JPH01231325A - Method and device for deciding end point of etching - Google Patents

Abstract

PURPOSE:To decide the end point of the plasma etching of a material not changed in an etching region by counting the period of an interference color when a sample is etched by using a plasma. CONSTITUTION:An Si substrate is masked with SiO2, polysilicon, etc., as a mask material in a sample 10. When the sample 10 is etched and treated, the interference color of the mask material is generated. The interference color is emitted to the outside of a treating chamber 30 and reaches a filter 20, and an interference color having a fixed wavelength such as a wavelength of 337nm is selected. The interference color reaches a photomultiplier 40, and is converted into an electric signal and is input to an arithmetic and control unit 50. The number of the cycle of the input electric signal is counted by the unit 50. The number of cycles counted and the number of cycles set are compared and arithmetically operated, and the end point of etching of the sample 10 at a time when the number of cycles counted reaches the number of cycles set is decided. When substrate itself is composed of a material, through which light is transmitted, a material emitting the interference color, the end point of etching of the substrate may be decided by using the interference color from substrate itself.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an etching end point determination method and apparatus, and is particularly suitable for etching a sample whose material does not change in the etching region using plasma. and devices.

[Conventional technology]

As a technique for determining the etching end point of a sample to be etched by plasma, for example, a technique using optical spectroscopy is known.

In addition, related to this type of technology.

For example, JP-A-61-53728, JP-A-61-17
No. 1130 etc. are mentioned.

[Problem to be solved by the invention]

The above-mentioned conventional technology is effective as a technique for determining the etching end point even though the material is different at the etching end point of the etching region, but the material does not change at the etching end point of the etching region, that is,
If the material does not change in the etching region, no change in one emission intensity occurs, and therefore, there is a problem that the end point of etching cannot be determined.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and apparatus for determining the end point of plasma etching, which can determine the end point of plasma etching even though the material does not change in the etching region.

[Means to solve the problem]

The above object is to use an etching end point determination method that determines the etching end point of a sample based on the period of interference color during the etching process of the sample using plasma, and an etching end point determination device that determines the etching end point of the sample based on the period of interference color during the etching process of the sample using plasma. Means for selecting an interference color of a constant wavelength from among colors; Means for counting the period of the selected interference color and outputting the counted value; and the relationship between the etching depth of the sample and the period of the selected interference color. This can be achieved by providing a means for determining the end point of etching of the sample to be distributed based on the relationship and the n count value.

[For production]

A sample such as a semiconductor element substrate (wafer) is etched by plasma. If the sample is made of a material that allows light to pass through, interference colors will occur during the etching process. The interference color changes periodically as the thickness of the sample changes due to the discharge. Therefore, the intensity of a certain wavelength in the interference color also changes with a certain period during discharge. According to the inventor's knowledge, a predetermined relationship is established between the period of intensity change of a certain wavelength and the etching progress direction of the sample, that is, the etching depth. Therefore, the etching depth for one period of intensity change at a constant wavelength is determined in advance. From this, the strength of a certain wavelength 11r:f corresponding to the required etching depth I
The number of cycles for conversion is set. During the etching process of the sample, the intensity change at a certain wavelength is monitored, and the number of cycles is counted. When the counted number of cycles reaches the set number of cycles, the etching end point of the sample is determined.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, means for selecting an interference color of a certain wavelength from interference colors during etching treatment of a sample 10 with plasma;
For example, the filter beauty is provided outside the processing beauty and is capable of collecting interference colors. For example, there is one on the interference color exit side of the filter (9).

A photo cutout is provided. Calculation and control of microcomputers, etc.! The input end of JtIt 50 is electrically connected to the output end of the photomultiplex. Calculation.

11i (between the 1m devices, the relationship between the etching depth of the iK material and the period of intensity change of the selected interference color, for example, the etching depth for one cycle of the selected interference color) is determined in advance. In this case, the control device f 50 has a function of calculating and setting the number of cycles of intensity change of a constant wavelength corresponding to the required etching depth, and a function of calculating and setting the number of cycles of intensity change of the selected interference color. It has a function to count the number of cycles of change, and a function to compare and calculate the counted number of cycles with a set number of cycles to determine the etching end point of the sample 10.

In FIG. 1, a sample 10 is carried into a processing chamber.

In the processing chamber, plasma is generated under reduced pressure, and the sample 10 is etched by the plasma.

In this case, the sample 10 is, for example, an 81 substrate masked with a mask material such as SiO2, photoresist, polyimide film, organic material film, polysilicon, or the like.

During the etching process of the sample 10, interference colors of the mask material are generated. The interference color passes out of the processing chamber (9) and reaches the filter where it is filtered at a constant wavelength.

For example, 440nm (SiF2) or 519nm (00)
An interference color having a wavelength such as 337 nm (N) or 337 nm (N) is selected. The selected interference color reaches the photomultiplex, and its intensity is converted into an electrical signal at the photomultiplex. The electric signal is outputted from the photomultiplex and sent to the control device i.
50 is entered. The intensity of the selected interference color is determined by the etching time Ik! as shown in FIG. ! It changes periodically with the passage of time. The calculation and control device counts the number of cycles based on the relationship between the input electrical signal and the elapse of etching time. The calculation and control unit fif50 performs a comparison calculation between the counted number of cycles and the set number of cycles, and when the counted number of cycles reaches the set number of cycles, the etching end point of sample 10 is determined. be done. For example, when the etching end point is determined as in step 2, the calculation is performed immediately.

An operation stop signal is output from the control device to the plasma generation means (not shown), etc., thereby stopping plasma generation and completing the etching process of the sample 10. In addition,
Overetching is performed as necessary.

In this embodiment, the material in the etching area remains unchanged at 81, but the end point of etching is determined based on the period of interference color from the mask material during etching.
Moreover, the judgment can be made with high accuracy. In addition, even if the etch rate changes for each release, the period of intensity change of the selected interference color also changes accordingly, so the etching end point of the S1 crystal plate can be accurately set at the required predetermined depth. Can be judged well.

Further, when etching a large amount of samples continuously, even if the etch rate changes from the initial stage, the period of intensity change of the selected interference color changes accordingly, making it possible to prevent misjudgment.

In the above embodiment, the etching end point of the substrate is determined using the interference color from the mask material, but the substrate itself may be made of a material that allows light to pass through, that is, it emits interference color. For example, the etching end point of the substrate may be determined using the interference color from the substrate itself. Also, calculation.

As a control device, in addition to the functions described in the above embodiment.

It is also possible to use a device that has a function to display the etching end point and notify the operator.

〔Effect of the invention〕

According to the present invention, although the material does not change in the etching region, the end point of plasma etching can be judged as 1 by using the interference color as the IJ characteristic factor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an etching end point determination apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of the relationship between the intensity of interference color of a constant wavelength and etching time. 10...sample, 20...filter,
I...Processing room, Figure 11 --- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Claims (1)

[Scope of Claims] 1. An etching end point determination method, characterized in that the etching end point of a sample is determined based on the period of interference color during etching treatment of the sample with plasma. 2. A step of counting the period of the interference color, a step of determining the relationship between the etching depth of the sample and the period of the interference color, and a first step of determining the etching end point of the sample based on the relationship and the count value. An etching end point determination method according to the claims. 3. Means for selecting an interference color of a constant wavelength from interference colors during etching treatment of a sample by plasma, means for counting the cycle of the selected interference color and outputting the count value, and etching depth and selection of the sample. 1. An etching end point determination apparatus, comprising means for determining an etching end point of said sample based on said relationship and said count value, into which a relationship between said interference color and the period of said interference color is input in advance.