JPH0351090B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is used in, for example, ultra-LSI technology, which is configured to irradiate and absorb light on reaction gas molecules introduced into a reaction chamber to increase decomposition efficiency. The present invention relates to a photoexcitation process device.

Conventional technology With the recent development of VLSI technology, a damage-free, low-temperature process is required to replace the conventional reactive ion etching and plasma-based processes, and one of these is the use of photoexcited chemical reactions. (photo-excited CVD and etching technology)
is attracting attention. The photoexcitation process has the characteristics of low temperature, low substrate damage, and selectivity.
Regarding reaction selectivity, there is spatial reaction selectivity that allows a thin film to be formed or etched only in the area that is irradiated with light, and spatial reaction selectivity that allows only a specific type of molecule in the reaction gas to be excited or a type of molecule to be etched. There is so-called selectivity for chemical reactions, which allows controlling the excited states of different molecules. From this point of view, various basic studies on photoexcitation processes have been conducted. In these basic studies, methods are used, such as using a low-pressure Hg lamp, Hg-Xe lamp, or excimer laser as a light source, and guiding the light from the light source to the reaction chamber through a suitable optical system such as a mirror or lens. ing. However, in this configuration, since the light source is in the atmosphere, the efficiency of irradiating the ultraviolet light into the reaction chamber is significantly reduced due to absorption by oxygen in the air and absorption by the thick transmission window to withstand differential pressure. do. As a result, there is a drawback that the reaction rate is slow.

In order to eliminate these drawbacks, we first filed a patent application in 1982.
-179272, a discharge chamber is provided adjacent to the reaction chamber, and the excitation light generated in the discharge chamber is introduced into the reaction chamber through a transmission window that extends over substantially the entire surface of the reaction chamber without exposing it to the atmosphere. We also proposed a photoexcitation process device equipped with automatic leak valve means to prevent a substantial pressure difference from being applied to the transmission window between the discharge chamber and the reaction chamber. This avoids the absorption of ultraviolet light by oxygen in the air, and also reduces the differential pressure applied to the transmission window, allowing the window material to be made relatively thin, thereby increasing the irradiation rate of excitation light into the reaction chamber. I was able to do that.

Problems to be Solved by the Invention However, in the previously proposed device, the transparent window (for example, SiO ₂
There is a problem in that the windows (windows) are etched and gradually become cloudy, reducing the intensity of ultraviolet light introduced into the reaction chamber over time.

Therefore, an object of the present invention is to provide a photoexcitation process that prevents etching of the transmission window by activated discharge gas and maintains the irradiation efficiency of excitation light into the reaction chamber at a constant level over a long period of time. The goal is to provide equipment.

Means for Solving the Problems In order to achieve the above object, the present invention provides a photoexcitation process device that irradiates and absorbs light into reaction gas molecules introduced into a reaction chamber to increase decomposition efficiency. A discharge tube is provided with an optical window that extends from the atmosphere side into the reaction chamber through the reaction chamber wall and transmits discharge light generated by a microwave discharge device into the reaction chamber, and the optical window of the discharge tube was placed in the reaction chamber, the discharge tube was provided with a discharge gas inlet for introducing discharge gas into the discharge tube toward the optical window, and a microwave discharge device and a gas discharge port were placed on the atmospheric side. It is a feature.

Function In the device of the present invention configured as described above, the discharge gas is introduced from the discharge gas inlet provided near the optical window of the discharge tube, and is discharged from the other end, so that the optical window is always closed. Etching does not occur because it is covered with unactivated discharge gas. Thereby, the irradiation of excitation light into the reaction chamber can be maintained at a predetermined level for a long time.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

The drawing shows an embodiment of the optical excitation process apparatus of the present invention, in which 1 is a reaction chamber, in which a rotatable substrate holder 2 is arranged, and a substrate 3 to be processed is mounted on this substrate holder 2. has been done. As shown in the drawing, a reaction gas introduction port 4 and an exhaust port 5 connected to a vacuum pump (not shown) are provided on the wall of the reaction chamber 1.

Further, a cylindrical discharge tube 6 extends from the outside of the reaction chamber 1 through the wall of the reaction chamber 1 toward the substrate 3. A discharge gas supply section 8 equipped with a transmission window 7 is provided at one end 6a of the discharge tube 6. This discharge gas supply section 8 is vacuum-sealed around the outer circumference of the discharge tube 6, and is A gas inlet 9 is provided. On the other hand, the other end 6b of the discharge tube 6 is connected to a vacuum pump (not shown), and is also provided with a microwave cavity resonator 10 as shown.

In the operation of the illustrated device configured in this way,
The discharge gas enters the discharge gas supply section 8 through the discharge gas inlet 9 and is introduced into the discharge tube 6 from a gap on the transmission window 7 side along the outer periphery of one end 6a of the discharge tube 6, as shown in the figure. , and is discharged from the other end 6b. Then, microwave discharge is generated by the microwave cavity resonator 10, and ultraviolet light is generated within the discharge tube 6. This ultraviolet light passes through the transmission window 7 and is irradiated onto the entire surface of the substrate 3 on the substrate holder 2 placed in the reaction chamber 1 . In this case, since the discharge gas is introduced from the side of the transparent window 7, the transparent window 7 is always covered with unactivated gas, thus preventing etching of the transparent window.

In the illustrated embodiment, the discharge tubes 6 and their related devices may be arranged horizontally instead of vertically, and it is also possible to provide a plurality of discharge tubes.

Effects As explained above, in the device according to the present invention, the optical window that transmits light is always covered with inactivated gas, so the optical window is not etched. Since it does not fog, it is possible to irradiate light for a long time without reducing the light intensity. Therefore, it is possible to perform large-area photo-excited CVD and etching, making it possible to perform ultra-LSI
Mass production using the manufacturing process becomes possible.

[Brief explanation of drawings]

The drawing is a schematic cross-sectional view showing a photoexcitation process apparatus according to an embodiment of the present invention. In the figure, 1: reaction chamber, 6: discharge tube, 7: transmission window,
8: Discharge gas supply section, 10: Microwave cavity resonator.

Claims (1)

[Claims] 1 In a photoexcitation process device that irradiates and absorbs light into reaction gas molecules introduced into a reaction chamber to increase decomposition efficiency, the light extends into the reaction chamber from the atmosphere side through the reaction chamber wall, and is heated by a microwave discharge device. The optical window of the discharge tube is placed inside the reaction chamber, and the discharge gas is directed toward the optical window and into the discharge tube. 1. A photoexcitation process device, characterized in that a discharge gas inlet for introducing gas is provided, and a microwave discharge device and a gas discharge port are arranged on the atmosphere side.