JPS6190421A - Formation of deposited film - Google Patents

Abstract

PURPOSE:To enable the deposition of a good-quality single crystal film on an amorphous substrate and the fabrication of an amorphous film having the uniform bonding state of atoms by repeating a deposition process for forming a deposited film and an etching process for etching the deposited film alternately. CONSTITUTION:The beam 15 directed to a substrate from a light energy generator 14 by use of an optical system is projected to a material gas or the like and causes excitation and decomposition or polymerization thereby forming a deposited film of a-Si on the substrate 3. By using said device 14, a material gas and an etching gas are introduced into a deposition chamber 1 alternately and are irradiated with the beam 15. By controlling the gas pressure, the deposition process on a low-pressure side for depositing a film on the substrate 3 and the etching process on a high-pressure side are repeated alternately. When a temperature of the amorphous substrate 3 is high, by using a crystal Si, a deposited film having a good crystallizability according to both directions of the substrate 3 by anisotropy of etching can be formed. When a temperature of the substrate 3 is low, a deposited film of amorphous Si in which a bonding state of atoms is uniform is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a deposited film forming method suitable for depositing a deposited film, particularly a high quality photoconductive film, semiconductor film, insulating film, etc. with good control.

[Prior art] Conventionally, for example, a semiconductor film such as Si was
Normal pressure CVD, low pressure CVD, and plasma CVD have been used as methods for deposition using CI+ source gas. However, in methods that utilize thermal energy such as normal pressure and low pressure CVD methods, the temperature of the substrate where deposition occurs is high, and in the case of epitaxial growth using Si crystal as the substrate, the grown crystals have many defects and device If this is configured, the yield will be poor.

Furthermore, since the substrate is at a high temperature, the types of substrates that can be used are limited. When an amorphous material such as glass is used as the substrate, an amorphous film is often deposited, but due to the high temperature, the probability that useful bonded hydrogen in the film will be released increases. It becomes difficult to obtain desired characteristics.

Next, in the plasma CVD method, the substrate temperature can be lowered compared to the normal pressure and low pressure CVD methods. However, the deposited film may be damaged due to the influence of ions in the plasma, and control under stable conditions with reproducibility becomes difficult. This is particularly noticeable when forming a thick deposited film over a wide area.

In this way, when forming semiconducting, photoconductive, or insulating deposited films using gas, it is difficult to ensure uniform electrical and optical properties and quality stability, and the surface of the film being deposited is At present, there are still problems to be solved, such as turbulence and defects in the bulk that are likely to occur.

Therefore, in recent years, in order to solve these problems, a light energy deposition method (optical carbon
VD method) has been proposed and is attracting attention. According to the advanced energy deposition method, the above-mentioned problems can be significantly improved due to the advantage that a deposited film of a semiconductor or the like can be produced at a low temperature.

However, in the optical energy deposition method using gas as a raw material under relatively small excitation energy such as optical energy,
It is difficult to control the crystallinity on an amorphous substrate such as glass and the bonding state of atoms in a deposited film.

Therefore, even if the substrate is heated to a high temperature, a single crystal cannot be produced, and even when an amorphous film is produced at a low temperature, it is difficult to produce a film with uniform bonding states of atoms.

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

[Object of the invention] The object of the present invention is to
It is an object of the present invention to provide a method for forming a deposited film that can deposit a high-quality single crystal film at a low temperature and also produce an amorphous film with uniform bonding states of atoms at a similar low temperature.

[Summary of the Invention] The method for forming a deposited film according to the present invention is to decompose or polymerize a raw material gas introduced into a chamber containing a substrate by using light energy, and to deposit atoms contained in the raw material gas on the substrate. The method is characterized in that a deposition process for forming a deposited film containing .

[Example] The deposited film formed according to the present invention may be crystalline or amorphous, and the bonding of atoms in the film may be in any form from oligomer to polymer.

According to the method of the present invention, films of various materials can be formed by appropriately selecting source gases.

For example, semiconductor materials include Sf, Ge, and C.

, Semiconductors of group Ⅰ elements such as Sn, semiconductors consisting of two or more types of group Ⅰ elements such as 5i-Ge and 5i-C, ∎-group semiconductors represented by GaAs, ∎- group semiconductors represented by ZnS and ZrSe, etc. Group (3) semiconductors, oxide glasses, etc. can be formed. In addition, as an insulating material, 5i02°Si
-N-H, Al2O3, etc. may be formed. Si
The raw material gas for forming the film is SiH41Si.
When a silicon hydride, chloride or fluoride such as C14, SiF4 is used and a C film is formed, CH4,
C2H, etc., when forming a Ge film, GeH4, etc. -
When forming a V-group semiconductor, for example, Ga(CI 2
) 3 and As2 H6, for example, Zn(CH2) 2 when forming a ■-■ group semiconductor.

A mixed gas of H2S and H2Se is used.

Further, the etching gas used in the present invention is C
I2, F2 CCI 4, CF 4.801. HF
Gases mainly composed of halogens, such as, are used. 02.02 to these gases. H2 may also be included.

The present invention will be described in detail below, mainly in the case of a 5ijftfi film.

The raw material gas used in this example has the general formula Sin
H2n (n=3.4,5.s * * ) Cyclic silicon hydride compound represented by Te, Sin H2n+ 2
(n = 1.2°...number) linear or branched chain silicon hydride compound, SiF, Si
2 F 6.

7-/compounds of silicon such as Si3 F io, 5iC1
4.

Silicon chlorides such as Si2 C16 and Si3 G110.

Chlorinated silane compounds such as 5iHC13, SiH2012, and SiH3CI are used. In addition, as an etching gas for Si, ct2. F2, CF4 or a mixture thereof is used.

Note that the chamber in which the deposited film containing silicon is formed is
Although it is preferable to use the method under reduced pressure, 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, decompose, or polymerize the silicon compound is limited to light energy. It is characterized in that it can easily undergo excitation-decomposition or polymerization to form a high-quality silicon deposited film, and in this case, the substrate temperature can also be kept at a relatively low temperature. In addition, excitation energy is applied uniformly or selectively to the raw material that has reached the vicinity of the substrate, but if light energy is used,
A deposited film can be formed by irradiating the entire gas using an appropriate optical system, or a deposited film can be formed partially by irradiating only a desired part. It has the convenience of being able to form a deposited film by irradiating only a predetermined shape using a resist, etc.
Used to advantage.

In addition, two or more of the raw material compounds of the above general formula may be used in combination, but in this case, it is possible to obtain properties that are equivalent to the average of the film properties expected by each compound, or properties that are synergistically improved. It will be done.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The drawing is a schematic configuration diagram showing an example of a light energy irradiation type deposited film forming apparatus for use in an embodiment of 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 stand 2 inside. The substrate 3 may be conductive, semiconductive, or electrically insulating. For example, electrically insulating substrates include polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, Films or sheets of synthetic resins such as polystyrene and polyamide, glass, ceramics, paper, etc. are commonly used. Also,
An electrode layer, another silicon layer, etc. may be laminated on the base 3 in advance.

Other substrates that can be used include crystalline semiconductors such as St and Ge, crystalline insulators such as spinel and sapphire, amorphous materials such as SiO2, glass and quartz, metal plates, vapor-deposited metal g films, and the like.

Reference numeral 4 denotes a heater for heating the substrate, which is supplied with electricity via a conductive wire 5 and generates heat. The temperature of the substrate is not particularly limited, but when carrying out the method of the present invention, it is recommended that the temperature of the substrate be 5.
0 to 150°C, preferably 400 to 800°C for crystalline substrates.

6 to 9 are gas supply sources, and if a liquid one of the chain silicon hydride compounds represented by the above general formula is used, an appropriate vaporizer is provided. There are two types of vaporizers, such as a type that uses heating and boiling, and a type that passes a carrier gas through the liquid raw material.The number of gas supply sources is not limited to four, and the number of gas supply sources used is In Figure 0, the number of silicon hydride compounds, etching gas, carrier gas, diluent gas, etc., are selected as appropriate depending on the presence or absence of premixing with the compound of the general formula as the raw material gas, etc. For the signs of gas supply sources 6 to 9, a
Those marked with are branch pipes, those marked with b are flow meters, those marked with C are pressure gauges that measure the pressure on the high pressure side of each flow meter, and those marked with d or e are for opening and closing of each gas flow. and a valve for adjusting the 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, energized by a ventilation device (not shown), and introduced into the chamber 1. Alternatively, the gases are introduced into the chamber 1 alternately from each gas supply source. 11 is a pressure gauge for measuring the pressure of the gas introduced into the chamber l. Also, 12
is a gas exhaust pipe, which is connected to an exhaust device (not shown) for reducing the pressure inside the deposition chamber l and forcibly exhausting introduced gas.

13 is a regulator valve. When the inside of the chamber 1 is evacuated and brought into a reduced pressure state before introducing the raw material gas and the like, the atmospheric pressure inside the chamber is preferably 5×10 −5 Torr or less, more preferably I×10 −6 Tarr or less.

Further, in a state where the raw material gas and the like are introduced, the pressure inside the chamber 1 is preferably 1X10-2 to 100 Torr, more preferably 5X10-2 to 10 Torr.

As an example of the excitation energy supply source used in the present invention, 1
4 is a light energy generator, such as a mercury lamp,
A xenon lamp, carbon dioxide laser, argon ion laser, excimer laser, etc. are used. Note that the light energy used in the present invention is not limited to ultraviolet energy, and any wavelength range is not critical as long as it can excite, decompose, or polymerize the source gas and deposit decomposition products.

The light 15 directed from the light energy generator 14 to the entire substrate or a desired part of the substrate using an appropriate optical system is irradiated onto the raw material gas etc. flowing in the direction of the arrow 1G, causing excited decomposition or polymerization. An a-Si deposited film is formed on the entire substrate 3 or a desired portion thereof.

According to the method of the present invention, a deposition process and an etching process are performed in which a film is deposited on the substrate 3 by alternately introducing source gas and etching gas into the deposition chamber 1 using the above-mentioned apparatus and irradiating the film with light 15. The process is repeated alternately.

When the temperature of the substrate 3 is high, if crystalline Si is used for the substrate 3, a deposited film with good crystallinity will be formed according to the plane orientation of the substrate 3 due to the anisotropy of etching, and if the substrate 3 is amorphous, a deposited film with good crystallinity will be formed. A deposited film with good crystallinity is also formed.

When the temperature of the substrate 3 is low, a deposited film of amorphous Si with uniform atomic bonding states is formed on the substrate 3.

Further, according to the method of the present invention, a film deposition gas and an etching gas are introduced into the above-mentioned apparatus at the same time, and by applying light and adjusting the gas pressure, the deposition process and the etching process are alternately repeated. You can also do that. In this case, the pressure dependence of the etching, i.e. preferably 5 to 80 To
The property that etching is performed on the high pressure side and deposition is performed on the low pressure side with rr as the boundary is utilized.

In this way, deposition of any thickness from thin to thick can be achieved.
A membrane is obtained, and the membrane area can be arbitrarily selected as desired. The film thickness can be controlled by normal methods such as controlling the pressure, flow rate, concentration, etc. of raw material gas, and controlling the amount of excitation energy. When preparing an a-9i film where l!
The thickness is preferably 100 to 50,000, more preferably 500 to 10,000.

Specific examples of the present invention will be shown below.

(Example 1) Si2 H6 as source gas, C as etching gas
12 and a-Sil! using the L device. 2 was formed.

The glass substrate 3 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 10-6 Torr. First, at a substrate temperature of 100°C, 50% of the Si2 HB gas was added.
It is introduced at a flow rate of SCCM, and the atmospheric pressure inside the deposition chamber 1 is set to 0.1.
Hold at Torr. And a light energy generator 1
4, the substrate 3 was irradiated with light 15 perpendicularly using a low-pressure mercury lamp of 800 liters to form a film of 25 people in about 1 second.
After the pressure is reduced to , CI2 gas is introduced at a flow rate of 205 CCIII, and the inside of the deposition chamber 1 is maintained at I Tarr. Then, the substrate 3 was irradiated vertically with light 15 for about 1 second using the same low-pressure mercury lamp 800 mm. Subsequently, the process of exhausting the CI2 gas and introducing silane gas was repeated to deposit an a-Si film A with a thickness of 5000 on the substrate 3. For comparison, only Si2H6 was used to form a-Si[B with continuous irradiation light.

The thus obtained samples of each a-9i film A and B were placed in a vapor deposition tank and the pressure was reduced to -6 Torr, and then 150OA of aluminum was vapor-deposited at a vacuum level of 10-5 Torr and a film formation rate of 20 persons/sec. After forming the mold aluminum gap electrode (length 250 Bm, @5■l),
Applied voltage 10V-t' photocurrent (AMI, 100mW/
cm2) and dark current, photoconductivity σp, σp (Ω
・cm)" and the dark current σd, find the ratio σp/σd, and a
-9i membrane was evaluated. The results are shown in Table 1.

Table 1 (Example 2) The substrate in Example 1 was quartz glass, and the substrate temperature was 500.
℃, and Si film A was deposited in the same manner. For comparison, glow discharge method (discharge power IQQW/200m
A Si film B was formed using the same method (mφ) and evaluated based on the orientation and crystallinity of both crystals. The results are shown in Table 2.

Table 2 (Example 3) Si2 H6 as source gas, F as etching gas
2, an a-Si film was formed using the above apparatus.
, 1.

The glass substrate 3 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 −6 Torr.

At a substrate temperature of 100° C., Si2 H6 and F2 gases are each introduced at a flow rate of 505 CG14.205 CCH, and the atmospheric pressure in the deposition chamber 1 is maintained at 0.5 Torr. Then, using a low-pressure mercury lamp 80QW, light 1 was applied perpendicularly to the base 3.
Next, the pressure was increased to 20 ↑ orr, held for 30 seconds, and then reduced to the original pressure of 0.5 Torr. By repeating these processes, an a-Si film A having a thickness of 5,000 layers was deposited on the substrate 3, and the same evaluation as in Example 1 was performed, and the results are shown in Table 3.

Table 3 As shown in Tables 1 to 3, it can be seen that the silicon deposited film formed by the method of the present invention is of better quality than the conventional one. The same applies even if other source gases are used.

[Effects of the Invention] As explained above in detail, by the deposited film forming method according to the present invention, high quality single crystal films and amorphous films can be formed at low substrate temperatures.

[Brief explanation of drawings]

The accompanying drawing is a schematic configuration diagram showing an example of a light energy irradiation type deposited film forming apparatus for realizing an embodiment of the deposited film forming method according to the present invention. 1...Deposition chamber 2...Fist base support 3...Base 4...Heaters 8 to 8...Gas supply source 10...Gas inlet pipe 12...-Gas exhaust pipe 14φ
・Light energy generator

Claims (3)

[Claims] (1) A deposition process in which a source gas introduced into a chamber containing a substrate is excited using light energy and decomposed or polymerized to form a deposited film containing atoms contained in the source gas on the substrate. . An etching process of etching the deposited film with an etching gas introduced into the chamber; and a method for forming a deposited film, comprising alternately repeating these steps. (2) The deposited film forming method according to claim 1, wherein the source gas and the etching gas are alternately introduced into the chamber. (3) The source gas and the etching gas are simultaneously introduced into the chamber, and the deposition process and the etching process are alternately repeated by changing the pressure inside the chamber. The method for forming a deposited film according to item 1.