JP4897658B2 - Shape measuring device - Google Patents

Description

  The present invention is based on the projection image of the shape of the end face (end face) of the disk-shaped measurement object (mainly semiconductor wafer, other hard disk aluminum substrate, glass substrate, etc.) chamfered. The present invention relates to a shape measuring device to be measured.

When manufacturing a semiconductor wafer (hereinafter referred to as a wafer) or manufacturing a device using a wafer, the edge (edge) of the wafer may be damaged or chipped due to contact with other components or a wafer holding member. There is a case. In addition, the wafer may break due to the scratches and chips. It is considered that the ease of occurrence of scratches and chips at the edge of the wafer is related to the shape of the wafer end face (so-called edge profile portion). For this reason, it is important to correctly measure the edge profile of a disk-shaped measuring object represented by a wafer. The shape of the end face here is a profile in the thickness direction (one-dimensional direction) of the wafer, that is, the shape of the cross section in the thickness direction, and is hereinafter referred to as an edge profile.
A typical example of the edge profile measurement method is the nondestructive inspection method (SEMI-MF-) specified in the Semi Standard, which is a standard established by the Semiconductor Equipment and Materials International (SEMI). 928-0305 Standard Method B). In this non-destructive inspection method, light is projected from the direction (first direction) substantially parallel to the front and back surfaces of the wafer on the chamfered edge of the disk-shaped wafer, and the direction of light projection. Is a method in which a projected image of an end portion (including an end surface) of a wafer is captured by a camera from a direction facing the surface, and the shape of the end surface of the wafer is measured based on the projected image (hereinafter referred to as an optical projection measurement method) . The contour of the projection image obtained by this optical projection measurement method represents the cross-sectional shape of the edge of the wafer (the cross-sectional shape cut in the thickness direction).
For example, Patent Document 1 discloses a projection image obtained by collimating (collimating) a beam emitted from a point light source through a collimator lens and projecting the luminous flux onto a measurement object in the light projection measurement method. It has been proposed to prevent the occurrence of blurred outlines and diffraction fringes.
Thus, in order to perform highly accurate shape measurement by the light projection measurement method, it is necessary to project light beams parallel to the front and back surfaces of the plate-like measurement object.
JP 2006-145487 A

However, in the light projection measurement method, the parallelism between the light projection direction of the light beam (parallel light) and the front and back surfaces of the measurement unit in the measurement object is not sufficient, that is, the light projection direction If the front and back surfaces of the measurement unit are tilted, there is a problem that correct shape measurement cannot be performed based on the projected image. In particular, a thin measurement object such as a wafer may have some deflection due to manufacturing variations, gravity, etc., and this deflection causes the measurement unit to be inclined with respect to the direction of light projection. There is.
FIG. 9 is a diagram schematically showing the path of light rays when the light projection direction R1 with respect to the measurement object and the front and back surfaces of the measurement unit in the measurement object are parallel in the light projection measurement method. These are the figures which represented typically the path | route of the light ray in case the inclination has arisen in the projection direction R1 with respect to a measuring object and each front and back surface of the measurement part in a measuring object in the said light projection measuring method. 9 and 10 are views of a cross section at an end portion (measurement portion) of the disk-shaped wafer 1 that is a measurement object as viewed from a direction perpendicular to the cross section (radial direction of the wafer 1).
As shown in FIG. 9, when the front and back surfaces of the measurement unit are along the light projecting direction R <b> 1 (parallel), the projected image captured by the camera correctly represents the cross-sectional shape of the measurement unit. On the other hand, as shown in FIG. 10, when the light projection direction R1 and the surface of the measurement object are inclined, the influence of diffraction of light after passing around the measurement object becomes large. As a result, the degree of image blur of the projected image picked up increases, and the shape of the projected image does not represent the original cross-sectional shape of the measurement unit.
Therefore, the present invention has been made in view of the above circumstances, and its object is to measure the shape of the end of a disk-shaped measuring object such as a semiconductor wafer based on the projected image. An object of the present invention is to provide a shape measuring apparatus capable of performing correct shape measurement by adjusting a light projecting direction and a measurement object in parallel.

In order to achieve the above object, a shape measuring apparatus according to the present invention is based on a projected image of an end portion (generally, a chamfered portion) of a disk-shaped measuring object such as a semiconductor wafer. This is a device for measuring the shape of the end face, and includes the following components (1) to (6).
(1) Projection means for projecting parallel light to the end of the measurement object.
(2) Image pickup means for picking up a projected image of the end of the measurement object from a direction opposite to the light projecting direction by the light projecting means.
(3) An optical system holding member that holds the light projecting unit and the imaging unit.
(4) An optical system driving unit that drives the optical system holding member to change the inclination of the projection direction with respect to the surface of the measurement object.
(5) An inclination index detection unit that detects an index of the degree of inclination of the measurement object with respect to the light projection direction.
(6) First inclination adjusting means for adjusting the inclination of the light projection direction with respect to the surface of the measurement object by controlling the optical system driving means in accordance with the detection result of the inclination degree index.
As shown in FIG. 10, due to the bending of the measurement object, the parallelism between the light projecting direction and the measurement object may be insufficient (inclination occurs). And in the said light projection measuring method, if the parallelism of the projection direction of parallel light and the said measuring object is not enough, correct shape measurement cannot be performed.
However, in the shape measuring apparatus according to the present invention, the first inclination adjusting means corrects (eliminates) the inclination of the surface of the measurement object with respect to the light projecting direction (that is, the light projecting direction and the light projecting direction). The inclination of the optical system holding member (that is, the inclination of the light projecting direction with respect to the surface of the measurement object) is adjusted in advance so that the surface of the measurement object is parallel to the measurement object. Therefore, according to the shape measuring apparatus according to the present invention, a correct shape measurement can be performed while ensuring a parallel state between the light projecting direction and the measurement object.

Before SL gradient index detecting means and said first inclination adjusting means, examples having a structure shown in the following (2-1) and (2-2) can be considered.
(2-1) The measurement object in a direction orthogonal to the light projecting direction at a plurality of observation positions along the light projecting direction in a state where the tilt index detecting unit is held by the optical system holding member. Displacement detecting means for detecting the position of the surface of the object.
(2-2) The first inclination adjusting unit has a target positional relationship in which a positional relationship of the surface of the measurement object in a direction orthogonal to the light projecting direction at the plurality of observation positions is set in advance. The inclination of the light projecting direction is adjusted toward the approaching direction.
The target positional relationship is a positional relationship when the light projecting direction and the surface of the measurement object are parallel.
The relative position of the displacement detecting means held by the optical system holding member with respect to the light projecting direction is fixed. Therefore, the difference between the surface position distribution (positional relationship) detected by the displacement detection means and the target positional relationship uniquely corresponds to the inclination of the measurement object with respect to the light projection direction. The index value to be used.
The relationship between the amount of change in the inclination of the optical system holding member with respect to the drive amount of the optical system drive means is already known. Therefore, in order to make the light projection direction parallel to the measurement object from the difference between the surface position distribution (positional relationship) detected by the displacement detection means and the target positional relationship. The driving amount of the optical system driving means can be obtained. Therefore, the first inclination adjusting means is configured so that the light projecting direction and the measurement object are parallel by the open control of the optical system driving means according to one detection by the displacement detecting means. The inclination of the optical system holding member can be quickly adjusted.

By the way, the positional relationship of the target can be obtained by performing detection by the displacement detecting means in a state where the light projection direction and the measurement object are parallel, but the light projection direction and the measurement object are parallel. It is troublesome to confirm that the state is correct.
Therefore, the shape measuring apparatus according to the present invention, further, obtain Preparations each component shown in the following (2-3) - (2-5).
(2-3 ) Image processing is performed on the projected image of the calibration member obtained by measuring the calibration member, which is a plate- shaped member, with the light projecting unit and the imaging unit, and the outline of the projected image is blurred. An image processing means for calibration for detecting the degree of.
(2-4) Second inclination adjusting means for adjusting the inclination of the optical system holding member by controlling the optical system driving means so as to minimize the degree of image blurring of the contour of the projection image of the calibration member. .
(2-5) The position of the surface of the calibration member at the plurality of observation positions detected by the displacement detecting means in a state where the inclination of the optical system holding member is adjusted by the second inclination adjusting means. Target position relationship setting means for setting a relationship to the target position relationship.
Thereby, the setting of the positional relationship of the target can be automated. The calibration member that is the plate-like member includes the predetermined measurement object.
Further, it is preferable that the displacement detection means can prevent the surface of the measurement object from being damaged if it detects the position of the surface of the measurement object in a non-contact manner.

  According to the present invention, when measuring the shape of the end face of a disk-shaped measurement object such as a semiconductor wafer based on the projected image, it is possible to ensure a parallel state between the light projection direction and the surface of the measurement object. Shape measurement can be performed. In addition, according to the present invention, it is possible to adjust the parallel state in a non-contact manner with respect to the end portion of the measurement object, and it is possible to prevent damage to the surface of the measurement object.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
1 is a schematic plan view of the shape measuring apparatus X according to the embodiment of the present invention, FIG. 2 is a schematic side view of the shape measuring apparatus X, and FIG. 3 is an optical system rotation support mechanism provided in the shape measuring apparatus X. FIG. 4 is a schematic diagram for explaining the relationship between the light projection direction and the wafer in the shape measuring apparatus X, and FIG. 5 is an example of a projected image of the wafer imaged by the camera included in the shape measuring apparatus X. FIG. 6 is a diagram showing a state in which the light projecting direction and the surface of the wafer 1 are adjusted to be parallel in the shape measuring apparatus X, and FIG. FIG. 8 is a diagram showing how the tilt of the wafer is detected. FIG. 8 is adjusted so that the light projection direction and the surface of the object to be measured are parallel according to the tilt of the wafer detected by the displacement sensor in the shape measuring apparatus X. Fig. 9 shows the state. FIG. 10 is a diagram schematically showing the path of a light beam when the projection direction is parallel to the surface of the measurement object in the projection measurement method, and FIG. 10 is the projection direction of the measurement object and the measurement object in the light projection measurement method. It is the figure which represented typically the path | route of the light ray in case the inclination has arisen with the surface.

The shape measuring apparatus X according to the present invention is parallel to the front and back surfaces of the wafer 1 with respect to the end of the wafer 1 (semiconductor wafer), which is a disc-shaped measurement object (including the chamfered end surface). The light is projected from the direction by the light projecting unit, and a projected image of the end portion of the wafer 1 (hereinafter referred to as a measuring unit) is captured by the camera from the direction facing the light projecting direction, and the wafer is based on the projected image. 1 is an apparatus for measuring the shape and thickness of one end face.
The wafer 1 is made of, for example, a semiconductor having a radius of about 150 [mm] and a thickness of about 0.8 [mm], and its outer peripheral end (peripheral surface) is chamfered.
The configuration of the shape measuring apparatus X will be described below with reference to the plan view shown in FIG. 1 and the side view shown in FIG. In FIG. 2, some of the components shown in FIG. 1 are omitted.
As shown in FIGS. 1 and 2, the shape measuring apparatus X includes a point light source 2 as a light projecting unit, which is a light projecting optical system (an example of a light projecting unit), and converts the light from the point light source 2 into parallel light. A collimator lens 3 and a mask 8 are provided.
The point light source 2 is, for example, a light source that emits white LED light through a pinhole having a diameter of about 300 μm to 400 μm. The light emitting portion (pinhole) of the point light source 2 is disposed at the focal position of the collimator lens 3.
The collimator lens 3 is collimated (parallel) in a direction (light projecting direction) parallel to both the front and back surfaces of the measurement unit while passing the light emitted from the point light source 2 and traveling toward the measurement unit. It is a lens to be lightened.
The mask 8 is a plate-like member in which an opening 8o is formed. By restricting the passage of a light beam in a range outside the opening 8o, the mask 8 is a portion of the light beam traveling from the collimator lens 3 toward the wafer 1 side. , The passage of light outside the imaging range of the camera viewed from the light projecting direction R1 is blocked. The mask 8 blocks the passage of light at a position that is relatively far from the range of the projected image of the wafer 1 in the process from the collimator lens 3 to the wafer 1. Therefore, it is possible to prevent the non-parallel light component from being contained as much as possible. 1 and 2 show an example in which two masks 8 are provided, but an embodiment in which one or three or more of the masks 8 are provided, or an implementation in which the mask 8 is not provided. Examples are also possible.
An interval (distance) between the mask 8 (closest to the wafer 1) and the first lens 4 is set to about 200 [mm], for example, and the edge of the wafer 1 has a light flux (parallel) between them. (Light) in the optical path.
Then, the parallel light beam Lp after passing through the mask 8 is projected from the direction R1 parallel to the front and back surfaces of the wafer 1 to the measurement portion (edge portion) including the end surface of the wafer 1.

Furthermore, the shape measuring apparatus X is a first camera as a camera (corresponding to an imaging unit) that captures a projection image of a measurement unit (edge) including an end face of the wafer 1 from a direction R2 facing the light projection direction R1 with respect to the wafer 1. Lens 4, aperture 5, second lens 6, and image sensor 7 (CCD or the like).
The first lens 4, the diaphragm 5 and the second lens 6 constitute a telecentric lens, and light passing through the first lens 4 is input to the image sensor 7. A projected image of (edge) is captured.
As described above, the shape measuring apparatus X projects parallel light onto the wafer 1, so that the wafer 1 has a long depth length in the optical axis direction (projection direction R1) of the parallel light. In the image sensor 7, it is possible to obtain a good projection image with a small outline blur. Further, by adopting a point light source 2 using a white LED having a multi-wavelength component instead of a strong single-wavelength light, even if the wafer 1 has a long depth in the light projecting direction R1, In the image sensor 7, a good captured image with few diffraction fringes generated in the vicinity of the contour of the projected image can be obtained.

The shape measuring device X further includes a central suction support mechanism 9, an image processing device 10, a control device 11, an optical system holding member 20, and optical system rotation support mechanisms 30 to 32.
The image processing apparatus 10 is an arithmetic unit that executes image processing based on an image captured by the image sensor 7 (an image including a projected image of the wafer 1), and executes, for example, a predetermined program stored in the storage unit in advance. A DSP (Digital Signal Processor), a personal computer, or the like. The image processing apparatus 10 calculates an index value of the end face shape of the wafer 1 by executing predetermined image processing on a captured image (projected image) by the image sensor 7. The image processing apparatus 10 executes input of a captured image (image data) by the image sensor 7 and image processing based on the captured image in accordance with a control command from the control device 11.
The central suction support mechanism 9 supports the disk-shaped wafer 1 by vacuum suction of the central portion of one surface (for example, the lower surface). Further, the central suction support mechanism 9 rotates and stops the wafer 1 in the circumferential direction around the central portion (center point Ow) of the wafer 1 as a rotation axis, so that the end portion at any position in the circumferential direction of the wafer 1 is It is also a device that adjusts whether it is positioned in the optical path of the light beam as a measurement unit.
The central suction support mechanism 9 includes a rotation encoder (not shown) as an angle detection sensor for detecting the support angle (rotation angle) of the wafer 1, and positioning of the support position (support angle) of the wafer 1 based on the detection angle. I do. The central suction support mechanism 9 positions the support position of the wafer 1 in accordance with a control command from the control device 11. The central suction instruction mechanism 9 supports a base portion (main body portion) fixed to a pedestal 30 described later and a central portion of the wafer 1 and is provided so as to be rotatable with respect to the base portion. And the rotation angle of the support portion is detected by the encoder.
The control device 11 is a computer including a CPU and its peripheral devices, and the CPU executes a control program stored in advance in the storage unit, whereby the image processing device 10, the central suction support mechanism 9, and the optical device. It is a device that controls a drive motor (outputs a control command) in the system rotation support mechanisms 30 to 32.

The optical system holding member 20 includes the light projecting unit (the point light source 2, the collimator lens 3 and the mask 8), the camera (the first lens 4, the diaphragm 5, the second lens 6 and the like). It is a member that holds an optical device including the image sensor 7) in a state where their relative positional relationship is fixed. In the example shown in FIGS. 1 and 2, the optical system holding member 20 is a metal member (rigid body) having a substantially L-shaped cross section and extending along the light projecting direction of the light beam Lp. . In FIG. 1 and FIG. 2, description of a connecting portion that connects the optical system holding member 20 and each optical device is omitted.
The optical system rotation support mechanisms 30 to 32 support the optical system holding member 20 with a support shaft 31 orthogonal to the light projecting direction R1 and the optical system supported by the support shaft 31. The holding member 20 is driven to rotate about the support shaft 31.

Next, the optical system rotation support mechanisms 30 to 32 will be described with reference to FIG.
The optical system rotation support mechanism protrudes in a direction orthogonal to the light projecting direction R1, and supports a support shaft 31 that pivotally supports the optical system holding member 20, and a pedestal 30 that holds the support shaft 31. And a rotation drive unit 32 (an example of the rotation drive means) that rotates the optical system holding member 20 that is pivotally supported by the support shaft 31. Thus, the support shaft 31 that supports the optical system holding member 20 and the central suction instruction mechanism 9 that supports the wafer 1 are both held by the pedestal 30.
The rotation drive unit 32 includes a servo motor 32a held on the pedestal 30, a worm 32b provided on a rotation shaft of the servo motor 32a, and a worm wheel 32c fixed to the optical system holding member 20. And. The worm 32b and the worm wheel 32c constitute a worm gear in which gears mesh with each other.
Then, the control device 11 outputs a control command to the servo motor 32a to rotate the worm 32b by a necessary angle so that the optical system holding member 20 supported by the support shaft 31 is supported. (The inclination with respect to the wafer 1 supported by the central suction instruction mechanism 9) is adjusted. Thereby, the inclination of the light projection direction R1 with respect to the front surface (front and back surfaces) of the wafer 1 is adjusted.
Incidentally, the rotation drive unit 32 shown in FIG. 3, but is intended to drive rotating the optical system holding member 20 by the worm gear, other, the optical system holding member 20 by other drive mechanisms such as tangent screw A configuration for rotational driving is also conceivable.

FIG. 4 is a schematic diagram for explaining the relationship between the light projecting direction and the wafer 1 in the shape measuring apparatus X.
Here, a plane along the surface (supported surface) of the wafer 1 supported by the central suction instruction mechanism 9 is referred to as a wafer supported plane Fp, and a direction perpendicular to the wafer supported plane Fp is a Z-axis direction (Rz ).
Further, on the wafer support plane Fp, the direction of the straight line passing through the center Ow of the wafer 1 and the tip position Pt of the measurement unit when viewed from the Z-axis direction (Rz) is the Y-axis direction (Ry), and the Y-axis A direction orthogonal to the direction (Ry) is referred to as an X-axis direction (Rx).
In the shape measuring apparatus X, the central suction instruction mechanism 9 rotates the wafer 1 in the wafer supported plane Fp.
The support shaft 31 that pivotally supports the optical system holding member 20 is an axis that is orthogonal to the light projecting direction R1 and parallel to the Y-axis direction (Ry).
Therefore, the optical system rotation support mechanisms 30 to 32 rotate the optical system holding member 20 around the support shaft 31 in the peripheral direction Rc, thereby supporting the wafer supported in the light projecting direction R1. The inclination with respect to the plane Fp (the inclination with respect to the X-axis direction (Rx) and the Z-axis direction (Rz)) is adjusted. Further, during the adjustment, the light projecting direction R1 is maintained in a state orthogonal to the Y-axis direction (Ry).
The support shaft 31 may be arranged such that its axis is located on a straight line passing through the center Ow of the wafer 1 and the tip position Pt of the measurement unit when viewed from the Z-axis direction (Rz). Further, the support shaft 31 may be disposed at a position where the axis of the support shaft 31 overlaps the tip position Pt of the measurement unit when viewed from the Y-axis direction (Ry) direction.

When the shape measurement apparatus X performs shape measurement on a plurality of measurement portions in the circumferential direction of the wafer 1, the central suction support mechanism 9 rotates the wafer 1 while the central portion of the wafer 1 is sucked and supported. If positioning of 1 is performed, efficient measurement can be performed.
However, as shown in FIG. 10, when the parallelism between the light projecting direction R1 and the surface of the measurement unit is not sufficient due to the bending of the wafer 1, the correct shape measurement is performed. I can't.
Therefore, the controller 11 controls the servo motor 32a of the rotation drive unit 32 before measuring the shape of the wafer 1, thereby tilting the optical system holding member 20 (that is, the surface of the wafer 1). Tilt adjustment processing for adjusting the tilt of the light projection direction R1 with respect to (an example of the first tilt adjustment means). During the tilt adjustment processing, an index of the tilt degree of the end portion of the wafer 1 supported by the central suction support mechanism 9 with respect to the light projecting direction R1 is detected, and the rotation drive unit 32 is controlled according to the detection result. The servo motor 32a is controlled.
Hereinafter, specific examples (first embodiment and second embodiment) of the tilt detection process for detecting the index of the tilt degree of the wafer 1 with respect to the light projecting direction R1 will be described.

First, a first embodiment of the tilt detection process will be described with reference to FIG.
FIG. 5 is a diagram schematically showing an example of a projected image 1 ′ of the wafer 1 taken by the cameras 4 to 7, and FIG. 5A shows the measurement unit with respect to the light projection direction R1. When the surface of (the end portion of the wafer 1) is tilted, FIG. 5B shows the case where the light projection direction R1 and the surface of the measurement unit are substantially parallel.
As shown in FIG. 5, the greater the inclination of the wafer 1 with respect to the light projection direction R1, the greater the degree of image blurring of the outline of the projected image 1 ′, and the light projection direction R1 and the wafer 1 are in a parallel state. In addition, the degree of image blur in the outline of the projected image 1 ′ is the smallest.
Therefore, in the first embodiment of the tilt detection process, the image processing apparatus 10 determines the degree of image blur of the projection image 1 ′ by the image processing on the projection image 1 ′ at the edge of the wafer 1, and the projection direction R1. Is detected as an index value of the degree of inclination of the wafer 1 with respect to. For example, the image processing apparatus 10 determines the maximum amount of change in luminance per unit distance (hereinafter referred to as the maximum luminance gradient amount) along a predetermined reference line J (for example, a line in the thickness direction of the wafer 1) in the projection image 1 ′. Is calculated as an index value representing the degree of image blurring of the contour of the projection image 1 ′. The larger the degree of image blur in the contour of the projected image 1 ′, the smaller the maximum luminance gradient amount, and the smaller the degree of image blur in the contour of the projected image 1 ′, the larger the maximum luminance gradient amount (steeply). Become). It is also conceivable that the maximum luminance inclination amount is an average value of the maximum luminance change amounts per unit distance calculated for each of the plurality of reference lines J.
In the first embodiment, the image processing apparatus 10 for detecting the shape of the end face of the wafer 1 is also used as an apparatus for detecting an index value of the tilt of the wafer 1.
Then, the control device 11 controls the servo motor 32a of the rotation drive unit 32 in a direction in which the degree of image blur of the contour of the projected image 1 ′ at the end of the wafer 1 is minimized (the first inclination). An example of adjusting means).
For convenience of explanation, FIG. 5A shows a projected image 1 ′ in which image blur is emphasized more than reality.

By the way, although the degree of the image blur of the outline of the projected image 1 ′ has a correlation with the inclination of the end of the wafer 1, the state of the surface of the end of the wafer 1 (measurement site) and its peripheral part, or the end thereof The shape is not determined only by the inclination of the wafer 1, and the minimum value may be different if the measurement site is different.
Therefore, the control device 11 gradually changes the inclination of the optical system holding member 20 while feeding back a detection value (here, the luminance maximum inclination amount) of the degree of image blur of the outline of the projection image 1 ′. The inclination of the optical system holding member 20 is adjusted so that the detection result of the degree of image blur is minimized.
FIG. 6 is a view showing a state in which the light projecting direction R1 and the surface of the wafer 1 are adjusted to be parallel by the control device 11 in the shape measuring apparatus X. As shown in FIG. 6, in the shape measuring apparatus X, the projection direction R1 (direction of the parallel light Lp) and the wafer 1 are adjusted to be parallel before the shape measurement. Shape measurement can be performed.

Next, a second embodiment of the tilt detection process will be described with reference to FIGS.
As shown in FIG. 5, the shape measuring apparatus X that executes this inclination detection process (second embodiment) has two non-contact type displacement sensors 40 held (fixed) to the optical system holding member 20. It has.
These two displacement sensors 40 are arranged at an interval Lr along the light projecting direction R1, and at two observation positions P1 and P2 along the light projecting direction R1, directions perpendicular to the light projecting direction R1 (wafer) 1 is a sensor that detects the position (height) of the surface of the wafer 1 in a direction that intersects the front and back surfaces of 1 (an example of the displacement detection means). For example, as the displacement sensor 40, a reflection type laser displacement sensor, an eddy current type displacement sensor, an ultrasonic displacement sensor, or the like may be employed.
The control device 11 in the second embodiment has the relationship between the positions of the wafer 1 surface (surface heights h1 and h2) in the direction orthogonal to the light projection direction R1 at the two observation positions P1 and P2. The inclination of the light projecting direction R1 with respect to the surface of the wafer 1 is adjusted by controlling the servo motor 32a of the rotation driving unit 32 in a direction approaching a preset target positional relationship (the first inclination). An example of adjusting means). Here, the target positional relationship is a positional relationship when the light projecting direction R1 and the surface of the wafer 1 are parallel, and here, the detection position (detection height) of the displacement sensor 40 at one observation position P1. It is assumed that a relationship in which the difference between the height h1) and the detection position (detection height h2) of the displacement sensor 40 at the other observation position P2 is Δh0 is the target positional relationship.
The relative position of the displacement sensor 40 held with respect to the optical system holding member 20 with respect to the light projecting direction R1 is fixed. Therefore, the difference α (h1−h2 = Δh0 + α) between the distribution (positional relationship) of the surface positions h1 and h2 on the surface of the wafer 1 detected by the displacement sensor 40 and the target positional relationship is the wafer relative to the light projecting direction R1. The index value uniquely corresponds to the inclination θ of 1. That is, when the interval between the two observation positions P1 and P2 in the light projecting direction R1 is Lr (known value), the inclination θ is tan ⁻¹ (α / Lr).
Further, the relationship between the change amount of the inclination of the optical system holding member 20 with respect to the rotation angle of the servo motor 32a is the gear ratio of the worm gears 32b and 32c, and the positional relationship (distance) between the support shaft 31 and the worm gears 32b and 32c. ) And the like.
From the above, the control device 11 determines the light projection direction from the difference α between the positional relationship between the positions P1, P2 on the surface of the wafer 1 and the target positional relationship obtained by one detection by the displacement detection sensor 40. A rotation angle of the servo motor 32a for making R1 and the surface of the wafer 1 parallel to each other is calculated, and control (open control) is performed to rotate the servo motor 32a by the calculated rotation angle. Thereby, the inclination of the optical system holding member 20 is quickly adjusted so that the light projection direction R1 and the wafer 1 are parallel to each other.
FIG. 8 shows a state in which the shape measuring device X is adjusted by the control device 11 so that the light projecting direction R1 and the surface of the wafer 1 are parallel when the tilt detection processing by the displacement sensor 40 is performed. FIG. As shown in FIG. 8, in the shape measuring apparatus X, the light projection direction R1 (the direction of the parallel light Lp) and the wafer 1 are adjusted to be parallel before the shape measurement. Shape measurement can be performed.

By the way, in order to obtain the target positional relationship (h1−h2 = Δh0), it is troublesome to confirm that the light projecting direction R1 and the surface of the wafer 1 are parallel.
Therefore, for example, it is conceivable that the shape measuring apparatus X executes the target positional relationship setting process in advance according to the following procedure.
First, in a state where a predetermined plate-like member is supported by the central suction support mechanism 9, the plate-like member is measured by the light projecting unit and the camera, and a projected image of the plate-like member is captured. To do. Here, the plate-like member (an example of the calibration member) is, for example, a plate-like member in which the front and back surfaces are formed in a plane and in parallel with high accuracy, or the wafer to be measured first. 1st magnitude.
Next, the image processing device 10 performs image processing on the projection image of the plate-like member, thereby detecting the degree of image blurring of the outline of the projection image (an example of the calibration image processing means).
Further, the control device 11 controls the servo motor 32a of the rotation drive unit 32 so as to minimize the degree of image blurring of the outline of the projection image of the plate-like member, whereby the optical system holding member 20 is controlled. slope (i.e., the plate-like member (e.g., the slope of the light projection direction R1 with respect to the surface of the wafer 1, etc.) is the first measurement object) modulate (example 9 of the second inclination adjusting means) .
The processing described above is the same processing as that in the first embodiment of the tilt detection processing.
Then, the control device 11 adjusts the inclination of the optical system holding member 20 according to the degree of the image blur, and the plate-like shape at the two observation positions P1 and P2 detected by the displacement sensor 40 is detected . The relationship between the positions h1 and h2 on the surface of the member (for example, the wafer 1 as the first object to be measured ) is recorded (set) in the nonvolatile memory as the target positional relationship (h1−h2 = Δh0) to be used later. (An example of the target position relationship setting means).
Thereby, the setting of the positional relationship of the target can be automated.

By the way, in the second embodiment of the tilt process shown in FIGS. 7 and 8, the surface of the wafer 1 is observed at two observation positions P1 and P2 along the light projecting direction R1 by the two displacement sensors 40. A configuration for measuring the position is shown.
However, an embodiment in which the surface position of the wafer 1 is measured at three or more observation positions along the light projection direction R1 by three or more displacement sensors 40 is also conceivable.
In that case, for example, the control device 11 linearly approximates the distribution of the surface position (surface height) of the wafer 1 at three or more observation positions, and the inclination of the approximate straight line obtained by the linear approximation is preset. It is conceivable to adjust the inclination of the optical system holding member 20 in accordance with a difference from a target inclination (an example of the target positional relationship).
The displacement sensor 40 is preferably a non-contact type displacement sensor in order to prevent the surface of the wafer 1 from being scratched. However, the tilt detection process can be realized using a contact type displacement sensor. .
Further, in the shape measuring apparatus X, the rotation drive unit 32 drives to rotate the optical system holding member 20 that is pivotally supported, but the inclination of the optical system holding member 20 (that is, relative to the surface of the wafer 1). The mechanism for changing the inclination of the light projection direction R1 may be another mechanism including an actuator.
In addition to the embodiment described above, the state (degree) of warpage of the wafer 1 supported by the central suction support mechanism 9 is measured by a separately prepared measuring instrument, and the measurement result is measured by the control device 11. It is also conceivable that the control device 11 adjusts the inclination of the optical system holding member 20 by controlling the servo motor 32a of the rotation drive unit 32 based on the input result.

  The present invention can be used mainly for measuring the shape of an end face of a disk-shaped measuring object such as an aluminum substrate or a glass substrate for a semiconductor wafer or other hard disk.

1 is a schematic plan view of a shape measuring device X according to an embodiment of the present invention. The schematic side view of the shape measuring apparatus X. The figure showing the structure of the optical system rotation support mechanism with which the shape measuring apparatus X is provided. The schematic diagram for demonstrating the relationship between the light projection direction and the wafer in the shape measuring apparatus X. FIG. The figure which represented typically an example of the projection image of the wafer imaged with the camera with which the shape measuring apparatus X is provided. The figure showing the state adjusted in the shape measuring apparatus X so that a light projection direction and the surface of the wafer 1 may become parallel. The figure showing a mode that the inclination of a wafer was detected by the displacement sensor in the shape measuring apparatus X. The figure showing the state adjusted so that a light projection direction and the surface of a measurement object may become parallel according to the inclination of the wafer detected by the displacement sensor in the shape measuring apparatus X. The figure which represented typically the path | route of the light ray in case a light projection direction and the surface of a measurement object are parallel in the light projection measurement method. The figure which represented typically the path | route of the light ray in case the inclination has arisen in the light projection direction with respect to a measuring object and the surface of a measuring object in the light projection measurement method.

Explanation of symbols

X: Shape measuring device 1: Wafer 2: Point light source 3: Collimator lens 4: First lens 5: Aperture 6: Second lens 7: Image sensor 8: Mask 9: Central suction support mechanism 10: Image processing device 11 : Control device 20: Optical system holding member 30: Pedestal 31: Support shaft 32: Rotation drive part 32a: Servo motor 32b: Worm 32c: Worm wheel 40: Displacement sensor

Claims (5)

A light projecting means for projecting parallel light onto the edge of the disk-shaped object to be measured;
An imaging unit that captures a projected image of an end of the measurement object from a direction opposite to a light projecting direction by the light projecting unit;
An optical system holding member for holding the light projecting means and the imaging means;
An optical system driving means for driving the optical system holding member to change the inclination of the light projecting direction with respect to the surface of the measurement object;
An inclination index detecting means for detecting an index of the degree of inclination of the measurement object with respect to the light projecting direction;
First inclination adjusting means for adjusting the inclination of the light projecting direction with respect to the surface of the measurement object by controlling the optical system driving means according to the detection result of the index of the inclination degree,
The inclination index detection means is held on the optical system holding member, and the position of the surface of the measurement object in a direction orthogonal to the light projection direction at a plurality of observation positions along the light projection direction. Displacement detection means for detecting
The first inclination adjusting means is configured to project the projection in a direction in which a positional relationship of the surface of the measurement object in a direction orthogonal to the projection direction at the plurality of observation positions approaches a preset target positional relationship. To adjust the tilt of the light direction,
A shape measuring apparatus for measuring a shape of an end face of the measuring object based on the projected image obtained by the imaging means. Image processing is performed on the projection image of the calibration member obtained by measuring the calibration member, which is a plate- shaped member, with the light projecting unit and the imaging unit, and the degree of image blur of the contour of the projection image is detected. Calibration image processing means;
Second inclination adjusting means for adjusting the inclination of the light projecting direction with respect to the surface of the calibration member by controlling the optical system driving means so as to minimize the degree of image blur of the projected image of the calibration member. When,
The relationship between the position of the surface of the calibration member at the plurality of observation positions detected by the displacement detection means in a state where the inclination of the light projection direction is adjusted by the second inclination adjustment means is calculated as the target. The shape measuring apparatus according to claim 1 , further comprising target positional relationship setting means for setting the positional relationship. The shape measuring apparatus according to claim 1, wherein the calibration member includes the predetermined measurement object. The shape measuring apparatus according to any one of claims 1 to 3 , wherein the displacement detecting means detects the position of the surface of the measurement object in a non-contact manner. The optical system driving means changes the inclination of the light projecting direction with respect to the surface of the measurement object by rotationally driving the optical system holding member pivotally supported by a support shaft orthogonal to the light projecting direction. The shape measuring device according to any one of claims 1 to 4 .

Images