JP4889616B2 - Aligner equipment - Google Patents

Description

  The present invention relates to an aligner used for semiconductor manufacturing and used for positioning a circular thin plate-like wafer.

  Semiconductor manufacturing includes a plurality of processes on a circular thin wafer. Each processing is performed using an individual processing device. The wafer is transferred via a robot to a processing apparatus that performs the next processing every time processing in one processing apparatus is completed. In order to perform an appropriate process on a wafer in each processing apparatus, it is necessary to convey the wafer to an accurate position with an appropriate rotation angle with respect to each processing apparatus. For this reason, an aligner that positions a wafer at a predetermined reference position and reference angle is used for semiconductor manufacturing (see, for example, Patent Document 1).

  The aligner detects the outer peripheral edge of the wafer with an edge sensor while rotating the stage on which the wafer is placed around a vertical axis, and the amount of eccentricity and eccentricity of the wafer with respect to the stage based on the detection result of one edge sensor. Calculate the direction as well as the position of the notch or orientation flat. The edge sensor includes a light emitting unit and a light receiving unit that sandwich the wafer in the thickness direction (vertical direction) in the vicinity of the outer peripheral edge of the wafer, and receives a plurality of parallel lights arranged in the radial direction (horizontal direction) of the stage from the light emitting unit. Irradiation is directed toward the light receiving unit, and a detection signal corresponding to the light receiving position in the radial direction is output from the light receiving unit.

  On the other hand, in order to prevent damage in later processing, a film may be attached to the surface of the wafer when predetermined processing is completed. The film is formed to have a larger diameter than the wafer so that the entire surface of the wafer can be reliably covered without accurately defining the positional relationship with the wafer. The outer peripheral edge of the film protrudes outward from the outer peripheral edge of the wafer, and the amount of protrusion is not constant for the entire periphery of the wafer. For this reason, the conventional edge sensor can detect the outer peripheral edge of the film, but cannot detect the outer peripheral edge of the wafer.

Therefore, an aligner device having a linear scan camera instead of the conventional edge sensor has been proposed (see, for example, Patent Document 2). The linear scan camera includes an imaging optical system and a linear image sensor. The linear scan camera is arranged in the longitudinal direction along the radial direction of the stage and captures an image near the outer peripheral edge on the lower surface side of the wafer. The position of the outer peripheral edge of the wafer can be extracted based on the output signal of the linear scan camera.
JP-A-11-233594 JP 2006-023199 A

  However, in recent years, the thickness of the wafer has been reduced. In particular, a wafer having a thickness of 100 μm or less is likely to be warped, and the position of the outer peripheral edge of the wafer is displaced within a range of about 5 mm in the vertical direction in the direction perpendicular to the surface of the wafer. There may be. In general, linear scan cameras have a shallow depth of field, and when the wafer is warped, the outer edge of the wafer is not focused during wafer rotation, and the position of the outer edge of the wafer is accurately detected. Can not do.

  In consideration of an error in the wafer transfer position with respect to the aligner, the shape of the notch or orientation flat, etc., it is necessary to be able to image a relatively long range in the radial direction of the stage. For this reason, the aperture diameter of the imaging optical system becomes large, which not only increases the cost, but also makes it difficult to position a small diameter wafer due to interference with the stage. Further, the prime number of the linear image sensor increases, the transfer time of the detection signal becomes long, and the wafer positioning operation takes a long time.

  An object of the present invention is to accurately detect the position of the outer peripheral edge of a wafer with a linear scan camera having a relatively small imaging range even when an error or warpage of the transfer position occurs in a wafer to which a film is attached. It is in providing the aligner apparatus which can be performed.

  The aligner of the present invention includes a wafer rotation mechanism, a linear scan camera, a displacement sensor, a surface vibration tracking mechanism, an eccentric tracking mechanism, and a control unit. The wafer rotation mechanism rotates the wafer around a vertical axis. The linear scan camera is disposed below the wafer and captures an upper image within an imaging range having a predetermined length in the radial direction of the vertical axis. The displacement sensor detects the vertical position of the outer peripheral edge of the wafer. The surface vibration tracking mechanism moves the linear scan camera in the vertical direction relative to the wafer. The eccentric tracking mechanism moves the linear scan camera relative to the wafer in the horizontal direction. The controller operates the surface follow-up mechanism so that the outer peripheral edge of the wafer is positioned within the depth of field of the linear scan camera based on the detection result of the displacement sensor during one rotation of the wafer. Further, the control unit operates the eccentric tracking mechanism so that the outer peripheral edge of the wafer is positioned within the horizontal imaging range of the linear scan camera based on the imaging data of the image sensor during one rotation of the wafer.

  In this configuration, the linear scan camera moves in the vertical and horizontal directions relative to the wafer, following the vertical and horizontal positions of the outer peripheral edge of the wafer while the wafer is rotating. . Even when the vertical displacement of the outer peripheral edge of the wafer during one rotation of the wafer exceeds the depth of field of the linear scan camera, the horizontal displacement of the outer peripheral edge of the wafer during one rotation of the wafer Even when the imaging range exceeds the imaging range of the linear scan camera, the linear scan camera captures an image of the outer peripheral edge of the wafer in a focused state.

  In this configuration, the displacement sensor is arranged with the wafer vertically sandwiched between the linear scan camera within the imaging range, and moved in the horizontal direction relative to the outer peripheral edge of the wafer together with the linear scan camera. You may make it make it. The surface vibration follow-up mechanism can be immediately operated in accordance with the vertical displacement of the outer peripheral edge of the wafer to be imaged by the linear scan camera.

  The surface vibration follow-up mechanism may be a mechanism that moves the linear scan camera in the vertical direction. It is not necessary to provide a mechanism for moving the wafer up and down in the rotationally driven wafer rotation mechanism, and the configuration of the apparatus can be simplified.

  Furthermore, the eccentric tracking mechanism may be a mechanism that moves the wafer rotation mechanism in the horizontal direction. It is not necessary to move the linear scan camera and the displacement sensor positioned above and below the wafer in the horizontal direction, and the configuration of the apparatus can be simplified.

  The wafer rotation mechanism may be provided with a stage having a smaller diameter than the wafer and vacuum-sucking the lower surface of the wafer. It is not necessary to provide a mechanism for clamping the outer peripheral edge of the wafer, and the configuration of the apparatus can be simplified. In addition, the holding work for moving the wafer to an appropriate position becomes unnecessary, and the positioning work can be simplified.

  According to the present invention, the relative position of the linear scan camera with respect to the wafer can be moved in the vertical and horizontal directions following the vertical and horizontal positions of the outer peripheral edge of the wafer while the wafer is rotating. it can. When the vertical displacement amount of the outer peripheral edge of the wafer during one rotation of the wafer exceeds the depth of field of the linear scan camera, and the horizontal displacement amount of the outer peripheral edge of the wafer exceeds the imaging range of the linear scan camera. Even in this case, the image of the outer peripheral edge of the wafer can be taken in a focused state. This makes it possible to accurately detect the position of the wafer with a linear scan camera having a relatively small imaging range even when there is an error or warping of the transfer position on the wafer to which the film has been attached. Can be prevented.

  FIG. 1 is a side view of an aligner according to an embodiment of the present invention. The aligner apparatus 10 is used for positioning a wafer W of a circular thin plate having a film attached to the surface at the time of manufacturing a semiconductor. A wafer W is loaded into the aligner apparatus 10 via a robot arm (not shown). The aligner device 10 mounts a lower housing 102 on a base 101 and supports an upper housing 104 via an arm 103 above the lower housing 102. Housed in the lower housing 102 are a wafer rotation mechanism 1, a linear scan camera 2, a surface vibration follow-up mechanism 3, an eccentric follow-up mechanism 4, and a control unit 5. A displacement sensor 6 and an illumination 7 are housed in the upper housing 104.

  The wafer rotation mechanism main body 1 includes a stage 11, a spindle 12, a motor 13, and a base 14. The stage 11 has a disk shape smaller in diameter than the wafer 1 and vacuum-sucks the wafer W on the upper surface via a vacuum pump (not shown). It is not necessary to provide a mechanism for clamping the outer peripheral edge of the wafer W, the configuration of the apparatus can be simplified, the holding work for moving the wafer W to an appropriate position becomes unnecessary, and the positioning work can be simplified. The spindle 12 has a cylindrical shape and holds the stage 11 at the upper end. The motor 13 is housed inside the spindle 12 and rotates the stage 11. The base 14 is fixed to the lower end portion of the spindle 12 and is placed on the table 15 so as to be movable in two directions orthogonal to each other within a horizontal plane.

  The linear scan camera 2 is disposed below the wafer W placed on the stage 11 and includes a lens 21 and a CCD 22. The lens 21 forms an image above a predetermined focal length on the light receiving surface of the CCD 22 positioned below. Actually, the lens 21 forms an image within a predetermined depth of field on the light receiving surface of the CCD 22 in a focused state. The CCD 22 is a one-dimensional linear image sensor in which a plurality of light receiving elements are arranged in an imaging range having a predetermined length along the radial direction of the spindle 12 and outputs an electrical signal corresponding to the amount of light received at each pixel. Note that another solid-state imaging device such as a CMOS can be used instead of the CCD 22.

  As an example, the surface vibration follow-up mechanism 3 includes two solenoids 31 and 32 arranged to face each other along the vertical direction (Z-axis direction), and linearly moves to a position in the Z-axis direction corresponding to the drive voltage of the solenoids 31 and 32. The scan camera 2 is moved. The surface vibration follow-up mechanism 3 can have another configuration such as a ball screw that is rotationally driven by a motor on condition that the linear scan camera 2 is moved up and down accurately along the Z-axis direction.

  The surface vibration follow-up mechanism 3 may be any mechanism that can move the linear scan camera 2 in the vertical direction relative to the wafer W placed on the stage 11. It may be. However, the mechanism for raising and lowering the linear scan camera 2 is easier to simplify the configuration than the mechanism for raising and lowering the stage 11 that is rotationally driven.

  The eccentric follow-up mechanism 4 includes a linear motor 41 as an example, and reciprocates the base 14 in a direction close to or away from the linear scan camera 2 (X-axis direction) in a horizontal plane on the table 15. The eccentric follower mechanism 4 can have other configurations such as a ball screw that is rotationally driven by a motor on condition that the base 14 is accurately moved in the X-axis direction.

  The eccentric follower mechanism 4 may be any mechanism that can move the linear scan camera 2 in the X-axis direction relative to the wafer W placed on the stage 11. The mechanism to move may be sufficient. However, a mechanism for moving the base 14 in two orthogonal directions in the horizontal plane on the table is already provided, and the configuration can be simplified as compared with a mechanism for reciprocating the linear scan camera 2 together with the displacement sensor 6.

  The displacement sensor 6 is disposed at a position where the wafer W placed on the stage 11 is sandwiched between the displacement sensor 6 and the linear scan camera 2 in the vertical direction. As an example, the displacement sensor 6 is an ultrasonic sensor that measures the distance until the ultrasonic wave transmitted from the transmission unit is reflected by the object and returns, and measures the distance to the object. Send to. As the displacement sensor 6, a sensor other than the ultrasonic sensor can be used on condition that the position of the outer peripheral end of the wafer W placed on the stage 11 in the Z-axis direction can be accurately detected.

  The illumination 7 includes a light source 71 and a diffusion plate 72. The light source 71 is an LED as an example, and irradiates light downward. The diffusion plate 72 uniformly distributes the light emitted from the light source 71 in the vicinity of the outer peripheral edge of the wafer W placed on the stage 11. The illumination 7 can have other configurations and arrangement positions on the condition that light can be uniformly irradiated in the vicinity of the outer peripheral edge of the wafer W placed on the stage 11.

  FIG. 2 is a block diagram of a control unit provided in the aligner device. The controller 5 raises and lowers the linear scan camera 2 so that the outer peripheral edge of the wafer W is positioned within the depth of field of the linear scan camera 2 during one rotation of the wafer W, and the outer peripheral edge of the wafer W is linear. The base 14 is reciprocated so as to be positioned at the center of the imaging range of the scan camera 2. Further, the control unit 5 detects the eccentric amount and the eccentric direction of the wafer W placed on the stage 11 and the rotational position of a positioning unit such as a notch or orientation flat formed on a part of the outer periphery of the wafer W. The center position and rotation angle of the wafer W are corrected to an appropriate position and angle.

  For this reason, the control unit 5 is configured by connecting the linear scan camera 2, the displacement sensor 3, the ROM 52, the RAM 53, the interface 54, the motor driver 55, the solenoid driver 56, the linear motor driver 57, and the light source 71 to the CPU 51. .

  The CPU 51 drives the motor 12, the solenoids 31 and 32, and the linear motors 41 and 42 based on the image data of the linear scan camera 2 and the detection signal of the displacement sensor 3 in accordance with a program stored in advance in the ROM 52. Data input / output during this time is stored in a predetermined memory area of the RAM 53. The linear motor 42 reciprocates the base 14 in a horizontal plane on the table 15 along a direction orthogonal to the X axis.

  Image data captured by the linear scan camera 2 is input to the CPU 51. The CPU 51 analyzes the image data input from the linear scan camera 2 and detects the position of the outer peripheral edge of the wafer W. Based on the detection result of the position of the outer peripheral edge of the wafer W, the CPU 51 sends the drive data of the linear motor 41 to the linear motor driver 57 so that the outer peripheral edge of the wafer W is positioned at the center of the imaging range of the linear scan camera 2. Output to. The linear motor driver 57 drives the linear motor 41 based on the drive data.

  Further, distance data measured by the displacement sensor 3 is input to the CPU 51. The CPU 51 calculates the distance between the outer peripheral edge of the wafer W and the linear scan camera 2 based on the distance data input from the displacement sensor 3. The CPU 51 outputs drive data of the solenoids 31 and 32 to the solenoid driver 56 so that the calculated distance is within the depth of field of the linear scan camera 2. The solenoid driver 56 drives the solenoids 31 and 32 based on the drive data.

  The interface 54 connects the CPU 51 to an external device (not shown). The CPU 51 transmits / receives data to / from an external device via the interface 54.

  FIG. 3 is a flowchart showing a processing procedure of the control unit in the aligner apparatus. When the aligner apparatus 0 is powered on, the CPU 51 of the control unit 5 waits for the wafer W to be loaded (S1). When the wafer W is loaded, the CPU 51 drives a vacuum pump (not shown) to vacuum-suck the wafer W onto the upper surface of the stage 11 (S2).

  Next, the CPU 51 drives the linear motor 41 to bring the base 14 close to the linear scan camera 2 by a predetermined distance (S3), and then turns on the light source 71 of the illumination 7 to move the base 14 from the linear scan camera 2. Separate (S4, S5). At this time, the predetermined distance for bringing the base 14 close to the linear scan camera 2 is set to a value larger than at least the amount of eccentricity of the wafer W that occurs when the wafer W is loaded into the aligner apparatus 10.

  The CPU 51 reads the detection signal of the displacement sensor 6 while the base 14 moves away from the linear scan camera 2 (S6), and drives the solenoids 31 and 32 based on the detection distance represented by the detection signal. Then, the linear scan camera 2 is moved up and down (S7). At the same time, the CPU 51 analyzes the image data of the linear scan camera 2 (S8). When the outer peripheral edge of the wafer W reaches the center of the image, the driving of the linear motor 41 is stopped and the base 14 Is stopped (S9, S10).

  For example, as shown in FIG. 4A, when a translucent film F having a diameter larger than that of the wafer W is attached to the surface of the wafer W, the brightness data of the image is in the state shown in FIG. . Therefore, the CPU 51 detects the position where the brightness data of the image falls below the threshold value TH as the outer peripheral edge of the wafer W, and stops driving the linear motor 41 when this position reaches the center of the image data.

  Thereafter, the CPU 51 drives the motor 13 to rotate the stage 11 together with the wafer W (S11). The CPU 51 raises and lowers the linear scan camera 2 based on the detection distance of the displacement sensor 6 during one rotation of the wafer W (S12, S13), and the base 14 based on the analysis result of the image data of the linear scan camera 2. Are moved (S14, S15), and the movement amount of the base 14 is stored (S16). The CPU 51 stores the movement amount of the base 14 in the RAM 53 at a preset sampling cycle while the wafer W rotates once.

  When the wafer W makes one rotation, the CPU 51 stops driving the motor 13 (S17, S18), and from the stored contents of the RAM 53, the eccentric amount and eccentric direction of the wafer W and the rotation angle of the notch or orientation flat are determined. (S19). The CPU 51 drives the motor 13 and the linear motors 41 and 42 based on the calculation result of the position error of the wafer W, and moves the wafer W so that the position and the rotation angle of the wafer W become predetermined appropriate values. Move and rotate (S20).

  As described above, the aligner 10 moves the base 14 and raises / lowers the linear scan camera 2 in accordance with the horizontal and vertical displacements of the outer peripheral edge of the wafer W, so that the outer periphery of the linear scan camera 2 and the wafer W is increased. The position of the outer peripheral edge of the wafer W is measured while keeping the relative position to the edge constant.

  For this reason, even when the amount of vertical displacement of the outer peripheral edge of the wafer W during one rotation of the wafer W exceeds the depth of field of the linear scan camera 2, the linear scan camera 2 remains in focus and remains in focus. It is possible to take an image of the outer peripheral edge. Even when the amount of horizontal displacement of the outer peripheral edge of the wafer W during one rotation of the wafer W exceeds the imaging range of the linear scan camera 2, the linear scan camera 2 remains in focus and the outer peripheral edge of the wafer W is in focus. Images can be taken.

  Therefore, even when the wafer W having a translucent film such as a translucent film adhered to the surface is warped, a relatively small linear scan camera 2 having a shallow depth of field is used to detect the outer peripheral edge of the wafer W. The position can be accurately measured, and the position and rotation angle of the wafer W can be accurately corrected to the reference position and the reference angle.

  The displacement sensor 6 is disposed with the wafer W vertically sandwiched between the displacement sensor 6 and the linear scan camera 2 at the center of the imaging range, and is relative to the outer peripheral edge of the wafer W integrally with the linear scan camera 2. To move horizontally. For this reason, the displacement sensor 6 can accurately detect the position of the outer peripheral end of the wafer W in the Z-axis direction, and the surface of the outer peripheral end of the wafer W to be imaged by the linear scan camera 2 depends on the vertical displacement. The vibration follower mechanism 3 can be operated immediately.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

It is a side view of an aligner device concerning an embodiment of this invention. It is a block diagram of the control part of the aligner apparatus. It is a flowchart which shows the process sequence of the control part. (A) is an enlarged partial sectional view of a wafer having a translucent film attached to the surface, and (B) is a diagram showing brightness data of an image captured by the linear scan camera of the wafer.

Explanation of symbols

1-wafer rotation mechanism 2-linear scan camera 3-surface vibration follow-up mechanism 4-eccentric follow-up mechanism 5-control unit 6-displacement sensor W-wafer

Claims (5)

A wafer rotating mechanism for rotating a circular thin wafer around a vertical axis;
A linear scan camera that is disposed below the wafer and captures an upper image within an imaging range of a predetermined length in the radial direction of the vertical axis;
A displacement sensor for detecting a vertical position of the outer peripheral edge of the wafer;
A surface vibration follow-up mechanism that moves the linear scan camera in a direction perpendicular to the outer peripheral edge of the wafer;
An eccentric tracking mechanism for moving the linear scan camera and the displacement sensor in a horizontal direction relative to the outer peripheral edge of the wafer;
While the wafer rotating mechanism makes one rotation of the wafer, the surface vibration follow-up mechanism is arranged so that the outer peripheral edge of the wafer is located within the depth of field of the linear scan camera based on the detection result of the displacement sensor. A controller that operates and operates the eccentric tracking mechanism so that an outer peripheral edge of the wafer is positioned within the imaging range based on imaging data of the linear scan camera;
And an aligner that corrects the position and rotation angle of the wafer to a predetermined reference position and reference angle.   The aligner according to claim 1, wherein the displacement sensor is disposed between the linear scan camera and the wafer in a vertical direction within the imaging range.   The aligner apparatus according to claim 1, wherein the surface vibration tracking mechanism is a mechanism that moves the linear scan camera in a vertical direction.   4. The aligner apparatus according to claim 1, wherein the eccentric tracking mechanism is a mechanism that moves the wafer rotation mechanism in a horizontal direction orthogonal to the vertical axis.   The aligner apparatus according to any one of claims 1 to 4, wherein the wafer rotation mechanism includes a stage having a smaller diameter than the wafer and vacuum-sucking the lower surface of the wafer.

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