12 may be one in which the hydrogen atom is substituted with another chain silanyl group or a cyclic silanyl group.

Further, as the impurity element used in the present invention, as a p-type impurity, an element of Group Ⅰ A of the periodic table, such as B, A
Suitable examples include L, G@, In, Tt, etc., and examples of n-type impurities include elements of group V A of the periodic table,
For example, preferred examples include N, P, As, Sb, Bi, etc., especially B and Ga.

p, sb, etc. are optimal. The amount of impurities to be doped is determined as appropriate depending on the desired electrical and optical properties, but in the case of impurities from group Ⅰ A of the periodic table, it is 3 x 10.
It is sufficient to dope in the range of -2 to 4 atomic amounts, and in the case of impurities in group A of the periodic table, it is 5×1.
Doping may be carried out in an amount ranging from 0-5 to 2 atomic degrees.

As a compound containing such an impurity element as a component, it is preferable to select a compound that is in a gaseous state at room temperature and normal pressure, or at least a gaseous state under the conditions for forming a deposited film, and that can be easily vaporized using an appropriate vaporizing device. preferable. Such compounds include PI (3+P2H4, PF3, PF5
, PCl3. AsH2, AsF3, AsF5゜A
sCl2, BbH5, SbF5, S'lH5,
B10, BCl2゜BB”5 r B2H6+ B
4H10m B5H9+ B5H11w B6H10*
B6H12, AtCl3, etc. can be mentioned. The compound containing an impurity element may be used for 1 m, or two or more types may be used in combination.

In the present invention, in order to excite and decompose the cyclic silicon hydride compound of the general formula in the gaseous state, a halogen compound in the gaseous state (e.g., F2 gas, ct2 gas, gasified Br2, I2, etc.) is preferable because a radical generating reaction occurs between the halogen atoms 481 and H, and the excitation-decomposition of the silicon compound and therefore the formation of a deposited film are promoted. Further, it is expected that halogen will be injected into the deposited film to reduce structural defects, and will combine with the dangling bonds 81 to act as a terminator, resulting in a high-quality silicon film. The halogen to be introduced may be radicalized in advance.

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.

In the present invention, the excitation energy used to excite and decompose the compound containing the cyclic silicon hydride compound vapor impurity element of the general formula as a component is limited to light energy. A silicon halide compound can be easily excited and decomposed by applying light energy or relatively low thermal energy to form a high quality silicon deposited film, and in this case, the temperature of the substrate is also relatively low. It has equal length. In addition, excitation energy is applied uniformly or selectively to the raw material that has reached the vicinity of the substrate, but if optical energy is used, the entire substrate is irradiated using an appropriate optical system to form a deposited film. Alternatively, it is possible to selectively and controlly irradiate only desired areas to form a deposited film, or use a resist or the like to irradiate only a predetermined figure to form a deposited film. It is advantageously used because it has the convenience of being able to form.

In addition, two or more of the cyclic silicon hydride compounds having the above general formula may be used in combination, but in this case, the expected film properties of each compound may be averaged or synergistically improved. characteristics are obtained.

Below, the drawings will be explained in more detail with reference to the drawings.
1 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 are gas supply sources, and in the case of using a liquid compound among the cyclic silicon hydride compounds represented by the above general formula and impurity elements as components, an appropriate vaporization device is provided. let The vaporizer may be of any type, such as a type that utilizes heating and boiling, or a type that allows carrier and argas to pass through the liquid raw material. The number of gas supply sources is 4
However, the number of compounds containing the cyclic silicon hydride compound of the general formula and the impurity element to be used is not limited to. When using halogen gas, carrier gas, diluent gas, catalyst gas, etc., the presence or absence of premixing of these with a compound of the general formula as a raw material gas, a compound containing an impurity element as a component, and N-type and P-type membranes. It is selected as appropriate in consideration of the convenience in forming both on the same substrate. In the figure, gas supply source 6
To the codes from 9 to 9, a is added to the branch pipe, b is added to the flowmeter, C is added to the pressure needle that measures the pressure on the high pressure side of each flowmeter, and d or seasonal is added. The pulp is used to adjust the flow rate of each gas.

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). Reference numeral 11 denotes a pressure gauge for measuring the pressure of gas introduced into the chamber 1. Further, 12 is a gas exhaust pipe sb, 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 regirator 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 lamp, a xenon lamp, a carbon dioxide gas radar, an argon ion laser, an excimerade, or the like. It should be noted that the light energy used in the present invention is not limited to ultraviolet energy, and the wavelength range does not matter as long as it can excite and decompose the raw material gas and deposit decomposition products. Further, 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. The light 15 directed from the optical energy generating device 14 to the entire substrate or a desired part of the substrate using an appropriate optical system is irradiated to the raw material gas etc. 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 thin to thick can be obtained as desired, and the film area can also be varied as desired.
Can be selected arbitrarily. 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 an a-8i deposited film doped with an impurity element produced by carrying out the method of the present invention.
1 is a cross-sectional view of a typical INfi diode device; FIG.

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

The substrate 21 is semiconductive, preferably electrically insulating. As a semiconductive substrate: for example, Si
, G@, and other semiconductors.

Examples of electrically insulating substrates include polyester, polyethylene, polycarbonate, cellulose, acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, f!
Films or sheets of synthetic resins such as listyrene and polyamide, glass, ceramics, paper, etc. are commonly used. The thin film electrodes 22 and 27 are made of, for example, NiCr, AL, C
r, Mo, Au, Ir.

Nb, Ta, V, Ti, Pt, Pd,
In20B, 8n02゜ITO (In2O3+ 5n
It can be obtained by forming a thin film such as 02) on a substrate by a process such as vacuum evaporation, electron beam evaporation, or sputtering. The film thickness of the electrode 22 is preferably 30 to 5×1
04X, more preferably 100 to 5X10'X.

The film body constituting the semiconductor layer 27 of a-81 is made n-type 25 or p-type 23 as necessary.K is an n-type impurity, a p-type impurity, or both impurities among impurity elements during layer formation. This is accomplished by doping the layer into the formed layer in a controlled amount.

・Next, the operation for manufacturing the diode shown in FIG. 2 using the apparatus shown in FIG. 1 by the method of the present invention will be described.

A substrate 21 on which a thin film of an electrode 22 is provided is placed on a support base 2 in a deposition chamber 1, and the inside of the deposition chamber is evacuated through a 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 desirably 5 x 10-5 Torr or less, preferably 10-' Torr or less. Thin film electrode 2
In order to provide the P-type a-81 film 24 on the gaseous state, the pulp 6d, 6@ of the gas supply source 6 in which the cyclic silicon hydride compound of the general formula is stored is in the gaseous state. Open the valves 7d and 7* of the supply source 7 in which the compound containing the P-type impurity element as a component is respectively opened;
These raw material gases are mixed and sent into the deposition chamber 1.

At this time, the flow rate is adjusted while measuring with the corresponding flow meters 6b and 7b. The flow rate of silicon hydride gas is preferably 10 to 100,080 cm, more preferably 20 to 5 cm.
A range of 0.008 CCM is desirable. 'PfJ impurity gas flow rate is determined from (silicon hydride gas flow rate) x (doping concentration).

However, since there is a very small amount of impurity gas mixed in, 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~
100 Torr, preferably 10-2 to 1'
It is desirable to maintain it within the range of forr. An optical system (not shown) is incorporated so that the light energy generated by the operation of the light energy generating device 14 irradiates the substrate 3 housed in the deposition chamber 1 .

In this way, the mixed gas flowing near the surface of the substrate 3, i.e., silicon halide gas, hydrogen gas, and impurity gas, is given optical energy and is stimulated to be photoexcited and photodecomposed, resulting in a-81 as a product and a trace amount of P-type. Impurity atoms are deposited on the substrate. Decomposition products other than a-81 and undecomposed surplus raw material gas are discharged through the gas exhaust pipe 12, while new mixed gas is supplied through the gas introduction pipe 10.

In this way, a P-type a-81 film 24 is formed.

The film thickness of P-type a-8i is preferably 100 to 1
0'! , preferably 300 to 2. A range of OOOX is desirable.

Next, pal f6d is connected to gas supply source 6.7.

6e, 7d, and 7e are all closed to stop the introduction of gas into the deposition chamber 1. After the gas in the deposition chamber, especially the gas other than the raw material gas of m-81, such as pollutant gas and P-type impurity gas, is removed by the operation of the exhaust device (not shown), the valve 6a h is opened again.
6a is opened and silicon hydride gas is introduced into the deposition chamber 1. In this case, suitable flow conditions and pressure conditions are P-type a-
As in the case of forming the 8T film, an A-8L film 25 of an L type is formed by irradiation with light energy in the same manner as in the case of forming the 8T film.

The film thickness of type A-8i is preferably 500 to 5 x 10
'X is preferably in the range of 1000 to 100OOX.

Next, the valves 8d, 8. 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 the N-type impurity gas is determined from (flow rate of silicon hydride gas)×(doping concentration), as in the case of determining the flow rate of the P-type impurity gas.

In this way, optical energy is imparted to the silicon hydride gas, hydrogen gas, and N-type impurity gas flowing near the surface of the substrate 3, promoting photoexcitation and photodecomposition, and a-81 of the decomposition product.
is deposited on the substrate, and there is a trace amount of NI as a decomposition product in the deposit.
I! When impurity atoms are mixed in, an N-type a-8i film 25 is formed. The thickness of the N-type ---Si film 25 is preferably 100 to 10'! , preferably 300-2
,0OOX range is desirable. Nfi a-81 membrane 25
The upper thin film electrode 7 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 The exemplified compound 5i5H10 was used as the cyclic silicon hydride compound of the general formula, and PH3 or B2H6 was used as the compound containing an impurity element. A-8L deposited films doped with B (-Pi) or B (-Pi) were formed.

First, the polyethylene terephthalate film substrate was placed on the support stand 2, and the inside of the deposition chamber 1 was evacuated using an exhaust device to reduce the pressure to 10-' Torr. st5u1g 150 S, which is in a gaseous state at the substrate temperature shown in Table 1
CCM and PH3 gas or B2H4 gas (both 100
The doped A-81 film (film A thickness of 700X) was formed. The film formation rate was j51/ssc.

A similarly doped A-81 film was formed using Comparative Ivy S812H6. Film deposition rate is 15L/
It was I@e.

Next, the obtained A-81 film sample was placed in a vapor deposition tank and a comb-shaped AA gap electrode (length 250μ, width 5mm) was formed at a vacuum level of 10-5 Torr, and the dark current was measured at an applied voltage of 10V. Then, the a-8t film was evaluated by measuring the dark conductivity σd. The results are shown in Table 1.

Examples 2 to 4 The same a-8t films as in Example 1 were formed except that 5s3n6, 816H12, or 5i5H9 (81H3) was used in place of Si5H10. The dark conductivity was measured and the results are shown in Table 1.

From Table 1, according to the present invention, a high σ value, ie, a well-doped a-8L film can be obtained even at a low substrate temperature.

Example 5 5t3a4 as a cyclic silicon hydride compound of the general formula
The PIN type diode shown in FIG. 2 was manufactured using the apparatus shown in FIG.

First, the polyethylene naphthalate film 21 on which the ITO film 22 of '1000' was deposited was placed on a support stand, and
5i5H6150S gasified after reducing pressure to Torr
CCM, introduced gellan gas (82H611000pp diluted with hydrogen) and heated at 1k while maintaining at 0,1 Torr.
A P-type film-8i film 24 (thickness 7 mm) doped with B was formed by irradiation with a WXe lamp.

Next, the P-type membrane was
A ■-shaped film-8i film 25 (thickness: 5000×) was formed in the same manner as in the case of the 8t film.

Next, 7 male and fin gas (p
n51000 m) Pm hydrogen dilution) 40 SCCM,
N-type film-8 doped with P under the same conditions as P-type except that 208CCM of halodane gas was introduced from another system.
ijI26 (film thickness 700X) was formed. Furthermore, this N
An At electrode 2 with a film thickness of 1000X was vacuum deposited on the mold film.
7 was formed to obtain a PIN type diode.

For comparison, a PIN diode was similarly formed using Si2H4.

I- of the diode element thus obtained (area 1 of 2)
Measure V characteristics, evaluate rectification characteristics and photovoltaic effect,
Ta. The results are shown in Table 1.

In addition, regarding light irradiation characteristics, light is introduced from the substrate side,
At a light irradiation intensity AJ (approximately 100 mW/cm2), a conversion efficiency of 8.5% or more, an open circuit voltage of 0.92 V, and an fi circuit current of 10.5 mA/y++ were obtained.

Examples 6 to 8 As the cyclic silicon hydride compound of the general formula, 81sH
5i4H, 5i5HIQ or 516H12 for 4
A PIN type diode was obtained which was the same as in Example 1 except that .

The rectification characteristics and photovoltaic effect were evaluated and the results are shown in Table 1.

From Table 2, according to the present invention, a-81 has good optical and electrical characteristics even at a lower substrate temperature than before.
A deposited film is obtained.

〔Effect 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 is wide-area and thick, uniform electrical and optical characteristics can be obtained and quality stability can be ensured, which is an unprecedented and exceptional effect. In addition, it saves energy because it does not require high-temperature heating of the substrate, it can form a film even on substrates with poor heat resistance, the process can be shortened by low-temperature treatment, and the raw material compound can be easily synthesized. It is inexpensive, has excellent stability, and has the advantage of being less dangerous in handling.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of the optical energy irradiation type deposited film forming apparatus used in the present invention. FIG. 2 is a cross-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-81 membrane, 25-I fJl
a-81 film, 26/N type a-8l film, 28... conductor. Figure 2

Claims (1)

[Claims] The general formula: 5lnH2n C, where n is 3.4.5 or 6, is contained in a chamber containing the substrate. ) or a compound in which the cyclic silicon hydride is substituted with another silicon hydride, and group m or group (■) of the periodic table.
forming a gaseous atmosphere of a compound containing an element belonging to the group, and using light energy to excite and decompose the compound, thereby forming a deposited film containing silicon doped with the element on the substrate; A deposited film forming method characterized by forming a deposited film.