WO1994006151A1

WO1994006151A1 - Method of detecting end point of etching

Info

Publication number: WO1994006151A1
Application number: PCT/JP1993/001273
Authority: WO
Inventors: Kazuaki Sajiki; Akira Matsuno; Takashi Nile; Fumiko Wada
Original assignee: Kabushiki Kaisha Komatsu Seisakusho
Priority date: 1992-09-08
Filing date: 1993-09-08
Publication date: 1994-03-17

Abstract

A detection method which can determine highly accurately the end point of etching of a multilayer film such as of thin films or thick films by a simple device. In a process of etching thin films formed on a substrate (10a), a laser beam (m) is applied to an ITO (10c) to be etched. After etching this film, the laser beam (m) is applied to SiOn (10b) formed under the etched film, P light (s) is emitted from the SiOn film, and the end point of etching is determined by detecting this light emission.

Description

Description End point detection method in etching

The present invention relates to a method for detecting an end point of etching of a laminated film such as a thin film and a thick film. Background technology

Conventionally, when etching a thin film or the like using a laser beam or the like, there is a method in which a laser beam is transmitted and guided to a photoelectric tube, and the end point is detected by a change in transmittance in order to detect an etching end point. In addition, there is a method in which an end point is detected based on a change in reflectance using reflected light, or a method in which interference of reflected light is used (Japanese Patent Application Laid-Open Nos. Sho 61-174274, JP-A-4-17424). 280650, JP-A-5-213395). However, in such a detection method, since the thickness variation and the thickness of the thin film are different, it is necessary to monitor in advance the relationship between the thickness of the workpiece to be etched and the transmittance or the reflectance. Since it is necessary to calculate the transmittance and the reflectance from data and the like, there are problems that the detection accuracy of the end point is low and the device becomes complicated. Disclosure of the invention

According to the present invention, there is no need to monitor the relationship between the film thickness of the workpiece to be etched and the transmittance or reflectance, and there is no need to calculate the transmittance or reflectance from detected signals or data. It is an object of the present invention to provide a method for detecting an end point in etching based on a completely new principle, which can perform high-accuracy detection with a simple device.

When light is applied to a certain substance, the substance is emitted when the wavelength of light matches the absorption range of the substance. May absorb light and emit at another wavelength. Such a phenomenon is called photoluminescence. The present invention utilizes this phenomenon to detect the end point of etching. That is, there is a film to be etched on a film base that emits light when irradiated with a laser beam of a certain wavelength. If the thin film does not transmit the laser light, the laser light does not reach the film base, and the film base does not emit light. When the etching progresses and the film underlayer appears on the surface, the laser beam directly irradiates the film underlayer, so that the film underlayer starts to emit light. By detecting the light emission of the film base based on this principle, the etching end point can be detected.

According to the present invention, in a step of etching a thin film or the like laminated on at least one layer on a substrate, a film portion to be etched is irradiated with a laser beam, and the etching of the film portion is completed and the film is formed under the film. When a laser beam is applied to the underlying film, light (hereinafter referred to as P-light) is emitted from the laser, and the end point of etching is determined by detecting this light emission.

This end point detection method can be applied to a normal dry etching process such as RIE and plasma etching, and a laser etching process using laser light. In the dry etching step, the film exposed to the plasma for etching is irradiated with laser light necessary for light emission of the base. When the etching progresses and the laser beam directly irradiates the base, P light is emitted from it, and the end point can be detected.

In the laser etching step, the base may emit P light due to the laser light required for the etching process. In this case, this emission may be detected and used as the end point of the etching. Therefore, it is not necessary to newly emit a laser beam for detecting the end point. On the other hand, when the processing laser light does not emit P light on the base, it is necessary to irradiate the laser light for end point detection together with the processing laser light.

In some cases, the film to be etched emits light by laser light. However, if the wavelength of the P light of this film is different from the wavelength of the P light of the film base, the P light from the film base can be easily removed by attaching a filter or the like. Since only light can be detected, the end point of etching can be determined. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a configuration diagram of an apparatus according to a first embodiment of the present invention, FIG. 2 is an explanatory diagram of an etching start process of the first embodiment, FIG. 3 is an explanatory diagram of an etching intermediate process of the first embodiment, FIG. Is an explanatory diagram of the final etching step of the first embodiment, FIG. 5 is a diagram showing the relationship between wavelength and absorption and light emission in the film base, FIG. 6 is a diagram showing the relationship between wavelength and absorption and light emission in the etched film, and FIG. FIG. 8 is a configuration diagram of an apparatus according to a second embodiment of the present invention, FIG. 8 is an explanatory diagram of an etching start process of the second embodiment, FIG. 9 is an explanatory diagram of an etching intermediate process of the second embodiment, and FIG. FIG. 9 is an explanatory view of a final etching step of the second embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, an end point detection device 1 for etching includes a laser oscillation device 3 that oscillates a laser beam (m) such as an excimer laser and irradiates the thin film 10 via a mirror 4 with a laser beam (m). It comprises a light detection sensor 17 for detecting P light (s) emitted from the base of the film due to the irradiation, and a etching chamber 5 provided with a window 6 for introducing laser light (m) and a suction / exhaust hole. When the film to be etched also emits light, a filter 19 for selecting P light (s) emitted from the base of the film to be etched is mounted. The detection sensor 7 for detecting the P light (s) may be visually detected as necessary. In the thin film element 10 to be etched, an insulating film 10b serving as a film base such as SiON is formed on a glass substrate 10a to a thickness of 0.2 m by sputtering or the like. A transparent electrode (hereinafter referred to as I T0) 10 c serving as a film to be overlaid thereon is formed to a thickness of 0.5 μm by sputtering or the like. On top of that, a photoresist 11 is patterned.

In such a configuration, the detection method of the first embodiment will be described with reference to FIGS. First, the thin film element 10 is set in the etching chamber 5. After evacuating the etching chamber 5 to a vacuum, a reactive atmosphere gas such as an HC1 atmosphere is introduced. Thin film element 1 0 As shown in FIG. 2, a laser beam (m) is applied to the etching portion 10d where the upper photoresist 11 is not formed. As shown in FIG. 3, the IT100c is etched one after another, but the laser light (m) does not pass through this film while the ITO10c remains. Next, as shown in Fig. 4, IT010c disappears, and the end point of the etching, that is, the film underlayer (hereinafter referred to as SiON) 10b of SiON is directly irradiated with the laser beam (m). Then, Si ON 10b starts to emit P light (s) in the visible light region. This P light (s) is detected to determine the end point of the etching.

Also, by irradiating the laser beam (m) through a mask (not shown) or by scanning, it is possible to pattern the ITO l Ob without using the photo resist 11. it can.

Thus, the ITO1Oc to be etched does not transmit the laser light (m), and the Si0N1Ob has a P light (s) at a different wavelength from the ITO10c to be etched. When irradiating, the end point of the etching can be easily detected.

Is a film base which emits light by irradiation of the laser beam (m), there are _{S i 0 2, S i C} , C a F 2, M g F 2 and the like. Organic films, ITO, and metals such as A1, W, and Ta are examples of films that are etched and do not transmit ultraviolet light such as laser light (m).

These film bases and the etching film may emit P light (s) and (s,) when irradiated with laser light (m), as shown in Figs. 5 and 6, respectively. Since the wavelengths of (s) and (s1) are different from each other, only the P light (s) under the film can be easily detected by detecting through the filter 9 as shown in FIG.

Next, a second embodiment of the present invention will be described in detail with reference to the drawings. However, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 7, an end point detection device 20 for etching oscillates a laser beam (m) such as an excimer laser and irradiates the thin film 10 via a mirror 4 with a laser oscillation device 3. ) To detect P light (s) from the underlayer of the film An output sensor 1 and an etching chamber 5 are provided. The etching chamber 5 is provided with a plasma generator 25 including an electrode 21, an insulator 22, a matching box 23, and a high-frequency power supply 24. When the etching film also emits light, a filter 19 for selecting the P light (s) is mounted. The structure of the thin film element 10 to be etched is the same as that of the first embodiment.

In the above configuration, the detection method of the second embodiment will be described with reference to FIGS. First, the thin film element 10 is set in the etching chamber 5 and evacuated to a vacuum. Then, an etching gas such as Ar is introduced, the plasma generator 25 is operated to generate plasma, and etching is started. Then, as shown in FIG. 8, plasma etching (dry etching) is performed on the etched portion 10d where the photoresist 11 is not formed on the thin film element 10 and laser light (m) is irradiated. Irradiate. As shown in FIG. 9, the ITO 10 c is gradually etched by the plasma, but the laser light (m) does not pass through this film while the I TO 10 c remains. Next, as shown in FIG. 10, IT 010 c disappears, and when the end point of the etching, that is, S i 0 N 10 b is directly irradiated with the laser beam (m), S i ON l O b Begins to emit P light (s) in the visible light region. At this time, the etching is completed.

These film bases and the etching film may emit P light (s) and (s,) by irradiation of laser light (m), respectively, as in the first embodiment. Since the wavelengths of) and (S i) are different from each other, only the P light (s) under the film can be easily detected by detecting through the filter-9 as shown in FIG. Industrial applicability

In the present invention, since the object to be detected is the sample itself to be etched, there is no need to monitor the relationship between the film thickness of the sample and the transmittance or reflectance, and it is not necessary to calculate the transmittance or reflectance from detected signals or data. It is useful as a method for detecting the end point in simple and reliable etching.

Claims

The scope of the claims

1. In the process of etching one or more thin films stacked on a substrate, a film portion to be etched is irradiated with a laser beam, and the etching of the film portion is completed and formed in a layer below the film portion. When a laser beam is applied to the underlying film, P light is emitted from the laser beam, and this emission is detected to determine the end point of the etching.

2. Etching of the film portion is performed by laser light irradiation, and when the film base is irradiated with laser light, P light is emitted from the film base, and the laser light used for this etching is used as probe light. 2. The method for detecting an end point in etching according to claim 1, wherein an end point of the etching is obtained.

3. Etching of the film portion is performed by plasma etching (dry etching). When the laser beam being irradiated at the same time irradiates the film base, P light is radiated from there. 2. The method for detecting an end point in etching according to claim 1, wherein the end point is obtained.

4. The final inspection method for etching according to claim 1, wherein an end point of etching is obtained by detecting P light emitted from the film base through a filter.