JPH088328A - Wafer positioning apparatus - Google Patents

Abstract

PURPOSE:To realize highly accurate centering of a wafer by measuring the positional shift between the centers of the wafer and a rotary stage and the position of orientation flat based on the signals from an angle sensor and a CCD linear sensor. CONSTITUTION:A wafer 1 is sucked to a wafer chuck 2 fixed to a rotary stage 3 also fixed with an angle detector 4. A light projecting section comprises an LED array 9 and a CCD linear sensor 10 is disposed on the water surface closely to the under side thereof. An operation control section 12 measures the positional shift between the centers of the wafer and the rotary stage, as well as the position of orientation flat, using the single CCD linear sensor 10 so that the positional shift can be corrected and the orientation flat can be positioned. This structure can decrease the number of components and since no error is produced theoretically, highly accurate centering of wafer can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer positioning device used for manufacturing semiconductor devices, and more particularly to a wafer positioning device using a CCD linear sensor.

[0002]

2. Description of the Related Art As shown in FIG. 6, a conventional wafer positioning apparatus has a wafer chuck 2 for vacuum-sucking a wafer (semiconductor wafer) 1, and carries the chuck to hold the wafer in a plane substantially parallel to the wafer surface. A rotating stage 3 for rotating, an X stage 5 and a Y stage 7 that carry the rotating stage and move the wafers in XY directions orthogonal to each other in a plane parallel to the plane, and a wafer 1 disposed on a fixed portion Pair of C to detect the outer peripheral position of
A CD linear sensor 16, an encoder 4 for detecting a rotational position, a pulse motor 6 for driving an X stage, a pulse motor 8 for driving a Y stage, a lamp 13 for radiating a parallel light flux to the CCD linear sensor 16 in a pulse shape, and a range. 1
4 and a calculation for controlling all the driving units, including a function of detecting the position of the XY stage based on the number of drive pulses of each of the pulse motors 6 and 8 and a function of detecting the position of the rotary stage based on the encoder 4.・ It has a control device. The above prior art is disclosed in, for example, JP-A-63-70436.

[0003]

In this conventional wafer positioning apparatus, a pair of CCD linear sensors, that is, two CCD linear sensors are required, and the signal storage section also requires the corresponding capacity. Requires a relatively large number. In addition, since a pair of CCD linear sensors are arranged parallel to the Y-axis, the rotation angle and CCD
There is a problem in that an error occurs in the measurement position angle of the linear sensor, resulting in an error in the wafer center position.

[0004]

A wafer positioning apparatus of the present invention comprises an XY stage for moving a wafer in an orthogonal direction, a rotary stage for rotating the wafer, an angle detector for detecting the rotation angle, and an outer periphery of the wafer. A light projecting unit for projecting light onto the wafer, a CCD linear sensor arranged at a position for receiving the light, a lift-up unit for lifting the wafer, an angle detector, and the center of the wafer and the center of the rotary stage based on signals from the CCD linear sensor. Calculates the amount of positional deviation and the position of the orientation flat, drives the XY stage so that the center of each is aligned, and drives the rotary stage so as to align the position of the orientation flat at a predetermined position. I have it.

[0005]

FIG. 1 is a diagram schematically showing one embodiment of the present invention, and FIG. 5 is a flow chart showing an operation from loading of a wafer to positioning of an orientation flat in the embodiment.

In FIG. 1, a wafer (semiconductor wafer) 1 is attracted to a wafer chuck 2 mounted on a rotary stage 3. An encoder 4 as an angle detector is attached to the rotary stage 3 and both are fixed to the X stage 5. The X stage 5 is attached to the Y stage 6, and performs rotation, movement in the X-axis direction and the Y-axis direction by the above-described portions.

The LED array 9 is used as a light projecting unit, and one CCD linear sensor 10 is provided near the lower side of the wafer surface so that the light projected from the LED array 9 is transferred to the wafer 1.
Is obtained from the position signal where the outer circumference of the light-shielding light is shielded. The LED array 9 and the CCD linear sensor 10 are provided on the X axis passing through the origin of the Y stage 6. Further, the LED array 9 and the CCD linear sensor 10 are provided at positions where they do not come into contact with each other even if the wafer is lifted by the wafer lift 11.

The arithmetic and control unit 12 includes an encoder 4 and a CC
A signal from the D linear sensor 10 is input. The input signal is stored in the storage unit in the arithmetic / control unit 12, and when the signal required for the calculation is input, the signal is extracted from the storage unit to calculate the X / Y position shift amount and the position of the orientation flat, The X / Y stage motors 6 and 8, the rotary stage 3, and the wafer lift 11 are operated to perform alignment between the center of the wafer and the center of the X / Y stage and orientation flat alignment.

Next, a description will be given of a method of detecting the position shift amount and the orientation flat position.

FIG. 2 shows a state in which the wafer 1 is loaded into the wafer positioning apparatus of the present invention. Generally, the position of the orientation flat is undefined at the time of loading, but for the sake of simplicity, the description will be made assuming that the wafer 1 is circular.

[0011] with respect to the rotation stage center O as shown in FIG. 2, if the wafer center O _W is [Delta] x _O, the [Delta] y _O Zureta state, when the rotary stage, the signal from the CCD linear sensor 10 in FIG. 3 The waveform becomes like A. The waveform of B is a waveform obtained by delaying the phase of A by 180 °.

When calculating the position shift amount in the present invention, C
= A-B (FIG. 4). The basic C waveform is C = 2a, where a is the distance from O to O _W (Fig. 2).
× {sin (θ + α)} Since the X axis and the Y axis have a 90 ° phase shift relationship, in the case of FIG. 2, half of the value at 0 ° of the waveform of C shown in FIG. 4 is Δx _O , and half of the value at 90 ° is half. Δy _O. Therefore, if the XY stage is moved in the X-axis and Y-axis directions by the amount of this value, the center of the wafer will coincide with the center of the rotary stage.

Next, the case where the orientation flat is at the position indicated by the two-dot chain line in FIG. 2 will be described. In this case, the signal of the CCD linear sensor 10 has a form in which A _OF is added to the waveform of A shown in FIG. Therefore, the waveform whose phase is delayed by 180 ° has a form in which B _OF is added to the waveform of B, and the difference between the two waveforms is a form in which C _OF is added to the waveform of C as shown in FIG. In this case, if the method described above is used, the value of Δx _O becomes C _OF
Minute error. In this case, the method described above can be used by rotating the reference axis to a position where there is no influence of C _OF .

The X-axis ₄₅ , Y-axis ₄₅ and Δx in FIGS.
₄₅ , Δy ₄₅ indicate them.

[0015] Also, the basic waveform as other methods can be used regardless of the method described above by performing the waveform shaping for the portion of the C _OF because it is may be sin wave orientation flat position.

[0016] Next a method for determining the position of the orientation flat, the position when the signal obtained by differentiating the waveform of the A _OF is by determining the angle becomes zero, as seen in the direction of rotation from 0 to 2 You can know.

In addition, -2a × {sin (θ +
alpha)} signal only waveform C _OF it is possible to extract the addition of, when a signal obtained by differentiating this is by determining the angle becomes zero, as seen in the direction of rotation from O _W in FIG. 2 Although it is possible to know the position, in this case, since the angle at which the two positions zero occurs, it is necessary to determine the angle and positioning of the a _oF in Fig.

[0018]

As described above, according to the present invention, one C
The CD linear sensor measures the amount of misalignment between the center of the wafer and the center of the rotary stage and the position of the orientation flat, and corrects the amount of misalignment and positions the orientation flat, thus reducing the number of parts. Becomes In addition, since no error occurs in principle, it is possible to locate the center of the wafer with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention.

FIG. 2 is a plan view showing a state where the wafer of the embodiment shown in FIG. 1 is loaded.

FIG. 3 is a diagram showing a signal waveform of a CCD linear sensor.

FIG. 4 is a diagram showing a position shift waveform synthesized by an arithmetic and control unit.

FIG. 5 is a flowchart showing an operation.

FIG. 6 is a schematic diagram of a conventional technique.

[Explanation of symbols]

 Reference Signs List 1 wafer 2 wafer chuck 3 rotary stage 4 encoder 5 X stage 6 X motor 7 Y stage 8 Y motor 9 LED array 10 CCD linear sensor 11 wafer lift 12 calculation / control unit 13 lamp 14 lens 15 base 16 pair of CCD linear sensors

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical indication H01L 21/027 27/14

Claims (2)

[Claims] 1. An XY stage for moving a wafer in an orthogonal direction, a rotary stage for rotating a wafer, an angle detector for detecting the rotation angle thereof, a light projecting unit for projecting light on the outer periphery of the wafer, and the light therefor. CC placed in a position to receive
From the signals of the D linear sensor, the lift-up part that lifts the wafer, the angle detector and the CCD linear sensor, calculate the positional deviation amount between the wafer center and the rotation stage center and the position of the orientation flat, and align each center. A wafer positioning apparatus comprising: an XY stage drive unit; and an arithmetic control unit that drives a rotary stage so as to align a position of an orientation flat with a predetermined position. 2. The wafer positioning device according to claim 1, wherein only one of said CCD linear sensors extends in one direction.