JPS63143807A - Film forming equipment - Google Patents

Abstract

PURPOSE:To enable a high quality film to be uniformly formed at a high film forming speed on a material on which the film is formed by providing the material at the side of and in parallel with a comb-like transmitting electrode outside of a pair of the electrodes by applying high frequency power to the conductive comb-like electrode which can transmit a gaseous material. CONSTITUTION:A comb-like electrode (gas transmitting electrode 3) applied with high frequency power is connected to an impedance matching circuit which enables impedance matching. A film forming equipment is so constructed that a material on which a film is formed is provided at the side of and in parallel with the transmitting electrode 3 outside of a pair of the electrodes and a raw material gas supplied in plasma is brought on the surface of the material on which a thin film is formed through the gas transmitting electrode 3. Since the interval between the gas transmitting electrode and the material on which the thin film is formed controls the speed of forming the thin film, if the interval is made constant at any position of the material, the speed of forming the thin film can be made constant irrespective of the position and the uniform thickness and high quality thin film can be formed irrespective of the shape or the size of the material on which the thin film is formed.

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a film forming apparatus using high frequency discharge, and in particular,
The present invention relates to a film forming apparatus suitable for uniformly forming a thin film on an object.

[Prior art and its problems]

Conventionally, thin film forming apparatuses using high frequency discharge have been used, for example, as schematically shown in FIG. It has been used to form carbide films. However, it has been difficult to uniformly form *H shadows on a large area, whether it is a complicated shaped object or a simple shaped object such as a plate. In order to solve this difficulty, attempts have been made to make the discharge electrode 1i much larger than the object to be formed. However, because the object to be formed was in the process of discharging, it was not possible to eliminate disturbances in the discharge, and uniform formation on objects with complex shapes, even on large-area objects, was still unsatisfactory. . Furthermore, as a matter of course, this method requires an extremely large thin film forming apparatus and cannot meet the demand for cost reduction. Furthermore, as shown in FIG. 3, attempts have been made to use a mesh-like third electrode 4 between the discharge electrodes 2'' and 2'', but this method has the problem of extremely slowing down the thin film formation rate. The present inventor previously proposed a technology for forming an amorphous silicon film from disilane at high speed.Also, disilane is easily decomposed, but it is also easily reactive.For this reason, there is a large amount of raw material disilane. The inventors have found that under these conditions, the reaction between the decomposition products and the raw material disilane becomes the main reaction, and the photoelectric conversion properties of the film deteriorate. In the case of using raw materials that are also easily reactive, the resulting thin film has not yet achieved satisfactory characteristics for use in photoelectric conversion devices. [Basic idea] As a result of a detailed study of It was also found that the amount of raw materials such as disilane was extremely reduced. The present invention was made based on this knowledge. [Object of the Invention] The object of the present invention is to maintain uniform high-frequency discharge. Another object of the present invention is to provide a film forming apparatus that enables reduction of the amount of source gas present without disturbing the discharge due to objects to be formed.
Another object of the present invention is to provide a 'p4 film forming apparatus that can uniformly form a high quality film at a high film formation rate on an object to be formed. [Disclosure of the Invention] That is, the present invention provides (1) a thin film forming chamber having source gas introduction means, evacuation means, and heating means, in which a pair of electrodes connected to a high frequency power source are disposed opposite each other in order to generate glow discharge. At least one electrode of the pair of electrodes is a conductive electrode that allows gaseous substances to pass through, preferably having a comb-like structure, and high-frequency power is applied to the comb-like electrode. The film forming apparatus is characterized in that the object on which the thin film is to be formed is arranged outside the electrode pair and parallel to the interdigital transmissive electrode. The transducer-shaped electrode (hereinafter referred to as a gas-permeable electrode) to which the high frequency is applied is connected to an impedance matching circuit to enable impedance matching. The distance between the gas-permeable electrode and the thin film formation is adjustable, and it is particularly preferred to keep this distance constant. In order to maintain a constant spacing, it is extremely effective to make the surface shape of the gas permeable electrode and the surface shape of the thin film substantially equal. As shown in FIG. 2, the blind-like material used in the present invention is a conductive plate-like material (a) with a width of 0.2 to 2.0 ms and a thickness of 0.1 to 1-1. It has a structure in which the plate-like objects are arranged almost evenly in parallel with an interval (b) of 2 to 2.0 mm, and the respective plate-like objects are electrically connected. Preferred materials for the gas permeable electrode are those that can practically withstand etching of silicon, such as aluminum, stainless steel, tungsten, and tantalum. The other electrode (hereinafter referred to as a counter electrode) disposed opposite to the gas permeable electrode preferably has a surface shape similar to that of the gas permeable electrode. The material of the counter electrode is a conductive metal. The method of supplying the raw material gas is not particularly limited, and any raw material supply means may be used to supply the raw material gas into the plasma. Especially the 1st v! As shown in J, it is a preferable example to use it as a raw material gas supply means and supply the raw material gas through this counter electrode. In the present invention, one of the key points is to minimize the amount of source gas present near the thin film forming surface, and the inventors have discovered that the decomposition of the source gas occurs most violently near the high frequency application electrode. It is. For this reason, it is desirable that the source gas reaches the thin film forming surface from the plasma via the high frequency application electrode. That is, it is an important requirement in the present invention to configure the film forming apparatus so that the source gas supplied into the plasma reaches the surface of the object on which the I film is formed via the gas permeable electrode. The distance between the gas permeable electrode and the object on which the thin film is formed controls the rate of thin film formation, so if this distance is made constant at any position on the object, the speed of thin film formation can be increased. can be made constant regardless of the location, and a high-quality thin film with a uniform thickness can be formed regardless of the shape or size of the object to be formed. Note that the interval is adjusted depending on the shape of the object to be formed. At this time, it is convenient to form the gas permeable electrode into a shape that corresponds to the shape of the object to be formed. For example, if the surface shape of the object to be formed is flat, the gas permeable electrodes are also formed flat, and the interval between them is selected as appropriate. Further, if the surface shape of the object to be formed has irregularities, the gas permeable electrode may also be formed with irregularities corresponding to the irregularities. Any method can be used to adjust the distance between the object to be formed and the gas-permeable electrode, and there is no particular limitation. It is not preferred, therefore, that the interval is at least 1 turn, preferably 2 ms or more, more preferably 4@11 or more. On the other hand, if this interval is too large, the once decomposed source gases will react and combine, resulting in a decrease in the electrical characteristics of the resulting WI film. This distance varies depending on the discharge power, but is within 100 mm, preferably within 50 m. The raw material gas that can be used in the present invention is Si@H1nh* (
It is a silane gas such as n-1, 2, 3-...-...), and n-1, 2, and 3 correspond to monosilane, disilane, and trisilane, respectively. Also 5iH-
Fa-x<x heat 0.1.2.3) and Si! HyFi-
Fluorinated silane represented by y(y-0,1,2,3,5)); germane (GeHa) and GeHzFa-z (2
Of course, fluorogermane represented by 0,1,2.3) can also be used as the raw material gas of the present invention. By using these raw material gases, fluorine-containing silicon and 5iGe alloy can be easily formed. Furthermore, a silicon thin film containing carbon or nitrogen can also be formed by using a carbon-containing compound or a nitrogen-containing compound together with silane gas. In forming these semiconductor thin films, P-type and N-type semiconductor thin films can be respectively formed by using a compound of an element that controls valence electrons, such as boron or phosphorus. Further, these raw material gases including silane gas can be used in an undiluted state, but it is also preferable to use them diluted with hydrogen or helium because this increases the stability of the discharge state. In the present invention, the object on which a thin film is to be formed (hereinafter referred to as the substrate) is not particularly limited, and may be insulating or conductive, transparent or opaque, and basically includes glass, alumina, In addition to non-metals, semiconductors, and metals such as silicon, stainless steel, aluminum, and molybdenum, film or plate-shaped materials formed of heat-resistant polymers and other substances can be effectively used as the substrate. Note that it is also possible to manufacture a semiconductor device such as a charge conversion element using the present invention, but in that case, it is necessary to impart conductivity to the base. Those skilled in the art will readily understand that for this purpose, a conductive substrate or a substrate formed by forming a conductive thin film on an insulating substrate may be used. Materials for forming such a conductive thin film include aluminum, molybdenum, nichrome,
Thin films or plates of indium oxide, tin oxide, stainless steel, etc. are effectively used. Furthermore, if the substrate is used on the light incident side, the substrate must be transparent, but there are no other restrictions. [Preferred form for carrying out the invention] In the present invention, a thin film forming apparatus includes an electrode connected to a high frequency power source to generate a glow discharge in a thin film forming chamber having a source gas introduction means, a vacuum evacuation means, and a heating means. A thin film forming apparatus is formed by arranging a pair of electrodes facing each other, and at least one of the electrodes has a structure that allows gaseous substances to pass through, such as a conductive interdigital structure, and the interdigital electrode has a high frequency The object to which electric power is applied and on which a thin film is to be formed is placed outside the electrode pair and parallel to the transparent electrode side. However, as a high frequency power source, 100KHz to 20MHz
A power supply having an oscillation frequency of is connected to the discharge electrode of the film forming apparatus via an impedance matching circuit. The film was formed at a pressure of 0.001 = 10 Torr, and a spacing between discharge electrodes of 1 to 100 m.
Heated in the range up to ℃, discharge power density 0.01
~IW/cm''. [Examples 1 to 7] As shown in FIG. 1, a thin film forming chamber 1 was equipped with a substrate heating means 6, a vacuum evacuation means 1O1, and a substrate transport means 7 which also served as a substrate holding means.
and a capacitively coupled electrode pair, namely 1. A thin film forming apparatus was used, which had a gas permeable electrode 3 made of a screen-shaped material having a thickness of 0.5 ms and a width of 11I11 arranged at intervals of 0.5 ms, and a counter electrode 2 having a source gas introducing means 9. Electrode 3 is connected to 13.56 M via an impedance matching circuit.
It is connected to a high frequency power source 8 having an oscillation frequency of n2. 30% of disilane is introduced by the raw material gas introduction means.
While supplying at a flow rate of 3CCH and exhausting with a vacuum evacuation means,
After appropriately selecting the zero frequency for adjusting the pressure in the film forming chamber to 0.6 Torr as shown in Table 1, the high frequency power was adjusted to 3 Torr.
Apply 0W to start glow discharge. A glass substrate is transported to a film forming chamber by the substrate transport means, and formation of an amorphous silicon film is started. The substrate was maintained at 250° C. during film formation. After completing the film formation for a certain period of time, the substrate was taken out from the film forming chamber by the substrate transport means. The film thickness, photoconductivity, and dark conductivity of the obtained amorphous silicon film were measured. The results are shown in Table 1. It is clear that even under high-speed film formation conditions, the film quality was excellent in uniformity and the photoelectric conversion characteristics were also good. [Industrial Applicability] As is clear from the above examples, by using the apparatus of the present invention, it is possible to obtain an amorphous silicon film with excellent charging characteristics while maintaining a high film formation rate. It is clear that the present invention can be used in the formation of thin film semiconductors.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a film forming apparatus of the present invention, in which the substrate is located outside the opposing electrodes and on the gas permeable electrode side. Second
The figure is a plan view showing interdigital electrodes, a, b and C.
3 represents a conductive plate, an opening, and an electrical connection, respectively. FIG. 3 is a schematic diagram showing a conventional film forming apparatus.
A substrate exists between opposing electrodes. In the figure, 1--・--- thin film forming chamber, 2--- one counter electrode,
2°, 2″・−・−・Discharge electrode, 3・・・−・・Gas permeable electrode, 4−・・−・−・Mesh-like third electrode, 5−・・
-.--. Soaking plate, 6.--. Substrate heating means, respectively. Patent Applicant Mitsui Toatsu Kagaku Co., Ltd. Hand 1klE Complaint (Method) March 1, 1986 Director-General of the Patent Office Kuro 1) Akio Yu 1, Indication of Case Patent Application No. 290576 of 1988 2 , Name of the invention Film forming apparatus 3, Person making the amendment Relationship to the case Patent applicant address 3-2-5-4 Kasumigaseki, Chiyoda-ku, Tokyo Date and time of the amendment order

Claims (4)

[Claims] (1) A film forming apparatus is constructed in which a pair of electrodes connected to a high frequency power source are arranged opposite each other to generate glow discharge in a thin film forming chamber having source gas introducing means, evacuation means, and heating means, and the electrode pair At least one of the electrodes has a conductive interdigital structure that allows gaseous substances to pass through, and high-frequency power is applied to the interdigital electrode, and the object on which a thin film is to be formed is connected to the electrode. A film forming apparatus characterized in that the film forming apparatus is arranged on the outside of the pair and parallel to the interdigital transmissive electrode. (2) Claim 1, wherein the distance between the interdigital transmissive electrode and the object on which the thin film is to be formed can be adjusted.
The film forming apparatus described in Section 1. (3) The film forming apparatus according to claim 1, wherein a constant distance is maintained between the interdigital transmissive electrode and the object on which the thin film is to be formed. (4) The film forming apparatus according to claim 1, wherein the surface shape of the interdigital transmissive electrode and the surface shape of the object on which the thin film is to be formed are made substantially equal to maintain a constant interval.