JPS58123880A - Plasma etching device - Google Patents

Abstract

PURPOSE:To make the completion of windowing in Si-oxide films possible without damaging semiconductor substrates by detecting the change in the generation intensity of CO generated in a reaction chamber during etching, converting the same to an electrical signal and turning off the applied high frequency voltage. CONSTITUTION:A high frequency voltage is applied between an upper electrode 4 and a lower electrode 3 in a reaction chamber 1 by a high frequency oscillator 5 to generate reacting gas plasma. The gas plasma etches the Si-oxide films of samples 10 to be etched and forms CO during the etching reaction. Since CO generates intrinsic light emission, the emission intensity thereof is detected with an optical detector 11, and is converted and amplified to an electric signal by an amplifier 12. The electric signal is fed to a high frequency oscillator 5. When the windowing of the Si oxide films on the samples 10 is completed, the generation of CO is decreased sharply. The change thereof is detected with the detector 11 and is transmitted to the amplifier 12. The oscillator 5 is stopped by the electric signal fed from the amplifier 12 and the irradiation of plasma is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plasma etching apparatus for etching an 81 oxide film on a semiconductor substrate using gas plasma.

81 is widely used as an insulating protective film for semiconductor integrated circuits.
If an oxide film is used, after opening a space in this insulating protective film, a mu film or a munic alloy film is deposited as an electrode or wiring material, and interconnections between transistors and other elements under the insulating protective film are made. ing. With the increasing density of semiconductor integrated circuits, the size of the chamber formed by processing the insulating protective film is extremely small, approximately 2 to 5 μm in area. Therefore, in recent years,
Plasma etching equipment that utilizes gas plasma has come to be widely used for such hole-opening processing of insulating protective films.

Conventionally used methods include, for example, a method using an aqueous solution of Hv (heptonic acid), but since the aqueous solution seeps in laterally, the chamber becomes larger than the specified size, making it difficult to process small holes. . There are also problems with waste liquid treatment. In comparison, plasma etching equipment that uses gas plasma does not cause lateral seepage, has the property of being able to open a predetermined chamber in a heavy manner (anisotropic etching), does not require waste liquid treatment, and can be automated. It has many advantages, such as:

However, when a plasma etching device is used to open the insulating protective film, it is not certain when the opening is completed, and conventional plasma etching devices perform management based on time. Furthermore, since the size of the chamber to be opened in the 81@ film is very small, it is impossible to visually judge the size.

Furthermore, if the gas plasma irradiation is continued after the completion of opening the insulating protective film and becomes excessive, the semiconductor substrate may be damaged.
The element becomes defective. Therefore, when using a plasma etching device to open a window in an insulating protective film, it is very important to detect the completion point of the opening by some method and to stop the gas plasma irradiation.

The present invention eliminates such drawbacks in plasma etching equipment, and optically detects the emission intensity of 00 (-carbon oxide) generated during plasma etching of an 81 oxide film, converts it electrically, and... ■.

This plasma etching apparatus is characterized by having a function of cutting off the high frequency applied voltage. Hereinafter, the present invention will be described in detail based on Examples.

Figure 1 shows an example of a conventional plasma etching apparatus.
After the reaction gas is introduced into the reaction chamber 1 from the introduction valve 7,
A high frequency voltage is applied between the upper electrode 4 and the lower electrode 3 by a high frequency oscillator 5 .

When a high-frequency voltage is applied, the reaction gas between the upper electrode 4 and the lower electrode 3 becomes gas plasma (separated into positive and negative ions or radicals, etc.), and the lower electrode 3
The oxide film 81 of the sample 9 to be etched above is etched. The lower electrode 3 to which a high frequency voltage is applied and the reaction chamber outer wall 2 are insulated by an insulator 9. The reaction gas in the reaction chamber 1 is constantly exhausted by a rotary pump 6 through an exhaust valve 8. In such a conventional plasma etching apparatus, it is not certain when the etching of the 81 oxide film is completed in the sample 10 on the lower electrode 3 (the end point of etching), and the high frequency pressure is turned off and the plasma etching is started by time management. was terminating. Therefore,
Even after the S1 oxide film has been cleared, there is a great risk of damage to the semi-solid substrate due to plasma irradiation.

In order to eliminate such drawbacks of the conventional plasma etching apparatus described above, FIG. A high-frequency oscillator 12 is installed between the upper electrode 4 and the lower electrode 3 in the reaction chamber 1, which is a plasma etching apparatus according to an example of the present invention. A high frequency voltage is applied by the device 5, and gas plasma is generated. The gas plasma etches the S1@ film of the sample 10 to be etched, and during the etching reaction, 00 (-carbon oxide) is generated, producing light emission unique to CO. This luminescent strong motion is detected by an optical detector 11 and converted into an electrical signal by an amplifier 12.

When the opening of the 81 oxide film of the sample 10 to be etched is completed, the occurrence of 000 is drastically reduced, and this change is detected by the optical detector 11.
captures the signal and transmits it to the amplifier 12.

Next, an electrical signal is sent to the high-frequency oscillator 5, and the high-frequency application is cut off to stop plasma irradiation.

As described above, the present invention optically detects the emission intensity specific to 0O (-carbon oxide) in a gas plasma etching apparatus for S1 oxide film, captures the change in the 00 emission intensity at the time of completion of chamber opening, and transfers it to both electrodes. This plasma etching apparatus is characterized by having a function of automatically stopping the application of high frequency.

Although the number of samples 10 to be etched is not particularly mentioned in the embodiments of the present invention, it goes without saying that the present invention can be applied to processing of one sample or multiple samples. It goes without saying that the present invention can be applied not only to an apparatus in which the sample to be etched is placed on the lower electrode, but also to a plasma etching apparatus in which the sample to be etched is mounted on the upper electrode using a vacuum chuck or an electrostatic chuck. stomach.

[Brief explanation of drawings]

11th i! l! 2 is a diagram showing a conventional plasma etching apparatus, and 2nd WJ is a diagram showing a plasma etching apparatus according to an embodiment of the present invention.

Claims (1)

[Claims] In a plasma etching apparatus that introduces gas into a vacuum chamber and applies a high-frequency voltage between electrodes to generate gas plasma to etch the sample to be etched in the vacuum chamber, the 00000 generated in the reaction chamber during etching is used. 1. A plasma etching apparatus characterized by having a function of detecting the emission intensity of (-clearing carbon) with an optical detector, converting it into an electrical signal, and cutting off the high-frequency applied voltage.