JP2637396B2 - Deposition film formation method - Google Patents

Description

The present invention relates to a functional film, particularly to an electronic device such as a semiconductor device, a photosensitive device for electrophotography, and a light input sensor device for an optical image input device. The present invention relates to a method for forming a functional deposited film useful for an application.

[Conventional technology]

Conventionally, amorphous or polycrystalline functional films such as a semiconductor film, an insulating film, a photoconductive film, a magnetic film, and a metal film have been individually formed from the viewpoints of desired physical properties and applications. The method has been adopted.

For example, if necessary, amorphous or polycrystalline non-single-crystal silicon (hereinafter “NON-Si (H)” in which unpaired electrons are compensated by a compensating agent such as a hydrogen atom (H) or a halogen atom (X). , X) ", among which" A-Si (H, X) "when indicating amorphous silicon and" poly-Si (H, X) "when indicating polycrystalline silicon. A silicon deposited film such as a film (microcrystalline silicon, which is commonly referred to as A-Si (H, X), needless to say fall within the category of A-Si) is formed by a vacuum deposition method. Plasma CVD, thermal CVD, reactive sputtering, ion plating, optical CVD, etc. have been attempted. In general, plasma CVD is widely used.
It has been commercialized.

[Problems to be solved by the invention]

However, the reaction process in forming a silicon deposition film by the plasma CVD method, which has been generally used in the past, is considerably complicated as compared with the conventional CVD method, and the reaction mechanism is unclear. Absent. In addition, there are many parameters for forming the deposited film (for example, substrate temperature, flow rate and ratio of introduced gas, pressure during formation, high-frequency power, electrode structure, structure of reaction vessel, exhaust speed, plasma generation method, etc.). Due to a combination of many parameters, the plasma sometimes becomes unstable and often has a significant adverse effect on the formed deposited film. In addition, it has been the reality that device-specific parameters must be selected for each device, making it difficult to generalize manufacturing conditions.

On the other hand, at present, it is considered best to form a silicon deposited film by a plasma CVD method in order to develop a silicon deposited film capable of sufficiently satisfying electrical and optical characteristics for each application.

However, depending on the application of the silicon deposited film, it is necessary to sufficiently satisfy the requirements of large area, uniform film thickness, and uniform film quality to achieve reproducible mass production.
In the formation of a silicon deposited film by the D method, a large amount of equipment investment is required for mass production equipment, and the management items for mass production are complicated, the management tolerance is narrow, and the adjustment of the equipment is delicate, These are pointed out as problems to be improved in the future.

In the case of the plasma CVD method, since plasma is directly generated by high frequency or microwave in a film formation space where a substrate on which a film is formed is arranged, generated electrons and a large number of ion species are generated. This causes damage to the film during the film formation process, which causes deterioration in film quality and unevenness in film quality.

A method proposed as an improvement in this respect is an indirect plasma CVD method.

In the indirect plasma CVD method, a plasma is generated by a microwave or the like at an upstream position away from the film formation space, and the plasma is transported to the film formation space, thereby selectively using chemical species effective for film formation. It was measured as possible.

However, even in such a plasma CVD method, since the transport of the plasma is essential, the life of the chemical species effective for film formation must be long, and naturally the gas species to be used is limited, and various types of gases are used. Problems such as the inability to obtain a deposited film, the need for a large amount of energy to generate plasma, and the fact that the generation and quantity of chemical species effective for film formation are essentially not under simple control. Is left behind.

Compared with the plasma CVD method, the optical CVD method is advantageous in that it does not generate ion species or electrons that damage the film quality at the time of film formation, but there are not so many types of light sources and the wavelength of the light source Is also biased toward ultraviolet light, a large light source and its power supply are required for industrialization, and the window for introducing light from the light source into the film formation space is coated during film formation. In other words, there is a problem that the light from the light source does not enter the film formation space.

As described above, there are still many points to be solved in the formation of a silicon deposited film, and mass production is performed by reducing energy consumption with low-cost equipment while maintaining its practical characteristics and uniformity. It is desired to develop a possible forming method. These problems can be cited as similar problems to be solved in other functional films such as a silicon nitride film, a silicon carbide film, a silicon oxide film, and a germanium-based film.

〔Purpose〕

An object of the present invention is to provide a novel method for forming a deposited film which does not rely on a conventional forming method, while eliminating the above-mentioned drawbacks of the deposited film forming method.

Another object of the present invention is to provide a method for forming a deposited film capable of easily conserving film quality and obtaining a deposited film having uniform characteristics over a large area while saving energy.

Still another object of the present invention is to provide a method for forming a deposited film, which is excellent in productivity and mass productivity, and which can easily obtain a high-quality film excellent in electrical, optical, semiconductor and other physical properties. is there.

[Means for solving the problem]

A method of forming a deposited film according to the present invention that achieves the above object is characterized in that a germanium-containing gas and a gaseous oxidant are mixed in a vacuum chamber to form a germanium oxide film.

[Action]

According to the method of forming a deposited film of the present invention described above, energy saving and large area, uniformity of film thickness and uniformity of film quality are sufficiently satisfied, and simplification of management and mass production are achieved. No capital investment is required, and the control items for mass production are clarified, the allowable range of control is wide, and the adjustment of the device is simplified.

In the method of forming a deposited film of the present invention, the gaseous raw material used for forming the deposited film used is subjected to an oxidizing action by chemical contact with a gaseous oxidizing agent, and the type of the intended deposited film is It is appropriately selected as desired according to characteristics, characteristics, applications, and the like. In the present invention, the above-mentioned gaseous raw material and gaseous oxidizing agent only need to be in a gaseous state when they come into chemical contact. No problem.

When the raw material or oxidizing agent for forming the deposited film is a liquid or a solid, use a carrier gas such as Ar, He, N ₂ , H ₂ , and perform bubbling while applying heat as necessary. A raw material and an oxidizing agent for forming a deposited film are introduced into the reaction space in a gaseous state.

At this time, the partial pressure and the mixing ratio of the gaseous raw material and the gaseous oxidizing agent are set by adjusting the flow rate of the carrier gas or the vapor pressure of the raw material for forming the deposited film and the gaseous oxidizing agent.

As a raw material for forming a deposited film used in the present invention, for example, a chain germanium compound or the like may be used as long as a tetrahedral-based deposited film such as a semiconductive or electrically insulating germanium deposited film is obtained. It can be cited as effective.

Ge _m H _{2m + 2} (m = 1,2,3,
4,5) and the like. In addition, tin hydride such as SnH ₄ can be cited as an effective raw material if a tin deposition film is formed, for example.

Of course, these raw materials can be used alone or in combination of two or more.

The oxidizing agent used in the present invention is gasified when introduced into the reaction space, and is effective only by chemical contact with the gaseous raw material for forming a deposited film which is simultaneously introduced into the reaction space. It has the property of oxidizing air, and oxygen, such as air, oxygen, ozone, etc., oxygen or nitrogen compounds such as N ₂ O ₄ , N ₂ O ₃ , N ₂ O, and H ₂ O _2, etc. Oxides and the like can be mentioned as effective ones.

These oxidizing agents are in a gaseous state, are given a desired flow rate and supply pressure together with the gas of the raw material for forming the deposited film, are introduced into the reaction space, and are mixed and collided with the raw material to chemically react. The precursor is brought into contact and oxidizes the raw material to efficiently generate a plurality of types of precursors including a precursor in an excited state. The generated excited state precursors and other precursors serve as sources of the components of the deposited film on which at least one of them is formed.

The generated precursor decomposes or reacts to form a precursor in another excited state or a precursor in another excited state, or emits energy as necessary but forms a film as it is A deposited film having a three-dimensional network structure is created by touching the surface of the substrate disposed in the space.

It is preferable that the energy level to be excited is an energy level accompanied by light emission in the process of the energy transition of the precursor in the excited state to a lower energy level or a change to another chemical species. By forming an activated precursor including an excited state precursor accompanied by light emission in such energy transition, the deposited film forming process of the present invention proceeds more efficiently, with more energy saving, and proceeds on the entire surface of the film. A deposited film that is uniform and has better physical properties throughout is formed.

In the present invention, the deposited film forming process proceeds smoothly, and a film having high quality and desired physical characteristics can be formed. The mixing ratio such as, the pressure during mixing, the flow rate, the internal pressure of the film forming space, the particle type of the gas, and the film forming temperature (substrate temperature) are appropriately selected as desired. These film formation factors are organically related and are not determined independently, but are determined according to each other in a mutual relationship. In the present invention, the ratio of the amount of the gaseous raw material and the amount of the gaseous oxidizing agent to be introduced into the reaction space for forming a deposited film depends on the relationship between the above-mentioned film forming factors and the related film forming factors. It is appropriately determined as desired, but the introduction flow ratio is preferably 1/100 to 100/1, and more preferably 1/50 to 50/1.

In order to stochastically increase the chemical contact between the gaseous raw material and the gaseous acid agent, the pressure at the time of mixing at the time of being introduced into the reaction space is preferably higher, but the reactivity is taken into consideration. It is better to determine the optimum value as needed.
The pressure at the time of the mixing is determined as described above, and the pressure at the time of each introduction is preferably 1 × 10 ⁻⁷ to 10 atm, more preferably 1 × 10 ^{−6 to} 3 atm. Is desirable.

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

When the film formation space is openly continuous with the reaction space, the internal pressure of the film formation space is determined by the introduction and flow rate in the reaction space between the base material for deposition film formation and the gaseous oxidant. In this regard, adjustment can be made by adding a device such as differential exhaust or use of a large exhaust device.

Alternatively, when the conductance at the connection between the reaction space and the film formation space is small, an appropriate exhaust device may be provided in the film formation space, and the pressure in the film formation space may be adjusted by controlling the exhaust amount of the device. I can do it.

If the reaction space and the film formation space are integrated, and the reaction position and the film formation position are only spatially different, differential exhaust as described above or a large exhaust The exhaust device may be provided.

As described above, the pressure in the film formation space is determined by the relationship between the gaseous raw material introduced into the reaction space and the introduction pressure of the gaseous halogen oxidizing agent, and is preferably 0.001 T
It is desirable that the pressure be in the range of orr to 100 Torr, more preferably 0.01 to 30 Torr, and most preferably 0.05 to 10 Torr.

Regarding the gas flow type, when the raw material for forming the deposited film and the oxidizing agent are introduced into the reaction space, they are uniformly and efficiently mixed, and the precursor (E) is efficiently formed. It is necessary to take into account the geometrical arrangement of the gas inlet, the base, and the gas outlet so that the film is formed and the film is formed appropriately without any trouble. One preferred example of this geometric arrangement is shown in FIG.

The substrate temperature (Ts) at the time of film formation is individually and appropriately set as desired according to the kind of gas used, the number of kinds of deposited film to be formed, and required characteristics. Is preferably from room temperature to 450 ° C, more preferably from 50 to 400 ° C. In particular, when a silicon deposited film having better properties such as semiconductor properties and photoconductivity is formed, the substrate temperature (Ts) is desirably 70 to 350 ° C. When a polycrystalline film is obtained, the temperature is preferably 200 to 650 ° C, more preferably 300 to 600 ° C.

As the atmosphere temperature (Tat) of the film formation space, the precursor (E) and the precursor (D) to be produced do not change into chemical species unsuitable for film formation, and the precursor (E) is efficiently used. ) Is appropriately determined as desired in relation to the substrate temperature (Ts) so as to produce (T).

The substrate used in the present invention may be conductive or electrically insulating as long as it is appropriately selected as desired according to the use of the deposited film to be formed. As the conductive substrate, for example, NiCr, stainless steel, Al, Cr, Mo,
Metals such as Au, Ir, Nb, Ta, V, Ti, Pt, and Pd and alloys thereof are exemplified.

As the electrically insulating substrate, a film or sheet of synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, etc., glass, ceramic, paper and the like are usually used. Preferably, at least one surface of these electrically insulating substrates is subjected to a conductive treatment, and another layer is provided on the conductive-treated surface side.

For example, in the case of glass, the surface is NiCr, Al, Cr, M
o, Au, Ir, Nb, Ta, V, Ti, Pt, Pd, In ₂ O ₃ , SnO ₂ , IT
Conductive treatment by providing a thin film such as O (In ₂ O ₃ + SnO ₂ ) or a synthetic resin film such as a polyester film such as NiCr, Al, Ag, Pb, Zn, Ni, Au, Cr, Mo,
A metal such as Ir, Nb, Ta, V, Ti, or Pt is processed by vacuum evaporation, electron beam evaporation, sputtering, or the like, or is laminated with the metal, and the surface is subjected to a conductive treatment. The shape of the support may be any shape such as a cylindrical shape, a belt shape, and a plate shape, and the shape is determined as desired.

The substrate is preferably selected from the above in consideration of adhesion and reactivity between the substrate and the film. Further, if the difference between the two thermal expansions is large, a large amount of strain is generated in the film, and a film of good quality may not be obtained. Is preferred.

Further, since the surface condition of the substrate is directly related to the structure (orientation) of the film and the generation of a cone-shaped structure, it is necessary to treat the surface of the substrate so as to have a film structure and a film structure with desired characteristics. Is desirable.

FIG. 1 shows an example of an apparatus suitable for implementing the method of forming a deposited film 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 formation space.

101 to 108 are cylinders filled with gas used for film formation, 101a to 108a are gas supply pipes,
101b-108b are mass flow controllers for adjusting the flow rate of gas from each cylinder, 101c-108c are gas pressure gauges, 101d-108d and 101e-108e are valves, 101f-10
8f is a pressure gauge indicating the pressure in the corresponding gas cylinder.

Reference numeral 120 denotes a vacuum chamber having a structure in which a gas introduction pipe is provided at an upper portion thereof, and a reaction space is formed downstream of the pipe.
Has a structure in which a film-forming space in which the base holder 112 is provided is formed such that the substrate is installed. Piping for introducing scum
It has a triple concentric arrangement, with a gas cylinder 10
A first gas introduction pipe 109 into which gases from 1,102 are introduced, a second gas introduction pipe 110 into which gases from gas cylinders 103 to 105 are introduced, and a third gas into which gases from gas cylinders 106 to 108 are introduced. It has a gas introduction pipe 111.

The gas is introduced into the reaction space of each gas inlet tube so that the inner side of the tube is located farther from the surface of the substrate as the position becomes closer to the inner tube. That is, the respective gas introduction pipes are arranged so as to surround the inner pipe as the outer pipe becomes closer.

The supply of gas from the pipe cylinders to the respective inlet pipes is performed by gas supply pipelines 123 to 125, respectively.

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

The substrate 118 is set at a desired distance from the position of each gas introduction tube by moving the substrate 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 tube is in an appropriate state in consideration of the type of deposited film to be formed and its desired characteristics, gas flow rate, internal pressure of the vacuum chamber, and the like. It is preferably determined as
cm, more preferably about 5 mm to 15 cm.

113 heats the substrate 118 to an appropriate temperature during film formation,
Alternatively, the substrate 118 is pre-heated during film formation, and further,
This is a substrate heating heater that heats the film after film formation to anneal the film.

Electric power is supplied to the base heater 113 from a power supply 115 through a conductive wire 114.

Reference numeral 116 denotes a thermocouple for measuring the temperature of the substrate temperature (Ts), which is electrically connected to the temperature display device 117.

 Hereinafter, the present invention will be described specifically with reference to examples.

Reference Example 1 Using the film forming apparatus shown in FIG. 1, a deposited film was formed by the method of the present invention as follows.

The SiH ₄ gas filled in the cylinder 101 was flowed at a flow rate of 20 sccm from the gas introduction pipe 109, the O ₂ gas filled in the cylinder 106 was flowed at ₂ sccm, and the He gas filled in the cylinder 107 was flowed at a flow rate of 4
The gas was introduced into the vacuum chamber 102 from the gas introduction tube 111 at 0 sccm.

At this time, the pressure in the vacuum chamber 120 is reduced by the vacuum valve 1
The opening / closing degree of 19 was adjusted to 100 mTorr. Quartz glass (15 cm × 15 cm) was used as the substrate, and the distance between the gas inlet 111 and the substrate was set to 3 cm. The pale emission was strongly observed in the mixed castle of SiH ₄ gas and F ₂ gas. The substrate temperature (Ts) was set between room temperature and 400 ° C. for each sample as shown in Table 1.

When gas was flowed for 3 hours in this state, Si: O: H having a film pressure as shown in Table 1 was deposited on the substrate.

Next, Table 2 shows the film pressure of each sample when the substrate temperature was fixed at 300 ° C. and the flow rate of SiH ₄ was varied.

At this time, the gas flow time was 3 hours for each sample. In addition, each sample had an O ₂ gas flow rate of ₂ sccm and a He gas flow rate of 4 sccm.
The pressure was 0 sccm and the internal pressure was 100 mTorr.

Next, the substrate temperature was set to 300 ° C., the flow rate of the SiH ₄ gas was set to 20 sccm, the flow rate of the O ₂ gas was set to ₂ sccm, the inner thickness was set to 100 mTorr. Table 3 shows the film thickness values.

Next, Table 4 shows the values of the film thickness of each sample prepared by setting the substrate temperature at 300 ° C., the flow rate of the SiH ₄ gas at 20 sccm, the flow rate of the O ₂ gas at ₂ sccm, and the flow rate of the He gas at 10 sccm and changing the internal pressure variously.

The uneven thickness distribution of each sample shown in Tables 1 to 4 depended on the distance between the gas introduction pipe 111 and the substrate, the gas flow rate flowing through the gas introduction pipes 109 and 111, and the internal pressure. In each film formation, by adjusting the distance between the gas introduction pipe and the substrate, the unevenness of the film thickness distribution is obtained.
On a 15 cm × 15 cm substrate, it could be kept within ± 5%. This position almost always corresponded to the position where the emission intensity was the highest. In addition, it was confirmed from the results of electron beam diffraction that the formed Si: H: F films were amorphous.

Further, a comb electrode of Al (gab length: 200 μm) was deposited on the amorphous Si: O: H film of each sample to prepare a sample for conductivity measurement. Put each sample in vacuum cryostat and apply voltage
Applying 100V, measuring the current with a microammeter (YHP4140B) and trying to find the conductivity (σd), but below the measurement limit, the conductivity at room temperature was estimated to be 10 ^-14 s / cm or less. Was done.

Example 1 A film was formed by introducing GeH ₄ gas from a 104 cylinder instead of introducing SiH ₄ gas in Reference Example 1 (Sample 4).

 The film forming conditions at this time are as follows.

GeH ₄ 20sccm O ₂ 5sccm He 40sccm inner pressure 100mTorr After gas blowing distance 3 cm 3 hours with the substrate temperature 300 ° C. Gas outlet and the substrate, about on a quartz glass substrate 3000
The A-Ge: O: H film of Å was deposited. It was confirmed by electron beam diffraction that the film was amorphous.

On the A-Ge: O: H film, a comb electrode of Al (gap length 200
μm) was placed in a vacuum cryostat, and the dark conductivity (σd) was measured.

Reference Example 2 A film was formed by introducing SiH ₄ gas and introducing GeH ₄ gas from a 104 cylinder in Reference Example 1 (Sample 3).

 The film forming conditions at this time are as follows.

_{SiH 4 20sccm GeH 4 5sccm O 2} 5sccm He 40sccm inner pressure 100mTorr After gas blowing distance 3 cm 3 hours with the substrate temperature 300 ° C. Gas outlet and the substrate, about on a quartz glass substrate 5000
The A-SiGe: O: H film of Å was deposited. It was confirmed by electron beam diffraction that the film was amorphous.

On the A-SiGe: O: H film, a comb electrode of Al (gap length 20
0 μm) was vacuum-deposited, sample 5 was placed in a vacuum cryostat, and the dark conductivity (σd) was measured.

Reference Example 3 A film was formed by introducing C ₂ H ₄ gas from a 105 cylinder instead of introducing GeH ₄ gas in Reference Example 2 (Sample 6).

 The film forming conditions at this time are as follows.

_{SiH 4 20sccm C 2 H 4 5sccm} O 2 5sccm He 40sccm inner pressure 100mTorr After gas blowing distance 3 cm 3 hours with the substrate temperature 300 ° C. Gas outlet and the substrate, about on a quartz glass substrate 1.0
A μm A-Si: C: O: H film was deposited. It was confirmed by electron beam diffraction that the film was amorphous.

On the A-Si: C: O: H film, a comb electrode of Al (gap length 20
0 μm) was vacuum-deposited, the sample 6 was placed in a vacuum cryostat, and the dark conductivity (σd) was measured.

〔effect〕

According to the above detailed description and each embodiment, according to the deposited film forming method of the present invention, it is possible to obtain a deposited film having uniform physical characteristics over a large area while saving energy and easily controlling the film quality. Further, it is possible to easily obtain a film which is excellent in productivity and mass productivity, high in quality, and excellent in physical properties such as electrical, optical and semiconductor properties.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a film forming apparatus used in an embodiment of the present invention. 101-108 Gas cylinder 101a-108a Gas introduction pipe 101b-108b Mass flow meter 101c-108c Gas pressure gauge 101d-108d and 101e-108e Valve 101f-108f Pressure gauge 109,110,111 ... gas inlet tube 112 ... substrate holder 113 ... substrate heating heater 116 ... substrate temperature monitoring thermocouple 118 ... substrate 119 ... vacuum evacuation valve

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-76870 (JP, A) JP-A-59-41842 (JP, A) JP-B-39-2426 (JP, B2)

Claims (5)

(57) [Claims] 1. A germanium oxide film is formed by forming a precursor in an excited state by oxidizing the on-chain germane compound by making chemical contact by mixing and collision of a chain germane compound gas and an oxygen-containing gas. Forming a deposited film. 2. The chain germane compound gas is GeH4, Ge2.
2. The method according to claim 1, wherein the method is one selected from H6, Ge3H8, Ge4H10, and Ge5H12. 3. The method according to claim 1, wherein said oxygen-containing gas is one selected from the group consisting of air, oxygen, and ozone. 4. The method according to claim 1, wherein said oxygen-containing gas is nitrogen oxide. 5. The method according to claim 1, wherein said oxygen-containing gas is a peroxide.