JPH0314229A - End point detecting device - Google Patents

Abstract

PURPOSE:To correct a reduction in the quantity of light of a plasma light, which is caused by an adhesion of reaction products to a detection window, and to make it possible to detect correctly the end point of etching by a method wherein an end point detecting device is provided with a bias automatic adjusting device, which adjusts automatically the bias of an actinometer corresponding to the integrated time of high-frequency power applying times, and the like. CONSTITUTION:In case process gas introduced in a vacuum treating chamber 1 is brought into a plasma state by applying high-frequency power and a surface to be etched on a semiconductor substrate 12 is etched using the plasma, an end point detecting device is provided with an actinometer 3 for measuring the quantity of light of a plasma light from the outside of the chamber 1, an integrating device 8 for integrating high-frequency power applying times and a bias automatic adjusting device 4 for automatically adjusting the bias of the actinometer 3 corresponding to the time of integrating the high-frequency power applying times. For example, a change in the quantity of light of a plasma light, which is reduced with the removal of a material to be etched, is measured by a quantity of light measuring device 3 and the end point of etching is detected. During the operation of the device 3, a bias automatic adjusting device 4 amplifies an output signal from the measuring device 3 in proportion to an integrated time and the signal is sent to an end point detector 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to semiconductor manufacturing equipment, and more particularly to a device for detecting an etching end point in plasma etching.

[Conventional technology]

FIG. 2 is a block diagram of a plasma processing apparatus showing an example of a conventional end point detection apparatus. As shown in the figure, this plasma processing apparatus has an electrode 6 in a vacuum processing chamber 1, and is connected to a power supply 7 via a power supply cable 10. Also,
A light amount measuring device 3 is attached to the side surface of the vacuum processing chamber 1 via a detection window 2, and an end point detector 5 is further provided via a signal cable 9. To explain the operation of this plasma processing apparatus, first, the gas introduction pipe 11 is introduced into the vacuum processing chamber 1.
Introduce more process gas. Next, power is supplied to the power supply 7!
Plasma is generated by applying high frequency power between 6 and 6. The object to be etched on the semiconductor substrate 12 is etched using this plasma. Since the plasma light generated at the etching end point of the object to be etched decreases as the object to be etched is removed, the change in the amount of light is measured by the light intensity measuring device 3 through the detection window 2 to detect the end point of etching. . Conventionally, in this type of end point detection device, the detection window 2 is exposed to the vacuum processing chamber 1 and is exposed to reaction products generated by plasma etching during processing. Therefore, as the detector is used for a long time, reaction products gradually adhere to the detection window 2, and the amount of plasma light outside the detection window 2 decreases.

Along with this, the output signal from the light amount measuring device 3 also decreases.

[Problem to be solved by the invention]

When the conventional end point detection device described above is used for a long time, the output signal from the light amount measuring device also decreases as the amount of plasma light outside the detection window decreases, making it impossible to accurately detect the end point of etching. There are drawbacks. An object of the present invention is to provide an end point detection device that solves this problem.

[Means to solve the problem]

The end point detection device of the present invention converts a process gas introduced into a vacuum processing chamber into plasma by applying high frequency power, and when etching a surface to be etched on a semiconductor substrate using this plasma, a process gas is etched from outside the vacuum processing chamber. A light intensity measuring device that measures the amount of plasma light, an integrating device that integrates the application time of high-frequency power, and an automatic bias adjuster that automatically adjusts the bias of the light amount measuring device in accordance with the integrated time of high-frequency power application. It has

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of a plasma processing apparatus showing an embodiment of the end point detection device of the present invention. This end point detection device is a conventional device with the addition of an application time integration device 8 that integrates the plasma application time and an automatic bias adjuster 4 that amplifies the output signal of the light amount measuring device 3 that detects the amount of light. .

Next, the operation of the plasma processing apparatus to which this end point detection device is added will be explained. Since the plasma light generated during the etching process of the object to be etched decreases as the object to be etched is removed, the change in the amount of light is measured by the light amount measuring device 3 through the detection window 2 to detect the end point of etching. During this operation, the automatic bias adjuster 4 amplifies the output signal from the light amount measuring device 3 in proportion to the integrated time counted by the application time integrating device 8 and transmits it to the end point detector 5. Therefore, even if the amount of plasma light outside the detection window 2 decreases due to reaction products adhering to the detection window 2,
The output signal to the end point detector 5 does not decrease.

〔Effect of the invention〕

As described above, the present invention has the advantage that by providing an automatic bias adjuster and an application time integration device, an end point detection device that can accurately detect the end point of etching can be obtained.

9... Signal cable, 10... Power supply cable, 11
...Gas introduction pipe, 12...Semiconductor substrate.

Claims (1)

[Claims] A process gas introduced into a vacuum processing chamber is turned into plasma by application of high-frequency power, and when this plasma is used to etch a surface to be etched on a semiconductor substrate, the light intensity is measured from outside the vacuum processing chamber. An end point characterized by having a measuring device, an integrating device that integrates the application time of high-frequency power, and an automatic bias adjuster that automatically adjusts the bias of the light amount measuring device in accordance with the cumulative time of applying high-frequency power. Detection device.