JPS62224673A - Formation of deposited film - Google Patents

Abstract

PURPOSE:To economize on energy and to make characteristics uniform by specifying the intensity ratio of the light emitted by Si-H and Si-halogen in a method for bringing a gaseous raw material contg. Si and H atoms and gaseous halogen oxidizing agent into contact with each other in a reaction space. CONSTITUTION:For example, gaseous SiH4 filled in a cylinder 101 is introduced from an introducing pipe 109 into a vacuum chamber 120, and F2, H2 respectively filled in cylinders 106, 107 are introduced from an introducing pipe 111 into the vacuum chamber 120, respectively at prescribed flow rates. The pressure in the chamber 120 is adjusted to a prescribed degree of vacuum by regulating the opening degree of a vacuum valve 119. SiH4 receives an oxidation effect by the contact with F2 and forms plural precursors including the precursors in an excited state by accompanying the light emission. A deposited film is formed on a substrate 118 kept at a prescribed temp. with such precursors as the supply source for the element to constitute the deposited film. The intensity ratio (Si-H)/(Si-X) between the light emitted by the Si-H and the light emitted by the Si-X (X: halogen) is kept at <=1 in this stage.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to functional films, particularly electronic devices such as semiconductor devices, photosensitive devices for electronic photography, and optical input sensor devices for optical image input devices. The present invention relates to a method for forming a functional deposited film useful for applications.

[Conventional technology]

Conventionally, amorphous or polycrystalline functional films such as semiconductor films, insulating films, photoconductive films, magnetic films, or metal films have been formed by forming films that are individually suited from the viewpoint of desired physical properties and applications. method has been adopted.

For example, if necessary, amorphous or polycrystalline non-single crystal silicon (rNON-Si (H,
X) J,! : Abbreviation shi, especially rA-Si (H,
i (H,
, X) can be formed using vacuum deposition method, plasma CVD method, and thermal CVD method.

Reactive sputtering method, ion blating method, optical C
VD method etc. have been tried, and generally plasma C
The VD method is widely used and commercialized.

[Problem that the invention seeks to solve]

However, the reaction process in forming silicon deposited films by the conventionally popular plasma CVD method is considerably more complicated than that of the conventional CVD method, and there are still many unknowns about the reaction mechanism. do not have. In addition, there are many formation parameters for the deposited film (for example, substrate temperature, flow rate and ratio of introduced gas, etc.).

Due to the combination of these many parameters (pressure during formation, high frequency power, electrode structure 1 reaction vessel structure, pumping speed, plasma generation method, etc.), the plasma sometimes becomes unstable and the formed deposited film This often had a significant negative impact on Moreover, it is necessary to select device-specific parameters for each device, making it difficult to generalize manufacturing conditions.

On the other hand, in order to develop a silicon deposited film that satisfies the electrical and optical properties for each application, it is currently considered best to form it by plasma CVD.

However, depending on the application of silicon deposited films, plasma CV
Forming a silicon deposited film using the D method requires a large investment in equipment for mass production, and the management items for mass production are also complex, the tolerance for management is narrow, and the adjustment of the equipment is delicate. For these reasons, these have been pointed out as problems that should be improved in the future.

In addition, in the case of plasma CVD method, since plasma is directly generated by high frequency waves or microwaves in the film forming space where the substrate to be film is placed, the generated electrons and many ion species are This causes damage to the film during the formation process, causing deterioration of film quality and non-uniformity of film quality.

An indirect plasma CVD method has been proposed as an improvement in this respect.

In the indirect plasma CVD method, plasma is generated using microwaves or the like at an upstream position far from the film-forming space, and the plasma is transported to the film-forming space to selectively select chemical species that are effective for film-forming. It was designed to be usable.

However, since the plasma CVD method also requires plasma transport, the lifetime of the chemical species effective for film formation must be long, which naturally limits the types of gases that can be used, and Problems include the inability to obtain a film, the need for a large amount of energy to generate plasma, and the fact that the generation and amount of chemical species effective for film formation cannot be easily controlled. There are some leftovers.

The photo-CVD method has an advantage over the plasma CVD method in that it does not generate ion species or electrons that can damage the film quality, but it does not have as many types of light sources and is The wavelength is also biased toward ultraviolet, a dog-shaped light source and its power source are required for industrialization, and the window that introduces the light from the light source into the deposition space is covered with a film during deposition. Another problem is that the optical density decreases, and even more so, the light from the light source no longer enters the film forming space.

As mentioned above, there are still many issues to be solved regarding the formation of silicon deposited films, and it is important to mass-produce them using low-cost equipment that saves energy while maintaining its practical properties and uniformity. There is a strong desire to develop a forming method that can do this. These problems can be cited as similar problems to be solved in other functional films, such as silicon nitride films, silicon carbide films, and silicon oxide films.

〔the purpose〕

An object of the present invention is to eliminate the disadvantages of the above-mentioned deposited film forming method, and at the same time to provide a novel deposited film forming method that does not rely on conventional forming methods.

Another object of the present invention is to provide a method for forming a deposited film that saves energy, allows easy control of film quality, and provides a deposited film with uniform characteristics over a large area.

Still another object of the present invention is to provide a method for forming a deposited film that is highly productive and mass-producible, and can easily produce a film with high quality and excellent physical properties such as electrical, optical, and semiconductor properties. be.

[Means to solve the problem]

The method for forming a deposited film of the present invention that achieves the object described in item L includes a gaseous raw material containing at least silicon atoms and hydrogen atoms for forming a deposited film, and a gaseous raw material having the property of oxidizing the raw material. By introducing a halogen-based oxidizing agent into the reaction space and bringing it into contact, a plurality of precursors including a plurality of precursors including excited state precursors are generated with light emission, and at least one of these precursors is produced. In a deposited film forming method in which a deposited film is formed on a substrate in a film forming space using one precursor as a source of deposited film constituent elements, light emission due to Si-H and emission due to Si-X (X: halogen atom) are detected. Emission intensity ratio ([
It is characterized in that S i -H]/[S i-X]) is set to 1 or less.

[Effect]

According to the deposited film forming method of the present invention described above, it is possible to save energy, increase the area, uniformity of film thickness, and uniformity of film quality, simplify management and mass production, and save a lot of money on mass production equipment. It does not require major capital investment, the control items for mass production become clear, the control tolerance is wide, and equipment adjustment becomes easy.

In the deposited film forming method of the present invention, the gaseous raw material for deposited film formation used contains at least silicon atoms and hydrogen atoms, and further has an oxidizing effect upon contact with a gaseous halogen-based oxidizing agent. Uke, Si-Hc7) Luminous S E
It emits light of X (X: halogen atom), and is appropriately selected depending on the type, characteristics, intended use, etc. of the desired deposited film. In the case of non-invention, the above-mentioned gaseous raw materials and base halogen-based oxidizing agent may be those that are made into a gaseous state upon chemical contact, and in normal cases, they may be gaseous, liquid, or solid. There is no problem even if it is.

When the raw material for forming a deposited film or /\\rogen-based acid oxidizing agent is liquid or solid, Ar.

Use a carrier gas such as He, N2, H2, etc.

If necessary, bubbling is performed while applying heat to introduce the raw material for forming the deposited film and the halogen-based oxidizing agent in gaseous form into the reaction space.

At this time, the partial pressure and mixing ratio of the gaseous raw material and the gaseous/\halogen-based acid oxidizing agent are adjusted by adjusting the flow rate of the carrier gas or the pressure of the raw material and the gaseous halogen-based oxidizing agent for forming the deposited film. It is set by

As the raw materials for forming the deposited film used in the present invention, for example, in order to obtain a semiconductor or electrically insulating silicon deposited film, linear and branched chain silane compounds, Effective examples include cyclic silane compounds.

Specifically, the linear silane compound is SinH2n.
+2 (n=1.2.3,4,5°6.7.8), branched chain silane compound is SiH3SiH (SiH3
) SiH2SiH3 and the like.

Of course, these raw materials can be used not only alone, but also as a mixture of two or more.

The halogen-based oxidizing agent used in the present invention is in a gaseous state when introduced into the reaction space, and is simultaneously introduced into the reaction space through chemical contact with the gaseous raw material for forming a deposited film. It has the property of effectively oxidizing, and F2
, Fci.

Cu2. Br2. Examples include halogen gases such as I2.

These halogen-based oxidizing agents are gaseous, and the above-mentioned deposits 1! i
It is introduced into the reaction space together with the gas of the raw material material for film formation, given a desired flow rate and supply pressure, and is brought into contact with the raw material material by mixing and colliding, thereby oxidizing the raw material material and bringing it into an excited state. effectively produce multiple types of precursors, including precursors of The excited state precursors and other precursors that are generated serve as a source of components for the deposited film in which at least one of them is formed.

The precursors produced may decompose or react to form another excited state precursor or a precursor in another excited state, or may be formed in that form, releasing energy if necessary. A deposited film with a three-dimensional network structure is created by touching the surface of the substrate disposed in the film space.

As the energy level is excited, the excited state precursor undergoes an energy transition to a lower energy level. Alternatively, the energy level is preferably one that accompanies luminescence in the process of changing into another chemical species. By forming activated precursors including excited state precursors that are accompanied by light emission due to such energy transition, the deposited film forming process of the present invention proceeds more efficiently and with more energy savings.
A deposited film is formed that is uniform over the entire surface of the film and has better physical properties.

A deposited film is formed by bringing a gaseous raw material for forming a deposited film (containing at least silicon atoms and hydrogen atoms) into contact with a gaseous/\rogen-based acid oxidizing agent having the property of oxidizing the gaseous raw material. In this case, taking the reaction of SiH4 and F2 as an example, it is known that the oxidation reaction of SiH4 with F2 includes the following process.

S i H2+ F + S iH* + HF
(1) SiH+F2→SiF)lc+HF
(2) Si+F2 →S i F)+C+F
C3) (*marks indicate luminescent species) In this way, the oxidation of SiH4 by F2 is the oxidation of S by F2.
Hydrogen is extracted from iH4, and then an exchange reaction of SiH hydrogen with fluorine, etc. occurs.

If the reaction between SiH+ and F2 progresses and SiH4 is oxidized to SiF4, SiF4 will not be deposited, so a deposited film cannot be obtained.

Therefore, it is important to control the progress of the oxidation reaction.

In the present invention, SiH and SiX (x:
As a result of intensive experiments and research focusing on the fact that halogen atoms (halogen atoms) emit light, it was discovered that the emission ratio of SiH and SiX has an important effect on the characteristics and reproducibility of the deposited film.

In order to obtain a deposited film with good quality characteristics with good reproducibility.

Emission ratio of SiH and SrX ([SiH]/[SiX
]) is preferably 1 or less, more preferably 0.8 or less, and optimally 0.5 or less.

In the present invention, the type and combination of raw material and halogen-based oxidizing agent are used as film-forming factors so that the deposited film forming process can proceed smoothly and a film with high quality and desired physical properties can be formed.

These mixing ratios, pressure during mixing, flow rate, internal pressure of film forming space,
The waveform of the gas and the film forming temperature (substrate temperature and ambient temperature) are appropriately selected as desired.

These film-forming factors are organically related and are not determined independently, but are determined depending on each other in relation to each other.

In the present invention, the ratio between the gaseous raw material for forming a deposited film and the gaseous halogen-based oxidizing agent introduced into the reaction space is determined depending on the relationship with the relevant film-forming factors among the above-mentioned film-forming factors. Although it can be determined as desired, the ratio of introduced flow coral is preferably 1/100 to 100/1, more preferably 1150 to 50/1.

The pressure at the time of mixing when introduced into the reaction space is preferably as high as 1, in order to increase the probability of chemical contact between the gaseous raw material and the gaseous/\rogen-based oxidant. The appropriate value should be determined as desired in consideration of the reactivity. The pressure at the time of mixing is determined as described above, but the pressure at the time of each introduction is preferably lXl0- 7 atm to 10 atm, more preferably I
It is desirable that the pressure is between 10' and 3 atmospheres.

The pressure in the film-forming space, that is, the pressure in the space where the substrate on which the film is to be formed is disposed, is the pressure of the excited state precursor (E) generated in the reaction space and, if necessary, the precursor. The precursor (D) derived from the body (E) is appropriately set as desired so as to effectively contribute to the formation of n.

When the film forming space is open and continuous with the reaction space, the internal pressure of the film forming space is determined by the introduction of the substrate-like raw material for forming the deposited film and the gaseous halogen-based oxidizing agent into the reaction space. In relation to the flow rate, it is possible to adjust the amount by adding measures such as using differential exhaust or a large exhaust device.

Alternatively, if the conductance of the connection between the reaction space and the film-forming space is small, an appropriate exhaust system may be provided in the film-forming space.
By controlling the exhaust volume of the device, the pressure in the film forming space can be adjusted.

In addition, if the reaction space and film-forming space are integrated and the reaction position and film-forming position are only spatially different, use differential pumping as in the previous example, or use a large-scale pump with sufficient exhaust capacity. It is best to install an exhaust system.

As described above, the pressure in the film forming space is determined based on the relationship between the gaseous raw material introduced into the reaction space and the introduction pressure of the gaseous halogen oxidizing agent, but is preferably 0.00.
It is desirable that the torque is 1 Torr to 100 Torr, more preferably 0.0 ITorr to 30 Torr, and optimally 0.05 to 10 Torr.

Regarding the flow rate of the gas, when introducing the raw material for forming the deposited film and/\\rogen-based oxidizing agent into the reaction space, these are uniformly and efficiently mixed, and the precursor (E) is efficiently The geometrical arrangement of the gas inlet, the substrate, and the gas outlet must be designed in consideration of the geometrical arrangement of the gas inlet, the substrate, and the gas outlet so that the gas can be generated and the film can be formed properly without any problems. One preferred example of this geometry is shown in FIG.

The substrate temperature (Ts) during film formation is set individually as desired depending on the type of gas used and the integer and required characteristics of the deposited film to be formed. When obtained, the temperature is preferably from room temperature to 450°C, more preferably from 50 to 400°C. In particular, silicon deposition with better properties such as semiconductivity and photoconductivity +1/
When forming J, the substrate temperature (Ts) is 70 to 35
It is desirable that the temperature be 0°C. Further, when obtaining a polycrystalline film, the temperature is preferably 200 to 650°C, more preferably 300 to 600°C.

The atmospheric temperature (T a t ) in the film forming space is set so that the precursor (E) and the precursor (D) to be produced do not change into chemical species unsuitable for film formation, and the precursor is efficiently (
E) is determined as desired in relation to the substrate temperature (Ts).

The substrate used in the present invention may be electrically conductive or electrically insulating, as long as it is selected as desired depending on the use of the deposited film to be formed. , for example, NiCr, stainless steel, Ai, Cr
, Mo.

Au, Ir, Nb, Ta, V, Ti, Pt.

Examples include metals such as Pd and alloys thereof.

Polyester is used as the electrically insulating substrate.

Polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride.

Films or sheets of synthetic resins such as polyvinylidene chloride, polystyrene, polyamide, etc., and glass.

Ceramic, paper, etc. are commonly used. Preferably, at least one surface of these electrically insulating substrates is subjected to a conductive treatment, and another layer is preferably provided on the conductive treated surface side.

For example, if it is glass, its surface is NiCr.

Au, Cr, Mo, Au, Ir, Nb, Ta
.

V, Yi, Pt, Pd, In2O3,5n02゜I
TO(I n203+5n02) etc. c7) 14 If it is conductive treated by providing a film, or if it is a synthetic resin film such as polyester film, NiCr, AM,
Ag, Pb, Zn, Ni.

Au, Cr, Mo, Ir, Nb, Ta, V.

The surface is treated with a metal such as Ti or Pt by vacuum deposition, electron beam deposition, sputtering, etc., or laminated with the metal, and the surface thereof is subjected to conductive treatment. The shape of the support may be any shape, such as a cylinder, a belt, or a plate, and the shape is determined according to desire.

It is preferable to select the substrate from among the above in consideration of the adhesion and reactivity between the substrate and the film. Furthermore, if the difference in thermal expansion between the two is large, a large amount of distortion will occur in the film, making it difficult to obtain a good quality film. Therefore, it is preferable to select and use a substrate whose thermal expansion difference is close to that of the two substrates.

Furthermore, since the surface condition of the substrate is directly related to the structure (orientation) of the film and the generation of cone-shaped structures, the surface of the substrate is treated to obtain a film structure and structure that provides the desired properties. is desirable.

FIG. 1 shows an example of an apparatus suitable for implementing the deposited film forming method of the present invention.

The deposited film forming apparatus shown in FIG. 1 is roughly divided into three parts: an apparatus main body, an exhaust system, and a gas supply system.

The apparatus main body is provided with a reaction space and a film forming space.

101 to 108 are cylinders filled with gas used for film formation, 101a to 108a are gas supply pipes, 101b to 108b are mass flow controllers for adjusting the flow rate of gas from each cylinder, and 101C.
~108c are gas pressure gauges,told~108d
and 101e to 108e are valves, 101f-1
08f is a pressure gauge that indicates the pressure inside the corresponding gas cylinder.

Reference numeral 120 denotes a vacuum chamber, which has a structure in which a gas introduction pipe is provided at the upper part and a reaction space is formed downstream of the pipe.
It has a structure in which a film forming space is formed in which a substrate holder 112 is provided such that a substrate holder 18 is installed therein. The gas introduction pipes have a triple concentric arrangement structure, with a first gas introduction pipe 109 into which gas from gas cylinders 101 and 102 is introduced, and a second gas introduction pipe into which gas from gas cylinders 103 to 105 is introduced. gas introduction pipe 110 and gas cylinder 1
It has a third gas introduction pipe 111 into which gases from 06 to 108 are introduced.

Each gas introduction tube is designed to discharge gas into the reaction space so that the inner tube is located further away from the surface of the substrate. That is, the gas introduction pipes are arranged so that the outer pipes surround the inner pipes.

Gas is supplied from the tube cylinder to each introduction pipe through gas supply pipelines 123 to 125, respectively.

Each gas introduction pipe, each gas supply pipeline, and the vacuum chamber 120 are evacuated via the main vacuum valve 119 by a vacuum evacuation device (not shown).

The base body 118 is installed at a desired distance from the position of each gas introduction pipe by moving the base body holder 112 up and down.

In the case of the present invention, the distance between the substrate and the gas outlet of the gas inlet pipe is determined appropriately by taking into consideration the type of deposited film to be formed, its desired characteristics, gas flow rate, internal pressure of the vacuum chamber, etc. It can be determined as desired, but preferably several mm to 2
It is more preferably about 5 mm to 15 cm than 0 cm.

113 is a substrate heating process that heats the substrate 118 to an appropriate temperature for film formation, or preheats the substrate 118 before film formation, or further heats the film after film formation to anneal the film. It's a heater.

The base heater 113 is connected to the TL source 11 by a conductive wire 114.
Power is supplied by 5.

116 is a thermocouple for measuring the substrate temperature (Ts), and is electrically connected to the temperature display device 117.

The light emitted by the oxidation reaction between the raw material gas for forming the deposited film and the halogen-based oxidizing agent is analyzed by an emission spectrometer 127 through a window 126 and monitored.

Hereinafter, the present invention will be specifically explained according to Examples.

Example 1 Using the film forming apparatus shown in FIG. 1, a deposited film was produced by the method of the present invention under the conditions shown in Table 1 as follows.

The SiH4 gas filled in the cylinder 101 has a flow rate of 20
The F2 gas filled in the cylinder 106 is supplied from the gas introduction pipe 109 at a flow rate of 10105c to the cylinder 107.
The F2 gas filled in the chamber was introduced into the vacuum chamber 102 through the gas introduction pipe 111 at a flow rate of 500 seconds.

At this time, the pressure inside the vacuum chamber 120 was adjusted to 400 mTorr by adjusting the opening/closing degree of the vacuum valve 119. A quartz glass (15 cm x 15 cm) was used as the base, and the distance between the gas inlet ill and the base was set to 3 cm. In this way, the ratio of the Si-H emission to the SiF emission was set to 0.1.

The substrate temperature (Ts) was set at 300'0.

When gas is flowed in this state for 3 hours, a film of S with a thickness of 2.0 μm is formed.
i:H:Fff! ! was deposited on the substrate.

Furthermore, the unevenness in film thickness distribution was within ±5%. It was confirmed by electron beam diffraction that the formed St:H:F films were amorphous in all samples.

Furthermore, when the ESR of the deposited Si:H:F film was measured, the spin density was -5X 10164/cm',
The local level density was sufficient for practical use.

Example 2 As in Example 1, a second film was formed using the film forming apparatus shown in FIG.
A 2.0 μm thick Si:H:F film was deposited on the substrate under the conditions shown in the table.

ESR measurements were performed on each St:H:F film,
The results shown in Table 3 were obtained.

〔effect〕

From the detailed explanations and examples below, it is clear that the deposited film forming method of the present invention saves energy, makes it easy to control film quality, and produces deposited films with uniform physical properties over a large area with reproducibility. Good results. Furthermore, it is possible to easily obtain high-quality films with excellent physical properties such as electrical, optical, and semiconductor properties due to productivity and mass production.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a film forming apparatus used in an example of the present invention. 101 to 108------------Gas cylinder, 101 a -108a----1------
Gas inlet pipe, 101b to 108b------Mass flow meter, 101c -108c---------
----- Gas pressure gauge. 101d-108ci and 101e-108e
-Valve, 101f~108f--1------
--------Pressure gauge, 109, 110, 111-1------Gas introduction tube, 112-------
-----------Substrate holder, 113---
-----------Heater for heating one substrate, 11
6-------Thermocouple for monitoring substrate temperature, 1
18----------1------------
-------- Monosubstrate. 119------------------- One vacuum exhaust valve, 126--------------
−−−−−−−−−−−−−−−−−−127−−−−−
−−−−−−−−−−−−−−−−−−−Emission spectrometer,
respectively.

Claims (14)

[Claims] (1) A gaseous raw material containing at least silicon atoms and hydrogen atoms for forming a deposited film, and a gaseous halogen-based oxidizing agent having a property of oxidizing the raw material are introduced into the reaction space. A plurality of precursors including excited state precursors are generated with light emission by bringing them into contact with each other, and at least one of these precursors is used as a source of a deposited film component in a deposition space. In the layered film formation method that forms a deposited film on a certain substrate, light emission due to Si-H and Si-X
(X: halogen atom) intensity ratio of light emission ([Si-H
]/[Si-X]) is 1 or less. (2) The deposited film forming method according to claim 1, wherein the gaseous raw material is a chain silane compound. (3) The deposited film forming method according to claim 2, wherein the chain silane compound is a linear silane compound. (4) The linear silane compound has the general formula Si_nH_
The deposited film forming method according to claim 3, which is represented by 2_n_+_2 (n is an integer from 1 to 8). (5) The deposited film forming method according to claim 2, wherein the chain silane compound is a branched chain silane compound. (6) The deposited film forming method according to claim 1, wherein the gaseous raw material is a silane compound having a silicon ring structure. (7) The deposited film forming method according to claim 1, wherein the gaseous halogen-based oxidizing agent contains halogen gas. (8) The deposited film forming method according to claim 1, wherein the gaseous halogen-based oxidizing agent contains fluorine gas. (9) The deposited film forming method according to claim 1, wherein the gaseous halogen-based oxidizing agent contains chlorine gas. (10) The deposited film forming method according to claim 1, wherein the gaseous halogen-based oxidizing agent is a gas containing fluorine atoms as a constituent component. (11) The deposited film forming method according to claim 1, wherein the gaseous halogen-based oxidizing agent contains halogen in a nascent state. (12) The deposition according to claim 1, wherein the substrate is disposed at a position opposite to the direction in which the gaseous raw material and the gaseous halogen-based oxidizing agent are introduced into the reaction space. Film formation method. (13) The deposited film forming method according to claim 1, wherein the gaseous raw material and the gaseous halogen-based oxidizing agent are introduced into the reaction space from a transport pipe having a multi-tube structure. (14) Deposited film formation according to claim 1, wherein the gaseous raw material and the gaseous halogen-based oxidant are diluted with an inert gas H_2 gas and N_2 gas and introduced into the reaction space. Law.