JPH04366754A - Resist image defect inspection device - Google Patents

Abstract

PURPOSE:To enable resist pattern defects which are transparent to any white light source to be inspected by infrared absorption by using infrared radiation as a light source for inspection, and receiving light transmitted through a subjected for inspection at an infrared image sensor. CONSTITUTION:A half mirror 8 and a mirror 13 are both provided in such a manner as being capable of going into and out of an optical path. The mirrors 8, 13 are retreated from an infrared optical axis and a shutter 12a is opened and a shutter 12b closed. Then light from an infrared light source 9 is transmitted through a wafer 10 from its reverse side and taken as a first image into an infrared image sensor 11. Next a stage 5 is moved and another resist pattern on the wafer 10 is similarly taken as a second image into the sensor 11. The first and second images are subjected to comparison processing and inspection by an image processor 6 and a computer 7. To observe pattern defects, the mirrors 8, 13 are placed on the optical axis and the shutter 12a is closed and the shutter 12b opened and thereby the infrared light source 9 is cut off and visual observation using a white light source 1 is made possible.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist image defect inspection apparatus, and more particularly to a pattern matching type resist image defect inspection apparatus.

0002

2. Description of the Related Art In the manufacture of semiconductor devices, preventing common pattern defects caused by exposure equipment and reticles is an important item in maintaining high manufacturing yields. One method for this is to fill an exposure device with a reticle, then print a resist single layer pattern onto a flat wafer, and then inspect it with a resist image defect device to confirm in advance whether there are any pattern defects.

[0003] There are two types of resist image defect inspection equipment.
There are pattern matching methods that compare and inspect two identical patterns to detect pattern defects, and methods that compare statistically processed images obtained by sampling the same image multiple times.

FIG. 3 shows a configuration diagram of a conventional pattern matching type resist image defect inspection apparatus. Light from a white light source 1 is irradiated from the back side of a quartz wafer 3 on a stage 5 through a lens 2, and a first resist image formed by the transmitted light is sent to a visible light image sensor 4.
Import it with.

Next, a second resist image to be pattern matched is moved on stage 5 and captured in the same manner. These two images are processed by image processor 6.
Then, the computer 7 performs comparison processing and performs a comparative inspection.

[0006] Actual pattern defects are observed through a half mirror 8.

There is also an apparatus that uses a silicon wafer to perform inspection using a reflected image. However, it tends to be inferior in defect detection sensitivity, and the current mainstream method is to perform inspection using transmitted images.

[0008]

[Problems to be Solved by the Invention] Conventional pattern matching type resist image defect inspection equipment uses a white light source as a light source, so it has the disadvantage that it is difficult to detect transparent resist pattern defects. was there.

An object of the present invention is to provide a resist image defect inspection device that can easily detect resist pattern defects on transparent surfaces.

0010

[Means for Solving the Problems] In order to achieve the above object, a resist image defect inspection apparatus according to the present invention is a pattern matching type resist image defect inspection apparatus, and uses infrared light as an inspection light source. use,
Furthermore, it has an infrared image sensor that captures a transmitted image from the object to be inspected that has been irradiated with infrared light.

[0011]

[Operation] In the present invention, by using infrared light as the inspection light source, resist pattern defects that are transparent to a white light source can be inspected by infrared absorption.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIGS. 1 and 2 are diagrams showing an embodiment of the present invention. In this embodiment, an infrared light source 9 is used as the inspection light source, and a stage 5 that supports a shutter 12a, a lens 2a, and a wafer 10 on the optical axis of the infrared light emitted from the infrared light source 9; An infrared image sensor 11 that captures an infrared image is provided. 6 is an image processor, 7
is a computer.

Further, the white light source 1 is disposed perpendicularly to the optical axis of the infrared light, and a half-light source 1 is provided at a position where the optical axis of the white light emitted from the white light source 1 and the optical axis of the infrared light intersect. A mirror 8 is removably located, and a shutter 12b and a lens 2b are installed between the half mirror 8 and the white light source 1.

Further, a mirror 13 is installed behind the half mirror 8 so as to be retractable from the optical axis of the infrared light, and a lens 2b is installed on the reflection side of the mirror 13.

FIG. 2 shows resist image defect inspection in an embodiment of the present invention. In this case, the half mirror 8 and the mirror 13 are moved back from the optical axis of the infrared light, and the shutter 12a is opened.
Close b. In this state, light from the infrared light source 9 illuminates the wafer 10 from the back surface, and a transmitted image from the wafer 10 is captured by the infrared image sensor 11 as a first image. The actual image is formed from contrast differences due to the transmission of infrared light. In other words, infrared rays are absorbed in areas where there is a resist pattern or transparent defects, and are not absorbed only in areas where there is no resist pattern.

Next, the stage 5 is moved and the wafer 1
Another resist pattern on 0 is transferred onto the optical axis of the infrared light, and the transmission image from this pattern is similarly captured as a second image. The first image and the second image are compared and processed by the image processor 6 and the computer 7 to perform a comparison test.

FIG. 2 is a diagram showing pattern defect observation in an embodiment of the present invention. The infrared light source 9 is the shutter 1
It is cut by 2a. White light from a white light source 1 is irradiated onto the wafer 10 via a half mirror 8 that is automatically set on the optical axis of the infrared light, and the reflected light is visually observed via a mirror 13 that is automatically set on the optical axis. becomes possible.

[0019]

[Effects of the Invention] As described above, the present invention has the effect that by using infrared light as an inspection light source, even resist pattern defects that are transparent to a white light source can be detected by infrared absorption. .

Furthermore, a silicon wafer that is transparent to infrared light can be used, and transmission inspection can be performed without using an expensive quartz wafer.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram at the time of inspection in an embodiment of the present invention.

FIG. 2 is a configuration diagram during defect observation in an embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional resist pattern defect inspection apparatus.

[Explanation of symbols]

1 White light source 2a, 2b Lens 5 Stage 6 Image processor 7 Computer 8 Half mirror 9 Infrared light source 10 Silicon wafer 11 Infrared image sensor 12a, 12b Shutter 13 Mirror

Claims (1)

[Claims] [Claim 1] Pattern matching type resist.
An image defect inspection device that uses infrared light as an inspection light source and further includes an infrared image sensor that captures a transmitted image from an object to be inspected irradiated with the infrared light. Defect inspection equipment.