JPS61110772A - Multi-layer thin film forming device - Google Patents

Abstract

PURPOSE:To form a multi-layer thin film of optional constitution by communicating a plasma CVD reaction chamber with an optical CVD reaction chamber through a connecting port which can be closed up, and moving a substrate between each reaction chamber by a carrying means. CONSTITUTION:A connecting port 5 between plasma CVD reaction chambers 1, 2 and an optical CVD reaction chamber 3, and a carrying chamber 4 is partitioned by an opening and closing valve 6. A tray 8 to which a substrate 7 has been set is put into the carrying chamber 4, and the inside of the carrying chamber 4 is exhausted by closing an opening and closing valve 9. The tray 8 moves on a carrying rail 10, and stops in front of a desired reaction chamber. By opening an opening and closing valve 5, the tray 8 is put into the reaction chamber which has been brought to vacuum exhaust in advance. By closing the opening and closing valve 5 and leading in a prescribed gas, the first thin film is formed on the substrate 7. By opening the opening and closing valve 5 again, the tray 8 is fed out to the carrying chamber 4, put into the next reaction chamber, and the second thin film is superposed and formed. By repeating it, a desired multi-layer thin film is formed.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a multilayer thin film forming apparatus for manufacturing an electronic device in which a plurality of semiconductor thin films are laminated, such as a photoelectric conversion device having a p-1-n structure of amorphous silicon.

[Prior art and its problems]

In recent years, research has been active on electronic devices using thin film semiconductors, particularly photoelectric conversion devices using amorphous silicon (hereinafter referred to as a-5i), and they are being put to practical use in power supplies for calculators and various sensors. Currently, as a method for forming these a-8i, a plasma CVD method is widely adopted in which a thin film is grown on a substrate by glow discharge decomposition in monosilane (Sime) gas. A raw material gas 22 is introduced into a reaction chamber 21 whose principle is shown in FIG. By adding this, plasma is generated in the space 28 between the electrode 26 and the substrate 23. In the space 2B, active molecules are formed by collision of electrons in the plasma with source gas molecules, and these are deposited on the substrate 23, as shown in the reaction diagram. However, since harmful and useless ions are generated at the same time, ion damage may occur on the substrate, and impurities adhering to the walls of the reaction chamber may be knocked out, which may have an adverse effect on the thin film. Alternatively, the plasma may damage underlying layers already provided on the substrate.

[Purpose of the invention]

An object of the present invention is to provide a multilayer thin film forming apparatus that can be used to eliminate the drawbacks of the plasma CVD method as described above and to manufacture multilayer thin film electronic devices with good characteristics.

[Key points of the invention]

In order to achieve the above-mentioned objects, the present invention utilizes plasma CVD
This is a combination of the method and the photo-CVD method. Optical CVD
This method is a well-known method in which source gas molecules are decomposed and dissociated using ultraviolet radiant energy. That is, as shown in FIG. 3, a raw material gas 32 is introduced into a reaction chamber 31, and ultraviolet light 36 from an ultraviolet light source 37 is emitted into a space 38 above a substrate 33 on a support 35 heated by a heater 34. is made incident. In the space of 3 days, photons collide with raw material molecules to form active molecules, which are deposited on the substrate 33, as shown in the reaction diagram shown. According to this method, although the speed of 1111 growth is slower than that of the plasma CVD method, as is clear from FIG. 3, no ions are generated, so the drawbacks of the plasma CVD method described above do not exist. The multilayer llR forming apparatus according to the present invention has r
The plasma CVD method and the photo CVD method can be performed by providing a plasma CVD reaction chamber and a photo CVD reaction chamber that communicate with each other through a five-layer communication port, and a transport means that can move the substrate in any direction between the reaction chambers. Combine appropriately to create multilayer III! ! Make it possible to manufacture electronic devices.

[Embodiments of the invention]

FIG. 1 is a plan sectional view of the main parts of an apparatus according to an embodiment of the present invention. The main part consists of three reaction chambers 1.2.3 and a transfer chamber 4. Reaction chamber 1.2 is a chamber for forming a thin film by plasma CVD, and reaction chamber 3 is a chamber for forming a thin film by photoCVD. The communication port 5 between each reaction chamber 1, 2.3 and the transfer chamber 4 is partitioned by an opening/closing pulp 6, so that the tray 8 carrying the substrate 7 can be moved between the reaction chamber and the Wi transfer chamber. is open and closed during film deposition. Further, an opening/closing pulp 9 is provided to take the tray 8 in and out of the transfer chamber 4. A transport rail 10 is provided within the transport chamber 4 in the direction in which the reaction chambers 1, 2.3 are lined up. Here, we will describe the procedure for actually forming a multilayer thin film. The tray 8 on which the substrate 7 is set is placed in the transfer chamber 4, the open/close pulp 9 is closed, and the transfer chamber is evacuated through the exhaust pipe 11. This tray moves on the conveyor rail 10 and stops in front of a desired reaction chamber (for example, reaction chamber 1). Next, the opening/closing pulp 5 is opened, and the tray 8 is preliminarily vacuumed by moving rollers (described later). Place in the evacuated reaction chamber 1. Opening and closing pulp 5
After closing and introducing a predetermined gas, a first thin film is formed on the substrate 7 by plasma reaction. The open/close pulp 5 is opened again, the tray 8 is sent to the transfer chamber 4, and a second thin film is overlaid and formed in the next reaction chamber. By manipulating this, a desired multilayer thin film is formed. In order to explain the configuration of each reaction chamber in detail, FIG.
4 and 5 are cross-sectional views of the ' plane. FIG. 4 is a cross-sectional view of the reaction chamber 1 (plasma CVD method). Here, there is a heater 24 for raising the temperature of the substrate to a predetermined temperature, and two discharge electrodes 26 installed parallel to the heater 24. The tray 8 loaded with substrates is hung on a moving roller 28. The heater 24 and the tray 8 are electrically grounded, while the discharge electrode 26 is connected to the output of a high frequency power source (not shown). FIG. 5 is a sectional view of the reaction chamber 3 (photo-CVD chamber). Heater 34. The moving roller 38 and the like are connected to the heater 24 of the plasma reaction chamber. Although it is similar to the moving roller 28, a low pressure mercury lamp 37 for emitting ultraviolet light is installed at the position of the discharge electrode. FIG. 6 briefly shows two types of process examples when this apparatus is applied to the production of A-31 solar cells. In both of the two examples shown here, p-1-n three layers are formed on a glass substrate on which transparent electrodes have already been formed. In the case of (a), nine layers are first formed in the reaction chamber 3 to a thickness of about 100 layers by photo-CVD. The raw material gas used is a mixed gas of disilane (Si, H,) and diborane (BJa), and one layer is formed by glow discharge decomposition of monosilane in the zero-order reaction chamber 1, which is grown at a substrate temperature of about 200°C. In reaction chamber 2, a layer is formed by gummy discharge decomposition of monosilane and phosphine (Pffs). The solar cell manufactured by this process has the following excellent features. Normally, ITO (indium and tin oxide) is used as a transparent electrode, but when nine layers are formed using the glow discharge decomposition method,
The 170 surface is reduced by the plasma to form a thin insulating layer. As a result, the series resistance increases and the output characteristics deteriorate.
However, in this process of forming the p-layer by the photo-CVD method, as described above, no ions are generated, so this phenomenon does not occur. Next, in the steps shown in FIGS. 6-), the p-layer and n-layer are formed by plasma CVD using glow discharge decomposition, and one layer is formed by photo-CVD. In this case, the p-layer and n-layer are a-3T containing a microcrystalline (me) phase, which reduces light absorption loss in the p-layer and reduces contact resistance between the n-layer and the metal electrode formed on it. This will reduce the amount of This is an obvious fact. However, the most effective method is to form one layer by photo-CVD, which can prevent impurities from being purchased from the inner wall of the reaction tank. Note that in both steps, the photoCVD method is applied to only one layer, which can compensate for the slow growth rate. Although the application examples of the present invention have been described above with respect to amorphous silicon having a p-1-n three-layer structure, it goes without saying that the present invention is not limited to these examples. The structure shown in FIG. 5 illustrates the concept of the device according to the invention and is not to be taken as such. As is clear from the process example shown in FIG. 6, the apparatus according to the present invention can use any combination of plasma CVD and photoCVD, and there is no need to change the structure of the apparatus.

【Effect of the invention】

The present invention includes a photo-CVD reaction chamber and a plasma reaction chamber,
This is a photo-CVD method that allows substrates to be transported between these chambers without being exposed to the outside air. Multilayer thin films with arbitrary configurations can be formed by taking advantage of the advantages of the plasma CVD method, and the interface between the thin films of each layer is also kept clean, so it is possible to form multilayer IS devices such as photoelectric conversion elements or thin film transistors with good characteristics. It can be used extremely effectively in the production of

[Brief explanation of the drawing]

FIG. 1 is a plan sectional view of essential parts of an apparatus according to an embodiment of the present invention, and FIGS. 2 and 3 are sectional views of the apparatus showing the principles of plasma CVD and photoCVD, including reaction diagrams, respectively. , FIGS. 4 and 5 are cross-sectional views taken along the line A-^° of the plasma CVD reaction chamber and photoCVD reaction chamber shown in FIG. 1, respectively. FIG. 6 is a process diagram of two process examples using the apparatus according to the present invention. It is. 1.2: Plasma CVD method, 3: Photo CVD chamber, 4: Wi
Conveying chamber, 5+ communication port, 6+M closed pulp, 7: Substrate, 8 Nidle, 10: Transport rail, U+exhaust pipe, 26: Discharge electrode, 2B, 38: Moving roller, 37: Mercury tube Figure 1

Claims (1)

[Claims] 1) A vacuum-tight chamber is equipped with a plasma CVD reaction chamber and a photoCVD reaction chamber that communicate with each other via a closable communication port, and a transfer means that can move the substrate in any direction between the reaction chambers. Multilayer thin film forming equipment.