JPS62237743A - Wafer matching apparatus - Google Patents

Abstract

PURPOSE:To accurately match an eccentric position with respect to a rotary base in a direction of the orientation flat portion of a wafer in a predetermined direction and position by recognizing the orientation flat portion and calculating the eccentric amount with respect to the base to detect the outer edge position in noncontact with the outer periphery of the wafer. CONSTITUTION:A wafer 2 is attracted in vacuum on a rotary base 1, and the base 1 is secured to a rotational shaft 6 rotatably driven via gears 4, 5 by a drive motor 3. A rotating angle detector 7 is provided at the lower end of the shaft 6. A light 10 is emitted through a condensing lens 9 from a light source 8 at the outer edge of the wafer 2 to focus an image at the outer edge position of the wafer 2 on a one-dimensional image sensor 12. After position information data of l/2 rotation of the wafer 2 is input by a controller 13, parameter necessary for wafer matching operation is calculated by the data, and the direction of an orientation flat portion 14 of the wafer 2 and the eccentric position of the base 1 are detected with the parameters.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uses a one-dimensional image sensor to detect semiconductor wafers (
The present invention relates to a wafer alignment position that detects the outer edge position of a wafer (hereinafter simply referred to as a wafer) and aligns the wafer in a predetermined direction and position, and particularly relates to a wafer alignment apparatus that detects the outer edge position in a non-contact manner.

[Conventional technology]

Highly integrated LS I'1! The wafer alignment device used in the i-manufacturing equipment detects the outer edge position of the wafer in a non-contact manner and uses the results to determine the orientation of the wafer, the direction of the flat, and the eccentric position relative to the rotary table on which the wafer is placed. Methods for aligning in a predetermined direction and position are known. According to this method, since alignment is performed without contact, it is possible to prevent damage caused by chipping of the wafer during alignment or peeling off of the resist coated on the wafer. However, no consideration was given to the case where the wafer had chipping or peeling of the resist from the beginning. As a result, there has been a problem in ensuring high precision alignment and high reliability.

[Problem that the invention seeks to solve]

The present invention solves the problem of the conventional wafer alignment apparatus described above, in which it is difficult to align the wafer in a predetermined direction and position with high precision when there is chipping or peeling of the resist on the wafer. To provide a wafer alignment device that can solve the problem and, even in this case, detect the outer edge position without contacting the wafer outer periphery and accurately align the direction of the wafer orientation flat and the eccentric position with respect to the rotary table in a predetermined direction and position. The purpose is to

[Means for solving problems]

In order to achieve the above object, the present invention provides a rotary table fixed to a rotary shaft rotationally driven by a drive source and movable up and down in the direction of the rotary shaft, and a semiconductor mounted on the rotary table. Using a wafer alignment device comprising a wafer outer edge position data detection means for detecting the outer edge position of the wafer using transmitted light, and a rotation angle detection means for detecting the amount of rotation of the rotary table,
This wafer aligning device is provided with a control device having means for importing and memorizing the wafer outer edge position data, and means for removing noise components from the processed data. The amount of eccentricity with respect to the rotary table is calculated.

[Effect]

According to the above configuration, the wafer is rotated and the wafer outer edge position information is detected at each fixed angle using a simple and highly accurate optical-dimensional image sensor (COD), and the control device captures this detection data for one rotation. By performing storage, processing, and calculation, it is possible to recognize the center position of the wafer orientation flat and to calculate the amount of eccentricity of the wafer with respect to the rotary table.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a wafer alignment apparatus according to the present invention will be described below with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 to 5.

In FIG. 1, a wafer 2 is vacuum-adsorbed on a rotary table 1, and a gear 4,
It is fixed to a rotating shaft 6 which is rotationally driven via a rotary shaft 5 .

A rotation angle detector 7 is provided at the lower end of the rotation shaft 6. The outer edge of the wafer 2 is irradiated with light 10 from a light source 8 via a condensing lens 9, and the outer edge position of the wafer 2 is imaged onto a one-dimensional image sensor 12 via an imaging lens 11. . By rotating the wafer 2 once, the position information of the wafer 2 at each fixed angle is transmitted to the control device 1.
It is configured to be taken into 3.

Next, the operation of this embodiment will be explained. After the control device 13 captures the positional information data for one rotation of the wafer 2, parameters necessary for wafer alignment operation are calculated using this data, and based on these parameters, the orientation of the wafer 2 is determined in the direction of the flange 1-14. and the eccentric position with respect to the rotary table 1 is detected.

FIGS. 2(a) and 2(b) show outer edge position data of the wafer 2 imaged on the -dimensional image sensor 12 at each constant angle. here. indicates the center of rotation of the rotary table 1, and W indicates the center of the wafer 2. In actual process wafers, there are chips in the wafer, peeling of the resist, etc.
), the wafer outer edge position data may contain noise components. In order to solve this problem, data compression is performed so that the data of the noise component and the correct data of the elimination flat part can be distinguished. This data compression method is shown in FIG. 3(c). First, adjacent wafer outer edge position data are multiplied by weight functions of =Lt/N and Lz/N, respectively, and the results are added. Here, N, Ll, L2.
are arbitrary constants to distinguish between noise components, normal raw data, and orientation flats, respectively.

The result of this operation is assumed to be an integer and the decimal places are rounded down.

By performing such processing, the compressed data shown in FIG. 3(b) can be obtained from the wafer outer edge position data shown in FIG. 3(a). This figure shows that the compressed data is zero except for noise components caused by chipping of the rewafer 2, peeling of the resist, etc., and orientation flats. Furthermore, both ends of the orientation flat are determined by using the following features that appear in the orientation flat when the compression method is used.

In other words, when the amount of eccentricity is within ±100 μm, the compressed data will be - to the left and right of the center of the orientation flat.
It is divided into ten. Furthermore, the number of pieces of compressed data divided into left and right sides is limited to a certain range depending on the size of the wafer. Furthermore, since the central angle of the orientation flat is determined by the wafer size, the number of outer edge position data that can fit within the orientation flat is limited to a certain range. If there is a large number of outer edge position data that satisfy the above conditions, the largest one that satisfies the conditions is recognized as both ends of the orientation flat.

Next, detection of the center of the orientation flat will be explained with reference to FIG. From the data at both ends of the orientation flat detected by the above compression method, the opposite position data ml corresponding to the outer edge position data Ql is detected, and similarly as shown in FIG. 4(a), (u
2. mz)......Detect n points of (Q, n, mn). Next, each average value (Ql+m+)/2 is stored in the memory within the control device 13. The mode α is detected from among the stored values, and a valid range ±β is set from this mode as shown in Fig. 4(c), and only data within this valid range is Detect the center of the orientation flat using

Next, as shown in FIG.
The amount of correction to match the center of rotation O is detected. The algorithm for calculating this correction amount is as shown in FIG. If there is noise due to α, Az, Bz + C, which is separated by β shifted from α.
The correction amount is calculated for the four points z + Dz. In this case, the above-mentioned compressed data is used for noise determination.

FIG. 5(b) shows the relationship between the wafer outer edge position data at seven points around the Bz point and the rotation angle of the wafer 2, and FIG. 5(c) shows the relationship between the wafer outer edge position data at seven points around the Bz point, and FIG. In the case of Fig. 5(a), which shows a similar relationship, there is a noise component at point A1, so four points, Az, Bz + Cz, and Dz, which are separated by β degrees from the center of the orientation flat, are selected, and each The outer edge position data is adjusted using the least squares method for data at seven points around the point.

According to this embodiment, it is possible to align the wafer 2 with high accuracy by removing noise components caused by chipping of the wafer, peeling of the resist, etc., and increasing the reliability of the outer edge position data.

〔Effect of the invention〕

As described above, the present invention allows the wafer orientation, flat direction, and center of rotation to be set in the predetermined direction with high precision even if there is a chipping of the wafer or peeling of the resist on the outer periphery of the wafer. alignment, and can improve wafer yield.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of a wafer alignment device according to the present invention, Fig. 2 is a plan view and graph showing the relationship between a wafer and a one-dimensional image sensor, and Fig. 3 is compression of wafer outer edge position data. Fig. 4 is a graph showing a means for detecting the center of the orientation flat, and Fig. 5 is a graph showing a means for detecting a correction amount for aligning the center of the wafer with the center of the rotary table. . 1... Turntable, 2... Wafer, 3... Drive source, 6
...Rotation axis, 7...Rotation angle checker, 8...Light source,
12...-Dimension-Image sensor, 13...Control device, Orientation support 3 Figure Haya 4 Figure

Claims (1)

[Claims] 1. A rotary table fixed to a rotary shaft driven by a drive source and movable up and down in the direction of the rotary shaft, and detecting the outer edge position of a semiconductor wafer placed on this rotary table using transmitted light. In a wafer alignment apparatus comprising a wafer outer edge position data detection means and a rotation angle detection means for detecting the amount of rotation of the rotary table, there is a means for capturing and storing the wafer outer edge position data, and a noise component is extracted from the processed data. A wafer aligning apparatus comprising: a control device having a means for removing the wafer, and the control device recognizes the orientation flat portion of the wafer and calculates the amount of eccentricity of the wafer with respect to the rotary table.