METHOD FOR FORMING DEPOSITED FILM

Abstract: A method for forming a deposited film by introducing a gaseous starting material for formation of a deposited film and a gaseous halogenic oxidizing agent having the property of oxidation action on said starting material separately from each other into a reaction space to form a deposited film ac­ cording to a chemical reaction, which comprises activating previously a gaseous substance (D) for formation of a valence electron controller in an activation space to form an activated species and introducing said activated species into the reac­ tion space to form a doped deposited film.

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a method for formation of a functional film, particularly a semiconductive deposited film which is useful for uses such as semiconductor device, photosensitive device for electrophotography, electronic device such as optical input sensor device for optical image inputting device, etc. Description of the Prior Art Hitherto, for functional films, especially amorphous or polycrystalline semiconductive films, film forming methods have been employed, chosen according to desired physical characteristics, uses, etc of the film. Various methods have been attempted for formation of silicon type deposited films such as amorphous or polycrystalline non-single crystalline silicon which are optionally compensated for lone pair electrons with a compensating agent such as hydrogen atoms (H) or halogen atoms (X), etc, generally "NON-Si (H,X)", or "A-Si (H,X)" for amorphous or microcrystalline silicon and "poly-Si (H,X)" for polycrystalline silicon . These methods include vacuum vapor deposition plasma CVD, thermal CVD, reactive sputtering, ion plating, optical CVD, etc. Generally, plasma CVD has been widely used industrially. EP-A-0 104 907 describes the plasma CVD of amorphous semiconductor films. However, the prior art reaction progress for plasma CVD formation of a silicon-deposited film is more complicated than the conventional CVD method, and its reaction mechanism is not clear. Also, there is a large number of parameters for formation of a deposited film (for example, substrate temperature, flow rate and flow rate ratio of the introduced gases, pressure during formation, high frequency power, electrode structure, structure of the reaction vessel, speed of evacuation, plasma generating system, etc). Because of the combination of such a large number of parameters, the plasma may sometimes become unstable state, whereby marked deleterious influences were exerted frequently on the deposited film formed. Besides, the characteristic parameters of the device must be selected for each device and therefore under the present situation it has been difficult to generalize the production conditions. On the other hand, for the silicon type deposited film to exhibit sufficiently satisfactory electric and optical characteristics for respective uses, it is now accepted that the best way to form it is by plasma CVD. However, depending on the intended use of a silicon type deposited film, reproducible production in bulk may be required, whilst ensuring enlargement of area, uniformity of film thickness as well as uniformity of film quality. Therefore for formation of silicon type deposited film by plasma CVD, enormous investment is required in bulk production equipment. Also management items for such bulk production equipment become complicated, with management and control tolerances being narrow. These problems are pointed out as requiring solution in the future. Also, since plasma for plasma CVD is directly generated (by high frequency or microwave, etc) in a space where film formation is to occur, electrons or ion species may damage the film being formed, causing lowering of film quality or non-uniform film quality. In order to overcome these problems, the indirect plasma CVD method has been proposed. The indirect plasma CVD method uses a principal substance for formation of a deposited film from which activated species are formed, by microwave, etc. The activated species are formed at an upstream position separate from a film forming space, and are then transported to the film forming space. DE-A-3 429 899 describes an indirect CVD method. Since transport activated species is required, they must have long life. This limits the kinds of gases which can be employed. Some film-types cannot therefore be made. Also, enormous energy is required for plasma generation and for generation of the film-forming chemical species. Their amounts cannot be simply controlled. Thus, various problems remain to be solved. As contrasted to the plasma CVD method, the optical CVD method is advantageous in that no ion species or electrons are generated which damage the film quality during film formation. However, there are problems: kinds of light source are limited, the wavelength of the light source tends to be toward the UV, a large scale light source and its power source are required in the case of industrialization, a window allowing that light to be introduced into the film forming space needs to be coated with a film which results in lowering in dose during film formation, which may further lead to shut-down of the light. As described above, in formation of silicon type deposited film, the points to be solved still remain, and it has been earnestly desired to develop a method for forming a deposited film which is capable of bulk production by attempting to save energy by means of a device of low cost, while maintaining the characteristics as well as uniformity which are practicably available. Especially, the above points are highly demanded when forming a semiconductor film of the p-type, n-type or i-type conduction type while enhancing the doping rate therein. These are also applicable in the case of enhancing the doping rate in other functional films, for example, semiconductive films such as silicon type films including silicon nitride films, silicon carbide films, silicon oxide films or germanium type films as the similar problems which should be solved respectively. SUMMARY OF THE INVENTION An object of the present invention is to provide a novel method for forming a deposited film while removing the drawbacks of the method for forming deposited films as described above and at the same time without use of the formation method of the prior art. Another object of the present invention is to provide a method for forming a deposited film for saving energy and at the same time capable of obtaining a deposited film doped with a valance electron controller and with uniform characteristics over a large area, with easy management of film quality. Still another object of the present invention is to provide a method for forming a deposited film by which a film excellent in productivity and bulk productivity, having high quality as well as excellent physical characteristics such as electrical, optical, and semiconductor characteristics can be easily obtained. Thus the present invention provides a method for forming a doped deposited film, which comprises: (a) providing a reaction space; (b) providing a gaseous substance (D) for forming a valence electron controller; (c) activating substance (D) in an activation space to form the valence electron controller comprising an activated dopant species (DA); and (d) introducing into the reaction space: (i) separately a gaseous starting material for forming a deposited film, and a gaseous halogenic oxidizing agent having the property of oxidizing said starting material; and (ii) said activated species (DA); thereby forming a doped deposited film. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 a schematic illustration of a film forming device used in Examples of the present invention. Fig. 2 and Fig. 3 are schematic illustrations of the activation devices used in Examples of the present invention. Fig. 4 is a schematic illustration of a thin film transistor used in the Example of the present invention. Fig. 5 is a schematic illustration of a solar battery used in the Example of the present invention. Fig. 6 is a schematic illustration of an image forming member for electrophotography used in the Example of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT According to the method for forming a deposited film of the present invention, simplification of management and bulk production can be effected with full satisfaction of enlargement of area, uniformity of film thickness, and uniformity of film quality simultaneously with saving energy, without requiring enormous installation investment for bulk production apparatus, and also the management items for its bulk production become clear to afford broad width of management tolerance and simple adjustment of the device. In the method for forming a deposited film of the present invention, the gaseous starting material to be used for formation of a deposited film and the gaseous substance (D) containing a component for a valence electron controller as the constituent can be previously in an activation chamber activated by discharging, light, heat energy, etc. The substance (D) may be capable of undergoing chemical reaction with a gaseous halogenic oxidizing agent. The gaseous substance (D) can be selected suitably as desired depending on the kind, the characteristic, use, etc, of the desired deposited film. When the starting material for formation of a deposited film and the halogenic oxidizing agent are liquid or solid under ordinary state, they are introduced in gaseous state into the reaction space while performing bubbling with the use of carrier gas such as Ar, He, N₂, H₂, etc, optionally with application of heat. When the gaseous substance (D) is liquid or solid under ordinary state, the substance (D) is made gaseous by performing bubbling with the use of carrier gas such as Ar, He, H₂, etc, optionally with application of heat. The gaseous substance (D) is previously induced into the activation space, and activated with discharging, light, heat energy, etc, followed by the introduction of the activated gaseous substance (D) (in the present specification, this is also referred to "activated species") and/or activated species (DA) generated from the gaseous substance (D) subjected to an activation treatment into the reaction space. During this operation, the partial pressures and mixing ratio of the activated gaseous substance (D) and/or the activated species (DA), generated from the gaseous substance (D), the above gaseous starting material, and the gaseous halogenic oxidising agent in the reaction space may be set by controlling the flow rate of the carrier gas and the vapor pressures of the gaseous starting material for formation of the deposited film and the gaseous halogenic oxidizing agent. As the starting material for formation of a deposited film to be used in the present invention, for example, if deposited films containing group IV A elements such as semiconductive or electrically insulating silicon type deposited films or germanium type deposited films, etc. are desired to be obtained, straight chain and branched chain silane compounds, cyclic silane compounds, chain germanium compounds etc may be employed as the starting material. Specifically, examples of straight chain silane compounds may include Si n H 2n+2 ( n = 1, 2, 3, 4, 5, 6, 7, 8), examples of branched chain silane compounds include SiH₃SiH(SiH₃)SiH₂SiH₃, and examples of chain germanium compounds include Ge m H 2m+2 ( m = 1, 2, 3, 4, 5), etc. Otherwise, for example, if deposited films of tin are desired to he prepared, hydrogenated tin such as SnH₄, etc., may be employed as effective starting material. Of course, these silicon type compounds and germanium type compounds may be used either as a single kind or as a mixture of two or more kinds. The halogenic oxidizing agent to be used in the present invention is made gaseous when introduced into the reaction space and at the same time has the property of effectively oxidizing the gaseous starting material for formation of a deposited film introduced into the reaction space by mere chemical contact therewith, including halogenic gas such as F₂, Cl₂, Br₂, I₂, etc., and fluorine, chlorine, bromine, etc., under nascent state as effective ones. These halogenic oxidizing agents are introduced into the reaction space under gaseous state together with the activated gaseous substance (D) and/or the activated species (DA) generated from the gaseous substance (D), and the gas of the starting material for formation of a deposited film as described above with desired flow rate and feeding pressure are given, wherein they are mixed with and the halogenic oxidizing agents are collided against the activated substance (D), the activated species (DA), and the above starting material. Chemical reaction occurs, thereby oxidising the starting material. Oxidation of the substance (D) and the activated species (DA) may occur. A plurality of precursors containing precursors under excited state are efficiently generated. Of the precursors under excited state and other precursors generated, at least one of them functions as the feeding source for the constituent element of the deposited film formed. The precursors generated may undergo decomposition or reaction to be converted to other precursors under excited state or to precursors under another excited state, or alternatively in their original forms, if desired, although releasing energy to contact the substrate surface arranged in a film forming space, whereby a deposited film having a three-dimensional network structure is prepared. As the energy level to be excited, it is preferable that the precursor in the above excited stated should be subject to energy transition to a lower energy level, or alternatively it should be at an energy level such that luminescence occurs in the process of changing to another chemical species. By formation of an activated precursor including the precursor under excited state accompanied with luminescence in such a transition of energy, the deposited film forming process of the present invention proceeds with better efficiency and more save of energy to form a deposited film having uniform and better physical characteristics over the whole film surface. As the material (D) to be used in the present invention, in the case of a silicon type semiconductor film and a germanium type semiconductor film, there may be employed compounds containing the p type valence electron controller, which functions as the so-called p type impurity, namely an element in the group IIIA of the periodic table such as B, Al, Ga, In, Tl, etc., and the n type valence electron controller which functions as the so-called n type impurity, namely an element in the group VA of the periodic table such as N, P, As, Sb, Bi, etc. Specific examples may include NH₃, HN₃, N₂H₅N₃, N₂H₄, NH₄N₃, PH₃, P₂H₄, AsH₃, SbH₃, BiH₃, B₂H₆, B₄H₁₀, B₅H₉, B₅H₁₁, B₆H₁₀, B₆H₁₂, Al(CH₃)₃, Al(C₂H₅)₃, Ga(CH₃)₃, In(CH₃)₃, etc., as effective ones. For introducing the gas of the above substance (D) into the activation space, it can be introduced from a plural number of independent gas feeding sources. In the present invention, so that the deposit film forming process may proceed smoothly to form a film of high quality and having desired physical characteristics, as the film forming factors, the kinds and combination of the starting material for formation of a deposited film, the activated gaseous substance (D) or the activated species (DA) generated from the gaseous substance (D), and the halogenic oxidizing agent, mixing ratio of these, pressure during mixing, flow rate, the inner pressure in the film forming space, the flow types of the gases, the film forming temperature (substrate temperature and atmosphere temperature) are suitably selected as desired. These film forming factors are organically related to each other, and they are not determined individually but determined respectively under mutual relationships. In the present invention, the ratio of the gaseous starting material for formation of a deposited film and the gaseous halogenic oxidizing agent introduced into the reaction space may be determined suitably as determined in relationship of the film forming factors related among the film forming factors as mentioned above. It is preferably 1/20 to 100/1, more preferably 1/10 - 50/1 in terms of flow rate ratio introduced. The introduction proportion of the activated gaseous substance (D) or the activated species (DA) obtained by the activation of the gaseous substance (D) in the activation space into the reaction space may be set suitably as desired depending on the kind of the above gaseous starting material and the desired semiconductor characteristics of the deposited film to be prepared. It is preferably 1/1000000 to 1/10, more preferably 1/100000 to 1/20, optimally 1/100000 to 1/50 based on the above gaseous starting material. The pressure during mixing when introduced into the reaction space may be preferably higher in order to enhance the chemical contact among the above gaseous starting material, the activated gaseous substance (D) and/or the activated species (DA), and the above gaseous halogenic oxidising agent in probability. It is better to determine the optimum value suitably as desired in view of the reactivity. Although the pressure during mixing may be determined as described above, each of the pressure during introduction may be preferably from 1x10⁻² to 1x10⁻⁶ Pa, more preferably from 1x10⁻¹ to 3x10⁵ Pa (preferably 1x10⁻⁷ atm to 10 atm, more preferably 1x10⁻⁶ atm to 3 atm). The pressure within the film forming space, namely the pressure in the space in which the substrate of which surfaces is effected a film formation is arranged may be suitably as desired so that the precursors (E) under excited stated state generated in the reaction space and, sometimes the precursors (F) formed as secondary products from said precursors (E), may contribute effectively to film formation. The inner pressure in the film forming space, when the film forming space is continuous openly to the reaction space, can be controlled in relationship with the introduction pressures and flow rates in the reaction space of the gaseous starting material for formation of a deposited film, said substance (D), and a gaseous halogenic oxidising agent, for example, by application of a contrivance such as differential evacuation or use of a large scale evacuating device. Alternatively, when the conductance at the connecting portion between the reaction space and the film forming space is small, the pressure in the film forming space can be controlled by providing an appropriate evacuating device in the film forming space and controlling the evacuation amount of said device. On the other hand, when the reaction space and the film forming space is integrally made and the reaction position and the film forming position are only spatially different, it is possible to effect differential evacuation or provide a large scale evacuating device having sufficient evacuating capacity as described above. As described above, the pressure in the film forming space may be determined in the relationship with the introduction pressures of the gaseous starting material, said activated gaseous substance (D), and the activated species (DA), and the gaseous halogenic oxidising agent introduced into the reaction space. It is preferably 0.13 Pa to 1.3 x 10⁴ Pa, more preferably from 1.3 to 4x10³ Pa, optimally 6.67 Pa to 1.3x10³ Pa (preferably 0.001 Torr to 100 Torr, more preferably 0.01 Torr to 30 Torr, optimally 0.05 to 10 Torr). Further, the pressure in the activation space is intimately related with the pressure in the reaction space and it should desirably be higher than the inner pressure in the reaction space. As for the flow type of the gases, it is necessary to design the flow type in view of the geometric arrangement of the gas introducing inlet, the substrate, and the gas evacuating outlet so that the starting material for formation of a deposited film, the activated gaseous substance (D) and/or the activated species (DA), and the halogenic oxidizing agent may be efficiently mixed during introduction of these into the reaction space, the above precursors (E) may be efficiently generated, and film formation may be adequately carried out without trouble. A preferable example of the geometric arrangement is shown in Fig. 1. As the substrate temperature (Ts) during film formation, it can be set suitably as desired individually depending on the gas species employed, and the kinds and the required characteristics of the deposited film formed. In the case of obtaining an amorphous film, it is preferably from room temperature to 450°C, more preferably from 50 to 400 °C. Particularly, in the case of forming a silicon type deposited film with better semiconductor characteristics and photoconductive characteristics, etc., the substrate temperature (Ts) should desirably be made 70 to 350 °C. On the other hand, in the case obtaining a polycrystalline film, it should preferably be 200 to 650 °C, more preferably 300 to 600 °C. As the atmosphere temperature (Tat) in the film forming space, it may be determined suitably as desired in relationship with the substrate temperature so that the above precursors (E) generated and the above precursors (F) are not changed to unsuitable chemical species for film formation, and also the above precursors (E) may be efficiently generated. The substrate to be used in the present invention may be either electroconductive or electrically insulating, provided that it is selected as desired depending on the use of the deposited film formed. As the electroconductive substrate, there may be mentioned metals such as NiCr, stainless steel, Al, Cr, Mo, Au, Ir, Nb, Ta, V, Ti, Pt, Pd, etc. or alloys thereof. As insulating substrates, there may be conventionally be used films or sheets of synthetic resins, including polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, etc., glasses, ceramics, papers, and so on. At lease one side surface of these insulating substrates is preferably subjected to treatment for imparting electroconductivity, and it is desirable to provide other layers on the side to which said electroconductive treatment has been applied. For example, electroconductive treatment of a glass can be effected by providing a thin film of NiCr, Al, Cr, Mo, Au, Ir, Nb, Ta, V, Ti, Pt, Pd, In₂O₃, SnO₂, ITO (In₂O₃ + SnO₂) or the like thereon. Alternatively, a synthetic resin film such as polyester film can be subjected to the electroconductive treatment on its surface by vacuum vapor deposition, electron-beam deposition or sputtering of a metal such as NiCr, Al, Ag, Pb, Zn, Ni, Au, Cr, Mo, Ir, Nb, Ta, V, Ti, Pt, etc., or by laminating treatment with said metal, thereby imparting electroconductivity to the surface. The substrate may be shaped in any form such as cylinders, belts, plates or others, and its form may be determined as desired. The substrate should be preferably selected from among those set forth above in view of adhesion and reactivity between the substrate and the film. Further, if the difference in thermal expansion between both is great, a large amoung of strains may be created within the film to give sometimes no film of good quality, and therefore it is preferable to use a substrate so that the difference in thermal expansion between both is small. Also, the surface state of the substrate is directly related to the structure of the film (orientation) or generation of a stylet structures, and therefore it is desirable to treat the surface of the substrate so that a film structure and a film texture which give desired characteristics may be obtained. Fig. 1 shows an example of a preferable device for practicing the method for forming a deposited film of the present invention. The deposited film forming device shown in Fig. 1 is broadly classified into the four of a main device, an evacuation system, a gas feeding system, and an activation chamber for valence controller. In the main device, a reaction space and a film forming space are provided. 101 - 108, 126, and 127 are respectively bombs filled with the gases to be used for film formation, 101a - 108a, 126a, and 127a are respectively gas feeding pipes, 101b - 108b, 126b, and 127b are respectively mass flow controllers for controlling the flow rates of the gases from the respective bombs, 101c - 108c, 126c, and 127c are respectively gas pressure gauges, 101d - 108d, 126d, 127d, 101e - 108e, 126e, and 127e are respectively valves, and 101f - 108f, 126f, and 127f are respectively pressure gauges indicating the pressures in the corresponding gas bombs. 128 is an activation chamber, 129 and 130 are electrodes, 131 is a high frequence power source, 132 an activated species feeding pipeline, and 133 an activated species introducing pipe. 120 is a vacuum chamber equipped at the upper portion with a pipeline for gas introduction, having a structure for formation of the reaction space downstream of the pipeline, and also having a structure for formation of a film forming space in which a substrate holder 112 is provided so that a substrate 118 may be provided as opposed to the gas discharging outlet of said pipeline. The pipeline for gas introduction has a quadruple concentric arrangement structure, having from the innerside a first gas introducing pipe 109 for introducing the gases from the gas bombs 101 and 102, a second gas introducing pipe 110 for introducing the gases from the gas bombs 103 - 105, a third gas introducing pipe 111 for introducing the gases from the gas bombs 106 - 108, and an introducing pipe 133 for introducing the activated species activated in the activation chamber 128. For gas discharging to the reaction space of each gas introducing pipe, each position is designed so as to be arranged at a position further from the surface position of the substrate as the pipe is nearer to the inner side. In other words, the gas introducing pipes are arranged so that the pipe on the outer side may enclose the pipe existing within the innerside thereof. The gases from the respective bombs are fed into the respective introducing pipes through the gas feeding pipelines 123 - 125, respectively. The activated species are fed through the activated species feeding pipeline 132 into the activated species introducing pipe 133. The respective gas introducing pipes, the respective gas feeding pipe lines, and the vacuum chamber 120 are evacuated to vacuum through the main vacuum valve 119 by means of a vacuum evacuating device not shown. The substrate 118 is set at a suitable desired distance from the positions of the respective gas introducing pipes by moving vertically the substrate holder 112. In the case of the present invention, the distance between the substrate and the gas discharging outlet of the gas introducing pipe may be determined appropriately in view of the kinds and the desired characteristics of the deposited film formed, the gas flow rates, the inner pressure in the vacuum chamber, etc. It is preferably several mm to 20 cm, more preferably 5 mm to about 15 cm. 113 is a heater for heating the substrate which is provided in order to heat the substrate to an appropriate temperature during film formation, to preheat the substrate 118 before film formation, or further to anneal the film after film formation. The substrate heating heater 113 is supplied with power through a conductive wire 114 from a power source 115. 116 is a thermocouple for measuring the substrate temperature (Ts) and is electrically connected to the temperature display device 117. The present invention is described in more detail by referring to the following Examples. Example 1 By use of the film forming device shown in Fig. 1, a thin film transistor (hereinafter called "TFT") as shown in Fig. 4 was prepared according to the method for formation of deposited film of the present invention. The above TFT was constituted of 7059 glass (produced by Corning Co.) 434, an amorphous silicon layer (first layer thickness 700nm, 7000Å) 433, an amorphous silicon layer doped with phosphorus to a high concentration (second layer thickness 50nm, 500Å) 432, a silicon oxide layer (third layer thickness 100nm, 1000Å) 431, and an aluminum electrode 429. In this Example, on deposition of the amorphous silicon layer (second layer) doped with phosphorus to a high concentration, in the activation chamber 128 shown in Fig. 1, after the valence electron controller PH₃ was activated by RF gllow discharge, the activated species formed from PH₃ was introduced into the deposition chamber 120 through the introducing pipe 133 to deposite an amorphous silicon layer (second layer) doped with phosphorus to a high concentration. As to other conditions, semiconductor layers and insulating layers necessary for TFT were prepared under the conditions shown in Table 1. The film thickness of each sample was measured with a layer thickness measuring apparatus of Alpha-Step (manufactured by TENCOR Co.). The TFT of the present Example exhibited an on-off ratio improved by 10 % in comparison with that prepared by PCVD method above. Example 2 In the deposited film forming device shown in Fig. 1, the high frequence power source 131 connected to the activation chamber 128 was replaced with a microwave power source, and a solar battery as shown in Fig. 5 was prepared according to the method for formation of deposited film of the present invention. The above solar battery was constituted of a glass No. 7059 (produced by Corning Co.) 500 having transparent electrodes vapor deposited thereon, a p-tpye semiconductor layer (first layer thickness 50nm, 500 Å) 501, an i-type semiconductor layer (second layer thickness 1 µm) 502, an n-type semiconductor layer (third layer thickness 50nm, 500 Å) 503, and an aluminum electrode 504. The layer thicknesses were measured in the same manner as in Example 1. During formation of the first layer and the third layer, after the valence electron controlling agent B₂H₆ or PH₃ was activated in the activation chamber 128, the activated species was introduced through the introducing pipe 133 into the deposited film forming chamber 120 to form the first layer and the third layer of p-type or n-tyupe therein. As to other conditions, semiconductor layers necessary for solar battery were formed under the conditions shown in Table 2. The solar battery thus obtained exhibited a conversion efficiency improved by 10 % as compared with the solar battery prepared by PCVD method alone. Example 3 In the deposited film forming device shown in Fig. 1, the activation chamber 128 was exchanged with an activation device utilizing optical energy of excimer laser shown in Fig. 2. The activation device shown in Fig. 2 is constituted of an activation chamber 201, an excimer laser 202, a window 205 for irradiation of excimer laser, and a gas feeding pipeline 203 connected to the gas feeding pipeline 134 in Fig. 1, and also a gas feeding line 204 connected to the gas feeding pipeline 132 in Fig. 1. By utilizing the deposited film forming device having the activation device utilizing optical energy as described above, an image forming member for electrophotography as shown in Fig. 6 was prepared according to the method for forming deposited film of the present invention. The above image forming member for electrophotography shown in Fig. 6 was constituted of an aluminum substrate 600, a charge injection impeding layer (first layer, amorphous silicon layer doped with B, 0.5 µm) 601, a photosensitive layer (second layer, amorphous silicon layer, 18 µm) 602, and a surface protective layer (third layer, amorphous silicon carbide layer, 0.5 µm) 603. In this Example, on depositing an amorphous silicon layer doped with boron to a high concentration, in the activation chamber 201 shown in Fig. 2, after the valence electron controlling agent B₂H₆ was activated, the activated specied formed from B₂H₆was introduced through the gas introducing pipe 133 into the deposition chamber 120 to deposit an amorphous silicon layer (first layer) doped with boron to a high concentration. The layer thickness were measured in the same manner as in Example 1. Following otherwise the conditions as shown in Table 3, an image forming member for electrophotography was prepared. The image forming member for electrophotography thus prepared exhibited a charging ability improved by 50 % or more in comparison with that in which all layers were prepared by PCVD method alone. Example 4 In the deposited film forming device in Fig. 1, the activation chamber 128 was exchanged with an activation chamber having an electric furnace shown in Fig. 3. The activation device shown in Fig. 3 is constituted of an activation chamber 301, an electric furnace 302, a gas feeding line 303 connected to the gas feeding pipeline 134 shown in Fig. 1 and a gas feeding line 304 connected to the gas feeding pipeline 132 shown in Fig. 1. By utilizing the deposited film forming device having the activation chamber utilizing heat energy as described above, a solar battery shown in Fig. 5 was prepared according to the method for forming deposited film of the present invention. The layer constitution of the solar batter of this Example was the same as in Example 2. In this Example, during formation of the first layer and the third layer, the charge controlling agent PH₃ or B₂H₆ was activated in the activation chamber 301 and then the activated species was introduced through the introducing pipe 133 into the deposited film forming chamber 120 to form an n-type or p-type first layer and third layer therein. Following otherwise the conditions shown in Table 4, semiconductor layers necessary for solar battery were formed. The layer thickness were measured in the same manner as in Example 1. The solar battery thus obtained exhibited a conversion efficiency improved by 12 % as compared with the solar battery prepared by PCVD method alone. As can be seen from the detailed description and the respective examples as set forth above, according to the deposited film forming method of the present invention, deposited films having uniform physical characteristics with good doping efficiency over a large area can be obtained with easy management of film quality at the same time as achievement of energy saving. Also, it is possible to obtain easily films excellent in productivity, bulk productivity, having high quality with excellent physical properties such as electrical, optical, and semiconductor properties, etc.

Claims: A method for forming a doped deposited film, which comprises: (a) providing a reaction space; (b) providing a gaseous substance (D) for forming a valence electron controller; (c) activating substance (D) in an activation space to form the valence electron controller, comprising an activated dopant species (DA); and (d) introducing into the reaction space (i) separately a gaseous starting material for forming a deposited film, and a gaseous halogenic oxidizing agent having the property of oxidizing said starting material; and (ii) said activated species (DA); thereby forming a doped deposited film. A method for forming a deposited film according to claim 1, wherein step (c) is accompanied by luminescence. A method for forming a deposited film according to claim 1, wherein said gaseous starting material is a chain silane compound. A method for forming a deposited film according to claim 3, wherein said chain silane compound is a straight chain silane compound. A method for forming a deposited film according to Claim 4, wherein said straight chain silane compound is represented by the formula Si n H 2n+2 ( n is an integer of 1 to 8). A method for forming a deposited film according to Claim 3, wherein said chain silane compound is a branched chain silane compound. A method for forming a deposited film according to Claim 1, wherein said gaseous starting material is a silane compound having a cyclic structure of silicon. A method for forming a deposited film according to Claim 1, wherein said gaseous starting material is a chain germanium compound. A method for forming a deposited film according to Claim 8, wherein said chain germanium compounds is represented by the formula Ge m H 2m+2 ( m is an integer of 1 to 5). A method for forming a deposited film according to Claim 1, wherein said gaseous starting material is a hydrogenated tin compound. A method for forming a deposited film according to Claim 1, wherein said gaseous starting material is a group IVA element-containing compound. A method for forming a deposited film according to Claim 1, wherein said gaseous halogenic oxidizing agent contains a halogenic gas. A method for forming a deposited film according to Claim 1, wherein said gaseous halogenic oxidizing agent contains fluorine gas. A method for forming a deposited film according to Claim 1, wherein said gaseous halogenic oxidizing agent contains chlorine gas. A method for forming a deposited film according to Claim 1, wherein said gaseous halogenic oxidizing agent contains fluorine atoms as the constituents. A method for forming a deposited film according to Claim 1, wherein said gaseous halogenic oxidizing agent contains a halogen under nascent state. A method for forming a deposited film according to Claim 1, wherein said substrate is arranged at a position opposed to the direction in which said gaseous starting material and said gaseous halogenic oxidizing agent are introduced into said reaction space. A methods for forming a deposited film according to Claim 1, wherein said gaseous starting material and said gaseous halogenic oxidizing agent are introduced into said reaction space through a transporting pipe of a multi-tubular structure. A method for forming a deposited film according to Claim 1, wherein said gaseous substance (D) contains an element in the group IIIA of the periodic table. A method for forming a deposited film according to Claim 1, wherein said gaseous substance (D) is diborane (B₂H₆) or boron fluoride (BF₃). A method for forming a deposited film according to Claim 1, wherein said gaseous substance (D) contains an element in the group VA of the periodic table. A method for forming a deposited film according to Claim 1, wherein said gaseous substance (D) is phosphine (PH₃), phosphorus pentafluoride (PF₅) or arsine (AsH₃). A method for forming a deposited film according to Claim 1, wherein said gaseous substance (D) is diluted with at least one gas among H₂, He, Ne, Ar, Kr, Xe, and Rn before introduction into the activation space. A method for forming a deposited film according to Claim 1, wherein discharging, light or heat energy is utilized as the activation method in said activation space.

Inventors: HANNA, JUNICHI, HIROOKA, MASAAKI, SAITOH, KEISHI, SHIMIZU, ISAMU
Applicants: CANON KABUSHIKI KAISHA
Application year: 1986
Main classification: H01L21
IPC codes: H01L31, C23C16, H01L21, G03G5