KR19990065311A - Etch end point detection method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching process of a semiconductor device, and more particularly, to a method of detecting an etching end point using a light emission signal in an etching apparatus using plasma. The light emission signal is detected over time. The detected signal is filtered through a Fourier transform. The first or second derivative of the filtered signal is differentiated. The etching end point is detected by the minimum or maximum value of the derivative.

Description

Etch end point detection method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching process of a semiconductor device, and more particularly, to a method of detecting an etching end point using a light emission signal in an etching apparatus using plasma.

As the degree of integration of semiconductor devices increases, etching processes for forming fine patterns become more important. During the etching process, there are various ways to find out the end point (etching should be finished), but generally, after forming a material layer having a different etching rate from the etching layer below the etching layer The plasma emission signal (generated during the etching process) generated at the interface between the etched layer and the material layer is sensed and used as a method of stopping the etching by recognizing it as an etch end point. In other words, in order to determine the etching end point, the emission end point of the specific wavelength is changed by using the emission analysis of plasma.

However, as the pattern becomes more complex and dense and the viewpoint of the chamber receiving the light emission signal becomes contaminated, the detection of the etch end point sometimes malfunctions, mainly due to the slight change in the light emission signal. That is, most of the etch endpoint detectors detect plasma emission signals over time and are based on the time when the slope changes. When the slope change is weak, an etch endpoint may be detected.

An object of the present invention is to provide an etching endpoint detection method capable of reliably detecting the etching endpoint when the etching process in the etching apparatus using a plasma.

1 is a flowchart illustrating a step-by-step method for detecting an etching endpoint according to the present invention.

In order to achieve the above object, the etching endpoint detection method according to the present invention comprises the steps of: detecting the emission signal over time, filtering the detected signal through a Fourier transform, and the first or second derivative of the filtered signal And detecting the etch endpoint by the minimum or maximum of the derivative.

Therefore, according to the present invention, the etch endpoint can be reliably detected during the etching process by performing numerical manipulation of the actually obtained luminescence signal by simple numerical analysis and making the derivative value at the etch end point minimum or maximum by performing one or two derivatives. .

Hereinafter, an etching endpoint detection method according to the present invention will be described in more detail with reference to the accompanying drawings.

The present invention is intended to detect a change in the signal through simple numerical manipulation without using a method such as viewpoint cleaning even if the plasma light emission signal is weak.

1 is a flowchart illustrating a step-by-step method for detecting an etching endpoint according to the present invention.

First, after detecting the plasma light emitting signal with time during the etching process, the light emitting signal detected through the Fourier transform is filtered to remove the background noise of the plasma light emitting signal with time. Subsequently, by differentially filtering the filtered signal with a program capable of first or second derivatives, the portion where the maximum or minimum derivative value occurs is recognized as an etch end point.

It can be seen that the slope of the light emission signal is clearly different when the light emission signal to be detected is subjected to daily or second derivative over time. Therefore, the etching end point can be detected with high reliability even though the change in the slope of the light emission signal is slight through simple numerical manipulation.

The present invention is not limited to the above embodiments, and it is apparent that many modifications are possible by those skilled in the art within the technical idea of the present invention.

According to the etching end point detection method according to the present invention, the etch end point during the etching process is reliably performed by numerically manipulating the actually obtained luminescence signal by simple numerical analysis method and by differentially dividing the first or second series to minimize or minimize the derivative value at the etching end point. It can be detected.

Claims (2)

Detecting a luminescent signal over time; Filtering the detected signal through a Fourier transform; Differentiating the filtered signal; And And detecting the etching end point by the minimum value or the maximum value of the derivative value. The method of claim 1, The step of differentiating is an etching endpoint detection method, characterized in that for performing the first derivative or the second derivative.