JPS6245120A - Etching device - Google Patents

Abstract

PURPOSE:To prevent excess etching by detecting a substance peculiar to a thin-film formed on the etching of the thin-film by an end-point detecting unit consisting of a spectroscope, etc. on the etching of the thin-film on a compound semiconductor substrate. CONSTITUTION:A substance peculiar to a film generated by etching a substrate (a wafer) 6 and the film is monitored by an end-point detecting unit 13 and the damping point of the substance peculiar to the film 7 is detected on the dry etching of the substrate 6 and the film 7. The presence of a substance peculiar to the substrate 6 generated on the etching of the substrate 6 is also detected by an end-point detecting unit 14. Accordingly, the end point of etching is decided by the detection of the damping point of the substance peculiar to the substrate 6 and the film 7 and the first detection of the substance peculiar to the substrate 6, thus generating no insufficient and excess etching, then allowing etching with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an etching device, and particularly to a try etching device that can detect the end point of etching with high accuracy.

[Background wave (nei)]

There are two types of etching: a wet method that uses a liquid as an edger, and a dry method that uses a gas. As a dry method etching device, thermal oxidation film (SiOx film) on a semiconductor substrate, CVD
-5i There is a device that selectively etches films (hereinafter also referred to as thin films) of O2, polysilicon, molybdenum, aluminum, etc.
November 1978 issue, published November 1, 1978, PL2
Various dry etching apparatuses are known as described in 8 to 132. For example, in a reactive ion dry etching device, a semiconductor substrate to be processed is disposed between a pair of parallel plate electrodes, a high frequency is applied by a high frequency power supply, and a high frequency plasma 7 is generated by supplying gas under a desired vacuum. This method selectively etches the exposed portions of the semiconductor substrate that are not covered by the thin film mask provided on the main surface of the semiconductor substrate.

Incidentally, as described in the above-mentioned literature, emission spectroscopy is known as one method for detecting the end point of etching. This emission spectroscopy uses a spectrometer to monitor the light emitted when a substance (reaction product) unique to the thin film is produced among the reaction products generated during etching of the thin film, and the point at which the substance unique to the thin film ceases to exist is monitored. That is, this is a method in which the etching end point is set at the time when the displacement point of the light is detected.

However, in this method, the reaction products specific to the thin film that appear as light vary depending on the uniformity of the thin film on the semiconductor substrate, the formation conditions, the processing conditions of the photoresist, etc. It is difficult to monitor the product and reproducibly determine when the reaction product has disappeared, and etching may continue even though the reaction product has disappeared, resulting in the semiconductor being damaged.
The inventor has found that the plate is also etched, which causes deterioration of the characteristics of the manufactured device.

[Purpose of the invention]

An object of the present invention is to provide an etching apparatus that can determine the end point of etching with high precision and good reproducibility.

Another object of the present invention is to provide an etching apparatus that can reduce costs by improving the manufacturing yield of semiconductor devices.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, in the etching apparatus of the present invention, when etching a thin film on a compound semiconductor substrate, an end point detection unit consisting of a spectrometer or the like detects a substance unique to the thin film generated during etching of the thin film, and also detects a substance that forms the base of the thin film. Substances specific to the substrate generated by etching the substrate are detected by an end point detection unit consisting of an analyzer, etc., and when the spectrometer etc. detects substances specific to the thin film, the spectrometer etc. detects substances specific to the substrate forming the base of the thin film. Since the first point at which a substance is detected is determined as the end point of etching, excessive etching does not occur and highly accurate etching can be achieved.

〔Example〕

FIG. 1 is a schematic diagram showing an outline of a dry etching apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing a part of a substrate on which a thin film is being etched, and FIG. FIG. 3 is an enlarged cross-sectional view of a portion of the substrate at the end point stage.

In this embodiment, an example in which the present invention is applied to a reactive dry etching apparatus will be explained. As shown in FIG. 1, the dry etching apparatus includes an electrode 2.3 consisting of a pair of parallel flat plates arranged in a reaction chamber 1.
3, a high frequency type 14 is applied.

One of the electrodes 2.3 also serves as a stage on which the object 5 to be processed is placed. The object to be processed 5 is composed of, for example, a GaAs substrate (also referred to as a wafer) 6, and a thin film (film) 7 made of a SiO□ film is adhered to its main surface (upper surface). Further, this thin film 7 is covered with a mask made of a photoresist film 8. This photoresist film 8 partially covers the thin film 7, as shown in FIG. Therefore, in this embodiment, the exposed areas of the thin film 7 not covered by the photoresist film 8 are etched.

On the other hand, a processing gas 10, for example, a fluorocarbon gas CHF3, is supplied onto the object to be processed 5 in the reaction chamber 1 by the gas supply section 9. Furthermore, a desired degree of vacuum is always maintained inside the reaction chamber 1 by an evacuation system 11. Further, a harmful gas processing unit 12 is disposed in this vacuum exhaust system 11, and a harmful gas treatment unit 12 is installed in the vacuum exhaust system 11.
Arsenic fragments such as F3°AsF3 are treated.

On the other hand, in this dry etching apparatus, as shown in FIG. 2, an emission spectrum (hereinafter also simply referred to as spectrum) due to a unique substance such as CO generated during the reactive dry etching of the thin film 7 is used. 15 (
As shown in FIG.
When the substrate 6 of
ASF3. up to 807nm. An end point detection unit 14 is provided, which includes an analyzer or the like that detects a spectrum 16 caused by arsenic fragments such as ASF.

In such a dry etching apparatus, the thin film 7 made of the 3i02 film on the GaAs substrate 1 as described above is used.
When etching by the reactive dry etching method, after the object to be processed 5 is placed on the electrode 3 serving as a stage, the reaction chamber 1 is made airtight, and the processing gas 10 is fed from the gas supply section 9. The interior of the reaction chamber 1 is always maintained at a desired degree of vacuum by the vacuum evacuation system 11, and high frequency is applied to the high frequency power source 4 to generate plasma between the pair of electrodes 2.3, and the main surface of the substrate 6 is The exposed areas of the thin film 7 not covered by the photoresist film 8 are etched. This reactive dry etching causes the SiO□ film to undergo a chemical reaction as shown by the following formula.

3SiO□+4CHF3→3slF'4 →2H20+
C○↑ Therefore, the end point detection unit 13 detects the spectrum due to this CO<514. 8 nm).

On the other hand, as the etching progresses and the thin film 7 disappears, the underlying GaAs substrate 1 naturally begins to be etched. Ga
Reactive dry etching of As causes a chemical reaction as shown by the following formula.

GaAs+CHF:+-Ga+CI+AsFa ↑Therefore, the end point detection unit 14 detects this As1'+ (
A desired spectrum (spectrum spanning from 404 to 807 nm) is detected. And the end point detection unit 13
During the detection of CO, the end point detection unit 14
The first point in time when 3 is detected is determined to be the etching end point.

As a result, in addition to being able to detect the attenuation tendency of CO in the end point detection unit 13, that is, the fact that the etching end point is approaching, it is also possible to detect the point in time when etching of the underlying GaAs starts. , GaAs
Since the etching start point is determined as the etching end point, there will be no under-etching or over-etching, and highly accurate etching can be performed. The fact that the end point of etching can be detected with high precision in this way makes it possible to miniaturize the etching pattern and to form fine patterns in device formation.

[Effects] (1) During dry etching of a film on a substrate, the plasma etching apparatus of the present invention detects the attenuation point of the film-specific substance by monitoring the film-specific substance derived by film etching with the end point detection unit. At the same time, the end point detection unit detects the presence or absence of a substance specific to the substrate that is generated when the substrate is etched, and the etching process is performed by detecting the attenuation point of the substance specific to the film and the first detection of the substance specific to the substrate. Since the end point is determined, insufficient etching or excessive etching does not occur, and the effect of highly accurate etching can be achieved.

(2) From the above (1), the plasma etching apparatus of the present invention has the effect of being able to perform etching with good reproducibility and high yield, since insufficient etching and excessive etching do not occur.

(3) From the above (1), the plasma etching apparatus of the present invention can perform highly accurate etching, and therefore has sufficient effects in manufacturing semiconductor devices that require fine pattern processing, such as ultra-high frequency transistors (GaAsFE'r). You can get the effect of demonstrating.

(4) According to (1) to (3) above, according to the dry etching apparatus of the present invention, it becomes possible to manufacture fine patterns in the manufacture of semiconductor devices due to improved etching accuracy, and also improves the yield of fine pattern manufacturing. A synergistic effect can be obtained in that the manufacturing cost of semiconductor devices can be reduced.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. For example, if more end point detection units are disposed, the etching end point detection accuracy can be further increased.

[Application field]

In the above explanation, the invention made by the present inventor was mainly applied to reactive dry etching technology, which is the background field of application, but it is not limited to this, and can be applied to all dry etching technologies. Applicable.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an outline of a dry etching apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing a part of a substrate where a thin film is being etched, and FIG. FIG. 3 is an enlarged cross-sectional view of a portion of the substrate at the end point stage.

Claims (1)

[Claims] 1. An etching device for etching a film in a workpiece consisting of a substrate and a film deposited on the substrate, the device including an end point for detecting the etching end point of the film. An etching apparatus characterized in that a plurality of detection units are provided. 2. The present invention has an end point detection unit that detects a film-specific substance derived from etching of the film, and an end point detection unit that detects a substrate-specific substance derived from etching of the substrate. Etching apparatus according to item 1.