TWI699465B - Wafer inner and outer layer imaging device - Google Patents

Abstract

An imaging device for the inner and outer layers of a wafer, comprising: a first camera unit, a second camera unit, a light source, a beam splitter group and an objective lens; the first camera unit has a first camera and a first camera Lens group; the second camera unit has a second camera and a second lens group; the beam splitter group has a light source beam splitter and a camera beam splitter; the camera beam splitter is located in the light source beam splitter and the first Between a lens group; wherein the second lens group can be adjusted and moved to adjust the distance between it and the second camera, thereby adjusting the focal length of the second camera to an object under test; wherein , The focal point of the first camera and the second camera for capturing images of the object to be measured is located on one and the other of the inner surface and the outer surface of the object to be measured.

Description

Wafer inner and outer layer imaging device

The invention relates to a wafer inner and outer layer imaging device that can simultaneously take images of the inner and outer layers of a wafer for subsequent inspection.

Wafers include at least silicon wafers and gallium arsenide wafers. After the wafer manufacturing is completed, the wafer needs to be inspected, and the inspection items include the use of images for inspection technology. When inspecting wafers with image-related technologies, the bottom layer of the wafer (ie, the outer layer) and the surface of the metal layer (ie, the inner layer) above the bottom of the wafer are usually taken from the bottom of the wafer to determine whether It is damaged or broken. The currently known imaging method is to use a single camera with a variable light source to obtain images of the outer surface of the bottom of the wafer with visible light under the irradiation of light of different wavelengths, and use infrared to obtain images of the inner surface of the wafer.

However, in the aforementioned known technology, the wavelength of the light source must be changed by switching the light source before image capturing can be performed. Therefore, in the image capturing process, the time for switching the light source will cause the overall image capturing time to be too long. In addition, since a single camera is used to capture images, there is only one set of image capture modules, and the magnification is therefore fixed and cannot be changed. Furthermore, due to the use of a single camera, when switching the light source and changing the wavelength, the chromatic aberration is too large, so the focal length cannot be adjusted without moving the camera height, which further derives the image taken under a certain wavelength of light , After changing the wavelength, the problem must be refocused.

Since the above-mentioned conventional technology using a single camera has many disadvantages, the present invention provides an imaging device for the inner and outer layers of a wafer, which can simultaneously image the inner and outer layers of the wafer when imaging the wafer , It improves the problem that the conventional technology needs to take images separately. In addition, the problem that the prior art requires refocusing during the process of capturing images of the inner and outer layers in stages is also solved by the technology of the present invention that simultaneously captures images of the inner and outer layers.

Based on the above description, an imaging device for the inner and outer layers of a wafer proposed by the present invention includes: a first camera unit, a second camera unit, a light source, a beam splitter group, and an objective lens; the first camera unit, It has a first camera and a first lens group. The first camera shoots an image formed by light in a first wavelength range. The second camera group has a second camera and a second lens group. The camera shoots an image composed of light in a second wavelength range, which is different from the first wavelength range; the light source, the light emitted by the light source has a wavelength range that covers the first wavelength range and the second wavelength Range; the beam splitter group has a light source beam splitter and a camera beam splitter, the light source beam splitter is to project the light emitted by the light source through the objective lens to an object to be measured, and allow the objective lens to receive the The light reflected by the object to be measured passes through; the camera beam splitter is located between the light source beam splitter and the first lens group for allowing part of the light to pass through and enter the first lens group for the first camera to take images, And reflecting part of the light, the reflected light enters the second lens group for the second camera to take an image; wherein the second lens group can be adjusted and moved to adjust the distance between it and the second camera , And then adjust the focal length of the second camera to image the object under test; wherein, the object under test has an outer layer and an inner layer covered by the outer layer. The first camera and the second camera are The focus of the object image is located on the inner surface and outer layer of the object to be tested The surface is one and the other, and the light in the first wavelength range can penetrate the outer layer of the test object to reach the inner surface of the test object.

Thereby, the present invention can simultaneously take images of the inner layer and the outer layer of the object to be measured when taking an image of the object to be measured, which improves the problem that the conventional technology needs to take images separately. In addition, since the imaging focus of the inner layer and the outer layer of the object to be measured in the present invention can be directly captured at different focus points after the adjustment is completed, there is no need to re-adjust the focus each time the image is captured, thus solving the problem of conventional technology. The problem of refocusing during the process of capturing images of the inner and outer layers.

10: Imaging device for the inner and outer layers of the wafer

11: The first camera crew

111: The first camera

112: The first lens group

13: The second camera crew

131: Second camera

132: Second lens group

15: light source

17: Spectroscope group

171: Light source beam splitter

172: Camera beam splitter

19: Objective

20: Imaging device for the inner and outer layers of the wafer

211: The first camera

212: The first lens group

213: Long wavelength filter

23: The second camera crew

231: Second Camera

232: second lens group

233: mirror

272: Camera beam splitter

30: Imaging device for the inner and outer layers of the wafer

311: The first camera

312: The first lens group

331: second camera

332: second lens group

333: mirror

334: Long wavelength filter

372: Camera beam splitter

91: DUT

911: Outer layer

912: inner layer

Fig. 1 is a block diagram of the first preferred embodiment of the present invention.

Fig. 2(A) is a schematic diagram of the operating state of the first preferred embodiment of the present invention, showing that the focus of the first camera is located on the inner surface of the object to be measured.

Figure 2(B) is a schematic diagram of the operating state of the first preferred embodiment of the present invention, showing that the focus of the first camera is located on the outer surface of the object to be measured.

Fig. 3 is a block diagram of the second preferred embodiment of the present invention. And FIG. 4 is a block diagram of the third preferred embodiment of the present invention.

In order to explain the technical features of the present invention in detail, the following preferred embodiments are described in conjunction with the drawings, in which: As shown in Figures 1 to 2(B), the first preferred embodiment of the present invention proposes a wafer inner and outer layer imaging device 10, which is mainly composed of a first camera unit 11, a second camera unit 13, A light source 15, a dichroic lens group 17, and an objective lens 19, wherein: the first camera unit 11 has a first camera 111 and a first lens group 112, the first camera 111 is used to photograph the first wavelength range The image formed by light. In the first embodiment, the first camera 111 is an infrared camera, and the first wavelength range is 900 nm to 1700 nm (nanometers).

The second camera unit 13 has a second camera 131 and a second lens group 132. The second camera 131 captures an image composed of light in a second wavelength range, which is different from the first wavelength. range. In the first embodiment, the second camera 131 is a visible light camera.

The light source 15 emits light whose wavelength range covers the first wavelength range and the second wavelength range.

The beam splitter group 17 has a light source beam splitter 171 and a camera beam splitter 172. The light source beam splitter 171 projects the light emitted by the light source 15 through the objective lens 19 to an object under test 91, and allows the objective lens The light reflected by the object 91 received by 19 passes. The camera beam splitter 172 is located between the light source beam splitter 171 and the first lens group 112 to allow part of the light to pass through and enter the first lens group 112 for the first camera 111 to capture images, and to reflect part of the light The reflected light enters the second lens group 132 for the second camera 131 to capture images.

The second lens group 132 can be adjusted and moved to adjust the distance between the second lens group 132 and the second camera 131, thereby adjusting the focal length of the second camera 131 to image the object 91 under test.

In addition, the test object 91 has an outer layer 911 and an inner layer 912 covered by the outer layer 911. The focus of the first camera 111 and the second camera 131 of the test object 91 is located at the One of the inner layer 912 surface and the outer layer 911 surface of the test object 91 and the other of the two. In the first embodiment, the focus of the first camera 111 is located on the surface of the inner layer 912 of the object 91; and the focus of the second camera 131 is located on the surface of the outer layer 911 of the object 91.

It can be understood that the above-mentioned components can be integrated and arranged in a housing, and the technology of arranging the components in the housing is a conventional technology, so it will not be specifically described here.

The structure of the first embodiment has been described above, and the operation state of the first embodiment will be described next.

As shown in Figs. 1 to 2(A) and 2(B), before taking an image, a test object 91 (ie, a wafer) is first positioned at the imaging position in front of the objective lens 19, as shown in Fig. 2( A) and FIG. 2(B), the test object 91 is located below the objective lens 19, and the bottom layer of the test object 91 is upside down, and the surface of the bottom layer is this embodiment Refers to the surface of the outer layer 911. Next, adjust the overall position of the present invention so that the focal point of the first camera 111 is located on the surface of the inner layer 912 of the object 91, and adjust the second lens group 132 so that the pick point of the second camera 131 is located on the object to be measured 91 of the outer layer 911 surface.

When taking an image of the test object 91 (ie wafer), the light emitted by the light source 15 is irradiated on the test object 91 through the objective lens 19 through the part of the light reflected by the light source beam splitter 171. The light reflected by the test object 91 partially passes through the light source beam splitter 171, and partly passes through the camera beam splitter 172, passes through the first lens group 112, and enters the first camera 111 for image capture. In addition, some of the light reflected by the test object 91 is reflected by the camera beam splitter 172 after passing through the light source beam splitter 171, and then enters the second camera 131 through the second lens group 132. Take an image. Since the wavelength range of the light emitted by the light source 15 covers the first wavelength range and the second wavelength range, Both the first camera 111 and the second camera 131 can image to achieve an image capturing effect. In addition, as shown in FIG. 2(A), since the focus of the first camera 111 is located on the surface of the inner layer 912 of the object 91, the image it obtains is the image of the surface of the inner layer 912 of the object 91. 2(B), since the focus of the second camera 131 is located on the surface of the outer layer 911 of the test object 91, the image obtained is the image of the outer layer 911 of the test object 91.

It can be seen from the above that the first embodiment of the present invention can simultaneously take images of the inner layer 912 and the outer layer 911 of the wafer under test 91 (ie, wafer), which improves the need for separate imaging of the conventional technology. The problem. In addition, since the imaging focus of the inner layer 912 and the outer layer 911 of the test object 91 of the present invention can be used after the adjustment is completed, there is no need to re-adjust the focus every time the image is taken, which solves the problem of the conventional technology. The problem of re-focusing during the process of capturing images of the inner and outer layers.

Please refer to FIG. 3 again. The imaging device 20 for the inner and outer layers of a wafer provided by the second preferred embodiment of the present invention is basically the same as that of the first embodiment, except that the first wavelength range is The wavelength range of near infrared (NIR, Near InfraRed) is 400~1200nm (nanometer).

The second embodiment further includes: a long-wavelength filter 213, which is disposed between the camera beam splitter 272 and the first lens group 212, and the long-wavelength filter 213 only passes long-wavelength light belonging to infrared rays. In this second embodiment, only infrared light with a wavelength greater than 900 nm (nanometer) passes through.

The first lens group 212 can be adjusted and moved to adjust the distance between it and the first camera 211, thereby adjusting the focal length of the first camera 211 to image the object 91 under test.

In addition, in the second embodiment, the second camera unit 23 further includes a reflector 233. The second lens group 232 is not aimed at the camera beam splitter 272, but aimed at the reflecting mirror 233, The light reflected by the camera beam splitter 272 is reflected by the reflecting mirror 233 to enter the second lens group 232 for the second camera 231 to take images.

Since the light captured by the first camera 211 is in the near-infrared wavelength range, it may be disturbed by visible light during shooting and make the image unclear. Therefore, in this case, the long-wavelength filter 213 is necessary. In order to filter out the visible light that will cause interference, only the infrared light enters the first camera 211 for imaging. In addition to the second lens group 232 can be moved to adjust the focus, the first lens group 212 can also be moved to adjust the design of the focus, which can achieve greater adjustment flexibility in adjusting the focus.

In addition, the setting of the reflecting mirror 233 allows the setting position of the second camera 231 group to be changed, thereby having greater flexibility in space setting.

The rest of the structure and achievable effects of the second embodiment are the same as those of the first embodiment disclosed above, and will not be repeated here.

Please refer to FIG. 4, the third preferred embodiment of the present invention proposes a wafer inner and outer layer imaging device 30, which is basically the same as the previous second embodiment, the difference is that the first camera 311 is visible light A camera, the second camera 331 is an infrared camera, the focus of the first camera 311 is located on the surface of the outer layer 911 of the test object 91, and the focus of the second camera 331 is located on the surface of the inner layer 912 of the test object 91.

In addition, the long-wavelength filter 334 is not provided between the first lens group 312 and the camera beam splitter 372, but is provided between the camera beam splitter 372 and the second lens group 332, and through the The reflecting mirror 333 reflects the light reflected by the camera beam splitter 372 so that the light enters the second camera 331 through the second lens group 332.

In the third embodiment, a visible light camera is used as the first camera 311 and an infrared camera is used as the second camera 331. Although the mirror 333 corresponds to an infrared camera, it can still achieve the same effect as before. The effect of the second embodiment is revealed.

The rest of the structure and achievable effects of the third embodiment are the same as those of the first embodiment disclosed above, and will not be repeated here.

10: Imaging device for the inner and outer layers of the wafer

11: The first camera crew

111: The first camera

112: The first lens group

13: The second camera crew

131: Second camera

132: Second lens group

15: light source

17: Spectroscope group

171: Light source beam splitter

172: Camera beam splitter

19: Objective

91: DUT

911: Outer layer

912: inner layer

Claims (7)

An imaging device for the inner and outer layers of a wafer, including: A first camera unit, a second camera unit, a light source, a beam splitter group and an objective lens; The first camera unit has a first camera and a first lens group, and the first camera captures an image composed of light in a first wavelength range; The second camera unit has a second camera and a second lens group. The second camera captures an image formed by light in a second wavelength range, the second wavelength range being different from the first wavelength range; For the light source, the wavelength range of the light emitted by the light source covers the first wavelength range and the second wavelength range; The beam splitter group has a light source beam splitter and a camera beam splitter. The light source beam splitter projects the light emitted by the light source through the objective lens to an object to be measured, and allows the objective lens to receive the light to be measured The light reflected by the object passes through; the camera beam splitter is located between the light source beam splitter and the first lens group to allow part of the light to pass through and enter the first lens group for the first camera to take images, and reflect Part of the light, the reflected light enters the second lens group for the second camera to take images; Wherein, the second lens group can be adjusted and moved, so as to adjust the distance between it and the second camera, and then adjust the focal length of the second camera to image the object to be measured; Wherein, the object under test has an outer layer and an inner layer covered by the outer layer. The focal points of the first camera and the second camera to take images of the object under test are located on the inner surface of the object under test and One and the other of the outer surface, and the light in the first wavelength range can penetrate the outer layer of the test object to reach the inner surface of the test object. The imaging device for the inner and outer layers of a wafer according to item 1 of the scope of patent application, wherein: the first camera is an infrared camera, the second camera is a visible light camera, and the focus of the first camera is located on the inner layer of the object to be measured On the surface, the focus of the second camera is located on the outer surface of the object to be measured. The imaging device for the inner and outer layers of the wafer according to item 2 of the scope of patent application, which further includes a long-wavelength filter arranged between the camera beam splitter and the first lens group. The long-wavelength filter is only used for Long-wavelength infrared rays pass through. The imaging device for the inner and outer layers of a wafer according to item 1 of the scope of patent application, wherein: the first camera is a visible light camera, the second camera is an infrared camera, and the focus of the first camera is on the outer surface of the object to be measured , The focal point of the second camera is located on the inner surface of the object under test. The imaging device for the inner and outer layers of the wafer according to item 4 of the scope of patent application, which further includes a long-wavelength filter arranged between the camera beam splitter and the second lens group. The long-wavelength filter is only used for Long-wavelength infrared rays pass through. The imaging device for the inner and outer layers of the wafer according to item 1 of the scope of patent application, wherein: the first lens group can be adjusted and moved, so as to adjust the distance between it and the first camera, and then adjust the first camera pair The focal length of the object to be tested. The imaging device for the inner and outer layers of the wafer according to item 1 of the scope of patent application, wherein: the second camera unit further includes a reflector, and the second lens group is not aligned with the camera beam splitter, and the reflector is the camera The light reflected by the beam splitter is then reflected to make it enter the second lens group for the second camera to take images.

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