FTIR spectrum monitoring based internal state maintenance method of plasma etcher

Abstract

The invention provides an FTIR spectrum monitoring based internal state maintenance method of a plasma etcher. The outer wall of a reaction chamber of a plasma etcher is provided with a window for installing an internal reflection crystal. An ATR-FTIR spectrum probe is installed at one end of the window, and an infrared detector is installed at the other end of the window. After light rays emitted by the Fourier transform infrared spectrum probe are reflected many times in the internal reflection crystal, the light rays are emitted from the other end of the internal reflection crystal, and are focused on the infrared detector. An HgCdTe detector is connected with a spectrum processing system so as to obtain the Fourier transform infrared spectrum graph of the inner wall of the reaction chamber of the plasma etcher regularly or at real time. The Fourier transform infrared spectrum graph is used for measuring the components of attached polymers, and is compared with a standard Fourier transform infrared spectrum graph to determine whether the reaction chamber needs cleaning. If so, the reaction chamber of the plasma etcher is cleaned.

Description

technical field [0001] The invention relates to a method for monitoring and maintaining the internal state of a plasma etching machine. Background technique [0002] Large-area high-density plasma etching machines, such as ICP (Inductively Coupled Plasma) and TCP (Transformer Coupled Plasma) plasma, have been used in the pattern formation process of deep submicron VLSI. In order to obtain the best product yield and device performance, it is necessary to keep the etching machine in a stable and optimal process window. The optimal process window depends on many parameters: such as plasma density, electron temperature, free radical density, gas flow and wafer temperature. Since these parameters often drift, it is necessary to control the equipment hardware parameters and process parameters in order to seek the best process conditions. As device geometries continue to shrink, more stringent requirements are placed on process control. It makes the robust characterization of th...

AI Technical Summary

Problems solved by technology

At present, the commonly used method is to observe the change of the intensity of the characteristic OES spectrum emitted by the plasma. If the polymer deposited on the inner wall of the reaction chamber is too thick, it will cause more obvious characteristic peaks to appear on the OES spectrum. , and the intensity of the peak has a large change. OES is to detect the concentration of various ions in the plasma, including the concentration of reactant ions, the concentration of reaction product ions, and the concentration of intermediate process products. By observing the concentration of ions in the plasma The relationship between the change of a certain ion concentration and the change of OES spectral intensity can be used to indirectly judge the impact of the polymer deposited on the inner wall of the reaction chamber on the plasma. Because the concentration of the plasma generated by the polymer is very low, and the plasma and the reaction The chemistry between the chamber walls is complex

When the corresponding OES characteristic peak can be observed, the thickness of the polymer has exceeded the value that the process window can tolerate, so this detection method is too rough to detect the interaction between the plasma and the inner wall of the reaction chamber in real time

Neither of these two methods can timely and accurately judge whether the equipment needs to be maintained, so it cannot effectively improve the equipment utilization efficiency of the plasma etching machine.

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