JP2007157968A - Angle regulator for semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle regulator for semiconductor wafer capable of detecting even a comparatively small notch, such as a notch formed by notching a part of outer periphery of the semiconductor wafer so as to have the shape of wedge or the like, and capable of effecting the angle regulation for the semiconductor wafer at a high speed with a high accuracy. <P>SOLUTION: The angle regulator is provided with a conical mirror 2 provided so as to be coaxial with the optical axis of an imaging device 1 for imaging the semiconductor wafer 4 to reflect light of incidence against the imaging device 1, and a bowl type mirror 3 provided so as to be coaxial with the optical axis of the imaging device 1 to reflect the light of incidence against the conical mirror 2. The imaging device is constituted so as not to image the whole of the semiconductor wafer 4 but to image the outer periphery of the semiconductor wafer 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor wafer angle adjusting device for adjusting the angle of a semiconductor wafer in a semiconductor exposure apparatus.

When the angle of the semiconductor wafer is adjusted, the angle is adjusted with a notch on the outer periphery of the semiconductor wafer. Specifically, a semiconductor wafer is placed on a stage, a notch is detected, an angular deviation is measured, and the stage is rotated as much as necessary to adjust the angular deviation.
Here, the following methods are generally known as methods for detecting notches in a semiconductor wafer.
A method of installing an imaging device so that a part of the outer periphery of the semiconductor wafer can be imaged, continuously imaging a part of the outer periphery while rotating at a predetermined speed, and processing the captured image to detect notches ( For example, see Patent Document 1).
A method for imaging the entire semiconductor wafer with an imaging device (for example, see Patent Document 2)
FIG. 4 is a configuration diagram of a semiconductor wafer angle adjusting apparatus showing the prior art, and is a diagram showing a configuration of the above-described two methods.
In FIG. 4, 1 is an imaging device, 4 is a semiconductor wafer, 5 is a stage, 6 is a control device, 7 is a light source, and 8 is a light source mirror.
Hereinafter, the operation of the conventional semiconductor wafer angle adjusting apparatus will be described with reference to FIG.
In the conventional imaging apparatus 1, the entire semiconductor wafer 4 is imaged by the imaging apparatus 1 using the light of the light source 7 reflected by the light source mirror 8, the image is processed by the control apparatus 6, and adjustment is performed by the stage 5. .
As described above, the conventional semiconductor wafer angle adjusting device detects a notch by continuously imaging a part of the outer periphery or by imaging the entire semiconductor wafer.
Japanese Patent Laid-Open No. 5-82628 (Fig. 2) JP-A-9-36206 (FIG. 1)

However, in the conventional semiconductor wafer angle adjusting apparatus, the method described in Patent Document 1 requires the table to be rotated in order to detect notches in the semiconductor wafer even before the angle adjustment of the semiconductor wafer, and the processing time is increased. There is a problem that it takes a lot.
Further, the method described in Patent Document 2 images the entire semiconductor wafer and observes the cutout, and therefore, a part of the outer periphery of the semiconductor wafer is cut out linearly due to the resolution limitation of the image pickup device in the image pickup apparatus. Applicable to semiconductor wafers with relatively large notches such as orientation flats, but not applicable to semiconductor wafers with relatively small notches such as notches formed by cutting a part of the outer periphery of the semiconductor wafer into a wedge shape, or There is a problem that the required accuracy cannot be obtained.
The present invention has been made in view of such problems, and a semiconductor capable of detecting notches by imaging only the outer periphery of a semiconductor wafer at a time and adjusting the angle of the semiconductor wafer at high speed and with high accuracy. An object of the present invention is to provide a wafer angle adjusting device.

In order to solve the above-mentioned problem, the invention described in claim 1 includes a stage that mounts and rotates a disk-shaped semiconductor wafer, and an irradiation unit that irradiates the semiconductor wafer with light and a light source mirror. An imaging device that optically images the semiconductor wafer from the rotational axis of the stage; and a control device that drives the stage by processing an image obtained from the imaging device. In a semiconductor wafer angle adjusting device that detects a cut-out portion and adjusts a circumferential angle thereof, the semiconductor wafer angle adjusting device is provided so as to be concentric with the optical axis of the imaging device, and reflects incident light to the imaging device. A conical mirror that is arranged concentrically with the optical axis of the imaging device, and a mortar-shaped mirror that reflects the incident light from the irradiation unit in an annular shape on the conical mirror, and Image device is characterized in that for imaging the periphery of the semiconductor wafer at one time.
According to a second aspect of the present invention, in the semiconductor wafer angle adjusting device according to the first aspect, the control device detects an edge between the semiconductor wafer and a background based on image data acquired from the imaging device. And calculating distance data between each detected point of the edge and the center, searching for the shortest distance point data that is the shortest distance point from the distance data, and angle adjustment targets based on the shortest distance point data And an angle formed by a portion formed by cutting out the outer periphery of the semiconductor wafer and a direction connecting the center of the semiconductor wafer.

According to the first aspect of the present invention, only the outer periphery of the semiconductor wafer can be imaged at a time, and a more accurate image of the outer periphery of the semiconductor wafer can be obtained at a higher speed than in the case of imaging the entire semiconductor wafer.
According to the second aspect of the present invention, the position of a relatively small notch such as a notch formed by notching the outer periphery of the semiconductor wafer can be detected, and the angle deviation of the wafer is calculated from the detected notch position. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a semiconductor wafer angle adjusting device showing the present invention.
In FIG. 1, 1 is an optical imaging device, that is, a camera, 2 is a conical mirror, 3 is a mortar mirror, 4 is a semiconductor wafer, 5 is a stage, 6 is a control device, 7 is a light source, and 8 is a light source mirror. It is.
The present invention is different from the prior art of FIG. 4 in that the semiconductor wafer angle adjusting device of the present invention is provided with a conical mirror 2 and a mortar-shaped mirror 3 so as to be concentric with the optical axis of the imaging device 1. Yes, only the outer periphery of the semiconductor wafer 4 can be imaged, not the entire semiconductor wafer 4.
Hereinafter, the configuration of the semiconductor wafer angle adjusting device of the present invention will be described in detail with reference to FIG.
The stage 5 is a mechanism that can hold and rotate the semiconductor wafer 4 by, for example, vacuum suction. The irradiation unit for irradiating the semiconductor wafer 4 includes a light source 7 and a light source mirror 8. In addition, the imaging device 1, the conical mirror 2, the mortar-shaped mirror 3, the semiconductor wafer 4, and the stage 5 are installed so that the central axes thereof coincide with each other. Further, the arrangement of the conical mirror 2 and the mortar-shaped mirror 3 is the same in height, and the light reflected by the light source mirror 8 passing near the outer periphery of the semiconductor wafer 4 is reflected horizontally by the reflecting surface of the mortar-shaped mirror 3. Then, toward the center, the reflection surface of the conical mirror 2 is reflected in a ring shape toward the imaging device 1.
Further, the light incident on the imaging device 1 is transmitted as image data to the control device 6, and the control device 6 calculates an angle shift of the semiconductor wafer 4 and rotates the stage 5 to adjust the angle shift. It has a structure that can be made.

FIG. 2 is an imaging view of the semiconductor wafer 4 obtained by the semiconductor wafer angle adjusting device of the present invention. In FIG. 2, reference numeral 11 denotes a notch formed by cutting a part of the outer periphery of the semiconductor wafer 4 into a wedge shape, and reference numeral 12 denotes a pixel of the imaging device 1.
Hereinafter, an imaging diagram of the semiconductor wafer 4 obtained by the semiconductor wafer angle adjusting device of the present invention will be described with reference to FIG. The captured image is basically the same as looking down from the top, and the difference is that the object, that is, the center of the semiconductor wafer is not imaged. In FIG. 2, the state of the image of the central portion is omitted.
The tip of the notch 11 formed by cutting out the outer periphery of the semiconductor wafer 4 is imaged closest to the imaging center in the outer periphery of the semiconductor wafer 4. The imaging center is the origin O, the coordinates of the pixel imaged closest to the imaging center among the pixels 12 of the imaging device 1 are (x, y), the distance between the pixel and the origin is r, and the angle adjustment target Is the y-axis, the angle θ between the tip of the notch 11 and the origin O · y axis is obtained by the following equation.
θ = cos ⁻¹ (y / r) (1)

FIG. 3 is a flowchart for calculating the deviation angle from the imaged image of the semiconductor wafer 4 in the control device 6 of the semiconductor wafer angle adjusting device of the present invention.
Hereinafter, the procedure for calculating the misalignment angle from the captured image of the semiconductor wafer 4 in the control device 6 of the semiconductor wafer angle adjusting device of the present invention will be described step by step with reference to FIG.
First, in step ST21, since the imaging drawing of the semiconductor wafer 4 is a binary image in which the semiconductor wafer 4 is a dark part and the other part is a bright part, only the outer periphery is made a bright part by edge extraction processing. Next, in step ST22, the distance from the origin O is calculated by distance calculation processing for each point of the bright portion of the obtained image. Next, in step ST23, the pixel 12 with the shortest distance is searched from the obtained distance group by the nearest neighbor search process. Finally, in step ST24, the angle θ, that is, the deviation angle is calculated from the discovered pixel 12 using the equation (1).

  As described above, the semiconductor wafer angle adjusting device according to the present embodiment includes the conical mirror 2 and the mortar-shaped mirror 3, so that only the outer periphery of the semiconductor wafer 4 can be imaged, not the entire semiconductor wafer 4. Thus, by imaging only the outer periphery of the semiconductor wafer 4, the resolution of the image for detecting the notch can be improved, and a highly accurate image of the outer periphery of the semiconductor wafer 4 can be obtained. Therefore, a relatively small notch such as a notch that is partially cut into a wedge shape can be detected at high speed. In addition, the semiconductor wafer angle adjusting device of the present invention can be arranged more freely than the conventional one, so that it is highly feasible even in a mass production machine with severe space constraints.

  The present invention is most suitable for a semiconductor exposure apparatus that detects notches on the outer periphery of a semiconductor wafer and adjusts the angle of the semiconductor wafer, particularly a semiconductor exposure apparatus that requires a reduction in cycle time.

Configuration diagram of semiconductor wafer angle adjusting device showing the present invention Imaging drawing of semiconductor wafer 4 obtained by semiconductor wafer angle adjusting device of the present invention Flowchart for calculating a misalignment angle from an imaging drawing of a semiconductor wafer 4 in the control device 6 of the semiconductor wafer angle adjusting device of the present invention. Configuration diagram of semiconductor wafer angle adjustment device showing conventional technology

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Conical mirror 3 Mortar-shaped mirror 4 Semiconductor wafer 5 Stage 6 Control device 7 Light source 8 Light source mirror 11 Notch 12 Pixel

Claims (2)

A stage (5) on which a disk-shaped semiconductor wafer (4) is placed and rotated;
An irradiating unit comprising a light source (7) and a light source mirror (8) for irradiating the semiconductor wafer (4) with light;
An imaging device (1) for optically imaging the semiconductor wafer (4) from the rotational axis of the stage (5);
A control device (6) for processing the image obtained from the imaging device (1) and driving the stage (5),
In the semiconductor wafer angle adjusting device for detecting the portion (11) formed by cutting out the outer periphery of the semiconductor wafer (4) and adjusting the circumferential angle thereof,
A conical mirror (2) provided concentrically with the optical axis of the imaging device (1) and reflecting incident light to the imaging device (1);
A mortar-shaped mirror (3) provided concentrically with the optical axis of the imaging device (1) and reflecting the incident light from the irradiation unit in a ring shape on the conical mirror (2);
The semiconductor wafer angle adjusting device, wherein the image pickup device (1) picks up an image of the outer periphery of the semiconductor wafer (4) at a time. The control device (6)
Detecting an edge between the semiconductor wafer (4) and a background based on image data acquired from the imaging device (1);
Calculate distance data between each point of the detected edge and the center,
Search the shortest distance point data which is the shortest point from the distance data,
A target direction for angle adjustment based on the shortest distance point data, and a direction connecting the center (11) of the semiconductor wafer (4) with the portion (11) formed by cutting the outer periphery of the semiconductor wafer (4). 2. The semiconductor wafer angle adjusting device according to claim 1, wherein an angle formed is obtained.

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