KR970010660B1 - Detection apparatus of etching end point of wafer - Google Patents

Abstract

It is for an etching end point detecter of a dry etching equipment using plasma. The present detecter precisely detects the end point by checking if the wafer is uniformly etched at important points, and prevents a miss-detection of the end point caused by larger wafers. The detecter comprises: a chamber surrounded by optical fibers and forming plasma inside of it; a wavelength detecter detecting a certain wavelength of plasma that comes through the optical fibers; a optical signal converter converting the wavelength to an electrical signal; a signal combination block; an error generator generating an etching error by comparing the output signal of the signal combination block with a prescribed value; an amplifier adjusting gain and offset by amplifying the optical signal converter output and ; and a microcomputer computing the amplifier output signal, detecting the etching end point, and terminating the etching process.

Description

Weiping etch end detection device

1 is a configuration diagram of an etching end point detection apparatus of a conventional wafer.

2 is an etching endpoint detection apparatus of the wafer of the present invention.

* Explanation of symbols for main parts of the drawings

10 fiber optic 11 chamber

12 photodiode 13 photomultiple

14: signal combination unit 14-1 to 14-3: end gate

15: error generating unit 16: amplifier

17: microcomputer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting an end point at the end of etching in an apparatus for dry etching using plasma, and particularly, whether or not to uniformly etch an important part as a wafer grows. The present invention relates to an etching end point detection device for a wafer that enables precise end point detection and prevents false end point detection.

1 is a configuration diagram of an apparatus for detecting an etching endpoint of a conventional wafer. As shown therein, a chamber 1 for forming a plasma and a photodiode 2 for detecting a specific wavelength at a wavelength of a plasma formed in the chamber 1 are illustrated. And a photomultiplier 3 for converting the sensitivity of a specific wavelength detected by the photodiode 2 into an electrical signal, and amplifying the electrical signal converted in the photomultiplier 3 to obtain desired gain and It is composed of an amplifier (4) for adjusting the offset (Offset) value, and the microcomputer (5) for calculating the output value of the amplifier (4) to find the etching end point to complete the etching, which will be described in detail as follows.

Gas (Gas) is injected into the chamber 1, and the inside of the chamber 1 is made into a specific vacuum pressure state, and then a high frequency (380-400 KHz or 13, 56 MHz) is supplied with microwave (2,45 GHz) power. When the plasma (plasma) is formed in the chamber (1).

The plasma formed as described above is emitted at different wavelengths according to an etching rate and reaction conditions (physical and chemical reactions) between the workpieces in the chamber 1. In this case, the photodiode 2 is output as described above. The specific wavelength is detected and output to the photomultiplier 3.

Then, the photomultiplier 3 converts the sensitivity of the specific wavelength into an electrical signal (voltage, current or resistance value), and the converted electrical signal is amplified by the amplifier 4 to a desired size and amount to gain. The Gain and Offset values are adjusted.

That is, when almost all of the material to be etched is etched and other materials below it start to be etched, the amount of light is changed by a difference in etching speed, that is, a selectivity, so that the photomultiplier ( The electrical signal value changed in 3) also changes.

Accordingly, the microcomputer 5 receives the change of the electrical signal and performs arithmetic functions such as differentiation or integration to find an end point at a desired change point and complete etching of the wafer.

However, the above-described conventional wafer etch end point detection apparatus has only one photodiode for detecting a specific wavelength, and is only installed at one specific position, thereby weakening the loading effect due to the increase of the wafer. If the etching speed drops or accelerates at a certain portion of the wafer, the etching state becomes uneven after the etching is completed, resulting in a large loss of the wafer due to the etching failure of the wafer.

In order to solve this problem, the present invention installs a plurality of optical fibers (Glass Fiber) around the chamber passing the wavelength of the plasma, and comprehensively processes the specific wavelength passing through the optical fiber, and if the value is less than the specific value, the etching is performed. When an error occurs to prevent the loss of a large amount of the wafer, and the value meets a specific value, the etching end point detection device of the wafer is devised to complete the etching by detecting the correct end point through calculation.

It is surrounded by a plurality of optical fibers, the chamber to form a plasma at a specific vacuum pressure in accordance with the gas inflow, wavelength detection means for detecting a specific wavelength at the wavelength of the plasma exiting through the optical fiber, and detected by the wavelength detection means An optical signal converting means for converting a wavelength into an electrical signal, a signal combining means for logically combining an output signal of the optical signal converting means, and an output signal of the signal combining means and a predetermined specific value, and comparing the preset signal with a specific value. Error generating means for generating an etch error, an amplifying means for amplifying an output signal of the optical signal converting means and adjusting a gain and an offset value, and calculating and etching an output signal of the amplifying means. It is composed of a microcomputer to complete the etching to find the end point, described with reference to the accompanying drawings as follows.

2 is a block diagram of an etch peak detection apparatus of the present invention, which is surrounded by four discontinuous optical fibers 10-1 to 10-4 as shown in FIG. The photodiode 12-1 which detects a specific wavelength at the wavelength of the plasma emitted through the chamber 11 forming the plasma according to the application and the optical fibers 10-1 to 10-4 surrounded by the chamber 11; 12-4), photomultipliers 13-1 to 13-4 for converting the wavelengths detected by the photodiodes 12-1 to 12-4 into electrical signals, respectively, and the photomultiplier ( When the input signal is equal to or less than the specified value by comparing the signal combination unit 14 which receives the output signals of 13-l to 13-4 and logically combines the output signal of the signal combination unit 14 with a preset specific value, Amplifying the output signal of the error generating section l5 and the photomultipliers 13-1 to 13-4 that generate a visual error; Amplifier 16 for adjusting gain and offset values, and a microcomputer 17 for calculating an end point by calculating an output signal of the amplifier 16 and completing etching. The signal combination section 14 includes an AND gate 14-1 for AND-combining the outputs of the photomultipliers 13-1 to 13-2, and the photomultipliers 13-3 and 13-4. And an AND gate 14-2 for AND-combining the outputs of ") and an AND gate 14-3 for AND-combining the outputs of the AND gates 14-1 and 14-2. 12-l to 12-4 may be replaced by monochromators, respectively.

Referring to the operation and effects of the present invention configured as described above in detail.

The gas is introduced into the chamber 11 to form a plasma by applying power in a state in which a specific vacuum region is formed.

In such a state, the chamber 11 is surrounded by the optical fiber (Glass Fiber) (10-l to l0-4). At this time, the optical fiber is not one continuum but two or more (in the present invention, four (10-1 to 10-4)) to form discontinuities.

When the chamber 11 is surrounded by the optical fibers 10-1 to 10-4, the plasma wavelength in the chamber 11 is emitted through each of the optical fibers 10-1 to 10-4 and the photodiode 12-1. 12-4) detect a specific exaggeration in the wavelength of the plasma and send it to each photomultiplier 13-1 to 13-4.

In this case, the photodiodes 12-1 to 12-4 may be replaced with a monochromator.

Then, the photomultipliers 13-1 to 13-4 convert the amount of the specific wavelength into an independent electrical signal, that is, a voltage, a current, or a resistance value, and output the converted signal to the signal combination unit 14.

In this case, the end gate 14-1 of the signal combination unit 14 combines the output signals of the photomultipliers 13-1 and 13-2, and the AND gate 14-2 is the photomultiple. The output signals of the rear 13-3 and 13-4 are AND-combined, and the rest of the AND gates 14-3 are AND-combined the outputs of the AND gates 14-1 and 14-2. 15).

Accordingly, the error generating unit 15 compares the output signal of the AND gate 14-3 with a preset special value, and if the output of the AND gate 14-3 is equal to or less than a specific value, that is, the optical fiber 10-1. If the amount of light emitted from -10-4) is non-uniform, an etch error signal can be generated to investigate the cause, and if the output of the AND gate l4-3 satisfies a specific value, the photomultiplier The output signals (13-1) to (13-4) are amplified by the amplifier 16 and adjusted to desired gain and offset values, which are input to the microcomputer 17.

Accordingly, the microcomputer 17 calculates the input value by differential or integration and detects the end point of the wave etching to complete the wafer etching at the end point.

As described above, according to the present invention, even if the size of the wafer increases, the wafer can be uniformly etched by increasing the accuracy of end point detection, and when a problem occurs during the endpoint detection process, the wafer can be detected so that the wafer can be detected. There is an effect that can prevent a large loss of the wafer.

Claims (5)

A chamber surrounded by an optical fiber and forming a plasma therein, wavelength detection means for detecting a specific wavelength at the wavelength of the plasma emitted through the optical fiber, and an optical signal for converting the specific wavelength detected by the wavelength detection means into an electrical signal Signal combination means for combining the conversion means, the output signal of the optical signal conversion means, error generation means for generating an etch error by comparing and determining the output signal of the signal combination means with a predetermined value, and the optical signal An amplification means for amplifying an output signal of the conversion means to adjust gain and offset values, and a microcomputer for calculating an output end point of the amplification means to find an etching end point and completing the etching; . The apparatus of claim 1, wherein the optical fiber comprises a plurality of discontinuities. The apparatus of claim 1, wherein the wavelength detecting means comprises photodiodes (12) formed in the same number as the optical fiber. The apparatus of claim 1, wherein the optical signal converting means comprises photomultipliers (13) formed in the same number as the optical fiber. 4. The apparatus of claim 3, wherein the photodiode (12) can be replaced with a monochronmator.