JPH0645887B2 - Deposited film formation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amorphous or crystalline functional thin film such as a semiconductor film, an insulator film, and a conductor film, particularly an active or passive semiconductor device, The present invention relates to a method for forming a deposited film that is useful for applications such as optical semiconductor devices, solar cells, and photosensitive devices for electrophotography.

A vacuum deposition method, a plasma CVD method, a thermal CVD method, an optical DVD method, a reactive sputtering method, an ion plating method, and the like have been tried for forming the deposited film, and the plasma CVD method is generally widely used. Have been commercialized.

However, since the deposited films obtained by these deposited film forming methods are required to be applied to electronic devices and optoelectronic devices that require higher functions, electrical and optical characteristics and repeated use There is room to improve the overall characteristics in terms of fatigue characteristics, usage environment characteristics, and productivity and mass productivity including uniformity and reproducibility.

Among them, for example, in the case of a chalcogenide film, it is currently the best to form it by a heating vacuum evaporation method in that it can express what has electrical and optical characteristics that can sufficiently satisfy each application. ing.

However, depending on the application of the deposited film, it is necessary to fully satisfy the requirements for large area, film thickness uniformity, and film quality uniformity, and to achieve reproducible mass production. The formation of a deposited film by means of a high vacuum requires a large amount of capital investment for mass production equipment, the management items for mass production are complicated, the control allowance is narrow, and the adjustment of equipment is delicate. Therefore, these are pointed out as problems to be improved in the future.

As described above, in forming a functional film, it has been earnestly desired to develop a method for forming a deposited film that can ensure practical properties and can be mass-produced by a low-cost device while maintaining uniformity.

〔Purpose〕

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

Another object of the present invention is to provide a deposited film forming method which can save energy and can easily control the film quality and can obtain a deposited film having uniform characteristics over a large area.

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

[Means for Solving Problems] A method for forming a deposited film according to the present invention, which achieves the above object, is a gaseous raw material for forming a deposited film, and a gaseous halogen-based material having a property of oxidizing the raw material. An excited state precursor is generated by introducing an oxidizing agent into the reaction space and chemically contacting them, and the precursor is deposited on the substrate in the film formation space as a supply source of the deposited film constituents. It is characterized in that a film is formed.

[Action]

According to the above-described deposited film forming method of the present invention, energy saving as well as large area, film thickness uniformity, and film quality uniformity are sufficiently satisfied to simplify management and mass production, and to be used in a mass production apparatus. It does not require a large capital investment, the management items for its mass production are clarified, the management allowance range is wide, and the adjustment of the device is easy.

In the deposited film forming method of the present invention, the gaseous raw material used for forming the deposited film is subjected to an oxidative action by chemical contact with a gaseous halogen-based oxidant, and the desired deposited film is obtained. It is appropriately selected according to the desired type, characteristics, application, etc. In the present invention, the above-mentioned gaseous raw material and gaseous halogen-based oxidizing agent may be those that are made gaseous when they are chemically contacted, and in the usual case, they are gas, liquid or solid. But it doesn't matter.

When the raw material for forming the deposited film or the halogen-based oxidant is a liquid or a solid, a carrier gas such as Ar, He, N ₂ or H ₂ is used, and bubbling is performed while adding heat as necessary. As a result, the raw material for forming the deposited film and the halogen-based oxidizing agent are introduced into the reaction space in a gaseous state.

At this time, the partial pressure and mixing ratio of the gaseous raw material and the gaseous halogen-based oxidant are adjusted 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 halogen-based oxidant. Is set.

As a raw material for forming a deposited film used in the present invention, for example, if a chalcogenide-based deposited film is obtained, a hydride of a chalcogenide-based element, a chlorinated compound, an organometallic compound, or the like is effective. Can be listed as a thing.

Specifically, Se-based compounds include SeH ₂ and SeCl.
_{2, Se (CH 3) 2} , Se (C 2 H 5) 2, Se 2 B
It is possible to cite r _{2 and the} like as effective raw materials.

Examples of the S-based compound include SH ₂ , SCl ₂ , S ₂ Cl ₂ ,
SOCl ₂ , SF _{6 and the} like can be cited as effective raw materials.

Te-based compounds include TeH ₂ , Te (CH ₃ ) ₂ ,
Te (C ₂ H ₅ ) _{2 and the} like can be mentioned as effective raw materials.

As-based compounds include AsH ₃ , AsCl ₃ , and AsBr.
_{3, As (CH 3) 3} , As (C 2 H 5) 3, As (C
₆ H ₅ ) ₃ , As (OCH ₃ ) ₃ , As (OC ₂ H ₅ ).
₃ , As (OC ₃ H ₇ ) ₃ , As (OC ₄ H ₉ ) _{3 and the} like can be mentioned as effective raw materials.

Of course, these atomic substances may be used not only in one kind but also in a mixture of two or more kinds.

The halogen-based oxidant used in the present invention is gasified when introduced into the reaction space, and at the same time, only by chemical contact with a gaseous raw material for forming a deposited film which is introduced into the reaction space. It has the property of effectively oxidizing, and F
Halogen gas such as ₂ , Cl ₂ , Br ₂ and I ₂ , nascent fluorine, chlorine, bromine and the like can be cited as effective ones.

These halogen-based oxidants are gaseous, and are introduced into the reaction space at a desired flow rate and supply pressure together with the gas of the raw material for forming the deposited film, and are mixed and collided with the raw material. The raw materials are brought into contact with each other and oxidized to efficiently generate a plurality of precursors including excited precursors. The excited state precursors and other precursors that are produced serve as a source of constituents of the deposited film, at least one of which is formed.

The generated precursor decomposes or reacts to become a precursor in another excited state or a precursor in another excited state, or releases 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 arranged in the space.

In the present invention, the deposited film forming process proceeds smoothly, and a film having high quality and desired physical properties can be formed. A combination, a mixing ratio of these, a pressure at the time of mixing, a flow rate, a film forming space internal pressure, a gas flow rate, and a film forming temperature (a substrate temperature and an atmospheric temperature) are appropriately selected as desired. These film forming factors are organically related, and are not determined individually but are determined according to each other under mutual relation. In the present invention, the ratio of the amounts of the gaseous raw material substance for forming a deposited film and the gaseous halogen-based oxidant introduced into the reaction space is related to the film forming factors related to the above film forming factors. In this case, the introduction flow rate ratio is preferably from 1/20 to 100/1, more preferably from 1/5 to 50/1, although it can be determined as desired.

The pressure at the time of mixing when introduced into the reaction space is preferably higher in order to stochastically enhance the chemical contact between the gaseous raw material and the gaseous halogen-based oxidant, but the reactivity is higher. Considering the above, it is preferable to appropriately determine the optimum value as desired. The pressure at the time of mixing is determined as described above, but the pressure at the time of introducing each is preferably 1 × 10 ⁻⁷ atm to 10 atm, more preferably 1 × 10 ⁻⁶ atm to 3 atm. It is desirable to be done.

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 precursor (E) in the excited state generated in the reaction space and the precursor in some cases. The precursor (D) derived from the body (E) is appropriately set as desired so as to effectively contribute to film formation.

The internal pressure of the film formation space is the pressure introduced into the reaction space between the base material for forming a deposited film and the gaseous halogen-based oxidant when the film formation space is open and continuous with the reaction space. In relation to the flow rate and the flow rate, it is possible to make adjustments by adding, for example, differential exhaust or using a large exhaust device.

Alternatively, when the conductance of the connecting portion between the reaction space and the film formation space is small, an appropriate exhaust device is provided in the film formation space,
The pressure in the film forming space can be adjusted by controlling the exhaust amount of the apparatus.

Further, when the reaction space and the film formation space are integrated and the reaction position and the film formation position are spatially different from each other, differential evacuation as described above or a large size with sufficient evacuation capacity is performed. It suffices if an exhaust device is provided.

As described above, the pressure in the film forming space is determined by the relationship between the gaseous source material introduced into the reaction space and the introduction pressure of the gaseous halogen oxidant, and preferably 0.001 T
orr to 100 Torr, more preferably 0.01 Torr
-30 Torr, optimally 0.05-10 Torr is desirable.

Regarding the gas flow rate, when the raw material for forming the deposited film and the halogen-based oxidizing agent are introduced into the reaction space, these are uniformly and efficiently mixed, and the precursor (E) is efficiently mixed. In order for the gas to be generated and the film to be formed properly without any trouble, it must be designed in consideration of the geometrical arrangement of the gas inlet, the substrate, and the gas outlet. One suitable example of this geometric arrangement is shown in FIG.

The substrate temperature (Ts) at the time of film formation is individually set as desired according to the gas species used, the number of species of the deposited film to be formed and the required characteristics. In order to obtain, it is preferable that the temperature is from room temperature to 200 ° C, more preferably from room temperature to 100 ° C. In particular, when forming a chalcogenide compound deposited film having better semiconductor properties and photoconductivity, the substrate temperature (Ts) is preferably room temperature to 70 ° C. Further, when a polycrystalline film is obtained, the temperature is preferably 100 to 200 ° C, more preferably 100 to 150 ° C.

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

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

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 and polyamide, glass, ceramics, paper and the like are usually used. It is preferable that at least one surface of these electrically insulating substrates is subjected to a conductive treatment, and another layer is provided on the surface subjected to the conductive treatment.

For example, in the case of glass, the surface is NiCr, Al, C
r, Mo, Au, Ir, Nb, Ta, V, Ti, Pt,
Pd, In ₂ O ₃ , SnO ₂ , ITO (In ₂ O ₃ + S
nO ₂ ), a conductive film is provided by a thin film, or a synthetic resin film such as a polyester film is NiCr, Al, Ag, Pb, Zn, Ni, Au,
The surface is subjected to a conductive treatment by treatment with a metal such as Cr, Mo, Ir, Nb, Ta, V, Ti, Pt by vacuum vapor deposition, electron beam vapor deposition, sputtering, or the like, or by laminating with the metal. 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 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 strain may occur in the film, and a good quality film may not be obtained. Therefore, select and use a substrate with a close difference in thermal expansion between the two. Is preferred.

Further, since the surface condition of the substrate is directly related to the structure (orientation) of the film and the generation of the conical structure, it is necessary to treat the surface of the substrate so that the film structure and the film structure can obtain desired characteristics. Is desirable.

FIG. 1 shows an example of an apparatus suitable for embodying 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.

A reaction space and a film formation space are provided in the apparatus body.

101 to 108, 128, and 129 are cylinders 101a each filled with a gas used for film formation.
˜108a, 128a, 129a are gas supply pipes, 101b˜108b, 128b, 129b are mass flow controllers for adjusting the flow rate of gas from each cylinder, 101c˜108c, 128c, 129c are gas pressure gauges, and 101d˜108d128d. , 129
d and 101e to 108e, 128e and 129e are valves respectively, and 101f to 108f, 128f and 129f are pressure gauges showing the pressures in the corresponding gas cylinders.

Reference numeral 120 denotes a vacuum chamber having a structure in which a gas introducing pipe is provided in an upper portion thereof, and a reaction space is formed in the downstream of the pipe, and the substrate 1 faces the gas outlet of the pipe.
It has a structure in which a film formation space in which the basic holder 112 is provided so that 18 is arranged is formed. The gas introduction pipe has a triple concentric circle arrangement structure, and the first gas introduction pipe 109 into which the gas from the gas cylinders 101 and 102 is introduced and the second gas from the gas cylinders 103 to 105 are introduced from the inside. Gas introduction pipe 110 and gas cylinder 1
It has the 3rd gas introduction pipe 111 into which gas from 06-108,128,129 is introduced.

For the gas discharge to the reaction space of each gas introduction pipe, it is designed such that the inner pipe is located farther from the surface position of the substrate. That is, the respective gas introduction pipes are arranged so that the outer pipes surround the inner pipes.

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

The gas introduction pipes, the gas supply pipelines, and the vacuum chamber 120 are vacuum-exhausted by a vacuum exhaust device (not shown) via the main vacuum valve 119.

The substrate 118 is installed at a desired distance from the position of each gas introduction pipe 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 introduction pipe is in an appropriate state in consideration of the type of the deposited film to be formed, its desired characteristics, the gas flow rate, the internal pressure of the vacuum chamber, etc. However, it is preferably several mm
It is desirable that the length is 20 cm, more preferably 5 mm to 15 cm.

Reference numeral 113 denotes a substrate heating heater that heats the substrate 118 to an appropriate temperature during film formation, preheats the substrate 118 before film formation, and further heats after film formation to anneal the film. is there.

The substrate heater 113 is connected to the power source 115 via the conductor 114.
Is supplied with electric power.

Reference numeral 116 is 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 specifically described with reference to Examples.

Example 1 Using the film forming apparatus shown in FIG. 1, a deposited film was formed under the conditions shown in Table 1.

Flow rate of SeH ₂ gas filled in the cylinder 101 is 7 s.
At a flow rate of 14 sccm, the AsH ₃ gas with which the cylinder 102 is filled with ccm is fed through the gas introduction pipe 109 with a flow rate of 20 sccm with which the F ₂ gas with which the bomb 106 is filled is filled.
He gas filling the cylinder 107 at a flow rate of 40 sc
It was introduced into the vacuum chamber 102 through the gas introduction pipe 111 in cm.

At this time, the pressure in the vacuum chamber 120 was adjusted to 800 mTorr by adjusting the opening / closing degree of the vacuum valve 119. 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 substrate temperature (Ts) was set to 60 ° as shown in Table 1.

When gas was flown for 56 minutes in this state, an AsxSe (1-x) (x = 0.42) film having a film thickness as shown in Table 1 was deposited on the substrate.

The unevenness of the film thickness distribution was within ± 5%. It was confirmed that all the formed AsxSe (1-x) (x = 0.42) films were amorphous by electron diffraction.

On the amorphous AsxSe (1-x) (x = 0.42) film of each sample, a comb-shaped electrode (gap length 200 μm) of Al was vapor-deposited to prepare a sample for conductivity measurement. A voltage of 100 V was applied to each material in a vacuum cryostat, the current was measured with a micro ammeter (YHP4140B), and the dark conductivity (σ
d) was determined. Further, light having a wavelength of 600 nm and 0.3 mw / cm ² was irradiated to determine the photoconductivity (σp). Further, the optical bandgap (E _G ^opt ) was determined from the absorption of light. The results are shown in Table 1.

Example 2 A deposited film was formed under the conditions shown in Table 2 using the film forming apparatus shown in FIG.

The film forming procedure and the evaluation of the deposited film were performed in the same manner as in Example 1. The results shown in Table 2 were obtained.

Example 3 Using the film forming apparatus shown in FIG. 1, a deposited film was formed under the conditions shown in Table 3.

The film forming procedure and the evaluation of the deposited film were performed in the same manner as in Example 1. The results shown in Table 2 were obtained.

Example 4 A deposited film was formed under the conditions shown in Table 4 using the film forming apparatus shown in FIG.

The film forming procedure and the evaluation of the deposited film were performed in the same manner as in Example 1. The results shown in Table 3 were obtained.

[Effect] From the above detailed description and each example, according to the deposited film forming method of the present invention, it is possible to achieve energy saving and at the same time easily control the film quality and to obtain a deposited film having uniform physical properties over a large area. can get. In addition, it has excellent productivity and mass productivity, high quality and electrical,
A film having excellent physical properties such as optical properties and semiconductor properties can be easily obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a film forming apparatus used in an example of the present invention. 101-108,128,129 ... Gas cylinder, 101a-108a-128a, 129a ... Gas introduction pipe, 101b, 108b, 128b, 129b ... Mass flow meter, 101c-108c, 128c, 129c ... Gas pressure gauge , 101d to 108d, 128d, 129d and 101e to 108e, 128e, 129e ... Valve, 101f to 108f, 128f, 129f ... Pressure gauge, 109, 110, 111 ... Gas introduction pipe, 112 ... Substrate holder, 113 .., a heater for heating the substrate, 116, a thermocouple for monitoring the substrate temperature, 118, a substrate, 119, a vacuum exhaust valve, respectively.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01L 31/04

Claims (10)

[Claims] 1. A gaseous raw material containing chalcogenide atoms for forming a deposited film and a gaseous halogen-based oxidizing agent having a property of oxidizing the raw material are introduced into a reaction space and brought into contact with each other. Thereby chemically producing a plurality of precursors, including excited state precursors, and depositing at least one of these precursors on the substrate in the deposition space as a source of deposition film constituents. A deposited film forming method characterized by forming a film. 2. The deposited film forming method according to claim 1, wherein the gaseous source material is a hydride. 3. The deposited film forming method according to claim 1, wherein the gaseous raw material is an organic metal. 4. The deposited film forming method according to claim 1, wherein the gaseous halogen-based oxidizing agent contains a halogen gas. 5. The method for forming a deposited film according to claim 1, wherein the gaseous halogen-based oxidizing agent contains fluorine gas. 6. The deposited film forming method according to claim 1, wherein the gaseous halogen-based oxidizing agent contains chlorine gas. 7. The deposited film forming method according to claim 1, wherein the gaseous halogen-based oxidizing agent is a gas containing a fluorine atom as a constituent component. 8. The deposited film forming method according to claim 1, wherein the gaseous halogen-based oxidizing agent contains halogen in a nascent state. 9. The method according to claim 1, wherein the gas is arranged at a position opposed to a direction in which the gaseous raw material substance and the gaseous halogen-based oxidant are introduced into the reaction space. Method for forming deposited film. 10. The method for forming a deposited film according to claim 1, wherein the gaseous raw material and the gaseous halogen-based oxidant are introduced into the reaction space through a transport pipe having a multi-tubular structure.