KR-102964295-B1 - Optical Diagnostic Apparatus

KR102964295B1KR 102964295 B1KR102964295 B1KR 102964295B1KR-102964295-B1

Abstract

An optical diagnostic device according to one embodiment of the present invention comprises: a pipe including a first flange coupled to a port of a vacuum chamber; a first waveguide disposed within the pipe through which an ultra-high frequency propagates; a transparent dielectric disposed at one end of the first waveguide; a frequency selective surface (FSS) structure disposed on the transparent dielectric that receives the ultra-high frequency and discharges the gas of the vacuum chamber to generate plasma; and a photodetector that receives light from the plasma.

Inventors

유신재
최민수
김시준
설유빈
조철희
정원녕

Assignees

충남대학교산학협력단

Dates

Publication Date: 20260512
Application Date: 20251014

Claims (13)

A pipe including a first flange that connects to a port of a vacuum chamber; A first waveguide disposed within the above pipe and through which ultra-high frequency propagates; A transparent dielectric disposed at one end of the first waveguide; A frequency selective surface (FSS) structure disposed on the transparent dielectric and receiving the ultra-high frequency to discharge the gas in the vacuum chamber to generate plasma; and An optical diagnostic device characterized by including a photodetector that receives light from the above plasma.
In paragraph 1, The first flange and the first waveguide are coupled, The above transparent dielectric is coupled to one end of the above first waveguide, and An optical diagnostic device characterized in that the interior of the first waveguide is at atmospheric pressure.
In paragraph 1, An optical diagnostic device characterized in that the first waveguide is a rectangular waveguide.
In paragraph 1, An optical diagnostic device characterized in that the resonant frequency of the frequency-selective surface structure is 5 GHz to 7 GHz.
In paragraph 1, The above frequency selection surface structure is: Challenge Ring; A square conductive plate including a circular opening spaced apart from the conductive ring and arranged to surround the conductive ring; and An optical diagnostic device characterized by including a connecting portion that locally connects the above-mentioned square conductive plate and the above-mentioned conductive ring.
In paragraph 5, The length of the above square conductive plate is 10mm, and The inner diameter of the above conductive ring is 7.2 mm, and The outer diameter of the above conductive ring is 7.6 mm, and An optical diagnostic device characterized in that the inner diameter of the circular opening of the square conductive plate is 8 mm.
In paragraph 5, An optical diagnostic device characterized by the thickness of the above-mentioned connection being 1 mm.
In paragraph 5, An optical diagnostic device characterized by the fact that the resonant frequency of the above frequency-selective surface structure is 6.13 GHz.
In paragraph 1, An optical diagnostic device characterized in that the above-mentioned port is formed in the exhaust line of the vacuum chamber or in the body of the vacuum chamber.
In paragraph 1, The above pipe includes an opening, A second flange connected to the other end of the above pipe; It further includes a dielectric reflector disposed within the first waveguide to transmit incident ultra-high frequency and reflect light of the plasma. An optical diagnostic device characterized by light reflected from the above-mentioned dielectric reflector traveling through the opening of the above-mentioned pipe.
In Paragraph 10, The above photodetector is: A light focusing unit coupled to the above pipe to focus light and transmit it to an optical fiber; A spectroscopic unit that spectrally separates light transmitted through the optical fiber according to wavelength; and The signal processing of the above-mentioned spectroscopic unit includes an optical signal processing unit, and The optical diagnostic device is characterized by the optical signal processing unit diagnosing the process according to the gas components of the vacuum chamber.
In Paragraph 10, A third flange coupled to the second flange above; An antenna disposed on the third flange and radiating the ultra-high frequency; and An optical diagnostic device characterized by further including an ultra-high frequency generator that supplies power to the above antenna.
vacuum chamber; and It includes an optical diagnostic module attached to a port of the vacuum chamber, and The above optical diagnostic module is: A pipe including a first flange coupled to the port of the vacuum chamber; A first waveguide disposed within the above pipe and through which ultra-high frequency propagates; A transparent dielectric disposed at one end of the first waveguide; A frequency selective surface (FSS) structure disposed on the transparent dielectric and receiving the ultra-high frequency to discharge the gas in the vacuum chamber to generate plasma; and A vacuum processing apparatus characterized by including a photodetector that receives light from the above plasma.

Description

Optical Diagnostic Apparatus The present invention relates to an optical diagnostic system for generating plasma in a vacuum chamber, and more specifically, to a system for generating and maintaining plasma and detecting light by utilizing a high electric field generated by utilizing the LC resonance phenomenon of a frequency selective surface (FSS) by designing the electrode portion of a plasma generator using a frequency selective surface (FSS). Semiconductor manufacturing technology performs thin film etching and deposition processes, such as etching and deposition, within a vacuum vessel. Both deposition and etching processes can be carried out using plasma. Failure to quickly detect changes occurring during the plasma process results in significant capital loss. For example, diagnostic technology is required to verify whether the vacuum equipment has reached a normal operating state capable of processing a substrate after performing preventive maintenance. Additionally, diagnostic technology is required to detect anomalies during the resonance of the vacuum equipment. Diagnostic technology is also required to detect the etching endpoint of the plasma processing equipment. Conventional optical diagnostic technologies include Optical Emission Spectroscopy (OES), which collects light directly within a plasma vacuum chamber, or Self-Plasma Optical Emission Spectroscopy (SPOES), which spectroscopy using a separate inductively coupled plasma source in the exhaust line connecting the vacuum chamber and the vacuum pump. The OES method has low light output and requires periodic maintenance, such as window cleaning, due to window contamination. The OES method has limitations in fixture design, requiring narrow windows and wide viewing angles. Therefore, to increase light output, the OES method necessitates wider windows and changes to the installation location, which affect the process. The SP-OES is installed by branching off from the exhaust line between the process chamber and the vacuum pump, making it insensitive to pressure changes in the process chamber and exhibiting a low reaction rate to changes in gas composition within the chamber. In particular, since the SP-OES is installed in a path branched from the exhaust line, the immediate inflow of process gas into the branched path is difficult, which can lead to errors. Inductively coupled plasma devices for SP-OES are difficult to install directly in the exhaust line. The present invention can provide an optical emission spectrometer that responds immediately to changes in pressure in a process chamber and rapidly to changes in gas composition by installing a plasma generator directly in an unbranched exhaust line. FIG. 1 is a conceptual diagram showing a vacuum processing apparatus according to one embodiment of the present invention. Figure 2 is a conceptual diagram showing the relationship between the vacuum processing device and the optical diagnostic module of Figure 1. Figure 3 is a cross-sectional view showing the optical diagnostic module of Figure 2. Figure 4 is a perspective view showing the optical diagnostic module of Figure 3. Figure 5 is a plan view showing the FSS. Figure 6a is a simulation result showing the electric field of the FSS. Figure 6b shows the reflection characteristics (S11) of the S parameters of FSS according to frequency. Figure 7a is a simulation result showing the pattern of an electric field according to the shape of a conductive ring according to one embodiment of the present invention. Figure 7b is a simulation result showing the resonance frequency according to the shape of the conductive ring. Figure 8a is a simulation result showing the pattern of an electric field according to the shape of a conductive ring according to one embodiment of the present invention. Figure 8b is a simulation result showing the resonance frequency according to the shape of the conductive ring. FIG. 9a is a simulation result showing the pattern of an electric field according to the shape of a conductive ring according to one embodiment of the present invention. Figure 9b is a simulation result showing the resonance frequency according to the shape of the conductive ring. FIG. 10 is a conceptual diagram showing a vacuum processing apparatus according to another embodiment of the present invention. FIG. 11 is a conceptual diagram showing an optical diagnostic module according to a modified embodiment of the present invention. FIG. 12 is a conceptual diagram showing an optical diagnostic module according to a modified embodiment of the present invention. Plasma is typically used in low pressure ranges of a few toro or less, and there are two main methods for generating plasma at low pressure: CCP (Capacitive Coupled Plasma) and ICP (Inductively Coupled Plasma). In the case of CCP, the electric field accelerates free electrons, and the accelerated free electrons ionize neutral species and cause electron avalanches to create a plasma state. In t