JP3116336B2 - Device for detecting the end point of wet etching - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for partially etching a predetermined portion of a semiconductor substrate or the like, and more particularly, to an apparatus for detecting an end point of wet etching for detecting an end point of etching.

[0002]

2. Description of the Related Art Conventionally, end point detection in wet etching is performed by immersing a sample in an etching solution for a predetermined time by calculation in consideration of an etching rate and a film thickness.

[0003]

However, in the above method, when the film thickness is not known or when the etching solution is deteriorated, an approximate registration is made and the film is pulled up early, and is taken in and out a plurality of times while confirming with a microscope. However, there is a problem that it takes time and it is difficult to complete the etching under appropriate etching conditions. The present invention has been made to solve the above-mentioned problems of the prior art. The ion concentration contained in an etching solution is monitored, and a sample whose concentration is saturated is pulled up to reduce the etching time. It is an object of the present invention to provide an apparatus for detecting an end point of a wet etching which is shortened.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a container containing an etching solution, a sample to be etched immersed in the etching solution, and a part of the etching solution. And decompose by heating , contained in the liquid
Heating means for ionizing the member to be etched, ion detection means for taking in the ions and counting the amount of the ions, and end point detection means for determining an end point of the etching based on a change rate of an output from the detection means; And a driving means for pulling up the sample from the etching liquid based on an output signal from the end point detecting means.

[0005]

When a sample is immersed in an etching solution, a portion to be etched is etched and diffuses into the etching solution.
The heating means introduces the etching solution, ionizes it, and sends it out to the ion detection means. The end point detection means monitors the ion concentration in the etching solution, determines that the saturated state is reached as the end point of the etching, and outputs an end point detection signal. The driving means pulls up the sample from the etching solution based on the output from the end point detecting means.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a main part configuration diagram showing an embodiment of a wet etching end point detecting apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a container containing an etching solution 2, in which a sample 4 is arranged at a predetermined interval in a basket 3. Numeral 6 denotes a driving means for supporting the basket 3 via the support rod 7.
The basket 3 is immersed in the etchant or pulled up by driving the support rod in the direction of arrow A.

Reference numeral 8 denotes a pipe having one end inserted into the etching liquid, and 9 denotes a pump for sending the etching liquid to the heating means 10 through the pipe 8. Numeral 12 denotes ion detecting means such as an inductively coupled plasma mass spectrometer 12a and a detector 12b. Numeral 14 denotes end point detecting means comprising, for example, a CPU which counts the number of ions based on a signal from the ion detecting means. Calculate the rate of change. The CPU sends a signal to the driving means 6 when the rate of change of the count reaches a predetermined value.

In the above configuration, first, the substrates to be etched are arranged in a basket, fixed to the tip of the support rod 7 and immersed in the etching solution 2. The member to be etched from the etched sample (substrate) diffuses into the etchant. The etching solution diffused by the member to be etched is sucked by the pump 9 through the pipe 8 and sent to the heating means 10. The heating means 10 heats the etching solution sent to ionize the member to be etched contained in the solution. The ionized member to be etched is analyzed by the mass spectrometer, and the number thereof is counted by the ion detector 13.

The value is sent to the CPU, and when the rate of change becomes almost zero, a drive signal is output to the drive unit 6, which drives the support rod 7 upward to lift the sample. . FIG. 2 shows the relationship between the etching time and the etched element (member to be etched). As shown in the figure, the amount of the element counted continues to increase at a predetermined rate until a certain time, but after a certain time has elapsed, the etching rate decreases extremely. Therefore, the CPU monitors this rate of change. It is to be noted that the tip of the pipe is arranged at a position representing the state of etching best, which is not limited to the illustrated example, and the pump and the pipe are configured to be able to send the etching solution as soon as possible.

[0010]

According to the present invention, as described above in detail with the embodiments, the concentration of ions contained in the etching solution is monitored, and the sample is pulled up when the concentration becomes saturated. As a result, the etching can be always completed in an appropriate etching time, and the yield can be improved. Further, since the rate of change of the etching rate is monitored, the etching liquid used a plurality of times can be used, and the etching can be automated.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an apparatus for detecting an end point of wet etching according to the present invention.

FIG. 2 is a diagram showing a relationship between an etching time and an etched element (a member to be etched).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Etching liquid 3 Basket 4 Sample 6 Driving means 7 Support rod 8 Piping 9 Pump 10 Heating means 12 Ion detection means 14 Computer

Claims (1)

(57) [Claims] 1. A container containing an etching solution, a sample to be etched immersed in the etching solution, and a part of the etching solution being introduced and thermally decomposed to be contained in the solution.
Heating means for ionizing the member to be etched, ion detection means for taking in the ions and counting the amount of the ions, and end point detection means for determining an end point of the etching based on a change rate of an output from the detection means; And a drive unit for pulling up the sample from the etching solution based on an output signal from the end point detection unit.