JPH0652138U - Wafer ID reader - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the depth of the dots forming the wafer ID is different or the thickness of the protective film on the ID pattern is different, the wafer ID can be correctly read. [Structure] A light beam from a light source 11 is horizontally incident on a beam splitter 12, the reflected light is irradiated onto a semiconductor wafer 13, and the reflected light is photographed by a video camera 14 through the beam splitter 12, and the video camera 14 Is processed by the image processor 15 to recognize the wafer ID on the semiconductor wafer and the result is displayed on the display 16. The optical axis of the light source 11 can be rotated in a vertical plane by the vertical variable mechanism 24, and the optical axis of the light source 11 can be rotated in a waterside plane by the horizontal variable mechanism 25. The angle of light can be varied in the horizontal and vertical planes to ensure accurate reading of the wafer ID as the best illumination.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a wafer ID reading device which is used to make a semiconductor integrated circuit, so-called IC, and optically reads an identification character, that is, a wafer ID, attached to a semiconductor wafer for lot management.

[0002]

[Prior art]

 In order to identify the semiconductor wafer, characters, so-called IDs, are written on the semiconductor wafer by a dot pattern by a laser or pattern etching on a thin film. For example, in processing each semiconductor wafer, its wafer ID is read in order to know from which lot it came.

As the reading device, the one shown in FIG. 4A has been conventionally used. That is, the light from the light source 11 is caused to travel substantially horizontally, the beam splitter 12 bisects the light, and one of the lights is bent downward at a substantially right angle, and this light is irradiated onto the semiconductor wafer 13, The reflected light of the semiconductor wafer 13 passes through the beam splitter 12 and is received by the video camera 14, and the output of the video camera 14 is processed by the image processing device 15 to recognize the characters written on the semiconductor wafer 13, that is, the ID. This is displayed on the display 16.

As described above, when light is incident on the semiconductor wafer 13 from the vertical direction to illuminate the semiconductor wafer 13 and the reflected light thereof is read by so-called epi-illumination (bright field illumination), the light cannot be read well. Light is obliquely incident on the plate surface of the semiconductor wafer 13 from 17, and the reflected light is received by the video camera 14 through the beam splitter 12, and the ID of the semiconductor wafer 13 is read by the image processing device 15. I am trying to do it. The latter illumination by oblique irradiation from the light source 17 is called dark field illumination. The ID is read by this dark-field illumination, and if it is difficult to read, it may be read by epi-illumination by the light source 11, that is, bright-field illumination.

[0005]

[Problems to be solved by the device]

 Thus, conventionally, two light sources 11 and 17 are provided, and one of bright-field illumination and dark-field illumination is read, and when reading is not possible, the illumination is switched to the other and reading is performed. However, the reflection state was different depending on the surface treatment state of the semiconductor wafer 13 and the dot shape forming the written characters, and the ID could not be read correctly even after switching. That is, the dots 18 for forming the ID are arrayed on the semiconductor wafer 13, and as shown in FIGS. 4B and 4C, the diameter of the surface of the dot 18, the depth of the dot, The inclination of the peripheral surface is different and not constant. For this reason, the light reflection states are considerably different between FIGS. 4B and 4C, and it is difficult to correctly read the ID on the semiconductor wafer in both cases simply by switching the dark-field illumination and the bright-field illumination. There were cases.

In some cases, as shown in FIGS. 4D and 4E, a metal thin film is formed on the semiconductor wafer 13 and the thin film is etched to form the character pattern 19 to form the ID of the semiconductor wafer. In this case, the pattern 19 is usually covered with a protective film 21 made of a transparent resin material, but the protective film 21 has different thicknesses as shown in FIGS. However, in some cases, due to surface reflection, it was not possible to reliably read the ID according to the pattern 19 simply by switching between bright field illumination and dark field illumination.

[0007]

[Means for Solving the Problems]

 According to this invention, there is provided a variable mechanism unit capable of adjusting the incident angle with respect to the semiconductor wafer or the light receiving angle of the video camera that receives the reflected light from the semiconductor wafer in the vertical plane and the horizontal plane, respectively. Therefore, if the ID on the semiconductor wafer is difficult to read, the semiconductor wafer can be illuminated from various angles by adjusting the variable mechanism part, or the ID can be read from various angles. It will be possible.

[0008]

【Example】

The principle of this invention is shown in FIG. 1A, and the portions corresponding to those in FIG. 4A are designated by the same reference numerals. In this example, the light 23 from the light source 11 is emitted almost horizontally, and one split light is hung down on the semiconductor wafer 13 by the beam splitter 12. In the present invention, the light source 11 is configured such that its outgoing light (light beam) 23 can be changed in the advancing direction angle in a vertical plane by a vertical variable mechanism 24, and the advancing direction in a horizontal plane by a horizontal variable mechanism 25. The angle can be adjusted. Accordingly, when the light beam 23 is rotated in the vertical plane by the vertical variable mechanism 24, the angle θ _z in the vertical plane which is reflected by the beam splitter 12 and is incident on the semiconductor wafer 13 is changed, for example, as shown by a dotted line. To do. When the light beam 23 is rotated in the horizontal plane by the horizontal variable mechanism 25, the angle of incidence of the light reflected by the beam splitter 12 on the semiconductor wafer 13 in the horizontal plane changes. Therefore, by adjusting both the variable mechanisms 24 and 25, the incident light θ _{xy Z} on the semiconductor wafer 13 can be changed in the vertical plane and in the horizontal plane, and various IDs are recorded on the semiconductor wafer 13. It is possible to irradiate from an angle, so that the ID can be read correctly.

Next, a specific structure of the embodiment of the present invention will be described with reference to FIGS. 1B and 2. A recess 32 reaching both ends is formed in the center of the upper surface of the base 31, and one end of the support plate 33 is fitted and fixed in the recess 32. The support plate 33 is extended in the horizontal direction, and a fixed cylindrical body 34 extending substantially at a right angle is attached to the upper side of the free end portion of the support plate 33. The movable tubular body 35 is rotatably attached to the lower surface of the end of the fixed tubular body 34 which is separated from the support plate 33. That is, a circular hole 36 is formed in the bottom surface of the end of the fixed cylindrical body 34 which is separated from the support plate 33, and the upper end of the movable cylindrical body 35 whose axis is perpendicular to the fixed cylindrical body 34 is formed in the circular hole 36. A cylindrical surface is rotatably fitted, a flange 37 is attached to the outer periphery of the insertion end of the movable cylinder 35, and the movable cylinder 35 is rotatably suspended and attached to the fixed cylinder 34. .

The light source 11 is vertically rotatably mounted on the base 31 side of the movable tubular body 35. For example, supporting pieces 38 and 39 are projected from both side plates of the movable tubular body 35, and circular arc-shaped slot holes 41 are formed in the supporting pieces 38 and 39 by extending in the vertical direction. Pins 42 protruding from both side surfaces of the end portion of 11 are respectively inserted so that the pins 42 can move along the slot 41. The position of the pin 42 can be fixed with a screw.

In a state in which the optical axis 43 of the light source 11 is horizontal, the axis 44 of the movable tubular body 35 is orthogonal to each other. The beam splitter 12 is attached to the inside of the movable cylindrical body 35 through the intersection at an angle of 45 degrees. The inside of the movable cylinder 35 communicates with the inside of the fixed cylinder 34, and the transmitted light from the beam splitter 12 is perpendicular to the horizontal direction, that is, parallel to the axis of the fixed cylinder 34 and to the support plate 33 side. A reflecting mirror 46 for reflecting is mounted in the fixed cylindrical body 34. A reflecting mirror 47 is attached to the other end of the fixed cylindrical body 34 so as to face the reflecting mirror 46 and bend the light from the reflecting mirror substantially horizontally at a right angle, that is, to the base 31 side. .

An opening is provided in the fixed cylindrical body 34 so that the light reflected by the reflecting mirror 47 toward the base 31 side is transmitted, and the light reflected by the reflecting mirror 47 is formed by the imaging lens 48 in the video camera. 14 is imaged. The video camera 14 is attached to the support plate 33 by an L-shaped fixture 49 on the base 31 of the support plate 33. An image forming lens 48 is attached to the opening (light receiving surface) side of the video camera 14. Note that FIG. 2B shows a state in which the optical axis of the light source 11 is horizontal and parallel to the optical axis of the imaging lens 48.

With this configuration, the screw of the pin 42 can be loosened to rotate the light source 11 so that the optical axis 43 of the light source 11 rotates in the vertical plane. Therefore, if the optical axis 43 is set to be horizontal, the semiconductor wafer 13 is subjected to epi-illumination, so-called bright-field illumination. When the light source 11, that is, the optical axis 43 is rotated in the vertical plane from this state to the state shown by the solid line in FIG. 2A, the semiconductor wafer 13 is obliquely irradiated with the light and the semiconductor wafer 13 is darkened. It becomes field illumination.

As described above, the bright field illumination and the dark field illumination can be freely set, and the incident angle of the dark field illumination with respect to the semiconductor wafer 13 can be considerably changed. Moreover, in both the dark field illumination and the bright field illumination, the light source 11 can be rotated in the horizontal plane about the axis 44, and the incident angle of the semiconductor wafer 13 in the horizontal plane can be changed. Therefore, the wafer ID must be correctly recognized even when the ID dot depth on the semiconductor wafer 13 is different, the inner peripheral wall of the dot is inclined, and the thickness of the protective film on the ID pattern is different. Can

In the above description, the optical axis of the light source 11 is rotated in the vertical plane and the horizontal plane, but as shown in FIG. 3A, the light source 11 is kept horizontal with the optical axis of the video camera 14, for example. The optical axis, that is, the light receiving angle may be rotated in the vertical plane and the horizontal plane. Alternatively, as shown in FIG. 3D, the angle of the beam splitter 12 may be rotated while the optical axes of the light source 11 and the video camera 14 are fixed.

[0016]

[Effect of device]

 As described above, according to the present invention, the incident angle with respect to the semiconductor wafer can be changed in the vertical plane and the horizontal plane, or the receiving angle of the video camera which receives light through the beam splitter can be changed in the horizontal plane and the vertical plane. Therefore, even if the wafer ID is formed in various states, the wafer ID can be illuminated in the most recognizable state and the wafer ID can be read correctly.

[Brief description of drawings]

1A is a diagram showing the principle of the present invention, and FIG. 1B is a plan view showing an embodiment of the present invention.

2A is a front view of FIG. 1B, and B is a right side view of FIG. 1B.

FIG. 3 is a schematic view showing another embodiment of the present invention.

FIG. 4A is a view showing a conventional wafer ID reading device,
B and C are sectional views showing the dot shape when the wafer ID is formed by dots, and C and D are sectional views when the wafer ID is formed by a pattern.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Hiromine Nagamine 727 Kihara, Kiyotake-cho, Miyazaki-gun, Miyazaki Prefecture Miyazaki Oki Electric Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A light from a light source is incident on a beam splitter to divide the light into two, one of the lights is incident on a semiconductor wafer, and the reflected light is received by a video camera through the beam splitter, and output from the video camera. In the wafer ID reader for reading the identification characters of the semiconductor wafer, there is provided a variable mechanism unit capable of adjusting an incident angle to the semiconductor wafer or a light receiving angle of reflected light from the semiconductor wafer of the video camera in a vertical plane and a horizontal plane, respectively. A wafer ID reading device, which is provided.