JP2531649B2 - Deposited film formation method - Google Patents

Description

Description: TECHNICAL FIELD The present invention is useful for functional films, particularly for electronic devices such as semiconductor devices, electrophotographic photoreceptors, and optical sensors for optical image input devices. The present invention relates to a deposited film forming method advantageous for manufacturing a functional film.

[Prior Art] Conventionally, a non-single crystalline functional film such as an amorphous or polycrystalline film such as a semiconductor film or an insulating film has been prepared by a deposition method suitable for an intended physical property or application. ing.

For example, amorphous or polycrystalline non-single-crystal silicon (hereinafter referred to as "NON-Si (H , X) ”, and in particular,“ A-Si (H, X) ”indicates amorphous silicon, and“ poly-Si (H, X) ”indicates polycrystalline silicon. It is to be noted that a vacuum evaporation method, The plasma CVD method, the thermal CVD method, the reactive sputtering method, the ion plating method, the optical CVD method, and the like have been tried, and generally, the plasma CVD method is widely used,
It has been commercialized.

However, the reaction process in this plasma CVD method is very complicated, and therefore there are many deposition film formation parameters (for example, substrate temperature, introduced gas flow rate and ratio, formation pressure, high-frequency power, electrode). (Structure of reaction vessel, pumping speed, plasma generation method, etc.) Since these parameters are combined, it is necessary to select the parameters specific to each device. Also, control of each parameter during formation of the deposited film is complicated.

By removing the drawbacks of the plasma CVD method and reducing the control parameters, it is possible to obtain a new deposited film forming method that can obtain a film with high quality and excellent electrical and optical characteristics comparable to those of plasma CVD. A precursor in an excited state is generated by introducing a raw material and a gaseous halogen-based oxidant into the reaction space and bringing them into contact with each other, and the precursor is used as a supply source of a deposited film constituent to form a deposited film on a substrate. A method of doing so (hereinafter, this deposited film forming method is referred to as a “chemical deposition method”) has been recently announced and is drawing attention.

In this chemical deposition method, a film can be deposited by only bringing a specific gas into contact, so that the manufacturing apparatus can be simplified and control parameters are reduced compared to the conventional method, so that the manufacturing conditions can be easily controlled. Become. However, the relationship between the control parameters and the characteristics of the deposited film in this chemical deposition method has not been clarified yet.

[Problems to be Solved by the Invention] The present invention has been made to provide a deposited film forming method capable of controlling the film composition and characteristics by controlling the parameters in the chemical deposition method described above.

[Means for Solving Problems] The method of forming a deposited film according to the present invention has a gaseous raw material for forming a deposited film and a property of oxidizing the raw material.
A halogen gas selected from ₂ , Cl ₂ , Br ₂ and I ₂ is introduced into the reaction space and brought into contact with each other to generate a plurality of precursors including a precursor in an excited state. In a deposited film forming method for forming a deposited film on a substrate by using at least one precursor as a supply source for a deposited film constituent, in the deposition film forming method, the gaseous raw material for forming the deposited film and the halogen gas are contacted from a position where It is characterized in that the length of the path until it is guided onto the substrate is changed during the formation of the deposited film.

According to the above-described deposited film forming method of the present invention, for example, a deposited film having a film structure having different compositions or characteristics in the film thickness direction can be easily formed.

Next, a description will be given of how the structure of the present invention and the operation thereof have been found.

The present inventor conducted various experiments in order to elucidate the relationship between the movement distance of a mixed gas of a gaseous raw material and a gaseous halogen-based oxidizer to a substrate and the physical characteristics of a deposited film in the chemical deposition method, and the results thereof It has been found that the bonding form of hydrogen in the deposited film is greatly affected by the migration distance of the gas mixture of the gaseous source material and the gaseous halogen-based oxidant.

For example, in the above-mentioned NON-Si (H, X) etc., the Si-H bond according to the infrared absorption spectrum has an absorption peak near 2000 cm ^-1 , and the Si-H ₂ bond has an absorption peak near 2100 cm ^-1. . It is known that the hydrogen bond morphology in the film has a great influence on the physical properties of the film, and as an application of it, a device containing Si—H bond and Si—H ₂ bond in a certain ratio (Japanese Patent Application Laid-Open No. 2000-242242). 56-88380, JP-A-56-152280, etc.)
A device in which a layer mainly composed of Si—H bond and a layer mainly composed of Si—H ₂ bond are laminated (Japanese Patent Laid-Open No. 58-153940) is proposed.

The present inventor performs various film depositions by the chemical deposition method by setting various migration distances of a mixed gas of a gaseous source material and a gaseous halogen-based oxidant to a substrate, and the infrared absorption spectrum of the deposited film is measured. With an absorption peak near 2000 cm ^-1
The ratio I of the intensity of the absorption peak of 2100 cm ^-1 vicinity (2000 cm ^-1) / I
(2100 cm ⁻¹ ), that is, the ratio of Si—H bond and Si—H2 bond in the deposited film increases as the distance from the gas inlet to the substrate increases.

For example, in the deposited film forming apparatus shown in FIG. 1, SiH ₄ gas in the cylinder 101 is supplied at 15 sccm from the gas introduction pipe 109 to the cylinder.
F ₂ gas diluted to 10% with He of 106 was introduced into the reaction chamber 120 from the gas introduction pipe 110 at 150 sccm, and the distance from the gas introduction port to the substrate was changed from 30 mm to 80 mm. S
An i (H, X) film was deposited. The internal pressure of the reaction chamber is 0.3 Torr,
The substrate temperature was constant at 300 ° C. At this time, the distance from the gas inlet to the substrate and I (2000 cm ^-1 ) / I (2100 cm) of the deposited film
^-1 ) is shown in Fig. 2. It can be seen that the ratio of Si-H bonds and Si-H ₂ bonds have changed significantly depending therefrom a distance from the gas inlet to the substrate. In addition, the above-mentioned F
_{The same} was true for halogen-based oxidizers other than ₂ , Cl ₂ , Br ₂ , and I ₂ .

That is, in the deposited film forming method of the present invention, the moving distance of the mixed gas of the gaseous raw material and the gaseous halogen-based oxidant to the substrate is such that the layer containing many Si—H bonds is formed during the deposited film formation. When it is attempted, it is changed to be relatively long, and when it is intended to form a layer containing many Si—H ₂ bonds, it is changed to be relatively short.

Incidentally, for example, when the apparatus shown in FIG. 1 is used, in order to change the moving distance of the mixed gas of the gaseous raw material and the gaseous halogen-based oxidant to the substrate in the reaction space, the gas introduction pipe may be moved. The substrate may be moved, and the speed of change of the distance may be set to be rapid when a rapid change in the film characteristics is required and slow when a gentle change in the film characteristics is required.

In addition, control of the film composition or characteristics by changing the moving distance of the mixed gas of such a gaseous raw material (a specific example will be described later) and a gaseous halogen-based oxidant (a specific example will be described later) is not possible. Not limited to single crystal silicon, other non-single crystal materials such as non-single crystal germanium A-Ge (H,
X), non-single crystal silicon germanium A-SiGe (H, X),
Non-single crystal silicon carbide A-SiC (H, X), non-single crystal silicon oxide A-SiO (H, X), non-single crystal silicon nitride A-SiN
It has been confirmed by measurement of the hydrogen bond state by infrared absorption spectrum, etc. that (H, X) and a combination thereof A-SiGeCON (H, X) and the like are also possible.

In the deposited film forming method of the present invention, the gaseous raw material used for forming the deposited film is an substance that undergoes an oxidizing action by chemical contact with a gaseous halogen-based oxidizing agent. It is appropriately selected according to the desired type, characteristics, application and the like. 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 oxidizer is liquid or solid, use carrier gas such as Ar, He, N ₂ , H ₂ and perform hub ring 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 the form of gas.

At this time, the partial pressure and the 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 the raw material for forming the deposited film used in the present invention, for example, a straight-chained substance may be used if a tetrahedral deposited film such as a semiconductor or electrically insulating silicon deposited film or a germanium deposited film is obtained. Further, a branched chain silane compound, a cyclic silane compound, a chain germanium compound and the like can be mentioned as effective compounds.

Specifically, as a linear silane compound, Si _n H _{2n + 2}
(N = 1,2,3,4,5,6,7,8), SiH ₃ SiH (SiH ₃ ) SiH ₂ SiH ₃ as the branched chain silane compound, Ge _m as the chain germane compound H _{2m + 2} (m = 1,2,3,4,5) and the like. In addition to this, for example, if a deposited film of tin is produced,
Tin hydride such as SnH ₄ can be cited as an effective raw material.

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

The halogen-based oxidizing agent used in the present invention is in a gaseous state when being introduced into the reaction space, and at the same time, only chemically contacts with a gaseous raw material for forming a deposited film which is introduced into the reaction space. In addition, halogen gas such as F ₂ , Cl ₂ , Br ₂ and I ₂ can be mentioned 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 precursor is chemically contacted with the raw material to oxidize the raw material to efficiently generate a plurality of precursors including a precursor in an excited state. 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.

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

In the present invention, the deposited film forming process proceeds smoothly, and a film having high quality and desired physical properties can be formed. The combination, the mixing ratio of these, the pressure at the time of mixing, the flow rate, the film forming space internal pressure, the gas flow type, the film forming temperature (base temperature and ambient temperature), and the distance from the gas inlet to the base are appropriately selected as desired. To be selected. It is considered that these film-forming factors are generally organically related and are not determined individually but are determined depending on 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 relevant film forming factor among the above film forming factors. In the above, it is appropriately determined according to the desire, but the introduction flow rate ratio is preferably 1/100 to 100/1, and more preferably 1/100 to 100/1.
50 to 50/1 is desirable.

In the present invention, the reaction space for contacting the gaseous raw material and the gaseous halogen-based oxidant to generate the precursor is a space where the precursor is deposited on the substrate to form a deposited film. It may be separated from the membrane space or may be integrated.

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 substrate-like raw material and the substrate-like 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 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.

The internal pressure of the film-forming space is the pressure introduced into the reaction space between the substrate-like source material for forming a deposited film and the substrate-like halogen-based oxidant when the film-forming 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 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.

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 formation space is determined by the relationship between the gaseous source material introduced into the reaction space and the introduction pressure of the gaseous halogen-based oxidant, but preferably 0.00
It is desirable that the pressure is 1 Torr to 100 Torr, more preferably 0.01 Torr 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 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 preferred 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 type of gas used, the type of deposited film to be formed, and the required characteristics. If obtained, preferably from room temperature to 450 ° C, preferably 5
The temperature is preferably 0 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, it is preferably 200
It is desirable to set the temperature 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, if it is glass, its surface is NiCr, Al, Cr,
Mo, Au, Ir, Nb, Ta, V, Ti, Pt, Pd, In ₂ O ₃ , SnO ₂ ,
Conductive treatment by providing a thin film of ITO (In ₂ O ₃ + SnO ₂ ) or NiCr, Al, Ag, Pb, Zn, Ni, Au, Cr, M for synthetic resin film such as polyester film
A metal such as o, Ir, Nb, Ta, V, Ti, or Pt is processed by vacuum vapor deposition, electron beam vapor deposition, sputtering, or the like, or is laminated with the metal, and the surface thereof 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 in thermal expansion between the two is large, a large amount of strain occurs in the film, and a good quality film cannot 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 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.

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

101 to 106 are cylinders filled with gas used for film formation, 101a to 106a are gas supply pipes,
101b-106b are mass flow controllers for adjusting the flow rate of gas from each cylinder, 101c-106c are gas pressure gauges, 101d-106d and 101e-106e are valves, 101f-
106f are pressure gauges showing the pressures inside the corresponding gas cylinders.

Reference numeral 120 denotes a vacuum chamber, which is provided with a gas introduction pipe at an upper portion thereof, has a structure in which a reaction space is formed downstream of the pipe, and faces a gas discharge port of the pipe to form a base 11.
It has a structure in which a film formation space in which a substrate holder 112 is provided so that 8 is installed is formed. The pipe for gas introduction has a double concentric circle arrangement structure, and the gas cylinder 101,
It has a first gas introduction pipe 109 into which gas from 102, 103, 104 and 105 is introduced, and a second gas introduction pipe 110 into which gas from a gas cylinder 106 is introduced.

Gas is supplied from the tube cylinders to the respective introduction tubes by gas supply pipelines 123 and 124, respectively.

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

The substrate 118 is arranged at a desired distance from the position of each gas introduction pipe by moving the substrate holder 112 or the gas introduction pipes 109 and 110 up and down.

In the case of the present invention, the distance between the substrate and the gas introduction port of the gas introduction pipe 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, etc. It is decided like this and changes within that range,
It is preferably several mm to 20 cm, more preferably about 5 mm to 15 cm.

113 is for heating the substrate 118 to an appropriate temperature during film formation,
Alternatively, it is a substrate heating heater that preheats the substrate 118 before film formation, or further heats after film formation to anneal the film.

Electric power is supplied to the substrate heater 113 from a power supply 115 by a conductor 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.

〔Example〕

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

Example 1 A deposited film was produced by the method of the present invention as follows using the deposited film forming apparatus shown in FIG.

The SiH ₄ gas filled in the cylinder 101 is supplied at a flow rate of 15 sccm from the gas introduction pipe 109 to the He filled in the cylinder 106 by 10
F ₂ gas diluted to 100% (hereinafter abbreviated as F ₂ / H ₂ gas) was introduced into the vacuum chamber 120 through the gas introduction pipe 110 at a flow rate of 150 sccm.

At this time, the pressure in the vacuum chamber 120 is reduced by the vacuum valve 1
I adjusted the opening and closing degree of 19 to 0.3 Torr. A Si wafer (1 inch in diameter) was used as the substrate, and the substrate temperature was set to 300 ° C. The distance between the gas inlet and the substrate was set to 40 mm, and film formation was performed for 20 minutes in this state. After 20 minutes, move the gas inlet pipe to change the distance between the gas inlet and the substrate to 80 mm, and
When film formation was continued for a minute, a Si: H: F film with a thickness of 1.2 μm was deposited. The average of all layers of the ratio of SiH bond to SiH ₂ bond was calculated from the amount of transmitted and absorbed infrared light at 2000 cm ^-1. SiH / SiH ₂ =
It was 3.1. This is a film (SiH / SiH ₂ = 1, deposition rate 7Å / sec, deposition time 20 minutes) fixed at a distance of 40 mm from the gas inlet to the substrate, and a film fixed at 80 mm ( SiH / SiH ₂ = 8, deposition rate 1Å / sec, deposition time 60 minutes)
Calculated value of the average value of SiH / SiH ₂ in the total film thickness of the laminated film obtained from the data of Matched with.

In addition, the ratio of the time for forming a film with the distance from the gas inlet to the substrate of 40 mm to the time for forming a film with 80 mm is 1/10, 1/1, 3/1, 10/1.
In the same manner as above, deposited films were prepared, and their infrared absorption ratios were investigated. All deposited films had relatively many SiH ₂ bonds (Si
It was confirmed that the H / SiH ₂ = 1) layer and a layer mainly composed of SiH bonds (SiH / SiH ₂ = 8) had a laminated structure.

Example 2 An electrophotographic photosensitive member was produced as an example of a functional deposited film by the method of the present invention. An Al substrate (15 cm × 15 cm) was set in the film forming apparatus shown in FIG. 1, and SiH ₄ gas in the cylinder 101, GeH ₄ gas in the cylinder 102, CH ₄ gas in the cylinder 103, F ₂ / He gas in the cylinder 106, B ₂ H ₆ diluted to 1000 ppm with He in cylinder 105
A gas (hereinafter abbreviated as B ₂ H ₆ / He gas) was used to form a four-layer deposited film while changing the distance from the gas inlet to the substrate under the conditions shown in Table 1.

The resulting deposited film is uniformly corona charged at + 6kV and 1u
When the electrostatic latent image was subjected to cascade development with a two-component developer after exposure with a pattern light of x · sec, a clear toner image, that is, a toner image which can be sufficiently used practically was obtained.

〔The invention's effect〕

As is clear from the description of the above examples, according to the deposited film forming method of the present invention, by changing the moving distance to the substrate in the reaction space of the gaseous raw material and the gaseous halogen-based oxidant, The composition and properties of the film can be freely controlled, for example, a deposited film having a film structure having different compositions and properties in the film thickness direction can be easily formed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration explanatory view showing an example of an apparatus suitable for embodying the deposited film forming method of the present invention. FIG. 2 is a curve diagram showing the relationship between the migration distance of the gaseous raw material and the composition of the deposited film when the method of the present invention is carried out, and the horizontal axis is from the gas inlet to the substrate. (Mm), the vertical axis represents the Si-H bond (2000 cm) in the deposited film.
^-1 vicinity), that represents the ratio of the ratio of the intensity of the absorption peak I (2000 cm ^-1) / I (2100 cm ^-1) of Si-H ₂ bonds (around 2100 ^-1 cm). 101-106 …… Gas cylinder, 109 …… First gas inlet pipe, 1
10 ... Second gas introduction pipe, 118 ... Substrate.

Claims (1)

(57) [Claims] 1. A reaction space comprising a gaseous source material for forming a deposited film and a halogen gas selected from F ₂ , Cl ₂ , Br ₂ and I ₂ having a property of oxidizing the source material. A plurality of precursors including excited state precursors are generated by introducing into the inside and contacting the precursors, and at least one of these precursors is used as a source of the deposited film constituent to deposit the deposited film on the substrate. In the deposited film forming method to be formed, changing the length of the path from the position where the gaseous raw material for forming the deposited film and the halogen gas are brought into contact with the halogen gas to the substrate is changed during the deposition film formation. Characteristic deposition film formation method.