JPH04280650A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable an teching end point to be accurately detected by a method wherein an etched film is irradiated with a laser beam of single wavelength until a base film is exposed and reflected, and the reflected laser beam are analyzed to obtain a laser beam reflection intensity to an elapsed time, and the etching end point is detected basing on the change of the obtained laser reflection intensity. CONSTITUTION:An Al film 14 or a TiN film 13 of an etched film 15 is irradiated with a laser beam of single wavelength until the TiN film 13 (an SiO2 film 12 when the etched film is the TiN film 13) is exposed and made to reflect the laser beam. The reflected laser rays concenrned are detected to obtain a laser beam reflection intensity to an elapsed time, and an etching end poing is detected based on the obtained laser beam reflection intensity. Therefore, when the etching end point of the Al film 14 which does not transmit laser light is detected, it can be accurately detected without being affected by the fluctuation of pressure, the contamination of a chamber, and the reduction in pressure.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a semiconductor device that can perform stable and highly accurate end point detection in a dry etching process of Al (aluminum), etc. .

[0002] Generally, methods such as emission spectrometry and laser interferometry are mainstream for detecting the end point of etching.
In the present invention, we focus on the reflection intensity when a single wavelength laser is used to irradiate the film to be etched, and the change in reflection intensity due to changes in film quality when the film to be etched changes to the base film at the end of etching. The idea is to provide a stable end point by considering the time function as a function of time.

[0003] In recent years, the throughput of etching equipment in mass-production factories has become enormous, and stable end point detection has become difficult for methods such as optical emission spectroscopy, which are easily affected by chamber contamination and fluctuations in process conditions such as pressure. I couldn't do it. For this reason, methods such as laser interferometry have been proposed, which have the advantage of being less susceptible to the above-mentioned effects. However, in cases where the film to be etched is made of a non-transparent film such as Al that does not allow the laser to pass through, the interferometry method cannot be used. I couldn't do it.

Therefore, the present invention focuses on this Al etching, and requires a method for manufacturing a semiconductor device that can perform stable and highly accurate end point detection in a non-permeable film such as Al.

[0005]

2. Description of the Related Art Conventionally, methods such as emission spectrometry and laser interference have been mainly used to detect the end point of dry etching.

[0006]

[Problems to be Solved by the Invention] However, in detecting the end point of dry etching using the conventional spectroscopic analysis method described above, it is easily affected by pressure fluctuations, which are process conditions.
Furthermore, due to the influence of contamination of the chamber due to an increase in the number of wafers processed, stable and highly accurate end point detection could not be performed.

Next, the above-mentioned conventional laser interference method for detecting the end point of dry etching has the advantage of being less susceptible to the effects of pressure fluctuations and chamber contamination. There was a problem in that interferometry could not be used on sexual membranes and the end point could not be detected.

[0008] Therefore, the present invention provides a semiconductor device that can perform stable and highly accurate end point detection without being affected by pressure fluctuations or chamber contamination when dry etching is used to detect the end point of a non-transparent film that does not allow laser to pass through. The purpose is to provide a method for manufacturing the device.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the method for manufacturing a semiconductor device according to the present invention irradiates a single wavelength laser onto a film to be etched until at least the base film is exposed, and causes the film to be reflected. This process includes the steps of detecting the laser, determining the laser reflection intensity with respect to elapsed time, and detecting the etching end point based on the amount of change in the determined laser reflection intensity.

0010

[Operation] In the present invention, as shown in FIGS. 1 to 4, which will be described later, the Al film 14 (or TiN film 1
3) A single wavelength laser is applied to the base film TiN film 13 (when the film to be etched 15 is the TiN film 13, the SiO2 film 12
) is exposed and reflected, the reflected laser is detected and the laser reflection intensity is determined with respect to the etching elapsed time, and the etching end point is determined based on the amount of change in the laser reflection intensity determined. . Therefore, when detecting the etching end point of the Al film 14 that does not transmit laser, stable and highly accurate end point detection can be performed without being affected by pressure fluctuations, chamber contamination, and low pressure.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings. 1 to 4 are diagrams illustrating an embodiment of a method for manufacturing a semiconductor device according to the present invention, and FIG. 1 is a schematic diagram showing the configuration of an etching apparatus and an end point detector according to an embodiment of the present invention. , FIG. 2 is a cross-sectional view showing the structure of a film to be etched according to an embodiment of the present invention, and FIG. 3 is a diagram showing changes in laser reflection intensity with respect to elapsed time of a film to be etched according to an embodiment of the present invention. FIG. 4 is a diagram illustrating an algorithm according to an embodiment of the present invention. The illustrated etching end point detection method can be applied to methods of manufacturing various semiconductor devices such as MOS and bipolar devices that involve an etching process. In these figures, 1 is a laser oscillator that generates laser, 2 is a mirror that reflects the laser in 3 directions of the wafer,
4 is a half mirror, 5 is a photodetector, 6 is a power meter, 7 is a personal computer, 8 is a chamber, 9 is an end point detector, 10 is an etching device, 11 is a substrate made of Si, etc., 12 is a SiO2 film, 13 is a TiN film , 14 is Al
The film 15 is a film to be etched.

Next, a method for detecting the etching end point when the film to be etched 15 is etched using the apparatus shown in FIG. 1 will be described. First, using the apparatus shown in FIG. 1, a laser oscillator 1 generates a single wavelength laser, and the wafer 3 (specifically, the film to be etched 15 shown in FIG. 2) is irradiated via a mirror 2 and a half mirror 4. and detect this reflected laser with a photodetector 5,
This detected signal is amplified by a power meter 6 and monitored by a personal computer 7. At this time, as shown in FIG. 3, the laser reflection intensity is monitored at regular intervals from the start of etching. Note that a, b, c, and d shown in FIG. 2 correspond to a, b, c, and d shown in FIG. 3. When the laser reflection intensity was monitored in this way, the laser reflection intensity hardly changed while etching the same film (Al film 14 shown in FIG. 2) as shown in a and b of FIG. 3, and as shown in c of FIG. ,d
As shown in FIG. 2, the base film (TiN film 13 shown in FIG.
When the film 12) is exposed, its laser reflection intensity changes significantly.

Specifically, as shown in FIG. 4, the change DI (difference) in the reflection intensity over time is determined using a preset parameter DT (unit time). Here, similarly to the case explained in FIG. 3, while etching the same film (Al film 14 and TiN film 13 shown in figure ■) as shown in ■ and ■ in FIG. 4(a), the laser reflection intensity change DI is Etching progresses with almost no change, and at the end point the base film (TiN film 13 shown in FIG. 2, Si
When the O2 film 12) is exposed, its laser reflection intensity changes greatly. This amount of change is the preset parameter K
The end point is determined when 2 is satisfied (FIG. 4(b)). Note that after the start of etching, the preset parameter TO (
During the stabilization time of the plasma device, only the laser reflection intensity is monitored and the end point is not detected. Additionally, the laser is independent of chamber pressure fluctuations, and the laser transmission window is not exposed to plasma, making it independent of deposition effects.

That is, in this embodiment, a laser beam of a single wavelength is applied to the Al film 14 (or TiN film 13) of the film to be etched 15 (film to be etched 15).
When is the TiN film 13, the SiO2 film 12) is irradiated and reflected until it is exposed, and the reflected laser is detected to determine the laser reflection intensity with respect to the etching elapsed time.
The etching end point is detected based on the amount of change in the laser reflection intensity thus determined. In this way, the etching end point is detected based on the amount of change in laser reflection intensity using a laser, so when detecting the etching end point of the Al film 14 that does not transmit the laser, it is possible to detect pressure fluctuations, chamber dirt, and low pressure. It is possible to perform stable and highly accurate end point detection without being affected by

[0015] In the present invention, since the interface in metal types (TiN/Al, etc.) of a laminated structure can be easily determined, applications such as two-step etching can also be realized.

[0016]

[Effects of the Invention] According to the present invention, when detecting the end point by dry etching a non-transparent film that does not transmit laser, stable and highly accurate end point detection can be performed without being affected by pressure fluctuations and chamber dirt. It has the effect of being able to.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of an etching apparatus and an end point detector according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of a film to be etched according to an embodiment of the present invention.

FIG. 3 is a diagram showing changes in laser reflection intensity of a film to be etched with respect to elapsed time according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating an algorithm according to an embodiment of the present invention.

[Explanation of symbols]

1 Laser oscillator 2 Mirror 3 Wafer 4 Half mirror 5 Photo detector 6 Power meter 7 PC 8 Chamber 9 End point detector 10 Etching equipment 11　　　　Substrate 12 SiO2 film 13 TiN film 14 Al film 15 Film to be etched

Claims (1)

[Claims] Claim 1: irradiating the film to be etched with a single wavelength laser until at least the base film is exposed and reflecting it;
1. A method for manufacturing a semiconductor device, comprising the steps of: detecting a reflected laser; determining the laser reflection intensity over elapsed time; and detecting an etching end point based on the amount of change in the determined laser reflection intensity.