JPH01267444A - Pattern detection - Google Patents

Abstract

PURPOSE:To detect a light shielding pattern of a sample with a high performance, by a method wherein a reflecting member is provided on the back side of a sample having a light shielding pattern formed on a transparent substrate and irradiated with light through the sample from a power source to detect the reflected light thereof. CONSTITUTION:A reflecting plate 20 comprising a transparent plate or the like 21 wherein a reflection layer 22 for light is provided on the back thereof is placed on the back side of the sample 10. Light of light sources 1A and 1B arranged on both upper sides of the sample 10 is made to irradiate the sample 10 as irradiation beams of light SK1 and SK2 through optical systems 2A and 2B. Consequently, the irradiation lights SK1 and SK2 penetrate a transparent substrate 12, reaches a reflecting layer 22 of the reflecting plate 20 to be reflected and penetrate the transparent substrate 12 of the sample 10 again as reflected light FK so that a light shielding pattern 11 is lighted from the back side of the transparent substrate 12. When a detector 3 such as image sensor having an optical system is arranged above the sample 10, the light shielding pattern 11 can be detected as clear image.

Description

[Detailed Description of the Invention] Object of the Invention; (Industrial Application Field) This invention is applicable to shadow masks, lead frames,
The present invention relates to a pattern detection method for detecting light-shielding patterns of photomasks used in liquid crystal display panels, plasma display panels, integrated circuits, etc. with high performance using a transmission method.

(Prior Art) Conventionally, in order to inspect a sample 241O having a light-shielding pattern 11 such as an emulsion formed on a transparent substrate 12 such as glass or a thin metal film (such as chrome) as shown in FIG. The sample IO is fixed with support members 6A and 6B, a detection device 3 such as a photoelectric element is provided above it, and an illumination device 7 such as a lamp is provided below, and light S is irradiated from the illumination device 7,
The light-shielding pattern 11 is detected by receiving the transmitted light T of the sample 10 by the detection device 3.

(Problem to be Solved by the Invention) However, since the above detection method is a method of transmitting light through the sample 10, it is necessary to attach a drive mechanism or a substrate support mechanism to the area of the sample 10 to be detected due to space issues. I can't. For this reason, conventionally, only the outer peripheral portion of the sample IO without the pattern 11 was supported by the supporting members 6A and 6B. Such a method has the drawback that bending as shown by the broken line occurs in a portion of the sample 10 that is large or thin and easy to bend, making it impossible to maintain high reading accuracy of the sample 10.

One possible solution to this problem is to place the test sample on a highly rigid transparent member such as a thick glass plate, but this method does not cause bending, but it does require the placement of a drive mechanism. Design constraints that say it is not possible cannot be resolved. Another method is to detect the pattern using epi-illumination used in a metallurgical microscope or the like. However, although this method does not have any restrictions on the stage, etc., it is difficult to detect emulsion patterns, or even in the case of samples that are easy to detect with reflected light such as chrome patterns, scratches on light-transmitting parts other than the patterns and light-blocking There is a problem in that redundant detection of foreign matter on the pattern is performed, and detection becomes unstable when the reflection characteristics are unstable.

This invention was made from the above-mentioned circumstances,
An object of the present invention is to provide a pattern detection method that eliminates constraints on the arrangement of stages and the like and that can always detect light-shielding patterns with high performance.

Structure of the Invention; (Means for Solving the Problems) The present invention provides a pattern detection method in which a light-shielding pattern formed on a transparent substrate is irradiated with light and the light-shielding pattern is detected by a detection means in a transmission manner. Regarding the object of the present invention, a reflector is provided on the opposite side of the detection means with respect to the transparent substrate, light is irradiated from the detection side of the light-shielding pattern, and the light reflected by the reflector illuminates the transparent substrate. This is achieved by detecting it with the detection means after passing through it.

(Function) In the pattern detection method of the present invention, a reflector is provided on the back side of a sample having a light-shielding pattern formed on a transparent substrate, and light is irradiated from a light source to the reflector through the sample, thereby shielding the sample from light. The pattern is detected with high performance by using a detection means to detect the reflected light that has passed through the back surface of the transparent substrate.

(Example) FIG. 1 shows an example of a pattern detection device that implements the pattern detection method of the present invention.

In this device, a reflection plate 20 consisting of a transparent plate or the like 21 having a light reflection layer 22 on the back side is placed on the back side of the sample 10.
I leave it there. Then, the light from the light sources IA and IB arranged above both sides of the sample 1 (l) is irradiated onto the sample lO through the optical systems 2A and 2B as irradiation lights SKI and S2, respectively.Irradiation lights SKI and SK2 The light passes through the transparent substrate 12 of the sample 10, reaches the reflective layer 22 of the reflector plate 20, is reflected, and passes through the transparent substrate 12 of the sample 10 again as reflected light PK, causing the light-shielding pattern 11 to pass through the transparent substrate 12. It is illuminated from the back side. Therefore, if a detection device 3 such as an image sensor with an optical system is disposed above the sample 10, the light-shielding pattern 11 can be detected as a clear image.

That is, since the light scattered by the reflective layer 22 acts as transmitted illumination for the sample 1o, the light-shielding pattern 11 can be detected satisfactorily. Further, by increasing the thickness of the transparent plate 21, etc., it is possible to reduce the influence of pattern shadows and unevenness of the reflecting surface on the irradiated light beam. When the irradiation light hits the detection area, the reflected light at that part affects the detection, so if the illumination light passes through the outside of the detection area and hits the reflective layer 22 directly under the detection area, the detection The system provides an effect equivalent to that of transmitted light illumination using a diffuser plate, and enables better pattern detection.

FIG. 2 shows another example of the pattern detection device of the present invention.

In this pattern detection device, the reflective layer 31 of the reflective plate 30 has a reflective surface with a sawtooth cross section as shown in the figure.
Light source 1. The irradiated light S from the optical system 2 is reflected as 3 and the reflected light F having vertical directionality as 1, and the reflected light FKI is read by the licensor 5 via the optical system 4. Therefore, in this device, the efficiency of irradiation light is higher than that in the device shown in FIG. 1, and the light-shielding pattern 11 can be detected at high speed.

In a liquid crystal projection exposure system, each RGB pattern is formed by repeating the application of colored layers such as R (red), G (green), and B (blue), exposure, and development. It is necessary to detect and align the pattern formed on the image before exposing it to light. Since the liquid crystal substrate is large and thin, it is difficult to create a stage with a structure that allows for transmitted illumination.
Alignment is performed by scanning with a laser or the like and detecting the reflected light. However, since the coating layer is colored, for example, in the case of B, red laser light does not pass through, and changes in the reflected light due to the pattern of the lower layer are minute, making detection difficult. In the present invention, if the illumination light is white light (the sensitive wavelength is blocked), there is always a transmitted wavelength band, and an optical image equivalent to transmitted light illumination can be obtained, allowing stable and accurate detection and alignment.

Note that in the above embodiment, the light source 1 for the sample 10
．． Irradiation light 5 from IA, IB and optical system 2.2A, 2B
The incident angle of KI-5K3 may be arbitrary. Also, the irradiation light SKI
5 to 3 may be irradiated so as to overlap with the light shielding pattern 11, or may be made to overlap with the reflected lights FK and FKI. Furthermore, the number of light sources and optical systems in the detection apparatus of FIGS. 1 and 2 is arbitrary.

Effects of the Invention: According to the pattern detection method of the present invention, even for patterns with a small proportion of light-shielding parts, such as photomask patterns for shadow masks, patterns using transmitted light can be detected using only illumination from the detection system. It has the advantage that it can be used for a wide range of applications such as coordinate width detection of various patterns, shape, and defect inspection. Further, an apparatus using the method of the present invention can increase or eliminate restrictions on the arrangement of optical systems, stages, etc., and can obtain high-performance images. Furthermore, the device has the advantage of a simple configuration and low cost.

Furthermore, since the sample is placed on the reflector and inspected, there is no bending of the sample even if the sample is flexible, and there is an advantage that a highly accurate image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a pattern detection device that implements the method of the present invention, FIG. 2 is a configuration diagram of another pattern detection device, and FIG. 3 is a diagram for explaining a conventional detection method. be. 1, IA, 1B... light source, 2.2A, 2B... optical system, 3... detector, 10... sample, 20.30...
·a reflector. Applicant's agent Yu Yasugata No. 3 F. Nagitsuru 2

Claims (1)

[Scope of Claims] 1. In a pattern detection method in which a light-shielding pattern formed on a transparent substrate is irradiated with light and a detection means detects the light-shielding pattern in a transmission manner, the detection means for the transparent substrate A reflector is provided on the opposite side of the light-shielding pattern, and light is irradiated from the detection side of the light-shielding pattern, and the light reflected by the reflector is transmitted through the transparent substrate and then detected by the detection means. A pattern detection method that uses 2. The pattern detection method according to claim 1, wherein the light is irradiated so as not to directly hit the detection area of the light-shielding pattern. 3. The pattern detection method according to claim 1, wherein the light is irradiated to a region of the reflector that includes a detection region of the light-shielding pattern. 4. The pattern detection method according to claim 1, wherein the reflector has a directivity such that the intensity of the reflected light directed toward the detection means is greater than that toward the input side.