JP6030471B2 - Shape measuring device - Google Patents

Description

  The present invention relates to a technique for measuring the surface shape of a wafer using a Shack-Hartmann sensor.

  When a device is manufactured from a wafer made of silicon, sapphire, or the like, a very fine wiring design of nanometer order is required. In order to realize this, there is an increasing demand for flatness of the surface shape of the wafer. Therefore, a very fine measurement accuracy is required also in a measuring apparatus for inspecting the flatness of a wafer.

  In the wafer measuring apparatus, it is necessary to measure the surface shape of the wafer, particularly a deviation shape from a plane in the vicinity of an edge called a roll-off portion (for example, a range of 1 to 5 mm from the edge end).

  FIG. 11 is a diagram for explaining a problem when a roll-off portion of a wafer is measured using an SH sensor that is a Shack-Hartmann wavefront sensor. The surface of the wafer is divided into a flat portion, a roll-off portion, and a chamfered portion from the center toward the edge.

  When measuring the surface shape of the roll-off part, it is necessary to determine the position coordinates of the roll-off part on the wafer. Usually, the coordinates are set on a line (radial direction) connecting the center and the edge of the wafer with reference to the edge position of the wafer. At this time, it is necessary to realize positioning of coordinates with high accuracy.

  When this is realized, the following problems occur. The SH sensor receives reflected light from the wafer of light source light and measures the surface shape. The reflected light from the roll-off part or the flat part can reach the imaging surface of the SH sensor. Therefore, the SH sensor can measure the surface shapes of the flat surface portion and the roll-off portion. However, since the reflected light reflected on the edge side from the chamfered portion is reflected toward the outside of the edge, it does not reach the imaging surface of the SH sensor, and the SH sensor cannot recognize the surface shape of this region. Therefore, there is a problem that the SH sensor cannot accurately determine the coordinates of the surface shapes of the flat surface portion and the roll-off portion when the edge position is used as a reference.

  Therefore, in Patent Document 1, in the shape measuring apparatus that calculates the surface shape data of the wafer using the SH sensor, the edge position of the wafer to be measured is detected by an imaging device provided separately from the SH sensor. It is disclosed that surface shape data is obtained based on an edge position.

JP 2011-226989 A

  However, the method of Patent Document 1 requires an imaging device for detecting an edge separately from the SH sensor, which causes a problem that the device configuration is complicated and the cost is increased.

  An object of the present invention is to provide a shape measuring apparatus capable of measuring the edge of a wafer and the surface shape of a measurement region using only an SH sensor.

A shape measuring apparatus according to an aspect of the present invention is a shape measuring apparatus that measures a surface shape of a predetermined measurement region on a surface of a wafer, and includes a Shack-Hartmann-type SH sensor that measures the surface shape of the wafer, and the measurement A first light source that irradiates a region; a second light source that is disposed on the opposite side of the wafer with respect to the SH sensor, irradiates an edge of the wafer, and causes a silhouette image of the edge to enter the SH sensor ; And a light guide unit that causes reflected light from a measurement region to enter the SH sensor, and causes the light irradiated to the edge to enter the SH sensor.

  According to this configuration, the light emitted from the first light source is reflected by the measurement region and guided to the SH sensor. Further, the light emitted from the second light source irradiates the edge and is guided to the SH sensor. Therefore, the SH sensor can measure the surface shape and the edge of the measurement region. As a result, the surface shape and the edge of the measurement region can be measured using one SH sensor without providing a sensor for measuring the edge separately from the SH sensor. In addition, since the surface shape and the edge of the measurement region are measured by one SH sensor, the surface shape data in which the position from the edge is accurately associated can be calculated.

Further , according to this configuration, since the edge silhouette image is incident on the SH sensor, the edge position can be detected from the silhouette image.

In the above aspect , each of the first and second light sources emits light having different wavelengths, transmits light having a wavelength emitted from the first light source, and guides the light to the SH sensor. You may further provide the wavelength selection filter containing the 2nd filter area | region which permeate | transmits the light of the wavelength irradiated from 2 light sources, and guides it to the said SH sensor.

  According to this configuration, the light emitted from the first light source and the light emitted from the second light source are separated by the wavelength selection filter. Therefore, it is possible to cause the SH sensor to perform surface shape measurement and edge measurement simultaneously.

In the above aspect, the first and second light sources irradiate light having different wavelengths, respectively, and the SH sensor receives light having sensitivity to light from the first light source and light from the second light source. You may provide the color image pick-up element by which the pixel with a sensitivity was arranged at least.

  According to this configuration, the first light source emits light of the same color as a certain color component of the color image sensor, and the second light source emits light of the same color as another color component of the color image sensor. Thereby, the existing color image sensor can be incorporated in the SH sensor, and the light from the first light source and the light from the second light source can be separated. It is also possible to cause the SH sensor to perform surface shape measurement and edge measurement simultaneously.

In the above aspect, a first polarizing filter that polarizes light emitted from the first light source in a first polarization direction; a second polarizing filter that polarizes light emitted from the second light source in a second polarization direction; A polarization selection filter further comprising: a first filter region that transmits light in the first polarization direction and guides it to the SH sensor; and a second filter region that transmits light in the second polarization direction and guides it to the SH sensor. You may prepare.

  According to this configuration, the light emitted from the first light source and the light emitted from the second light source are separated by the polarization selection filter. Therefore, it is possible to cause the SH sensor to perform surface shape measurement and edge measurement simultaneously.

The said aspect WHEREIN: You may further provide the lighting control part which lights the said 1st, 2nd light source at a respectively different timing.

  According to this configuration, since the first and second light sources are turned on at different timings, the SH sensor measures the surface shape while the first light source is turned on and while the second light source is turned on. Edges can be measured.

In the above aspect, the light beam incident on the SH sensor from the second light source is tracked, the position of the light beam on the wafer is detected, the edge position is detected based on the detected position, and the first light source It may further include a calculation unit that tracks a light beam incident on the SH sensor and detects a position of the light beam on the wafer when the edge position is set as a reference coordinate.

  According to this configuration, the light beam incident on the SH sensor from the second light source is traced in reverse to detect the position of the light beam on the wafer surface, and the edge position is detected from that position, so the edge position is accurately detected. can do. Further, the light beam incident on the SH sensor from the first light source is traced in reverse, and the position of the light beam on the wafer surface when the edge position is used as a reference is detected. Therefore, surface shape data in which the distance from the edge position is accurately reflected can be obtained.

In the above aspect, the measurement region may be a roll-off part.

  According to this configuration, the surface shape of the roll-off part can be measured.

  According to the present invention, the surface shape and the edge of the measurement region can be measured using one SH sensor without providing a sensor for measuring the edge separately from the SH sensor. In addition, since the surface shape and the edge of the measurement region are measured by one SH sensor, the surface shape data in which the position from the edge is accurately associated can be calculated.

It is the figure which showed an example of the hardware constitutions of the shape measuring apparatus by embodiment of this invention. In FIG. 1, only the optical path of the light irradiated from the first light source is shown, and the optical path of the light irradiated from the second light source is omitted. In FIG. 1, only the optical path of the light irradiated from the second light source is shown, and the optical path of the light irradiated from the first light source is omitted. It is explanatory drawing of the separation method 1, (A) is the figure which looked at the SH sensor from the direction (horizontal direction) orthogonal to an optical axis direction, (B) is the figure which looked at the wavelength selection filter from the BB direction. It is. It is explanatory drawing which shows the measurement principle of SH sensor. It is a figure for demonstrating the calculation formula of the wavefront angle in SH sensor. It is the schematic diagram which showed the light ray irradiated from the 1st light source, and the light ray irradiated from the 2nd light source. It is explanatory drawing of the process in which a calculation part calculates the position in the wafer of a light ray. (A) is a figure which shows an example of the hardware constitutions of the shape measuring apparatus at the time of applying the separation method 3, (B) is the figure which looked at the polarization selection filter from the BB direction. It is a figure which shows an example of the hardware constitutions of the shape measuring apparatus at the time of employ | adopting the separation method 4. It is a figure explaining the problem at the time of measuring the roll-off part of a wafer using SH sensor which is a wavefront sensor of a Shack-Hartmann system.

  As shown in FIG. 11, the surface of the wafer is divided into a flat portion, a roll-off portion, and a chamfered portion from the center toward the edge. The flat portion is a flat region on the surface of the wafer. The roll-off portion is a region having a gentle slope toward the edge portion. The chamfered portion is a region having a larger slope than the roll-off portion toward the edge portion. When evaluating a wafer, not only the surface shape of the flat surface portion but also the surface shape of the roll-off portion is an effective evaluation index. Therefore, in this embodiment, a case where the surface shape of the roll-off part is measured will be described as an example. However, this is only an example, and the surface shape may be measured by setting a region other than the roll-off portion within the angle of view of the SH sensor (for example, a flat portion) as a measurement region.

  FIG. 1 is a diagram illustrating an example of a hardware configuration of a shape measuring apparatus according to an embodiment of the present invention. The shape measuring device includes a first light source 11, a second light source 12, an SH (Shack-Hartmann) sensor 13, a half mirror 14 (an example of a light guide unit), a replacement unit 701, a sample support 702, and a calculation unit 80.

  The shape measuring apparatus according to the present embodiment is characterized in that a second light source 12 is provided separately from the first light source 11 for the SH sensor 13, and light from both light sources is received by one SH sensor 13.

  The first light source 11 irradiates the half mirror 14 with light 101 having a property of traveling in one direction. The first light source 11 is arranged so that the light 101 is parallel to the surface of the wafer W.

  The second light source 12 is disposed on the opposite side of the SH sensor 13 via the edge WE of the wafer W. The second light source 12 irradiates light 102 having a property of traveling in one direction from the back side of the wafer W toward the edge WE. Here, the second light source 12 is arranged so that the light 102 is orthogonal to the surface of the wafer W and a part of the light is shielded by the edge WE.

  The first and second light sources 11 and 12 include, for example, a laser light source and a collimating optical system that converts light emitted from the laser light source into parallel light.

  The SH sensor 13 is a Shack-Hartmann wavefront sensor and is disposed on the edge WE.

  FIG. 2 shows only the optical path of the light 101 emitted from the first light source 11 in FIG. 1 and omits the optical path of the light 102 emitted from the second light source 12. The half mirror 14 reflects the light 101, deflects it by 90 degrees, guides it to the roll-off part of the wafer W, transmits the light 101 reflected by the roll-off part, and guides it to the SH sensor 13. A part of the light 101 reflected by the half mirror 14 passes the outside of the edge WE and proceeds to the second light source 12 side.

  FIG. 3 shows only the optical path of the light 102 emitted from the second light source 12 in FIG. 1 and omits the optical path of the light 101 emitted from the first light source 11. A part of the light 102 irradiated from the second light source 12 is shielded by the wafer W, the rest passes through the outside of the edge WE, is transmitted by the half mirror 14 and is guided to the SH sensor 13. Thereby, a silhouette image of the wafer W appears on the SH sensor 13, and the SH sensor 13 can measure the edge WE.

  The light reaching the SH sensor 13 is in a state where the light emitted from the first light source 11 and the light emitted from the second light source partially overlap each other. Therefore, it is necessary to separate the two lights. Hereinafter, a method for separating light from the first light source 11 and the second light source will be described.

・ Separation method 1
4A and 4B are explanatory diagrams of the separation method 1. FIG. 4A is a view of the SH sensor 13 viewed from a direction (lateral direction) orthogonal to the optical axis direction, and FIG. 4B is a wavelength selection from the BB direction. It is the figure which looked at the filter 43. FIG. In FIG. 4, the vertical direction of the image sensor 41 is the X direction, and the horizontal direction is the Y direction. The Y direction corresponds to the radial direction of the wafer W. The SH sensor 13 includes an image sensor 41 and a microlens array 42 disposed in front of the image sensor 41.

  The separation method 1 is a method in which the first light source 11 and the second light source 12 are irradiated with light having different wavelengths, and the light from the first light source 11 and the light from the second light source 12 are separated by the wavelength selection filter 43. is there.

  The wavelength selection filter 43 is disposed in front of the microlens array 42. The wavelength selection filter 43 includes a filter region 431 (an example of a first filter region) and a filter region 432 (an example of a second filter region). The filter region 431 is configured by a filter that transmits the first wavelength light 101 emitted from the first light source 11, and guides the first wavelength light to the SH sensor 13. The filter region 432 includes a filter that transmits the second wavelength light 102 emitted from the second light source 12, and guides the second wavelength light to the SH sensor 13.

  The light 101 reflected by the roll-off part is light having the first wavelength. Therefore, the light 101 that reaches the filter region 431 enters the SH sensor 13, but the light 101 that reaches the filter region 432 cannot pass through the filter region 432 and does not enter the SH sensor 13.

  On the other hand, the light 102 emitted from the second light source 12 is light of the second wavelength. Therefore, the light 102 that reaches the filter region 432 enters the SH sensor 13, but the light 102 that reaches the filter region 431 cannot pass through the filter region 431 and does not enter the SH sensor 13.

  The light 102 is an edge silhouette image because part of the light is shielded by the wafer W. Therefore, in FIG. 4B, the filter region 432 receives light only in the region shown on the right side, and an edge silhouette image appears. Thereby, the SH sensor 13 can measure the edge of the wafer W.

  As described above, in the separation method 1, since the wavelength selection filter 43 is provided, the imaging surface 41a of the imaging device 41 is divided into a light receiving region 411 corresponding to the filter region 431 and a light receiving region 412 corresponding to the filter region 432. Divided. The position of the light receiving area 411 on the imaging surface 41 a and the position of the light receiving area 412 on the imaging surface 41 a are determined in advance from the sizes of the filter area 431 and the filter area 432. Therefore, the calculation unit 80 recognizes that the light received by the light receiving region 411 is the light 101 emitted from the first light source 11, and the light received by the light receiving region 412 is the light emitted from the second light source 12. 102 can be recognized. Therefore, the surface shape and edge of the roll-off part can be measured using only one SH sensor 13.

・ Separation method 2
In the separation method 2, for example, R (red) light is irradiated from the first light source 11, for example, G (green) light is irradiated from the second light source 12, and a color image sensor is used as the image sensor 41 of the SH sensor 13. It is the technique that was done. As the color imaging device, for example, an imaging device in which pixels having light receiving sensitivity to R, G, and B light are arranged in, for example, a Bayer array may be employed.

  Since the light 101 emitted from the first light source 11 is R light, it is received by the R pixel, and since the light 102 from the second light source 12 is G light, it is received by the G pixel. Therefore, the calculation unit 80 recognizes that the measurement image of the R color component is the light 101 in the measurement image captured by the image sensor 41 and recognizes that the measurement image of the G color component is the light 102. it can.

  In this configuration, the light 101 and the light 102 can be separated by the color component of the measurement image captured by the image sensor 41 without providing the wavelength selection filter 43.

  In the above description, the light 101 is R and the light 102 is G. However, this is only an example, and other colors may be adopted. In this case, the image sensor 41 may be configured with a color image sensor having pixels corresponding to the colors of the light 101 and 102.

  Returning to FIG. 1, the wafer W is placed on the sample support base 702. The sample support base 702 is provided with a plurality of pins 703. The pins 703 include support pins that support the wafer W, positioning pins for positioning the wafer W, and the like.

  The replacement unit 701 is an apparatus for replacing the wafer W currently installed on the sample support base 702 with another wafer W. Here, as the replacement unit 701, a robot mechanism that automatically replaces the wafer W may be employed, or a manual mechanism that manually replaces the wafer W may be employed.

  The calculation unit 80 is configured by a computer including a CPU, for example. The calculation unit 80 calculates surface shape data of the roll-off unit based on the measurement image captured by the SH sensor 13. FIG. 5 is an explanatory diagram showing the measurement principle of the SH sensor 13. The SH sensor 13 includes a microlens array 42 and an image sensor 41 provided behind the microlens array 42. The microlens array 42 is a lens in which a plurality of microlenses 421 are arranged in an array of predetermined rows × predetermined columns. The image sensor 41 is an image sensor in which a plurality of pixels are arranged in an array of predetermined rows × predetermined columns. For example, a CCD image sensor or a CMOS image sensor is employed.

  The SH sensor 13 forms incident light with the microlens 421 and causes the image pickup device 41 to pick up the obtained incident light image. The imaging surface 41a of the imaging element 41 is divided into a plurality of blocks 41b corresponding to the respective microlenses 421. When the incident light is a plane wave, as shown in FIG. 5A, the incident light is imaged at the center of each block 41b.

  On the other hand, when the incident light is distorted, as shown in FIG. 5 (B), the incident light is imaged at a position shifted from the center in each block 41b. Therefore, in each block 41b, by obtaining the deviation from the center of the imaging point 41c, the angle of the wavefront (wavefront angle) with respect to the plane wave is known, and the inclination at each position of the wafer is known from the wavefront angle, and the inclination is integrated. Thus, height data at each position of the wafer is obtained.

  FIG. 6 is a diagram for explaining a calculation formula of the wavefront angle in the SH sensor 13. The microlens 421 has a dome-shaped cross-section that is convex toward the image sensor 41. The reference image formation point P401 indicates an image formation point on the image sensor 41 of the plane wave WV1 whose wavefront is parallel to the image pickup surface of the image sensor 41. The reference imaging point P401 is an intersection between the optical axis 421a of the microlens 421 and the image sensor 41. An imaging point P402 indicates an imaging point on the imaging device 41 of the observation wave WV2 whose wavefront is inclined from the imaging surface of the imaging device 41. In FIG. 6, the distance between the microlens array 42 and the image sensor 41 is F. In addition, the distance between the reference image formation point P401 and the image formation point P402 is L.

From the geometrical relationship, the wavefront angle θ is represented by tan θ = L / F. Therefore, the calculation unit 80 obtains a shift amount (distance L) from the reference image formation point P401 of the image formation point P402 in each block 41b from the measurement image captured by the image sensor 41 of the SH sensor 13, and θ = tan. ⁻¹ (L / F), the wavefront angle θ in each block 41b is calculated.

  The SH sensor 13 captures two-dimensional image data with the Y axis in the radial direction of the wafer W and the X axis as a direction orthogonal to the Y axis. For this reason, the amount of deviation between the image formation point P402 and the reference image formation point P401 includes an amount of deviation between the X component and the Y component, but in this embodiment, the change in the height data of the wafer W along the radial direction is performed. The main focus is to measure. Therefore, the calculation unit 80 obtains the deviation amount of the Y component as the distance L shown in FIG. 4 and obtains the wavefront angle θ.

  FIG. 7 is a schematic diagram showing the light beam 101 a emitted from the first light source 11 and the light beam 102 a emitted from the second light source 12. The incident angle of the image pickup surface 41a varies depending on the shape of the roll-off portion. Further, since the wafer W is inclined more toward the imaging surface 41a toward the edge, the light beam 101a reflected near the edge is greatly inclined to the outside of the edge.

  Since the second light source 12 is disposed below the imaging surface 41a so that the irradiation surface is parallel to the imaging surface 41a, the light beam 102a is incident on the imaging surface 41a without being inclined.

  However, among the light rays 102a, there is also a light ray 102a that is incident on the imaging surface 41a with a slight inclination from a direction orthogonal to the surface of the wafer W and the imaging surface 41a of the SH sensor 13.

  On the other hand, the measured value of the SH sensor 13 includes information on the position and angle of the light beam 102a. Therefore, the position of the light beam 102a on the surface of the wafer W can be calculated by geometrically tracking the light beam 102a. Therefore, the calculation unit 80 reversely tracks the incident light ray 102a incident on the imaging surface 41a and calculates the position of the light ray 102a on the wafer W.

  FIG. 8 is an explanatory diagram of processing in which the calculation unit 80 calculates the position of the light beam 601 on the wafer W. A light beam 601 indicates a certain light beam 102 a emitted from the second light source 12. The reference coordinate R0 indicates the reference coordinate of the coordinate system of the SH sensor 13. a represents the distance of the Y component from the reference coordinate R0 of the imaging point P402. Let D be the distance between the microlens array 42 and the surface of the wafer W.

  The light ray 601 is incident at an inclination angle θ from a direction 602 orthogonal to the imaging surface 41a, and forms an imaging point P402 on the imaging surface 41a. As described with reference to FIG. 6, the wavefront angle θ of the light ray P601 is obtained from the deviation of the Y component of the imaging point P402 with respect to the reference imaging point P401. Since the wavefront angle θ is an angle formed by the straight line orthogonal to the light ray P601 and the imaging surface 41a, the wavefront angle θ represents the inclination angle θ. Therefore, the coordinate b of the Y component from the reference coordinate R0 of the position P602 on the surface of the wafer W of the light beam 601 is b = a−Dtanθ. Note that the coordinates of the X component at the position P602 may be coordinates corresponding to the block in which the imaging point P402 appears.

  Therefore, the calculation unit 80 can obtain the coordinates of the Y component at the position P602 from b = a−Dtanθ. Then, the calculation unit 80 obtains the coordinates of the position of the surface of the wafer W corresponding to all the image forming points P402 of the light beam 602 emitted from the second light source 12, and thereby the silhouette image of the edge received by the image sensor 41. And the edge position is obtained from the corrected silhouette image. Here, as a method for calculating the edge position, for example, a technique may be adopted in which the peak position is detected from the corrected silhouette image and the coordinates of the position are used as the edge position.

  In the above description, the light beam 102a from the second light source 12 is described as the light beam 601, but the same is true for the light beam 101a of the first light source 11.

  Therefore, the calculation unit 80 may obtain the coordinates of the position on the surface of the wafer W from the reference coordinates R0 and calculate the surface shape data for the light beam 101a as well as the light beam 102a. Here, the surface shape data has a data structure in which height data indicating the height of each position of the roll-off portion is arranged in a predetermined row × predetermined column. Specifically, as shown in FIG. 5A, since height data is obtained for each imaging point 41c from the measurement image P301, the surface shape data has a height corresponding to the imaging point 41c. It has a data structure in which data is arranged.

  As shown in FIG. 8, the inclination φ of the position P602 is represented by φ = (1/2) · θ. Here, the inclination of the position P602 indicates a microscopic inclination of the wafer W, and indicates an angle with respect to the global inclination of the surface of the wafer W indicated by a dotted line. Further, the coordinates of the Y component at the position P602 are represented by coordinates b. Therefore, the calculation unit 80 obtains the coordinates of the Y component of the position P602 when the coordinates of the Y component of the edge position are used as the reference coordinates. Then, the calculation unit 80 integrates φ with respect to Y in the entire region of the roll-off unit in one line parallel to the Y axis, and obtains height data Φ (= ∫φ (Y) dY). The calculation unit 80 performs this integration on all lines parallel to the Y axis, and obtains surface shape data in the entire area of the roll-off portion of the wafer W.

  In the present embodiment, the surface shape and the edge of the roll-off portion are measured using one SH sensor 13. Then, the surface shape data of the roll-off part is calculated using the edge position as a reference coordinate. Therefore, it is possible to calculate surface shape data in which the distance from the edge position is accurately reflected.

  In the above description, the separation methods 1 and 2 have been described as the separation methods of the light 101 and 102, but other separation methods may be adopted. This will be described below.

・ Separation method 3
In the separation method 3, the light 101 emitted from the first light source 11 is polarized in the first polarization direction, the light 102 emitted from the second light source 12 is polarized in the second polarization direction, and light is emitted based on the polarization direction. This is a technique for separating 101 and light 102.

  FIG. 9A is a diagram illustrating an example of a hardware configuration of the shape measuring apparatus when the separation method 3 is applied, and FIG. 9B is a diagram of the polarization selection filter 900 viewed from the BB direction.

  A polarizing filter 801 (an example of a first polarizing filter) is disposed in front of the first light source 11. The polarizing filter 801 polarizes the light 101 in the first polarization direction. In front of the second light source 12, a polarizing filter 802 (an example of a second polarizing filter) is disposed. The polarizing filter 802 polarizes the light 102 in the second polarization direction. Here, the first polarization direction and the second polarization direction are shifted by 90 degrees.

  A polarization selection filter 900 is provided in front of the SH sensor 13. As illustrated in FIG. 9B, the polarization selection filter 900 includes a filter region 901 (an example of a first filter region) and a filter region 902 (an example of a second filter region). In FIG. 9, the Y direction corresponds to the radial direction of the wafer W. The X direction is a direction orthogonal to the Y direction.

  The filter region 901 transmits the light 101 in the first polarization direction that has passed through the polarizing filter 801 and guides it to the SH sensor 13. The filter region 902 transmits the light 102 in the second polarization direction that has passed through the polarizing filter 802 and guides it to the SH sensor 13.

  The light 101 reflected by the roll-off unit is light in the first polarization direction. Therefore, the light 101 that reaches the filter region 901 enters the SH sensor 13, but the light 101 that reaches the filter region 902 cannot pass through the filter region 901 and does not enter the SH sensor 13.

  On the other hand, the light 102 emitted from the second light source 12 is light in the second polarization direction. Therefore, the light 102 that reaches the filter region 902 enters the SH sensor 13, but the light 102 that reaches the filter region 901 cannot pass through the filter region 901 and does not enter the SH sensor 13.

  The light 102 is an edge silhouette image because part of the light is shielded by the wafer W. Therefore, in FIG. 9B, the filter region 902 receives light only in the region shown on the right side, and an edge silhouette image appears. Thereby, the SH sensor 13 can measure the edge of the wafer W. In FIG. 9B, the colors of the lights 101 and 102 are displayed in different colors, but in actuality, only the polarization direction is different and the colors are not different.

  In the separation methods 1 to 3, since the first and second light sources 11 and 12 can be turned on simultaneously and the surface shape and the edge of the roll-off part can be measured simultaneously, the measurement time can be increased. Therefore, it is useful when a moving wafer W is a measurement target.

・ Separation method 4
The separation method 4 is a method of separating the light 101 of the first light source 11 and the light 102 of the second light source 12 by shifting the lighting timing of the first light source 11 and the second light source 12.

  FIG. 10 is a diagram illustrating an example of a hardware configuration of the shape measuring apparatus when the separation method 4 is employed. In the separation method 4, a lighting control unit 90 is further provided. A shutter 921 is disposed in front of the first light source 11. A shutter 922 is disposed in front of the second light source 12. As the shutters 921 and 922, electric or mechanical shutters can be employed. First, the lighting control unit 90 lights both the first and second light sources 11 and 12. When the lighting control unit 90 causes the SH sensor 13 to measure the surface shape of the roll-off unit, the lighting control unit 90 closes the shutter 922 and opens the shutter 921.

  On the other hand, when the lighting control unit 90 causes the SH sensor 13 to measure an edge, the lighting control unit 90 closes the shutter 921 and opens the shutter 922.

  When the shutter 922 is closed and the shutter 921 is opened, the calculation unit 80 calculates surface shape data of the roll-off unit from the measurement image measured by the SH sensor 13. On the other hand, when the shutter 921 is closed and the shutter 922 is opened, the calculation unit 80 calculates the edge position from the measurement image measured by the SH sensor 13. Then, the calculation unit 80 obtains surface coordinate shape data using the edge position as a reference coordinate.

  In the above description, the shutters 921 and 922 are provided, but may be omitted. In this case, the lighting control unit 90 may turn on the first light source 11 and turn off the second light source 12 when the SH sensor 13 measures the surface shape of the roll-off unit. On the other hand, when the SH sensor 13 is to measure an edge, the second light source 12 may be turned on and the first light source 11 may be turned off.

  In the separation method 4, it is possible to cause one SH sensor 13 to perform surface shape measurement and edge measurement without providing a filter or the like for spatially separating the light 101 and 102 in front of the SH sensor 13. it can.

11 1st light source 12 2nd light source 13 SH sensor 14 Half mirror (light guide part)
41 Image sensor 42 Micro lens array 43 Wavelength selection filter 80 Calculation unit 90 Lighting control unit 101, 102 Light 101a, 102a Light beam 431, 432 Filter region (first filter region, second filter region)
801, 802 Polarization filter 900 Polarization selection filter 901, 902 Filter region (first filter region, second filter region)

Claims (7)

A shape measuring device for measuring the surface shape of a predetermined measurement region on the surface of a wafer,
A Shack-Hartmann-type SH sensor for measuring the surface shape of the wafer;
A first light source that illuminates the measurement area;
A second light source disposed on the opposite side of the wafer with respect to the SH sensor, illuminating an edge of the wafer, and causing a silhouette image of the edge to be incident on the SH sensor ;
A shape measuring apparatus including: a light guide unit that causes reflected light from the measurement region to enter the SH sensor and light that has been applied to the edge to enter the SH sensor. The first and second light sources irradiate light having different wavelengths,
A first filter region that transmits light of a wavelength irradiated from the first light source and guides it to the SH sensor; and a second filter region that transmits light of a wavelength irradiated from the second light source and guides it to the SH sensor. DOO further comprising shape measuring apparatus according to claim 1, wherein a wavelength selective filter comprising a. The first and second light sources irradiate light having different wavelengths,
The SH sensor, shape measurement according to claim 1, wherein the pixel having a light receiving sensitivity to the light from the pixel and the second light source having a light-receiving sensitivity to light from the first light source comprises a color imaging device which is at least arranged apparatus. A first polarizing filter that polarizes light emitted from the first light source in a first polarization direction;
A second polarizing filter that polarizes light emitted from the second light source in a second polarization direction;
A polarization selection filter further comprising: a first filter region that transmits light in the first polarization direction and guides it to the SH sensor; and a second filter region that transmits light in the second polarization direction and guides it to the SH sensor. shape measuring device according to claim 1, further comprising. The first, further comprising Claim 1 shape measuring apparatus according to the lighting controller to light at different timings to the second light source. The light beam incident on the SH sensor from the second light source is traced, the position of the light beam on the wafer is detected, the edge position is detected based on the detected position, and the first light source is transmitted to the SH sensor. track rays incident, the shape measuring apparatus according to any one of claims 1 to 5, further comprising a calculation unit for detecting the position on the wafer of the light beam when the edge position as the reference coordinates. The measurement region, the shape measuring apparatus according to any one of claims 1 to 6, which is a roll-off portion.

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