JPH1019532A - Method for measuring pattern of photoresist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the pattern of a photoresist by means of an image and automate the measuring by irradiating the pattern of the photoresist with ultraviolet rays and image-picking up a fluorescence image generated thereby. SOLUTION: Ultraviolet rays are emitted from a light source 3. A dichroic mirror 6 is one type of interference filters and it has a feature that when it is placed at an angle of 45.degree. with respect to an optical axis, a short wave of which wavelength is shorter than a certain waveform is reflected thereby an long wave of which wavelength is longer than a certain waveform is passed therethrough. As a result, the ultraviolet rays are reflected and introduced to an objective lens 7, the fluorescence from the lens 7 is passed therethrough. The ultraviolet rays passing through the lens 7 is cast on a specimen 8 to be projected on a photoresist of the specimen 8, then fluorescence is generated. The fluorescence passes through the lens 7 and penetrates the mirror 6. An absorption filter 9 limits a using wavelength range to be narrowed by overlapping a penetration wavelength range of the mirror 6 through which the fluorescence passing by being reflected by the specimen 8 with a penetration wavelength range of the absorption filter 9 so that a sharp image is obtained. An imaging device 10 images a fluorescence image of a pattern of the photoresist that is generated by the fluorescence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a photoresist pattern formed on a metal plate when the pattern is formed.

[0002]

2. Description of the Related Art In a shadow mask used for a cathode ray tube of a television, a large number of small holes are formed at a constant pitch in a metal plate. As a method of processing such a fine shape into a metal plate, a method called photoetching is used, and this method is widely used for manufacturing an integrated circuit (IC).

FIG. 3 shows a method of forming a pattern on a metal plate by a photoetching method. First, a. As shown in (1), a photoresist 2 (photosensitive resin) is uniformly applied to a metal plate 1. Next, b. The pattern to be processed is exposed on the photoresist 2 as shown in FIG. The pattern baked on the photoresist 2 by this exposure is c. As shown in (2), when development is performed in the same manner as in a photograph, the photoresist 2 in the exposed portion is removed. This is the case of a positive resist. In the case of a negative resist, the exposed portion remains on the contrary, and the unexposed portion is removed. Next, d. As shown in (1), a portion of the metal plate 1 not covered with the photoresist 2 is corroded and dissolved to form a pattern. After this e. The photoresist 2 is removed as shown in FIG.

In the above steps, c. Inspection of the pattern formed on the photoresist 2 after development shown in FIG. Inspection of the pattern formed on the metal plate 1 after the removal of the photoresist shown in FIG. 1 is performed, and further, the removal inspection of the photoresist is performed. In the inspection after the development, whether or not a pattern as planned is formed on the photoresist is measured, and the position and the shape and dimension are confirmed.

[0005]

Since the photoresist is transparent, a metal crystal structure of the metal plate appears through the photoresist. Therefore, when visible light is applied to a state in which a pattern has been formed by exposure and development, this pattern and the metal crystal structure overlap. Some photoresists are made opaque by mixing a pigment, but the exposure characteristics deteriorate and the resolution deteriorates, which is not practical. FIG. 4 shows an image obtained by capturing the pattern of the photoresist with visible light.
In such an image, a pattern of a round hole can be identified by human eyes, but it is difficult to automatically extract this pattern by image processing. Therefore, conventionally, inspection has been performed visually. For this reason, the pattern inspection process after development could not be automated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a photoresist pattern measuring method capable of clearly identifying and measuring a photoresist pattern.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a photoresist is applied to a metal plate, and the pattern is exposed and developed, and the photoresist having a pattern shape is exposed to ultraviolet light. Is irradiated, and a fluorescent image by the fluorescent light emitted from the photoresist is captured, and the pattern of the photoresist is measured based on the fluorescent image.

[0008] When the photoresist is irradiated with ultraviolet light, the photoresist emits fluorescent light, and the distinction from a metal surface that does not emit fluorescent light becomes clear. By performing image processing on the fluorescent image represented by the fluorescent light, it is possible to automatically perform a pattern inspection.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic optical system of an epi-illumination fluorescence microscope for realizing an embodiment of the present invention.
As the light source 3, a light source that emits ultraviolet light such as a mercury lamp or a xenon lamp is used. The light from the light source is collected by the condenser lens 4. The excitation filter 5 is a filter that transmits only light in a short wavelength range, which is necessary for emitting fluorescence from the sample 8, and cuts light that is not used for excitation.

The dichroic mirror 6 is a type of interference filter, and has a characteristic of reflecting light having a wavelength shorter than a certain wavelength and transmitting light having a longer wavelength when placed at an angle of 45 ° with respect to the optical axis. Thereby, the ultraviolet rays are reflected and guided to the objective lens 7, and the fluorescence from the objective lens 7 is transmitted. The ultraviolet light that has passed through the objective lens 7 irradiates the sample 8 and hits the photoresist of the sample 8 to emit fluorescent light. Fluorescence is objective lens 7
And passes through the dichroic mirror 6.

The absorption filter 9 is reflected by the sample 8 and overlaps the transmission wavelength range of the dichroic mirror 6 with the transmission wavelength range of the absorption filter 9, thereby narrowing the wavelength range to be used and obtaining a sharp image. The imaging device 10 captures a fluorescent image of a photoresist pattern that has appeared due to fluorescence.

FIG. 2 shows a fluorescent image of a photoresist pattern of a shadow mask used for a cathode ray tube. The photoresist is a negative type in which the unexposed portion is removed, the photoresist in the unexposed portion of the light-shielding portion is removed by development to expose the metal plate, and the other is covered with the photoresist film. . Since the opening is a metal plate, no fluorescent light is generated and the opening is black. The edge of the opening is brightly bordered to form a sharp opening image, and the portion of the photoresist film other than the opening is darker than the edge of the opening but brighter than the opening. This image is a monochrome image.

The fluorescent light is supplied to an excitation filter 5, an absorption filter 9,
The combination of the dichroic mirror 6 has a specific color such as green or red. By using a color image pickup device, the opening is black, and the portion of the photoresist film other than the opening has a color unique to fluorescence. The edge of the opening is the same as that of the film portion, but is brightly colored to obtain a clearly identifiable image.

[0014]

As is apparent from the above description, the present invention provides a photo-resist by irradiating a photoresist pattern obtained by exposing and developing a photoresist with ultraviolet rays and capturing an image by generated fluorescence. The resist pattern can be measured. As a result, the inspection of the photoresist pattern, which has been conventionally performed visually, can be measured by image processing and automated.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an optical system for implementing the present invention.

FIG. 2 is an enlarged plan view showing a captured image of a photoresist pattern obtained according to the present invention.

FIG. 3 is an explanatory view showing a method of forming a pattern on a metal plate by lithography.

FIG. 4 is an enlarged plan view showing an image obtained by capturing a photoresist pattern with visible light.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 metal plate 2 photoresist 3 light source 5 excitation filter 6 dichroic mirror 8 sample 9 absorption filter

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirotaka Fukagawa 1101-20 Myouji-cho, Yokaichi-shi, Shiga Prefecture Toppan Printing Co., Ltd.

Claims (1)

[Claims] 1. A method of applying a photoresist to a metal plate, exposing and developing a pattern, irradiating the photoresist in a pattern shape with ultraviolet rays, and capturing a fluorescent image by fluorescence emitted from the photoresist; A method of measuring a pattern of a photoresist, comprising: measuring a pattern of the photoresist based on the fluorescent image.