JP5464932B2 - Shape measuring method and shape measuring apparatus - Google Patents

Description

  The present invention relates to an optical element having a step such as a diffraction grating, and a shape measuring method for measuring the surface shape of a surface to be measured such as a molding die for producing such an optical element. And a shape measuring apparatus.

  With the improvement in performance of various optical devices such as imaging cameras, laser beam printers, copiers, and semiconductor exposure devices, demands for optical elements incorporated in these optical devices are becoming increasingly sophisticated. A technique for measuring the shape of a surface to be measured using such an optical element or a molding die for manufacturing the optical element as a measurement object is known (see Patent Document 1). In this type of shape measurement method, first, measurement data is obtained by measuring a three-dimensional position of a probe by scanning a contact-type probe along the surface to be measured. The probe is measured according to scanning conditions such as a pre-designated needle pressure, scanning speed, scanning path, and measurement data sampling interval. After all scanning of the surface to be measured is completed, measurement data is analyzed to obtain surface shape data. In recent years, an optical element in which a diffraction grating using a light diffraction phenomenon is formed is used in various products. Many optical elements having such a diffraction grating have a structure in which irregularities of several μm to several tens of μm are regularly arranged on the surface to generate a diffraction phenomenon by adding a phase difference of light. . In order to measure the surface shape of an optical element or a molding die for manufacturing the optical element, a scanning type shape measuring device using a contact probe is used to directly measure the uneven step. ing.

JP 2001-141443 A

  By the way, in order to measure the surface shape with high resolution, it is preferable to use a probe having a spherical tip having a small curvature radius. However, as the curvature radius decreases, the contact area between the probe and the surface to be measured decreases. Therefore, even if the needle pressure is the same, the contact stress increases. Since an increase in contact stress leads to generation of scratches on the surface to be measured, it is required to make the needle pressure as small as possible. In addition, it is known that in order to perform highly accurate measurement, it is better to reduce the needle pressure and increase the measurement sensitivity.

  However, when scanning a surface to be measured having a step of several μm to several tens of μm, such as an optical element on which a diffraction grating is formed, if the stylus pressure is reduced, the probe jumps easily and the measurement data is lost. It is likely to become unstable. Therefore, in order to perform stable scanning while keeping the needle pressure small over the entire surface to be measured, the scanning speed of the probe must be slowed down over the entire surface to be measured, which greatly increases the measurement time. There was a problem.

  An object of the present invention is to provide a shape measuring method and a shape measuring apparatus capable of stably measuring a surface shape of a surface to be measured on which a step is formed with high accuracy and reducing a measuring time.

In the shape measuring method for measuring the surface shape of the surface to be measured of the object to be measured, the first probe is scanned with respect to the surface to be measured under a predetermined scanning condition, and the three-dimensional position of the first probe is measured. A first scanning step for obtaining measurement data including data, and a step position calculation step for calculating step position data indicating a step position of the measured surface based on the measurement data obtained in the first scanning step; Based on the step position data obtained in the step position calculation step, the scanning conditions of the second probe that can be measured with higher resolution than the first probe are the positions near the step on the measured surface and other than the vicinity of the step. and scanning condition determining step of determining in correspondence to the position of the is scanned by the scanning condition of the second probe was determined by the scanning condition determining step to the measurement surface, 3 of the second probe A second scanning step for obtaining measurement data including original position data, and a surface shape calculation step for calculating surface shape data indicating the surface shape of the surface to be measured based on the measurement data obtained in the second scanning step. It is characterized by comprising.

In the shape measuring apparatus for measuring the surface shape of the surface to be measured of the object to be measured, the present invention is movable in a three-dimensional direction with respect to the base holding the object to be measured. A probe moving mechanism in which any one of the second probes that can be measured with higher resolution than one probe is selectively mounted, and a scanning condition that designates the first probe in advance with respect to the surface to be measured A step position calculation unit for calculating step position data indicating the step position of the measurement target surface based on measurement data including the three-dimensional position data of the first probe obtained by scanning with the first probe; the scanning conditions based on the step position data obtained at the step position calculating unit, the scanning conditions determined for determining in correspondence to the position other than the position between the step near the step vicinity on the surface to be measured And measurement data including three-dimensional position data of the second probe obtained by scanning the second probe with the scanning condition determined by the scanning condition determining unit with respect to the measurement surface. And a surface shape calculation unit that calculates surface shape data indicating the surface shape of the measurement surface by calculation.

In the shape measuring apparatus for measuring the surface shape of the surface to be measured of the object to be measured, the present invention is movable in a three-dimensional direction with respect to the base holding the object to be measured. A probe moving mechanism in which second probes that can be measured with higher resolution than one probe are sequentially mounted from the downstream to the upstream in the scanning direction, and the first probe is scanned with respect to the surface to be measured under scanning conditions specified in advance. A step position calculation unit that obtains step position data indicating the step position of the surface to be measured by calculation based on measurement data including the three-dimensional position data of the first probe obtained by scanning; and a scanning condition of the second probe , said step position based on the step position data obtained by the arithmetic unit, the scanning condition determining unit that determines in correspondence to the position other than the position between the step near the step vicinity on the surface to be measured Based on the measurement data including the three-dimensional position data of the second probe obtained by scanning the second probe with the scanning condition determined by the scanning condition determining unit with respect to the measured surface, the measured surface And a surface shape calculation unit that obtains surface shape data indicating the surface shape of the surface by calculation.

According to the present invention, since the scanning condition of the second probe that can be measured with high resolution is determined based on the step position data, it is possible to measure the shape with high accuracy and stability. Since the scanning condition of the second probe is determined according to the position on the surface to be measured , the measurement time can be shortened compared with the case where the scanning condition is constant regardless of the position on the surface to be measured.

It is explanatory drawing which shows schematic structure of the shape measuring apparatus which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the front-end | tip part of a 1st probe. It is explanatory drawing of the operation | movement based on the scanning condition of a 2nd probe, (a) is explanatory drawing which shows the front-end | tip part of a 2nd probe, (b) is explanatory drawing which shows the sampling interval of measurement data. It is a flowchart which shows operation | movement of each part of the shape measuring apparatus which concerns on 1st Embodiment of this invention. It is a figure explaining the relationship between the level | step difference on a to-be-measured object, and a scanning path | route, (a) is a figure which shows the case where a to-be-measured object is square shape, (b) is a case where a to-be-measured object is circular shape. It is explanatory drawing which shows schematic structure of the shape measuring apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of each part of the shape measuring apparatus which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the front-end | tip part of the 1st probe of the shape measuring apparatus which concerns on 3rd Embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
The shape measuring apparatus 100 shown in FIG. 1 measures the surface shape of the surface 2a to be measured 2 of the device 2 to be measured. The DUT 2 is installed on the base 3. The base 3 is preferably provided with a vibration isolation function in order to suppress the influence of vibration from the floor. The shape measuring apparatus 100 includes a probe moving mechanism 40 to which any one of the first probe 1A and the second probe 1B (the first probe 1A in FIG. 1) is selectively attached.

  The probe moving mechanism 40 includes an XY stage 8 and a Z stage 5, and can move in a three-dimensional direction with respect to the base 3 that holds the DUT 2. More specifically, the XY stage 8 is supported so as to be movable in the horizontal direction (X and Y axis directions) along a plane parallel to the base 3. A drive unit 9 that drives the XY stage 8 in the horizontal direction is attached to the XY stage 8. The Z stage 5 is attached to the XY stage 8 via the housing 7 and moves in the horizontal direction together with the XY stage 8. The Z stage 5 is configured so that one probe 1A or 1B can be mounted, and the probe 1A (1B) is supported so as to be movable in a direction perpendicular to the base 3 (Z-axis direction). A force generator 6 is attached to the Z stage 5 so that the weight of the probe 1A (1B) can be compensated and the probe 1A (1B) can be pressed against the surface 2a to be measured with a specified needle pressure. The force generating unit 6 includes a permanent magnet and a coil (not shown). The permanent magnet is disposed on the probe shaft, the coil is disposed on the housing of the Z stage 5, and the probe 1A (1B) is moved in the Z-axis direction by energizing the coil. Can be driven. A mirror 4 is attached to the rear end of the probe 1A (1B), and the three-dimensional position and orientation of the probe 1A (1B) can be measured using an unillustrated interferometer or the like.

  The shape measuring apparatus 100 includes a control device 50 that controls the movement of the probe 1A (1B) by controlling the driving of the XY stage 8 by the driving unit 9 and the driving of the Z stage 5 by the force generating unit 6. The control device 50 includes a data sampling unit 10, a step position calculation unit 11, a scanning condition determination unit 12, and a surface shape calculation unit 13, and detailed operations of each unit will be described later.

  As shown in FIG. 2, the first probe 1A is a contact probe having a spherical tip 1Aa. The spherical tip 1Aa of the first probe 1A is formed with a radius of curvature R that is at least twice as high as the step height D of the measured surface 2a.

  Here, if the radius of curvature R is smaller than about 1 mm, the probe shaft 1Ab also needs to be thinned, so that the rigidity of the probe shaft 1Ab is weakened, and the spherical tip 1Aa is brought closer to the spherical body. It becomes difficult to produce a large opening angle θ. In general, the curvature and shape of the arc part can be corrected by measuring a true sphere, etc., but it is difficult to correct the shape of the part that is not an arc. The shape cannot be reconstructed. That is, in order to accurately measure the measured surface 2a, it is necessary to bring the arc portion of the spherical tip 1Aa into contact with the measured surface 2a. When the object to be measured 2 is installed so that the wall of the step is vertical when the spherical tip 1Aa is formed with a radius of curvature R that is twice the height D of the step and the opening angle θ is set to 120 degrees. Contact at the end of the arc portion. For this reason, if the opening angle θ of the arc portion is in the vicinity of 120 degrees, for example, about 130 degrees, the measurement can be performed by contacting only the arc portion. Further, if the spherical tip 1Aa is formed with a radius of curvature R that is at least twice the step height D of the surface 2a to be measured, when the opening angle θ of the arc portion is 120 degrees, only the arc portion can be contacted. Can be measured. Note that only the arc portion can be scanned by tilting the object to be measured and tilting the stepped wall.

  FIG. 2 shows a locus L1 at the center of the spherical tip 1Aa of the first probe 1A when the first probe 1A having a radius of curvature R twice the height D of the step is used. Yes. If there is no jump or the like and ideally follow the step, only the arc portion of the spherical tip 1Aa contacts and scans the surface 2a to be measured, and the locus L1 at the center of the spherical tip 1Aa of the probe 1A has a step. An arc having the same radius of curvature as the radius of curvature R of the probe 1A is drawn at the apex. It is possible to obtain the three-dimensional position of the step from such a geometrical relationship. When acquiring the three-dimensional position of the step, the radius of curvature R of the spherical tip 1Aa of the probe 1A is set to the height of the step. By setting it to twice or more of D, there is an effect that stable scanning can be performed with respect to the step.

  As shown in FIG. 3A, the second probe 1B is a contact type probe having a spherical tip 1Ba. In the second probe 1B, the spherical tip 1Ba has a smaller radius of curvature r than the spherical tip 1Aa of the first probe 1A, and can be measured with higher resolution than the first probe 1A. More specifically, the spherical tip 1Ba of the second probe 1B is formed to have a radius of curvature r smaller than the step height D of the measured surface 2a.

  Next, the operation of each part of the control device 50 of the surface measuring apparatus 100 will be described with reference to the flowchart shown in FIG. First, it is assumed that the first probe 1 </ b> A is attached to the Z stage 5 of the probe moving mechanism 40. The scanning condition determination unit 12 performs scanning measurement on the surface to be measured (S101: first scanning step). More specifically, the scanning condition determination unit 12 causes the first probe 1A to scan the measurement target surface 2a under scanning conditions specified in advance. The scanning conditions of the first probe 1A are the conditions of the needle pressure, scanning speed, scanning path, and measurement data sampling interval of the first probe 1A. The conditions of the needle pressure, the scanning speed, and the sampling interval of the measurement data in the scanning conditions of the first probe 1A are determined to be constant conditions at each position on the measurement surface 2a. More specifically, the predetermined needle pressure, the predetermined scanning speed, and the predetermined sampling interval are determined in advance regardless of the position of the measurement surface 2a. Here, the predetermined needle pressure and the predetermined scanning speed are set to values that do not jump at a step when the first probe 1A is scanned. The scanning path condition in the scanning condition of the first probe 1A is also determined as a predetermined scanning path specified in advance.

  The scanning condition determination unit 12 controls the driving unit 9 and the force generation unit 6 to scan the first probe 1A at a predetermined needle pressure and a predetermined scanning speed specified in advance. Then, the scanning condition determination unit 12 controls the data sampling unit 10 to cause the data sampling unit 10 to acquire measurement data at a predetermined sampling interval specified in advance. This measurement data includes at least three-dimensional position data of the first probe 1A. In the first embodiment, the measurement data includes the three-dimensional position data of the first probe 1A and the attitude data of the first probe 1A. The scanning condition determination unit 12 scans the first probe 1A over the entire surface to be measured 2a, and the measurement data of the entire surface to be measured 2a is stored in the data sampling unit 10. In the first embodiment, since the first probe 1A is scanned at a predetermined scanning speed regardless of the position near the step or the position other than the step vicinity, measurement data can be acquired in a short measurement time. It is.

  Next, after the measurement of the measurement target surface 2 a, the data sampling unit 10 transmits measurement data that is a measurement result of the entire measurement target surface 2 a to the step position calculation unit 11. The step position calculation unit 11 calculates step position data indicating the step position on the measurement target surface 2a based on the measurement data obtained by the data sampling unit 10 in step S101 (S102: step position calculation step). Here, in step S101, the first probe 1A is scanned on the surface to be measured 2a at a predetermined needle pressure and a predetermined scanning speed, so that it does not jump at the level difference of the surface to be measured 2a. In addition, as shown in FIG. 2, the first probe 1A has a radius R of curvature of the spherical tip 1Aa that is not less than twice the height D of the step, and therefore the locus L1 of the center of the spherical tip 1Aa of the first probe 1A. , An arc having the same curvature radius as the curvature radius R of the probe 1A is drawn at the top of the step. Therefore, in this step S102, the step position can be accurately obtained from the locus L1. The step position data obtained by the step position calculation unit 11 in step S102 is sent to the scanning condition determination unit 12.

  Next, the second probe 1B is mounted on the Z stage 5 of the probe moving mechanism 40 in place of the first probe 1A. The scanning condition determining unit 12 determines the scanning condition of the second probe 1B corresponding to the position on the measurement target surface 2a based on the step position data obtained by the step position calculating unit 11 in step S102 (S103: Scanning condition determination step). Here, as scanning conditions for the second probe 1B, conditions of needle pressure, scanning speed, scanning path, and sampling interval of measurement data are determined.

  In the first embodiment, the scanning condition is determined according to the position in the vicinity of the step of the measured surface 2a and the position other than the vicinity of the step. Specifically, as shown in FIG. 3A, the scanning condition is switched between the first scanning condition 1 at a position other than the vicinity of the step and the second scanning condition 2 at a position near the step. Note that the number of scanning conditions to be switched may be increased. Further, the position in the vicinity of the step of the measurement surface 2a and the position other than the vicinity of the step are determined based on the step position data.

  As the first scanning condition 1 at a position other than the vicinity of the step, the needle pressure is low, the scanning speed is high, and the sampling interval of the measurement data of the second probe 1B is wide. That is, the needle pressure is determined as the first needle pressure, the scanning speed is determined as the first scanning speed, and the sampling interval is determined as the first sampling interval.

  As the second scanning condition 2 near the step, the needle pressure is high, the scanning speed is low, and the sampling interval of the measurement data of the second probe 1B is preferably narrowed. That is, the needle pressure is a second needle pressure higher than the first needle pressure at a position other than the vicinity of the step, the scanning speed is a second scanning speed lower than the first scanning speed at a position other than the vicinity of the step, and the sampling interval is other than the vicinity of the step. The second sampling interval is determined to be narrower than the first sampling interval at the position.

  As described above, as the scanning condition of the second probe 1B, the scanning speed at the position of the step on the measured surface 2a is determined to be the second scanning speed that is slower than the first scanning speed at the position other than the step. The step following ability is improved, and the three-dimensional position of the second probe 1B can be accurately measured. In addition, at a position other than the step, the measurement time can be shortened by determining that the scanning speed is the first scanning speed higher than the second scanning speed.

  Further, as the scanning condition of the second probe 1B, the needle pressure at the position of the step on the surface to be measured 2a is determined to be the second needle pressure higher than the first needle pressure at the position other than the step. Thus, the three-dimensional position of the second probe 1B can be accurately measured. In addition, the measurement sensitivity can be increased by determining the needle pressure to be the first needle pressure lower than the second needle pressure at positions other than the step.

  The data sampling unit 10 acquires the measurement data at the determined first sampling interval or the second sampling interval, whereby the measurement data is obtained as a discrete data string d as shown in FIG. FIG. 3B shows a fitting curve L2 based on the acquired data string d. Here, in order to reconstruct the step shape from the discrete data string d, a sufficient number of data points is necessary, and if the number of data points is small in the vicinity of the step, it cannot be accurately reconstructed. However, if the data sampling interval is reduced in all aspects, the number of data points becomes enormous and the analysis time becomes very long. Therefore, in the first embodiment, the scanning condition determination unit 12 sets the sampling interval at the position of the step on the measurement surface 2a as the scanning condition of the second probe 1B from the first sampling interval at a position other than the step. Is determined to be a narrow second sampling interval.

  In this way, by changing the sampling interval of the measurement data between the position near the step and the position other than near the step, the calculation time can be shortened while maintaining the accuracy (reconstruction accuracy) of the measured surface shape. is there. And by determining the sampling interval of measurement data at the position near the step as the second sampling interval narrower than the first sampling interval, the number of sampling data increases near the step, and stable measurement data due to the averaging effect can be obtained. Can do. In addition, since the sampling interval of the measurement data is determined to be the first sampling interval wider than the second sampling interval at a position other than the step, the number of sampling data is reduced at positions other than the vicinity of the step, and the data calculation time is shortened. be able to.

  Next, the scanning condition determining unit 12 controls the force generating unit 6 and the driving unit 9 so as to scan and measure the second probe 1B with respect to the measurement target surface 2a under the scanning condition determined in step S103, and the data sampling unit. 10 is controlled (S104: second scanning step). That is, the scanning condition determination unit 12 controls the force generation unit 6 so that the second probe 1B has the determined needle pressure, and controls the driving unit 9 so that the determined scanning speed is achieved. Under the control of the scanning condition determination unit 12, the data sampling unit 10 acquires measurement data of the second probe 1B. The measurement data includes at least the three-dimensional position data of the second probe 1B. In the first embodiment, the measurement data includes the three-dimensional position data of the second probe 1B and the attitude data of the second probe 1B.

  Here, the scanning condition determination unit 12 controls the driving unit 9 so as to scan the second probe 1B in a direction orthogonal to the ridge line of the step of the measurement target surface 2a based on the step position data calculated in step S102. To do. FIG. 5 (a) shows a rectangular object to be measured 201 in which step ridges 201a are arranged in parallel. In such an object to be measured 201, scanning is performed in a direction orthogonal to the step ridge line 201a from the scanning start point S1, and after scanning to the end of the object to be measured 201, it is shifted in a direction parallel to the ridge line 201a. The return path is scanned in parallel with the forward path. This is repeated, and the scanning is finished at the scanning end point E1. That is, in step S103, the scanning path 201b shown in FIG. 5A is determined for the object to be measured 201 as the scanning condition of the second probe 1B. In step S104, the scanning condition determination unit 12 scans the second probe 1B along the scanning path 201b.

  FIG. 5B illustrates a circular object to be measured 202 in which stepped ridge lines 202a are arranged concentrically. In such an object to be measured 202, scanning is performed in a direction from the scanning start point S2 toward the center of the concentric circle, and after passing through the center to the end of the circle, the scanning is performed in a direction parallel to the ridgeline 202a and again the concentric circle. Scan in the direction toward the center. This is repeated and the scanning is finished at the scanning end point E2. That is, in step S103, the scanning path 202b shown in FIG. 5B is determined for the object to be measured 202 as the scanning condition of the second probe 1B. In step S104, the scanning condition determination unit 12 scans the second probe 1B along the scanning path 202b.

  In addition to these step arrangements, various step arrangements can be considered. In any case, the scanning path is determined so as to scan in a direction orthogonal to the ridge line of the step. Actually, there is an installation error or a processing error of the object to be measured, but in the first embodiment, the scanning path is obtained based on the step position data obtained in step S102. Even if there is a processing error, scanning can be performed in a direction orthogonal to the ridge line of the step. As described above, by scanning the second probe 1B in a direction orthogonal to the ridge line of the step, there is an effect of suppressing the sliding of the probe that occurs when the step is scanned obliquely.

  Next, the data sampling unit 10 transmits measurement data that is the result of measuring the entire surface to be measured 2 a to the surface shape calculation unit 13. The surface shape calculation unit 13 calculates surface shape data indicating the surface shape of the surface 2a to be measured based on the measurement data obtained by the data sampling unit 10 in step S104 (S105: surface shape calculation step). Thereby, the measurement of the surface shape is completed.

  As described above, according to the first embodiment, since the scanning condition of the second probe 1B that can be measured with high resolution is determined based on the step position data in step S103, a highly accurate and stable shape measurement is performed in step S104. It becomes possible. In step S103, since the scanning condition of the second probe 1B is determined according to the position of the measured surface 2a, the measurement time can be shortened compared to the case where the scanning condition is constant regardless of the position of the measured surface 2a. Can do.

[Second Embodiment]
Next, a shape measuring apparatus and a shape measuring method according to the second embodiment will be described. Note that in the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. In the second embodiment, the shape measuring apparatus 100A is movable in a three-dimensional direction with respect to the base 3 that holds the DUT 2, and two probes, the first probe 1A and the second probe 1B, are attached. The probe moving mechanism 40A is provided. The second probe 1B is disposed adjacent to the first probe 1A. The first probe 1A and the second probe 1B are sequentially attached to the probe moving mechanism 40A from the downstream in the scanning direction toward the upstream (from the downstream in the X-axis direction to the upstream in FIG. 6). That is, the 1st probe 1A is attached so that the front on the scanning path of the 2nd probe 1B may be scanned. By arranging these probes 1A and 1B, the second probe 1B can be scanned following the first probe 1A along the same scanning path as the first probe 1A.

  The probe moving mechanism 40A includes Z stages 5A and 5B corresponding to the two probes. The Z stages 5 </ b> A and 5 </ b> B are attached to the XY stage 8 via the housing 7, and move in the horizontal direction together with the XY stage 8. The Z stages 5A and 5B are configured to be able to mount the probes 1A and 1B, and are supported so that the probes 1A and 1B can move in a direction perpendicular to the base 3 (Z-axis direction). The Z stage 5A and 5B are provided with respective force generating portions 6A and 6B so that the weights of the probes 1A and 1B can be compensated and the probes 1A and 1B can be pressed against the measured surface 2a with a specified needle pressure. It has been. The force generators 6A and 6B are composed of permanent magnets and coils (not shown). The permanent magnets are disposed on the probe shaft, the coils are disposed on the housings of the Z stages 5A and 5B. It can be driven in the axial direction. Mirrors 4A and 4B are attached to the rear ends of the probes 1A and 1B, and the three-dimensional positions and orientations of the probes 1A and 1B can be measured using an unillustrated interferometer or the like.

  The shape measuring apparatus 100A includes a control device 50A that controls the movement of the probes 1A and 1B by controlling the driving of the XY stage 8 by the driving unit 9 and the driving of the Z stages 5A and 5B by the force generating units 6A and 6B. ing. The control device 50A includes data sampling units 10A and 10B, a step position calculation unit 11, a scanning condition determination unit 12, and a surface shape calculation unit 13.

  The data sampling units 10A and 10B acquire and store the measurement data of the corresponding probes 1A and 1B at the determined sampling intervals, respectively. With such a configuration, the first probe 1A and the second probe 1B can independently change the needle pressure and the sampling interval of the measurement data. In the second embodiment, the XY stage 8 is shared by the two probes 1A and 1B. However, the XY stage may be mounted on the two probes 1A and 1B, respectively. The scanning speed and scanning path can be changed independently.

  Next, the operation of each part of the control device 50A of the shape measuring apparatus 100A will be described with reference to the flowchart shown in FIG. In FIG. 7, scanning measurement on the measurement target surface 2a is started. First, the scanning condition determination unit 12 acquires measurement data of the first probe 1A (S201: first scanning step). More specifically, the scanning condition determination unit 12 causes the first probe 1A to scan the measurement target surface 2a under scanning conditions specified in advance. The scanning conditions of the first probe 1A are the conditions of the needle pressure of the first probe 1A, the scanning path, and the sampling interval of measurement data. The scanning condition determination unit 12 controls the force generation unit 6 to scan the first probe 1A with a predetermined needle pressure specified in advance. Then, the scanning condition determination unit 12 controls the data sampling unit 10A to cause the data sampling unit 10A to acquire measurement data at a predetermined sampling interval specified in advance. This measurement data includes at least three-dimensional position data of the first probe 1A. In the second embodiment, the measurement data includes the three-dimensional position data of the first probe 1A and the attitude data of the first probe 1A.

  Next, the data sampling unit 10A sequentially transmits the acquired measurement data to the step position calculation unit 11 during the scanning measurement of the measurement target surface 2a. The step position calculation unit 11 calculates the step position data indicating the step position on the measurement target surface 2a based on the measurement data obtained by the data sampling unit 10A in step S201 (step position calculation step). Then, the step position calculation unit 11 determines whether or not a step is detected based on the calculated step position data (S202). If a step is detected (S202: Yes), the step position data is stored in the data storage. Save (write) to s (S203).

  The scanning condition determination unit 12 determines the scanning condition of the second probe 1B in accordance with the position on the measurement surface 2a based on the step position data obtained by the step position calculation unit 11 (scanning condition determination step). . Here, as scanning conditions for the second probe 1B, conditions for needle pressure, scanning speed, and sampling interval of measurement data are determined. In the second embodiment, since the first probe 1A and the second probe 1B move on the same scanning path by the same XY stage 8, the scanning speeds of the first probe 1A and the second probe 1B are determined. The

  The scanning condition determination step will be specifically described. The scanning condition determination unit 12 reads the step position data from the data storage s, and determines whether or not the second probe 1B is in a position near the step (S205). Since the first probe 1A scans in front of the second probe 1B, the subsequent step position data around the second probe 1B is stored in the data storage s. When the scanning condition determination unit 12 determines that the second probe 1B is in a position near the step (S205: Yes), the scanning condition of the second probe 1B is the first scanning described in the first embodiment. The condition 1 is changed to the second scanning condition 2 (S206). When the scanning condition determination unit 12 determines that the second probe 1B is not at a position near the step, that is, at a position other than the vicinity of the step (S205: No), the scanning condition determination unit 12 sets the scanning condition of the second probe 1B to the first The scanning condition is returned to 1 (S207).

  Since the first probe 1A is attached in front of the second probe 1B, there is a time difference until the second probe 1B scans the portion scanned by the first probe 1A. By calculating the step position and determining the scanning condition within this time, the second probe 1B can change the scanning condition in the vicinity of the step. That is, the scanning condition determination unit 12 can control the scanning conditions by sending commands to the force generation unit 6B, the data sampling unit 10B, and the common driving unit 9 of the second probe 1B.

  The scanning condition determining unit 12 controls the force generating unit 6B and the driving unit 9 so as to scan and measure the second probe 1B with respect to the measurement target surface 2a under the scanning conditions determined in steps S206 and S207, and the data sampling unit 10B. To control. That is, the scanning condition determination unit 12 controls the force generation unit 6B so that the second probe 1B has the determined needle pressure, and controls the driving unit 9 so as to achieve the determined scanning speed. And the data sampling part 10B acquires the measurement data of the 2nd probe 1B under control of the scanning condition determination part 12 (S208: 2nd scanning process).

  Next, the scanning condition determination unit 12 determines whether or not the measurement of the entire surface to be measured 2a has been completed (S209). If the measurement has not been completed (S209: No), the process returns to step S201. Then, the processes of the first scanning step, the step position calculation step, the scanning condition determination step, and the second scanning step are repeatedly executed until the scanning of the entire surface to be measured 2a is completed. If the measurement is completed (S209: Yes), after the scanning measurement, surface shape data indicating the surface shape of the surface 2a to be measured is obtained by calculation based on the measured measurement data of the second probe 1B (S210: surface shape calculation step). ), The process is terminated.

  As described above, the second embodiment has the same effects as those of the first embodiment. Further, the first probe 1A that acquires the three-dimensional position of the step scans the front of the second probe 1B that measures the surface shape, thereby measuring the surface shape while acquiring the three-dimensional position data of the step. As a result, the measurement time can be shortened.

[Third Embodiment]
FIG. 8 is a view for explaining the state of the probe tip according to the third embodiment of the present invention. In the third embodiment, a non-contact type probe using optical means such as a laser is used as the first probe 101 in order to measure the step position. When a non-contact type probe is used, the light L is scattered at a place where the inclination of the measurement surface 2a is steep. By detecting the scattering of the light L, the step position can be measured. When acquiring the three-dimensional position of the step, using a non-contact type probe has an effect of performing stable scanning with respect to the step.

  Although the present invention has been described based on the above embodiment, the present invention is not limited to this. In the above embodiment, the case where the conditions of the needle pressure, the scanning speed, and the sampling interval are changed as the scanning conditions of the second probe has been described. However, the present invention is not limited to this, and at least one of these conditions May be changed.

1A, 101 First probe 1Aa Spherical tip 1B Second probe 1Ba Spherical tip 2 DUT 2a Surface to be measured 3 Base 11 Step position calculator 12 Scanning condition determiner 13 Surface shape calculator 40, 40A Probe moving mechanism 100 , 100A shape measuring device

Claims (17)

In the shape measuring method for measuring the surface shape of the surface to be measured of the object to be measured,
A first scanning step of scanning the measurement surface with a first probe under a scanning condition designated in advance, and obtaining measurement data including three-dimensional position data of the first probe;
A step position calculation step for calculating step position data indicating the step position of the measurement surface based on the measurement data obtained in the first scanning step;
Based on the step position data obtained in the step position calculation step, the scanning conditions of the second probe that can be measured with higher resolution than the first probe are the positions near the step on the measured surface and other than the vicinity of the step. Scanning condition determination step for determining each corresponding to the position of,
A second scanning step of scanning the second probe with the scanning condition determined in the scanning condition determining step to obtain measurement data including three-dimensional position data of the second probe;
A shape measurement method comprising: a surface shape calculation step for calculating surface shape data indicating a surface shape of the surface to be measured based on measurement data obtained in the second scanning step.   2. The shape measuring method according to claim 1, wherein the first probe is a contact probe having a spherical tip formed at a radius of curvature that is twice or more the height of the step of the surface to be measured. .   The shape measuring method according to claim 1, wherein the first probe is a non-contact type probe.   The said 2nd probe is a contact-type probe which has a spherical front-end | tip part formed in the curvature radius smaller than the height of the level | step difference of the said to-be-measured surface, It is any one of Claim 1 thru | or 3 characterized by the above-mentioned. Shape measurement method. The scanning condition of the second probe includes a scanning speed condition of the second probe,
In the scanning condition determining step, as the scanning condition of the second probe, the scanning speed at a position near the step on the surface to be measured is slower than the scanning speed at a position other than the vicinity of the step on the surface to be measured. The shape measuring method according to claim 4, wherein the shape measuring method is determined to be The scanning condition of the second probe includes a needle pressure condition of the second probe,
In the scanning condition determining step, as the scanning condition of the second probe, the needle pressure at a position near the step on the surface to be measured is set higher than the needle pressure at a position other than near the step on the surface to be measured. The shape measuring method according to claim 4 or 5, wherein the shape measuring method is determined so as to be. The scanning condition of the second probe includes a sampling interval condition of measurement data of the second probe,
In the scanning condition determining step, as the scanning condition of the second probe, the sampling interval at a position near the step on the surface to be measured is narrower than the sampling interval at a position other than the vicinity of the step on the surface to be measured. The shape measuring method according to claim 4, wherein the shape measuring method is determined so as to be.   The said 2nd scanning process scans the said 2nd probe in the direction orthogonal to the ridgeline of the level | step difference of the said to-be-measured surface based on the said level | step difference position data. The shape measuring method according to item. In the second scanning step, the second probe is scanned following the first probe along the same scanning path as the first probe,
The first scanning step, the step position calculation step, the scanning condition determination step, and the second scanning step are repeatedly executed until scanning of the entire surface to be measured is completed. The shape measuring method according to any one of 1 to 8 . In the shape measuring device for measuring the surface shape of the surface to be measured of the object to be measured,
One of the first probe and the second probe that can be measured with higher resolution than the first probe is selectively movable relative to the base holding the object to be measured. A probe moving mechanism attached to the
A step indicating a step position of the surface to be measured based on measurement data including three-dimensional position data of the first probe obtained by scanning the first surface with a scanning condition designated in advance on the surface to be measured. A step position calculation unit for calculating position data by calculation;
The scanning condition for the second probe, based on said stepped position data obtained at the step position calculating unit, the scanning condition determining in correspondence to the position and the position other than the step vicinity of the step near on the surface to be measured A decision unit;
Based on the measurement data including the three-dimensional position data of the second probe obtained by scanning the second probe with the scanning condition determined by the scanning condition determining unit with respect to the measured surface, A shape measuring apparatus comprising: a surface shape calculation unit that calculates surface shape data indicating a surface shape by calculation. In the shape measuring device for measuring the surface shape of the surface to be measured of the object to be measured,
The first probe and the second probe capable of measuring with higher resolution than the first probe are sequentially mounted from the downstream to the upstream in the scanning direction. A probe moving mechanism,
A step indicating a step position of the surface to be measured based on measurement data including three-dimensional position data of the first probe obtained by scanning the first surface with a scanning condition designated in advance on the surface to be measured. A step position calculation unit for calculating position data by calculation;
The scanning condition for the second probe, based on said stepped position data obtained at the step position calculating unit, the scanning condition determining in correspondence to the position and the position other than the step vicinity of the step near on the surface to be measured A decision unit;
Based on the measurement data including the three-dimensional position data of the second probe obtained by scanning the second probe with the scanning condition determined by the scanning condition determining unit with respect to the measured surface, A shape measuring apparatus comprising: a surface shape calculation unit that calculates surface shape data indicating a surface shape by calculation.   12. The shape according to claim 10, wherein the first probe is a contact probe having a spherical tip formed at a radius of curvature that is at least twice the height of the step of the surface to be measured. measuring device.   The shape measuring apparatus according to claim 10 or 11, wherein the first probe is a non-contact type probe.   The said 2nd probe is a contact-type probe which has a spherical front-end | tip part formed in the curvature radius smaller than the height of the level | step difference of the said to-be-measured surface, It is any one of Claim 10 thru | or 13 characterized by the above-mentioned. Shape measuring device.   The scanning pressure in the vicinity of the step of the second probe is set higher in the needle pressure than the scanning condition in a position other than the vicinity of the step of the second probe. Shape measuring device.   16. The scanning condition in the vicinity of the step of the second probe is set to be slower than the scanning condition in a position other than the vicinity of the step of the second probe. The shape measuring apparatus described.   15. The data sampling interval is set narrower in the scanning condition in the vicinity of the step of the second probe than in the scanning condition in a position other than the vicinity of the step of the second probe. The shape measuring apparatus according to any one of 16.

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