JPH04249339A - Alignment method of semiconductor wafer - Google Patents

Abstract

PURPOSE:To perform an alignment operation with high accuracy by detecting the accurate position of an orientation flat. CONSTITUTION:While a semiconductor wafer 1 placed on a chuck 2 for orientation-flat detection use is being turned, the position of an edge at said semiconductor wafer 1 is measured by using a light-emitting diode 6 and a line sensor 7. An orientation-flat part is judged on the basis of the measured edge. Said orientation-flat part is made parallel to the movement direction of a Y-stage for orientation-flat detection use. Said orientation flat is directed to a designated direction on the basis of the difference in an angle between the direction of the orientation-flat part and the designated direction. In this state, the semiconductor wafer 1 is aligned with a designated position.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aligning semiconductor wafers used in semiconductor manufacturing equipment.

0002

[Prior Art] As a method for aligning a semiconductor wafer used in a highly integrated LSI manufacturing apparatus, the position of the outer edge of the semiconductor wafer is detected in a non-contact manner, and the orientation flat (hereinafter referred to as "orientation flat") of the semiconductor wafer is determined based on the result. A method has been proposed in which a semiconductor wafer is aligned in a predetermined direction and position based on the orientation flat position.

The basic configuration for carrying out the above-mentioned semiconductor wafer alignment method is as shown in FIG.
While the orientation flat detection chuck 2 holding the semiconductor wafer 1 by suction is rotated by the orientation flat detection θ stage 3, the light emitting diode 6, which is a non-contact outer edge position detection means, is rotated.
and a line sensor 7 consisting of a photoelectric conversion element etc.,
The edge position for one circumference of the outer edge of the semiconductor wafer 1 is measured using the signal processing unit 9, and the orientation flat position is determined from the edge position measured by the arithmetic control unit 13. The line sensor 7 is installed parallel to the moving direction of the X stage 4 for orientation flat detection. Then, based on the obtained orientation flat position, corrected drive amounts for each of the X, Y, and θ axes are calculated to move the semiconductor wafer 1 to a predetermined position, and according to the results, the orientation flat detection The semiconductor wafer 1 is positioned by driving the X stage 4, the Y stage 5 for orientation flat detection, and the θ stage 3 for orientation flat detection.

0004

However, the above-mentioned conventional techniques do not take into consideration the case where the line sensor deviates from a predetermined position during assembly. Current line sensor assembly technology uses a high-precision jig such as an optical reticle to
Although alignment is possible with an accuracy of several μm, it is very difficult to achieve an accuracy of 10 −3 rad or more in the θ direction.

Errors that occur when the edge position of the semiconductor wafer 1 is measured using a line sensor assembled in an inclined state will be explained with reference to FIGS. 11 and 12.

FIG. 11 shows an x-
This shows the semiconductor wafer 1 in the y-coordinate system, and the line sensor 7 is assembled in a state inclined by Δθx with respect to the x-axis. The assembly in the x and y directions is performed at the center of the line sensor 7, and the accuracy thereof is assumed to be sufficiently high. FIG. 12 shows the relationship between the line sensor 7 in FIG. 11 and the outer edge of the wafer passing over the line sensor 7.
(e) is the rotation direction in Fig. 11 (arrow θ direction in the figure)
Orientation flat portion 102 when semiconductor wafer 1 is rotated
This shows the process in which the portion passes over the line sensor 7.

In FIG. 12(a), the vicinity of the boundary PA between the orientation flat part 102 and the circular arc part 101 is measured. At this time, originally the outer edge on the x-axis should be measured, but what is actually measured is the line sensor 7.
Since the outer edge is on the top, the distance from the center of the chuck is an error Δl
It will be measured for a long time. FIG. 12(b) shows a state further rotated in the θ direction from this state. Since the orientation flat part 102 becomes close to perpendicular to the x-axis,
The error Δl decreases. FIG. 12C shows a state in which the orientation flat portion 102 is perpendicular to the x-axis after further rotation in the θ direction. In this state, the measurement error is purely due to the inclination of the line sensor 7, and if the length along the line sensor 7 from the center P of the line sensor 7 to the measurement point is x, then in this state The error Δl is expressed as Δl=x*(l-cosΔθx), and as mentioned above, the orientation flat part 10
This is of a negligible order compared to the error when 2 is tilted. In the state shown in FIG. 12(d), which is further rotated in the θ direction, the state is opposite to FIG.
It will be measured too short. In FIG. 12(e), FIG.
The vicinity of the boundary PB with the circular arc portion 101 is measured in a state opposite to that in FIG. 12(a), and the error Δl increases compared to FIG. 12(d).

Although not shown, when the arcuate portion 101 is on the line sensor 7, it is almost the same as (c) in FIG.
There is almost no effect. Therefore, (a) to (e) in FIG.
The edge position of the orientation flat part 101 measured in the state shown in Fig. 1
This results in an S-shaped measurement value as shown by the broken line in Figure 1, and as a result, the orientation flat detection θ accuracy deteriorates. However, the S-order error curve shown in FIG. 11 is just an example, and the curve differs depending on where on the line sensor 7 the orientation flat portion 101 is measured. Since this is related to eccentricity between the center of the chuck and the center of the semiconductor wafer 1, a different amount of orientation flat detection θ error remains for each semiconductor wafer.

The present invention has been made in view of the problems of the conventional techniques described above, and provides a semiconductor wafer alignment method that enables highly accurate alignment by detecting the accurate position of the orientation flat. is intended to provide.

0010

[Means for Solving the Problems] The present invention uses non-contact outer edge position detection means for a light emitting means and a line sensor serving as a light receiving means for the light emitting means while rotating a semiconductor wafer for semiconductor manufacturing by a rotating means. The edge position of the semiconductor wafer is measured for one circumference of the outer edge of the semiconductor wafer, the orientation flat part of the semiconductor wafer is detected from the change in the measured edge position, and the orientation flat position indicating the orientation of the orientation flat part is determined. In the method for aligning a semiconductor wafer, the orientation flat section is orientated in a specified direction with reference to the orientation flat section, after determining the orientation flat position, the rotating means is driven based on the orientation flat position, and the orientation flat section is The semiconductor wafer is scanned in the direction of the line sensor using a moving means in a direction perpendicular to the direction of the line sensor, and edge positions at arbitrary two points of the orientation flat part are measured.
The inclination of the orientation flat part with respect to the moving direction of the moving means is determined from the edge position of the point, and the rotating means is driven according to the determined inclination to make the orientation flat part parallel to the moving direction of the moving means. The rotation means is driven to orient the orientation flat portion in the designated direction, and when the orientation flat portion is made parallel to the moving direction of the moving means, the distance from the center of rotation by the rotation means to the orientation flat portion or a line sensor that measures an orientation flat distance indicating the orientation flat portion, orients the orientation flat portion in the designated direction, and then calculates the amount of movement of the semiconductor wafer to a designated position in the designated direction based on the orientation flat distance. The semiconductor wafer is moved to a designated position using means for moving in two directions: a moving direction perpendicular to the direction of the moving direction and a moving direction perpendicular to the moving direction.

[0011]

[Operation] The semiconductor wafer positioning method of the present invention is as follows:
Orientation When orienting the flat part in the specified direction,
Orient the orientation flat toward the line sensor. Thereby, the orientation flat portion becomes substantially parallel to the moving direction of the moving means. In this state, the semiconductor wafer is scanned in the moving direction by the moving means in order to measure the edge positions of arbitrary two points of the orientation flat part using the line sensor. Since the part moves on the line sensor in a state substantially perpendicular to the line sensor, the measured edge positions of the two points of the orientation flat part are determined by assembly errors such as inclination of the line sensor. can be ignored, and the orientation of the flat portion can be detected accurately.

[0012] The edge positions of the two measured points and the two
From the distance between the points, the orientation flat part is determined from the distance between the points.
An inclination with respect to the moving direction is determined, and the orientation flat portion is made parallel to the moving direction. The parallelism at this time is not affected by the assembly error of the line sensor and has very high accuracy, so the orientation flat part can be directed in the specified direction based on the angular difference between the moving direction and the specified direction. Can be done.

[0013]

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

FIG. 1 is a diagram showing an orientation flat detection portion of a semiconductor exposure apparatus for implementing the semiconductor wafer alignment method of the present invention.

In this embodiment, the orientation flat detection chuck 2 that holds the semiconductor wafer 1 moves the semiconductor wafer within its plane with the center of the orientation flat detection chuck 2 (hereinafter referred to as "chuck center") as an axis. The orientation flat detection θ stage 3 rotates the semiconductor wafer 1 in the θ direction in the figure.
It is placed on an X stage 4 for orientation flat detection and a Y stage 5 for orientation flat detection, which are moving means for moving in the axis and y axis directions. Also, at the same y-coordinate position as the center of the chuck, there is a light emitting diode (
Hereinafter, it will be referred to as "LED". ) 6 is fixed, and furthermore, a line sensor 7, which is a light receiving element for the LED 6, is fixed at the same y-coordinate position as the center of the chuck and at a prescribed x-coordinate position, sandwiching the semiconductor wafer 1. ing.

The light beam emitted from the LED 6 is made into parallel light by a lens (not shown) and illuminates the edge portion of the semiconductor wafer 1, and is partially blocked by the semiconductor wafer 1 to form an image on the line sensor 7. .

An output signal corresponding to the amount of light received by the line sensor 7 is taken in by a signal processing section 9. The signal processing section 9 A/D converts the output signal from each pixel of the line sensor 7, and further detects pixels corresponding to edges. Then, in the arithmetic control unit 13, an edge position indicating an edge distance from the chuck center to the outer edge of the semiconductor wafer 1 is determined from the pixel signal detected by the signal processing unit 9 and the x-coordinate position of the line sensor 7 with respect to the chuck center. One circumference of the outer edge is measured in accordance with the rotation angle of the orientation flat detection chuck 2, and the approximate position of the orientation flat portion (hereinafter referred to as "orientation flat") of the semiconductor wafer 1 is detected from the change in the edge distance.

The θ stage 3 for orientation flat detection, the X stage 4 for orientation flat detection, and the Y stage 5 for orientation flat detection are operated by calculation control via a θ axis drive section 10, an X axis drive section 11, and a Y axis drive section 12, respectively. 13.

In order to move the semiconductor wafer 1 to a desired position based on the position of the orientation flat detected as described above, the calculation control unit 13 controls the orientation flat detection θ stage 3 and the orientation flat detection X stage 4. and the drive amount of the Y stage 5 for orientation flat detection are determined and driven. Further, the arithmetic control section 13 drives the LED 6 via the LED drive section 8 to turn it on and off at the start and end of orientation flat position detection.

Next, the operation of this embodiment will be explained along the flowchart shown in FIG.

In this embodiment, the position for transferring the semiconductor wafer 1 to a load hand (not shown) that transports the semiconductor wafer 1 to an exposure wafer stage (not shown) is designated as a designated position, and the semiconductor wafer 1 is transferred to the designated position. Perform alignment.

First, in order to detect the orientation flat position of the semiconductor wafer 1, the edge position of the semiconductor wafer 1 is measured (S201).

In this edge position measurement start state, the semiconductor wafer 1 is attracted to the orientation flat detection chuck 2 with the orientation flat facing in an arbitrary direction, and at this time, the center of the semiconductor wafer 1 and the center of the chuck are aligned. During this period, an eccentricity within a specified value occurs due to an error that occurs when the semiconductor wafer 1 is transported. Further, the orientation flat detection X stage 4 and the orientation flat detection Y stage 5 are in positions for performing measurement.

In this state, the arithmetic control unit 13 lights up the LED 6 via the LED drive unit 8, and drives the θ stage 3 for orientation flat detection via the θ axis drive unit 10, so that the chuck for orientation flat detection 2 is rotated, and while the orientation flat detection θ stage 3 is rotating at a constant speed, the signal processing unit 9 measures the edge position of the semiconductor wafer 1 around the outer edge at predetermined angular intervals. After the measurement is completed, the LED
The LED 6 is turned off via the drive section 8.

The edge position measurement method is to pass the charge accumulated by the amount of light received by the line sensor 7 from the LED 6 within a certain period of time at each measurement point to the signal processing unit 9, and obtain the edge position as an output. . From this edge position output and the mounting coordinate position of the line sensor 7 from the center of the chuck, the distance from the center of the chuck to the outer edge can be determined.

After the measurement of the edge position for one circumference of the outer edge of the semiconductor wafer 1 is completed, the angle rotated by the orientation flat detection θ stage 3 until it stops is stored as the overrun rotation amount β, and is fed back at the time of correction drive.

FIG. 3 shows the locus of change in the edge distance l from the chuck center to the outer edge of the semiconductor wafer 1 with respect to the rotation angle θ of the orientation flat detection θ stage 3.
(a) shows a semiconductor wafer with one orientation flat, (b)
shows a semiconductor wafer on which two orientation flats, first and second, are formed.

Note that when there is no eccentricity between the center of the chuck and the center of the semiconductor wafer 1, the gentle curve corresponding to the arc of the semiconductor wafer 1 in FIGS. 3(a) and 3(b) becomes a straight line.

Next, the orientation flat portion is determined from the edge position measured as described above (S202).

FIG. 4 shows a method for determining the orientation flat portion.
This will be explained according to the flowchart shown in .

Regarding the trajectory of the edge distance l, the data string l is scanned to search for the minimum value (S401), and the rotation angle at which the minimum value is obtained is stored. The rotation angle that takes this minimum value is 2 of θ1a and θ2a in the locus shown in FIG. 3(a).
In the trajectory shown in FIG. 3(b), θ1b, θ2b
, θ3b.

Next, it is checked whether all of the minimum values detected in step S401 satisfy the orientation flat condition. Various methods can be considered for setting the orientation flat condition, but for example, in an enlarged view near the minimum value as shown in FIG. 5, (1) The data string l must increase monotonically for the specified number of measurement points on both sides from the minimum value.

At this time, the specified number of measurement points must be definitely points on the orientation flat, and can be determined from the wafer diameter, the length of the orientation flat, and the maximum possibility of eccentricity.

Specifically, if the radius of the semiconductor wafer is r, the length of the orientation flat is s, the maximum value of eccentricity is d, and the number of measurement points at the edge position for one circumference of the outer edge is n, the specified number of measurement points is (1
) is expressed as an integer m obtained by the formula.

[0035]

[Equation 1] In FIG. 5, the specified number of measurement points is 1 including the minimum value.
It is 0 points.

■ The difference between the value lm of the measurement point separated by the specified number of measurement points from the local minimum value and the value lmin of the local minimum value is greater than the specified value Δl on each of the left and right sides. The method for determining Δl at this time is to make it larger than the amount of change of m points from the minimum value on the arc at the time of maximum eccentricity, and smaller than the amount of change of m points from the minimum value on the orientation flat at the time of maximum eccentricity. Since the amount of change Δlm for m points on the orientation flat at the time of maximum eccentricity is expressed by equation (2), it is sufficient to set Δl to a value slightly smaller than Δlm.

[0037]

[Equation 2] Since the minimum value caused by the eccentricity does not satisfy the orientation flat condition ■, in step S402, (a
θ1a shown in ) and θ2b shown in FIG. 3(b) are excluded. Furthermore, the minimum value that occurs when there is a chip or the like in the semiconductor wafer 1 is eliminated by the orientation flat condition (2). Therefore, only the minimum value of the portion corresponding to the orientation flat passes through step S402.

Next, in step S402, the number of local minimum values that satisfy the orientation flat condition is checked (S40
3).

As shown in FIG. 3A, when there is only one minimum value that satisfies the orientation flat condition, that portion corresponds to the orientation flat. Therefore, in this case, the rotation angle θ1a is set as the orientation flat position and the process of determining the orientation flat portion is ended. If there are three or more pieces, it is determined that the semiconductor wafer 1 has cracks, chips, etc. that cannot be distinguished from orientation flats, and the process ends with an error. In addition, as shown in FIG. 3(b), in the case of two θ1b and θ3b, it is checked whether the semiconductor wafer 1 whose orientation flat is currently being detected has a second orientation flat based on the ID information of the semiconductor wafer 1 ( S404). If a semiconductor wafer without a second orientation flat is being measured, step S40
For the same reason as the error branch from 3, it ends with an error. When measuring a semiconductor wafer 1 having a second orientation flat, since the angle between the first orientation flat and the second orientation flat is known in advance, the second orientation flat of the semiconductor wafer as seen from the first orientation flat is A first orientation flat is determined from the angle (S405).

In this embodiment, in the xy coordinate system with the origin at the center of the chuck shown in FIG.
If the angle of the second orientation flat 62 is 270° and the orientation flat detection θ stage 3 is rotated in the positive direction of the θ axis during measurement, then the line sensor 7 will have an angle of 90° after the first orientation flat measurement. The second orientation flat can be measured by the angle. Therefore, in FIG. 3(b), the portion θ1b is determined to be the first orientation flat.

If the eccentricity between the center of the chuck and the center of the semiconductor wafer 1 is large, the locus of change in the edge distance l may move beyond the measurement range of the line sensor 7 when the edge position is measured. is possible. In that case, accurate wafer outer edge position information cannot be obtained, but in the present invention, the wafer edge position information for one circumference of the outer edge of the semiconductor wafer 1 is used only for determining the approximate position of the orientation flat, so even in such a case, the orientation flat can be If it can be recognized, even if the eccentricity is large, it will have no effect on the orientation flat detection accuracy.

Furthermore, for the same reason, the orientation flat detection accuracy can be maintained even if the orientation flat detection speed is improved by reducing the number of edge position measurement points or increasing the rotational speed.

When the orientation flat is detected as described above, the arithmetic control section 13 adjusts so that the orientation flat and the running direction of the orientation flat detection Y stage 5 are parallel to each other (S203).

This adjustment method will be explained with reference to the flowchart shown in FIG.

In step 202, the overrun rotation amount β during measurement is added to the rotation angle θi which takes the minimum value and is determined to indicate the orientation flat position, so that the orientation flat faces the direction of the line sensor 7. Using equation (3), θ
Calculate the corrected drive amount Δθi and drive the θ-axis drive unit 10 to rotate the θ stage 3 for orientation flat detection (S701
).

[0046] Δθi = θi −β
(3) Next, the Y stage 5 for orientation flat detection is scanned and the edge positions at both ends of the orientation flat are measured by the line sensor 7 through the signal processing section 9,
Their X and Y coordinates are determined (S702). At this time,
The semiconductor wafer 1 has an eccentricity with respect to the orientation flat detection chuck 2, and the amount of eccentricity is unknown, so the inner edge position is actually measured not at both ends of the orientation flat, but with the safety of the maximum eccentricity. .

FIG. 8 shows the semiconductor wafer 1 with the orientation flat facing the line sensor 7 with the maximum eccentricity within the specified values. In this state, the orientation flat is approximately parallel to the running direction of the orientation flat detection Y stage 5, but this is not accurate. In FIG. 8, s is the length of the orientation flat, and d is the maximum value of eccentricity. The scanning range in the Y-axis direction from the center of the chuck should be determined so as to be reliably on the orientation flat, and the Y coordinates YA and YB of both ends A and B of the scanning range are respectively expressed by equation (4).

[0048]

[Equation 3] Next, based on the edge position measured in step S702, the θ correction drive amount Δθ for making the running directions of the orientation flat and the orientation flat detection Y stage 5 parallel is calculated (S7
03).

[0049] The X coordinate of the edge position at one end A is
A, and when the X coordinate of the edge position at the other end B is XB, the θ correction drive amount Δθ is expressed by equation (5).

[0050]

[Equation 4] Then, drive the θ-axis drive unit 10 to detect θ for orientation flat detection.
The stage 3 is rotated by the θ correction drive amount Δθ obtained in step S703 (S704).

Next, the θ correction drive amount Δθ is checked (S705). If this corrected drive amount Δθ is within the predetermined tolerance, the orientation flat detection Y stage 5 is returned to the origin in the next step S706, and this parallelization processing is completed. FIG. 9A shows the semiconductor wafer 1 at the end of this parallelization, that is, in a state where the orientation flat is parallel to the running direction of the Y stage 5 for orientation flat detection. In this state, the distance lOF from the center of the chuck to the orientation flat is measured using the line sensor 7.

On the other hand, if the θ correction drive amount Δθ is outside the tolerance, the process returns to step S702 and a follow-up process is performed.

When the orientation flat is made parallel to the running direction of the orientation flat detection Y stage 5 as described above, in steps 204 to 206, the semiconductor wafer 1 is transferred to a transfer position to a load hand (not shown). Positioning is performed based on the calculated values up to the point. Here, the delivery position is a position shown by a dashed line in FIG. 9(b), which will be described later, and the orientation flat of the semiconductor wafer 1 is aligned along that part.

First, in step 204, the θ-axis drive section 10 is driven to direct the orientation flat in the Y-axis negative direction, which is the specified direction of the orientation flat.
Rotate the θ stage 3 for 0° orientation flat detection. With this operation, the orientation flat of the semiconductor wafer 1 is moved as shown in FIG. 9(b).
As shown in the figure, the state is perpendicular to the running direction of the Y stage 5 for orientation flat detection.

At this time, the distance from the center of the chuck to the orientation flat has not changed from the state shown in FIG. 9(a),
Since it is lOF, the Y corrected drive amount ΔY is expressed by equation (6) where YOF is the distance from the X axis to the delivery position.

ΔY=lOF−YOF
(6) In step S205,
Based on the Y correction drive amount ΔY, the Y-axis drive section 12 is driven to move the orientation flat detection Y stage 5. This operation causes the orientation flat portion of the semiconductor wafer 1 to be aligned with the transfer position.

In this embodiment, the designated position of the orientation flat is set in the negative direction of the Y-axis, but if it is set in another direction, the Y-axis transfer is performed when the orientation flat is directed in the designated direction in order to position the orientation flat in the Y-direction. The distance from the center of the chuck to the edge that should match the position is determined in advance by the line sensor 7 in the X direction.
need to be measured.

Next, in step S206, while detecting the edge position through the signal processing section 9 using the line sensor 7 and the LED 6, the X-axis drive section 11 is driven to move the X stage 4 for orientation flat detection. The semiconductor wafer 1 is positioned at the delivery position by pushing from the direction and abutting against it. Then, the LED drive unit 8 is driven to turn off the LED 6, and the orientation flat detection sequence is completed.

Next, FIG. 10 shows another embodiment of the present invention.
Explain with reference to.

FIG. 10 is a flowchart showing another alignment operation of the present invention.

In this embodiment as well, the orientation flat detection section of the semiconductor exposure apparatus can be implemented with the same configuration as that shown in FIG. 1 described above.

In the case of this embodiment as well, the states of the various parts of the orientation flat detection section at the start of measurement of the edge position of the semiconductor wafer 1 are the same as in the above-mentioned embodiment. Determination of orientation flat position (S100
2) and the process up to making the orientation flat parallel to the running direction of the orientation flat detection Y stage 4 (S1003) are performed in the same manner as in the above case.

[0063] In step S1003, the orientation flat detection Y
After making it parallel to the running direction of stage 4, step S10
In step S1006, which will be described later, a follow-up measurement of the Y-correction driving amount is performed to correct the Y-axis of the semiconductor wafer 1. This method is effective when the measurement accuracy of the line sensor 7 is not the same in all areas due to distortion or blurring of an optical system (not shown). For example, if the measurement accuracy at the center of the line sensor 7 is excellent, the distance lOF from the chuck center to the orientation flat shown in FIG. 9(a) is measured at the center of the line sensor 7. is desirable. Therefore, the orientation flat detection X stage 4 is driven to drive the edge of the orientation flat to the center of the line sensor 7. If the drive amount of the X stage 4 for orientation flat detection at that time is Xst, and the distance from the center of the chuck to the center of the line sensor 7 before driving the X stage 4 for orientation flat detection is Xs, then the distance lOF from the center of the chuck to the orientation flat is , expressed by equation (7).

lOF=Xs−Xst
(7) Here, the orientation flat detection X stage 4 is returned to the position before the follow-up drive, and step S1004 is ended. The subsequent driving of the θ stage 3 for orientation flat detection, the Y stage 5 for orientation flat detection, and the X stage 4 for orientation flat detection (S1005 to S1007) is also performed in steps S204 to S in FIG.
This is similar to 206.

In each of the embodiments described above, as a method for determining the orientation flat portion, the minimum value of the wafer outer edge position data string is searched to match the orientation flat condition, and the first orientation flat is determined using relative angle information. Although this method was used, other orientation flat determination methods may of course be used.

Furthermore, when aligning the orientation flat and the running direction of the Y stage 5 for orientation flat detection, the θ correction amount was calculated by setting a measurement point that takes into account the safety of the eccentricity. It is also possible to measure the wafer edge in synchronization with the scanning of the stage 5, recognize that the wafer edge has become an arc portion from a point where the rate of change has changed, and use both ends of the orientation flat as measurement points for calculating the θ correction amount Δθ. If this method is used, although it takes time, the denominator of the θ correction drive amount Δθ calculation formula (5) becomes larger, so the θ accuracy is further improved.

In each embodiment, steps S205 and S2 in FIG. 2 are performed when aligning the semiconductor wafer.
Corresponding to 06, without performing correction drive processing by the orientation flat detection Y stage 5 and orientation flat detection X stage 4, only the correction drive amount measurement of each of the X and Y axes is performed, and the x, A method of position adjustment in the y direction can also be used. However, in this method, it is necessary to provide the load hand with a fine adjustment mechanism for each of the X and Y axes.

[0068]

[Effects of the Invention] Since the present invention is constructed as described above, it produces the following effects.

(1) Orientation of the semiconductor wafer By scanning the flat part of the semiconductor wafer in a state substantially perpendicular to the line sensor, which is the light receiving means, even if there is an error in the θ direction in the assembly of the line sensor, it will not be affected. First, the accuracy of semiconductor wafer alignment is improved.

(2) As described in claim 2, based on the orientation flat distance from the rotation center to the orientation flat section, which is measured when the orientation flat section is made parallel to the moving direction of the moving means, By determining the amount of movement to the specified position, the assembly error of the line sensor can be ignored with respect to the orientation flat distance, so the accuracy of alignment is further improved.

(3) After the orientation flat position of the semiconductor wafer is detected, the angle detection error of the orientation flat position is corrected, so the detection of the orientation flat position based on the edge position of the semiconductor wafer only needs to be able to recognize the approximate position of the orientation flat. This makes it possible to reduce the number of measurement points for the edge position or increase the rotational speed when measuring the edge position, thereby improving the throughput of orientation flat detection.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an orientation flat detection unit for carrying out the semiconductor wafer positioning method of the present invention.

FIG. 2 is a flowchart showing an embodiment of the semiconductor wafer positioning method of the present invention.

FIG. 3 is a diagram showing changes in the distance from the chuck center to the outer edge of the semiconductor wafer with respect to the rotation angle, (a) shows the case of a semiconductor wafer with only one orientation flat part, and (b)
) shows the case of a semiconductor wafer in which two orientation flat parts, first and second, are formed.

FIG. 4 is a flowchart showing the operation of orientation flat position determination.

FIG. 5 is a diagram showing changes in the distance from the center of the chuck to the outer edge of the orientation flat portion with respect to the rotation angle.

FIG. 6 is a plan view showing a semiconductor wafer in an xy coordinate system with the origin at the center of the chuck.

FIG. 7 is a flowchart showing an operation for making the orientation flat part parallel to the running direction of the orientation flat detection Y stage.

FIG. 8 is a plan view showing the semiconductor wafer facing the line sensor direction in an xy coordinate system with the origin at the center of the chuck.

FIG. 9 is a plan view showing a semiconductor wafer in an x-y coordinate system with the origin at the center of the chuck; (a) shows a state in which the orientation flat is parallel to the y-axis, and (b),
The orientation flat is shown facing the specified direction.

FIG. 10 is a flowchart showing another embodiment of the semiconductor wafer alignment method of the present invention.

FIG. 11 is a plan view showing a semiconductor wafer for explaining a conventional semiconductor wafer positioning method.

FIG. 12 is a plan view showing the outer edge of the semiconductor wafer passing over the line sensor, and (a) to (e) sequentially show the process in which the orientation flat portion of the semiconductor wafer passes over the line sensor.

[Explanation of symbols]

1 Semiconductor wafer 2 Orientation flat detection chuck 3 θ stage for orientation flat detection 4 X stage for orientation flat detection 5 Y stage for orientation flat detection 6 Light emitting diode 7 Line sensor 8 LED drive unit 9 Signal processing section 10　　　θ-axis drive section 11 X-axis drive section 12 Y-axis drive section 13 Arithmetic control section 61 1st orientation flat 62 Second orientation flat

Claims (3)

[Claims] Claim 1: While a semiconductor wafer for semiconductor manufacturing is rotated by a rotating means, a non-contact outer edge position detection means of a light emitting means and a line sensor serving as a light receiving means for the light emitting means is used to detect one circumference of the outer edge of the semiconductor wafer. The orientation flat portion of the semiconductor wafer is detected from the change in the measured edge position to determine the orientation flat position indicating the orientation of the orientation flat portion. In the method for aligning a semiconductor wafer in which the orientation flat part is directed in a designated direction, after determining the orientation flat position, the rotating means is driven based on the orientation flat position to orient the orientation flat part in the direction of the line sensor; The semiconductor wafer is scanned using a moving means in a direction perpendicular to the direction of the line sensor, the edge positions of arbitrary two points of the orientation flat part are measured, and the edge positions of the orientation flat part are measured from the two measured edge positions. determining the inclination of the part with respect to the moving direction of the moving means, and driving the rotating means according to the obtained inclination to make the orientation flat part parallel to the moving direction of the moving means, and then driving the rotating means, A method for aligning a semiconductor wafer, comprising orienting the orientation flat portion in the designated direction. 2. When the orientation flat part is made parallel to the moving direction of the moving means, an orientation flat distance indicating the distance from the center of rotation by the rotation means to the orientation flat part is measured, and the orientation flat part is oriented in a specified direction. 2. The semiconductor wafer positioning method according to claim 1, further comprising determining the amount of movement of the semiconductor wafer to the specified position in the specified direction based on the orientation flat distance. 3. The semiconductor device according to claim 2, wherein the semiconductor wafer is moved to a designated position using means for moving in two directions: a moving direction perpendicular to the direction of the line sensor and a moving direction perpendicular to the moving direction. How to align the wafer.