Etching end point detection method and device

Abstract

The invention provides an etching end point detection method and device. The etching end point detection method comprises the following steps: amplitude modulation is carried out on an etching power supply signal through a power supply modulation signal to obtain an etching amplitude modulation signal; acquiring a spectral signal which is acquired by a spectrograph and is generated based on plasma etching of the sample; wherein the plasma is generated by loading an etching process system based on an etching amplitude modulation signal; performing frequency mixing and filtering processing on the spectral signal through the power supply modulation signal; and detecting an etching end point according to the spectral signal subjected to the frequency mixing and filtering processing. According to the invention, element components contained in different film layer structures can be effectively detected, so that high-precision pulse etching end point detection and control are realized.

Description

technical field [0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular, to a method and device for detecting an etching end point. Background technique [0002] With the rapid development of integrated circuit technology, the core size of the device is constantly shrinking. The original technology has the bottleneck of monitoring the etching process for small windows, high aspect ratio, and ultra-thin etching films, especially for 28nm. The process preparation below the node, the etching preparation of 3D storage high aspect ratio and the MRAM ultra-thin layer etching process, due to the less effective exposure area of ​​etching during the etching process, the concentration of etching elements is low, resulting in the process in the process. The effective information of optical emission spectrum detection is basically covered by background noise, and the signal used for process endpoint judgment is difficult to be e...

AI Technical Summary

Problems solved by technology

[0007] 1. The traditional optical emission spectroscopy method used in plasma etching has no requirements for etching materials, but the etching elements in the etching process have a high exposure concentration. Due to small windows, high aspect ratios, and ultra-thin etching Due to the limited conditions of the film layer, the exposure concentration of the elements during the etching process is small, and the emission spectrum of the elements is submerged in the spectral background noise in the plasma etching, which cannot meet the requirements for small windows, high aspect ratios, and ultra-thin etching films. Applied plasma etching process

[0008] 2. The end point judgment of plasma etching can be realized by using laser interferometry, but since the detection process of laser interferometry depends on the selected test point and the refractive index of the etching material, the laser must be focused on the point where the wafer is etched, and the The area size and roughness information of the selected point will affect the test

Due to the problem of the optical focus of the selected potential and the measurement of the optical path of the ultra-thin film due to the small window and high aspect ratio, the end point judgment process using laser interferometry for small windows, high aspect ratio, and ultra-thin etching film is basically impossible. Meet the conditions of use

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