JPS59131518A - Formation of amorphous silicon film - Google Patents

Abstract

PURPOSE:The dopant gas containing a fluorine compound as a source of dopant element is previously excited and the resultant plasma gas is introduced into the reactor filled with a gas containing a silane to form the titled film rapidly in a high doping efficiency. CONSTITUTION:The drum-shaped electroconductive base plate 16 is heated and the reactor 4 is evacuated inside. An SiH4 gas is introduced into the reactor 4 from the top downward, while BF3 or PF5 gas, as a dopant gas, is sent to the microwave guide 46 where discharge is effected to form the pre-excited plasma gas and the gas is jetted out of the gas nozzles 42 on the metal box 40 to between the bases plates 16. The gas pressure in the reactor 4 is controlled to the prescribed value and the base plates are made to rotate. A prescribed high voltage is applied to the metal box 40 and the base plates are grounded to effect discharge to form the plasma gas containing silicon radicals from SiH4 gas. The resultant gas comes into contact with the side surface of the drum base plate 16 to form B type (BF3) or P type (PF5) a-Si film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for forming an amorphous silicon film on the circumferential side of a substrate, such as a drum-shaped conductive substrate.

[Technical background of the invention and its problems]

Conventional amorphous silicon M is produced by introducing a gas containing molecules containing silicon atoms, for example, 5tH4, into a sealed container as a reaction container under reduced pressure in which a drum-shaped conductive substrate is placed, and silicon radicals containing silicon atoms generated by discharge. was formed by bringing a plasma state into contact with the drum-shaped conductive substrate. Although the amorphous silicon film obtained in this manner exhibits excellent photoquadratic properties, it has a low dark resistance under light shielding, and is therefore not sufficient for use as an electrophotographic film. Therefore, attempts have been made to control the valence electrons in the amorphous silicon film and increase the resistance of the amorphous silicon film by doping various elements, such as B+P'x, into the amorphous silicon film.

However, when gases such as B2H6 and PH3 are
When doping is performed by mixing with H4 gas and performing glow discharge in this mixed gas, the amount of doping of B+P is extremely small, so % Hub Ar bHe
Since a dopant gas diluted with B2116 or PHs' is used in the above methods, there is a problem that the formation rate of an amorphous silicon film is slow.

Also, by mixing St H4 gas mixed with 5tF4 and a dopant gas containing B2H6 or pH3,
Doping is sometimes performed by mixing tH4 gas and a dopant gas containing EF or PFS f, but doping efficiency into the amorphous silicon film is low because 5Z F4, BF3, pp5, etc. are difficult to decompose. There is a problem with this.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for rapidly forming an amorphous silicon film with high doping efficiency.

[Summary of the invention]

The outline of the present invention for achieving the above object is that a plasma gas prepared by pre-exciting a dopant gas containing a fluoride of an element to be doped into an amorphous silicon film is introduced into a reaction vessel into which a silane-containing gas is introduced. It is characterized by being a person.

EXAMPLE An example of an apparatus for manufacturing an amorphous silicon photoreceptor directly used in carrying out the method of the present invention is shown in FIGS. 1 and 2.

As shown in FIGS. 1 and 2, the amorphous silicon photoreceptor manufacturing apparatus includes a vacuum chamber 4 airtightly mounted on a base 2, and an exhaust device such as a mechanical The booster pump 8 and the rotary pump 10 are configured to reduce the pressure in the vacuum chamber 4 to, for example, 10<-6 >Tor[gamma]. On the base 2 in the vacuum chamber 4, a plurality of drum holding devices 12, for example, six drum holding devices 12, are arranged in a row so as to be rotatable by a drive device 14; for example, a motor. The drum holding device 12 can be equipped with a cylindrical drum-shaped conductive substrate 16, and can have a heater 18 to heat the drum-shaped conductive substrate 16 to a predetermined temperature, for example, 150 to 600°C. configured to be able to do so. In addition, in the arrangement direction of the drum-shaped conductive substrates 16, a pair of metal casings 40 having rectangular opposing surfaces are sandwiched between the arrayed bases, for example, the drum-shaped conductive substrates 16' (il-). is erected, and on the opposing surfaces of the metal casing 40 there are spaces between the arranged drum-shaped conductive substrates 16 and between the drum-shaped conductive substrates 16 located at the ends of the arrangement and the inner wall of the vacuum chamber 4. A plurality of gas ejection holes 4 arranged vertically so that gas is introduced between them.
2 is opened, and a microwave waveguide 46 is connected to the opposite surface of the metal casing 40 via the gas introduction pipe 44, and the flow rate regulating pulp 4
8, the dopant gas whose flow rate is adjusted is guided into the micro waveguide 46, and the dopant gas is excited by discharge in the microwave waveguide 46 to generate a plasma gas, and this plasma gas is used to Gas ejection hole 4 in housing 40
2 so that it can be introduced into the vacuum chamber 4, and further,
By electrically connecting the metal casing 40 and the power source 22, a full potential gradient is formed between the metal casing 40 and the drum-shaped conductive substrate 16, allowing discharge.

The metal casing 40 has both functions as a gas ejection device and an electrode device. Note that the power supply 22 is
For example, 50W~4KW DC or 13.56MH
An alternating current high frequency power of z is applied to the metal casing 40. On the ceiling of the vacuum chamber 4, a flow rate regulating pulp 24 is installed.
A plurality of, for example seven, tip openings 28 of the pipe 26 are provided for completely introducing the gas containing silicon atom-containing molecules, the flow rate of which is regulated by the gas flow rate. In addition, what is shown by 60 is a flow rate adjusting pulp that is provided in the middle of the vibro and adjusts the flow rate of exhaust gas.

Next, the operation of the amorphous silicon I-grade nine body manufacturing apparatus and the method of the present invention will be described.

First, the vacuum chamber 4 is opened from the base 2 and the drum-shaped conductive substrate 16 is mounted on the drum holding device 12, and then the vacuum chamber 4 is airtightly mounted on the base 2. Next, the drum-shaped conductive substrate 16 is heated to 220° C. by the heater 18, and the pressure inside the vacuum chamber 4 is reduced to about 10 −6 Torr by the rotary pump 10FC. The exhaust system in the vacuum chamber 4 was replaced from the rotary pump 10 to the mechanical booster pump 8 K9J, and at the same time, the buff rev 2 was replaced.
6 open 100chi, 5 zH4 Ganugas 50 SCC
M is guided into the vacuum chamber 4. The SiH4 gas is
Pipe 26 drawn into the ceiling of vacuum chamber 4
The liquid is ejected from the tip opening 28 toward the base 2 and flows down between the metal casing 40 and the drum-shaped conductive substrate 16.

On the other hand, BF3 gas or PF5 gas as a dopant gas is guided through the microwave waveguide 46VC. BF3 gas i
l″lx, is used to form a p-type amorphous silicon film, and pF, gas is used to form a l-type amorphous silicon p7 film.

The microwave waveguide 46 includes, for example, 2450 AfH.
Microwaves of z are applied to complete the discharge in BF3 gas or PFs gas, producing a pre-excited plasma gas. The plasma gas is guided into the metal casing 40 via the gas introduction pipe 44, and is further introduced into the drum-shaped conductive substrate 1 through the gas ejection holes 42 in the metal casing 40.
6 is introduced between each other. 5tH4 in vacuum chamber 4
The gas and BF3 gas or PF5 gas are exhausted to the outside of the vacuum chamber 4 by a mechanical booster pump 8.

Therefore, the gas pressure inside the vacuum chamber 4 is s 0.4To
The flow control valves 24, 30, 48 and the mechanical booster pump 8 are adjusted so that γr is reached, and the drum holding device 12 is rotated by the drive device 14. For example, by applying a high voltage of 13.5 (S MHz) to the metal casing 40 and also grounding the drum-shaped conductive substrate 16, the distance between the metal casing 40 and the drum-shaped conductive substrate 16 is A potential gradient is formed, thereby causing a discharge, and a plasma gas containing silicon radicals is generated using 5tH4 gas.In the vacuum chamber 4, the pre-excited plasma gas is mixed with the plasma gas containing silicon radicals. When the mixed plasma gas comes into contact with the peripheral side of the drum-shaped conductive substrate 16, an amorphous silicon film doped with %B or P is formed.

When voltage application to the metal casing 40 is continued for 1 hour, 6 μm
A B- or nor-doped amorphous silicon film having a dark resistance of 10149α or more can be formed at a formation rate of /hour.

The formation rate of an amorphous silicon film using the conventional method is 2.
From 5 μb, an amorphous silicon film can be formed quickly.

Furthermore, since the dopant gas is pre-excited, the doping efficiency can be increased more than in conventional methods.

As mentioned above, the fluoride r of the doping atom
f pre-excitation can improve the doping efficiency and the formation rate of amorphous silicon film because
It is thought that this is because F radicals in the plasma gas generated by pre-excitation easily break all the bonds between Si and H on the amorphous silicon film that is being formed.

? By introducing a plasma gas formed by pre-exciting a dopant gas containing a fluoride of f, B, or P, it is possible to significantly improve the doping efficiency. The gas is ejected between the drum-shaped conductive substrates 16 from the gas ejection holes 42 of the metal casing 40, and the plasma gas contains fluorine radicals, thereby forming a potential gradient. Mutual 1 of drum-shaped conductive substrates 16
When the following reaction occurs, the drum-shaped conductive substrate 1
Silicon radicals can be generated at a high concentration between the two.

F +5tH4-→Another H,: ' + F Therefore,
Since the plasma gas having a high concentration of silicon radicals is differentiated around the entire circumference of the drum-shaped conductive substrate 16, an amorphous silicon film with uniform thickness and photosensitive characteristics is formed on the circumferential side of the drum-shaped conductive substrate 16. be able to.

Although the above embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and can be implemented with appropriate modifications within the scope of the gist of the invention. Needless to say.

In the above embodiments, the dopant gas is pre-excited by microwaves, but it may also be by applying electromagnetic waves such as radio waves or laser beams, or by applying alternating current power.

〔Effect of the invention〕

According to this invention, an amorphous silicon film doped with E, P, etc. can be rapidly formed with high doping efficiency by introducing a plasma gas prepared by pre-exciting a heptamide of the element to be doped.

[Brief explanation of the drawing]

FIG. 1 is a partial longitudinal cross-sectional view showing an amorphous silicon photoreceptor manufacturing apparatus directly used for carrying out the method of the present invention, and FIG. 2 is a partial cross-sectional view showing the amorphous silicon photoreceptor manufacturing apparatus. 4... Vacuum chamber, 16... Substrate, 40.
...Metal housing (electrode).

Claims (1)

Scope of Claims (11) The surface of the substrates is obtained by arranging a plurality of substrates in a certain direction in a reaction vessel, and forming a plasma state by introducing a gas having molecules containing silicon atoms into the reaction vessel. A method for forming an amorphous silicon film in which a fluoride-containing gas is pre-excited and introduced into the reaction vessel to create an amorphous silicon film. (2) Fluoride-containing gas But BF3 and PF5
2. The method for forming an amorphous silicon film according to claim 1, wherein the amorphous silicon film contains one or more fluorides selected from the group Yosunaru.