JP4557848B2 - Shape measuring method and shape measuring apparatus - Google Patents

Description

  The present invention relates to a shape measuring method and a shape measuring apparatus for measuring an object shape such as an optical element or an optical element molding die with high accuracy using a contact type or non-contact type probe.

  In recent years, with the improvement in performance of various optical devices such as imaging cameras, laser beam printers, copiers, and semiconductor exposure devices, the quality of optical elements such as lenses, mirrors, and prisms incorporated in these optical devices, especially the accuracy of shape, has been improved. Requirements are becoming more sophisticated. Specifically, the shape of the optical element is complicated from a conventional flat surface, spherical surface, or axisymmetric aspheric surface to a free-form surface, and the required shape accuracy of the optical surface becomes stricter as the shape becomes more complicated. .

  Under such circumstances, the shape measurement of the optical element or the mold for molding the optical element for manufacturing the optical element is possible because it is possible to measure a complicated shape such as a free-form surface, contact type or A shape measuring apparatus using a non-contact type probe is widely used. In particular, as a shape measuring apparatus that realizes a high degree of measurement accuracy, a three-dimensional shape measuring apparatus that performs measurement by scanning the probe with respect to the surface to be measured is used. A conventional technique for measuring the shape of a surface to be measured using a shape measuring device using an optical element or an optical element molding die as a measurement object will be described below.

  FIG. 6 is a flowchart showing a shape measuring method for measuring by scanning a surface to be measured with a contact or non-contact type probe. After the measurement is started in step S101, the shape of the surface to be measured is measured by scanning the surface to be measured with a contact or non-contact type probe in step S102. Here, the surface shape is measured in accordance with measurement conditions such as the number of measurement data points designated in advance, the probe scanning speed, and the measurement region. After all measurement of the shape of the surface to be measured is completed based on the designated measurement conditions, in step S103, the measurement data of the surface to be measured measured in step S102 is analyzed. In this measurement shape analysis, specifically, a position error, a posture error, a shape error, and the like of the measurement surface with respect to the design shape are analyzed as an error analysis with respect to the design shape of the measurement surface. After the measurement shape analysis is completed, the shape measurement of the surface to be measured is completed in step S104.

  FIG. 7 is a diagram for explaining the details of the surface shape measurement in step S102 shown in FIG. In the surface shape measurement according to the prior art, the probe follows the measurement path T specified by the measurement operator as a measurement condition in the control program of the shape measurement apparatus with respect to the measurement surface E of FIG. Measure the shape. Ts indicates the probe scanning start point, that is, the start point of the measurement path T, and Te indicates the probe scanning end point, that is, the end point of the measurement path T.

  In FIG. 7, in the XY orthogonal coordinate system, a raster scanning measurement path is shown in which the Y-axis direction is the main scanning direction of the probe and the X-axis direction is the sub-scanning direction. However, this measurement path is merely an example. is there. For example, surface shape measurement by raster scanning in which the main scanning direction of the probe is the X-axis direction in the figure and the sub-scanning direction is the Y-axis direction, or a surface in which the scanning path of the probe is concentric with the surface to be measured Shape measurements are also being implemented.

In the prior art, the probe scans all of the path from the start point Ts to the end point Te of the measurement path T specified in advance as the measurement condition, and after the surface shape measurement in step S102 in FIG. 6 is completed, the measurement is performed in step S103. Shape analysis is performed. An example of such a measurement procedure is the shape measurement method disclosed in Patent Document 1.
JP 2001-141443 A

  However, in the measurement method of measuring the shape of the surface to be measured by scanning the surface to be measured with a contact or non-contact type probe, the measurement may fail due to the following reasons.

(1) Measurement object instability (2) Measurement environment instability (3) Measurement area

  First, the case where measurement fails due to instability of the first object to be measured will be described in detail.

  When the object to be measured is an optical element such as a lens, prism, mirror, etc. manufactured by molding a plastic material or glass material using a mold, the molding material may be the end in the mold depending on the element shape and molding processing conditions. May not be filled. At this time, even if a desired shape is obtained with respect to the shape of the optical surface, the surface used as a reference when incorporating the optical element into the optical device, that is, the shape of the reference surface when defining the surface position of the optical surface, A desired shape may not be created due to insufficient filling of the molding material. When measuring the optical surface shape of an optical element made by molding or manufacturing a plastic material or glass material, the reference surface is generally used in combination with a shape measuring device, and a measuring jig or the like is used between the shape measuring device and the like. There is known a method of attaching an object to be measured to an apparatus via a device.

  Here, when the reference surface shape of the optical element that is the object to be measured is not created in a desired shape, it is difficult to stably attach the object to be measured to the measuring jig. At this time, in particular, in the measurement by the shape measuring device using the contact type probe that measures while bringing the probe into contact with the measurement surface, the measurement object is measured during the measurement due to the probe contact load received by the measurement object. It will move in the tool. The movement of the object to be measured in the measuring jig during the measurement means that the mounting position and posture of the object to be measured with respect to the shape measuring device changes. In such a case, highly accurate shape measurement is performed. Is impossible. As a result, the measurement fails, and it is necessary to readjust the mounting state of the object to be measured with respect to the measuring jig again and start the surface shape measurement from the beginning.

  In addition, when the object to be measured is directly attached to the shape measuring apparatus, or when attached to the shape measuring apparatus via the measuring jig, depending on the shape of the object to be measured and the method of holding the object to be measured, a so-called "cause of holding force" Holding deformation may occur in the object to be measured. The measured surface shape measured in the state where the holding deformation has occurred is measured as a measurement failure because the measured surface shape is different from the original surface shape of the object to be measured.

  Next, the case where measurement fails due to instability of the second measurement environment will be specifically described.

  In recent years, the shape accuracy required for optical elements is on the order of nm, and shape measurement accuracy on the order of nm is inevitably required for shape measurement of the surface to be measured. In such a high-accuracy measurement, when a contact-type or non-contact type probe scans the dust with dust on the surface to be measured in the order of μm, the probe is The shape is erroneously measured as the shape of the surface to be measured. In the shape measurement using a contact type probe, the dust adheres to the probe contact surface when the probe rides on the dust, and the shape of the surface to be measured on the subsequent measurement path is measured while dragging the dust. Sometimes it ends up. In any case, since an abnormal shape of μm order is obtained as a measurement shape with respect to the shape measurement accuracy of nm order, the measurement fails, and again the surface to be measured and the tip of the probe are washed again. It is necessary to carry out surface shape measurement.

  Other examples of instability in the measurement environment include temperature changes around the object to be measured. Due to the change in the ambient temperature of the object to be measured during the measurement, the object to be measured undergoes thermal deformation, and the deformation varies according to the change in the ambient temperature of the object to be measured. The deformation amount of the object to be measured sometimes becomes an error amount that cannot be ignored for the shape measurement accuracy of the nm order.

  In addition, in a shape measuring device using a contact or non-contact type probe, when a laser length measuring device is used to measure the coordinates of the shape of the surface to be measured, the length measurement data is obtained due to temperature changes around the object being measured, which is the measurement space. fluctuate. As a result, surface shape measurement data with a measurement error is obtained. In either case, the measurement failure is treated as described above.

  Finally, details of the measurement failure related to the third measurement region will be described.

  In surface shape measurement using the optical surface of the optical element as the surface to be measured, it is required to position and scan the probe with high accuracy with respect to the specified region in the measurement region. For example, when it is necessary to measure the entire optical effective surface, if a positional deviation occurs between the measurement region and the designated region, the measurement shape evaluation at the end of the optical surface cannot be performed, resulting in measurement failure and remeasurement. Such a positional deviation of the measurement area with respect to the designated area is caused by, for example, an input error with respect to measurement area information that is simply set in advance in the control computer of the shape measuring apparatus main body. In some cases, the actual optical surface is created in a position deviated from the position defined as the design shape with respect to the reference surface that defines the surface position and orientation of the optical surface in the optical element. In this case, conversely, as a result of designating the measurement region based on the design shape without making an input error, the measurement region is similarly displaced. In either case, the measurement shape evaluation described above cannot be performed, so that it is treated as a measurement failure.

  The above-mentioned measurement failures due to various causes are not possible in the shape measurement according to the prior art, during the measurement, that is, during the shape measurement by the contact type or non-contact type probe while the probe is scanning the surface to be measured. Confirmation is difficult. Therefore, after the probe scans to the end point of the measurement path and the surface shape measurement is completed, there is a common feature that it can be confirmed for the first time as a result of the measurement shape analysis.

  Unlike surface shape measurement using an interferometer, the shape measurement that measures the shape of the surface to be measured by scanning the surface to be measured with a contact or non-contact type probe, the size of the object to be measured, The measurement time may increase depending on the number of coordinate points to be measured. For example, when measuring the shape of the surface to be measured such that the size of the optical surface to be measured exceeds φ200 mm, a measurement time of 1 hour or more may be required depending on the probe scanning speed and the number of coordinate points to be measured. is there. When measuring a surface shape over a long period of time in this way, if a measurement failure occurs due to the above-mentioned various causes, the measurement failure can be confirmed because the measurement shape analysis performed after the completion of the measurement is completed as described above. This is the stage. If it becomes clear that the measurement has failed after the end of the long-time measurement, the cause of the measurement failure must be identified, the conditions must be corrected, and then the measurement must be performed again over the same time.

  That is, in the shape measurement according to the prior art, the measurement object including the remeasurement is included because the measurement failure cannot be determined until the surface shape measurement in which the probe follows the surface to be measured is completed. There is a risk of increasing the surface shape measurement tact with respect to.

  The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and in measuring the shape of an optical element or the like, the measurement failure due to various causes can be efficiently processed and the measurement tact time can be greatly shortened. An object is to provide a shape measuring method and a shape measuring apparatus.

In order to achieve the above object, the shape measuring method of the present invention is a shape measuring method for measuring the shape of a surface to be measured by two-dimensionally scanning a contact or non-contact type probe with respect to the object to be measured. A measurement process of setting measurement paths of at least three stages, measuring the shape of the surface to be measured by scanning the probe according to the set measurement paths of each stage, and obtaining measurement data of the measurement paths of each stage; After the shape measurement of at least one measurement path that is not the last step in the measurement process, the analysis result obtained by performing data analysis of at least one measurement data obtained before the shape measurement or obtained before the shape measurement based on the result of comparison to each other a plurality of analysis results of the data analysis was carried out of the measurement data of at least two of which were the analyzed result or the comparison result, previously constant If below the threshold that has been and continues the measuring step, when it exceeds the threshold value is characterized by having a selection step of selecting to kill, the.

In addition, the shape measuring apparatus of the present invention measures the shape of the surface to be measured by two-dimensionally scanning the contact object or non-contact type probe along the measurement path in at least three stages. In the shape measuring apparatus, the data analysis is performed on the measurement data obtained in the previous measurement path during the scanning of the probe along the measurement path after the second stage which is not the final stage, and the measured object Calculates the setting error of the object to be measured based on a comparison result obtained by comparing at least two of the shape error with respect to the design shape of the surface or the analysis result obtained by performing data analysis of a plurality of measurement data obtained before the shape measurement. First calculating means for performing, and second calculating means for determining whether the measurement is good or not based on the shape error or setting error calculated by the first calculating means, Serial based on the determination result by the second calculation means, wherein the analysis result or the comparison result, and continue the measurement process in the case of below a predetermined threshold, when exceeding the threshold value is selected to be killed It is characterized by that.

  With respect to the scanning path of the contact type or non-contact type probe that scans the surface to be measured, the interval from the probe scanning start point to the scanning end point is set in at least two measurement paths. When the probe scan for the measurement path at each stage is completed, data analysis is performed on the measurement data acquired so far, and the quality of the measurement is determined based on the result of the data analysis. Therefore, it is possible to determine the success / failure of the measurement without completing the probe scan of all the measurement paths, stop the measurement immediately in the case of the measurement failure, and perform the remeasurement after adjusting the measurement conditions again. .

  Compared to the case where measurement failure cannot be confirmed until probe scanning for all measurement paths is completed, the measurement tact time can be greatly reduced.

  The best mode for carrying out the present invention will be described with reference to the drawings.

  1 to 3 show the first embodiment. The shape measuring apparatus of FIG. 1 includes a contact type probe 101, and a probe tip sphere 102 having a spherical shape is provided at the tip of the probe 101. The probe tip sphere 102 may have a structure in which a sphere is arranged with respect to the probe 101 by some fixing method, or may be an integral structure with the contact probe 101.

  The probe 101 is supported so as to be relatively movable in the X, Y, and Z axis directions while bringing the probe tip sphere 102 into contact with the object 103 to be measured. This support structure includes an X-axis stage 201, a Y-axis stage 202, and a Z-axis stage 203, and the Z-axis stage 203 constitutes a moving stage that holds and moves the probe 101. Each axis stage 201, 202, 203 is driven by a driving motor 204, 205, 206, respectively, and in measuring the shape of the object 103 to be measured, the probe tip sphere 102 is brought into contact with the surface 104 to be measured of the object 103 to be measured. While moving relative. At this time, the movement locus of the center position of the probe tip sphere 102 is detected by a position detection sensor (not shown), and the movement locus data is transferred to the data sampling device 209 and sampled. As the position detection sensor, a laser length measuring device, a linear scale encoder, or the like is used as a position detection method for realizing highly accurate shape measurement. However, the position detection sensor is not limited to these position detection sensors.

  The drive motors 204, 205, and 206 are driven by the power supply based on the drive control signals from the XY-axis controller 207 and the Z-axis controller 208 to the drive motors 204, 205, and 206 for each axis. Is done. The XY axis control device 207 and the Z axis control device 208 operate in response to a drive control signal from the control / analysis computer 210. The control / analysis computer 210, which is an apparatus main body control computer, includes a processor (not shown) mainly composed of a CPU and the like, and a hard disk drive and other storage means (not shown). The control / analysis computer 210 is installed with a shape measurement program having a function of performing data analysis, which will be described later, and a measurement pass / fail judgment computing means 211 for performing a measurement pass / fail judgment process. In accordance with this shape measurement program, the measurement sequence described later is controlled.

  Here, the details of driving the Z-axis stage 203 during shape measurement will be described. The shape measuring apparatus of FIG. 1 has a function of detecting the contact force of the probe 101 with respect to the object to be measured 103, and a contact force signal corresponding to the magnitude of the detected contact force is output to the Z-axis control device 208. It is captured. The Z-axis control device 208 incorporates a processor (not shown) mainly composed of a DSP and the like and a storage means (not shown) such as a ROM, and controls so that the contact force signal is always kept constant. A control program is installed. In accordance with this control program, the Z-axis control device 208 outputs Z-axis drive power that maintains the contact force signal at a constant value, and the output drive power is supplied to the Z-axis drive motor 206. Further, the Z-axis stage 203 is driven by the Z-axis drive motor 206, and the contact force of the probe 101 to the object 103 to be measured is kept constant.

  Next, details of driving the X and Y axis stages 201 and 202 during shape measurement will be described. The control / analysis computer 210 transmits a drive control signal to the XY axis control device 207 in accordance with an instruction of the shape measurement program executed at the time of shape measurement. The XY axis control device 207 supplies drive power to the X and Y axis drive motors 204 and 205 based on the drive control signal received from the control / analysis computer 210. The X-axis stage 201 and the Y-axis stage 202 are driven by X and Y axis drive motors 204 and 205 that operate according to the drive power. As a result, the center position of the probe 101, specifically, the probe tip sphere 102, is controlled in the X and Y axis directions with respect to the object 103 to be measured.

  By driving the X, Y, and Z axis stages 201, 202, and 203 described above, the probe 101 scans the surface to be measured of the object 103 to be measured according to the measurement path set by the shape measurement program. During probe scanning, the output signal of the position detection sensor that detects the center position of the probe tip sphere 102 is captured by the data sampling device 209 at a constant sampling interval. The acquired data is sequentially measured from the data sampling device 209 to the control / analysis computer 210 at an appropriate sampling interval according to the measurement conditions set by the shape measurement program, and the measured surface shape data is X, Y, Z coordinates. Acquired as point cloud data. Finally, surface shape data (measurement data) is obtained by performing shape analysis processing after the end of probe scanning.

  Note that a non-contact type probe may be mounted instead of the contact type probe 101. The contact probe 101 moves relative to each axial direction while bringing the probe tip sphere 102 into contact with the object 103 to be measured, whereas the non-contact probe irradiates the object 103 with a light wave. However, it moves relatively in the X, Y, and Z axis directions. The contact type probe 101 drives the Z-axis so as to keep the contact force to the measured object 103 constant, whereas the non-contact type probe has a function of detecting the distance to the measured object. The difference is that the Z-axis is driven while controlling to keep the same distance constant. Other apparatus configurations are the same as those of the shape measuring apparatus including a contact type probe.

  FIG. 2 shows a shape measuring apparatus according to a modification. In this shape measuring apparatus, instead of the control / analysis computer 210 of the apparatus of FIG. 1, a control computer 310 and an analysis computer 311 in which the measurement pass / fail judgment calculation means 211 is installed are connected separately. Yes. As described above, even if the control computer 310 and the analysis computer 311 which are apparatus main body control computers are separately provided, the two computers may be connected in a form capable of bidirectional communication. The shape measuring method is carried out in the same manner as when the shape measuring apparatus shown in FIG. 1 is used. 2, the non-contact type probe may be mounted instead of the contact type probe 101 similarly to the apparatus of FIG. Further, the measurement pass / fail judgment calculation means 211 may be an apparatus configuration installed in the control computer 310 instead of the analysis computer 311.

  FIG. 3 is a flowchart showing a process of measuring an optical surface shape of an optical element or an optical element molding die using the shape measuring apparatus of FIG. 1 or FIG. In step S1, shape measurement is started, and in step S2 and subsequent steps, a probe is measured on the surface to be measured in accordance with measurement path information input as a measurement condition to the control / analysis computer 210 in FIG. 1 or the control computer 310 in FIG. The shape is measured by scanning 101.

  FIG. 1B shows a probe scanning path on the measurement surface 104 of the object 103 to be measured. In FIG. 1, the X and Y axes indicate X in the orthogonal coordinate system shown in FIG. It coincides with the direction of the axis and the Y axis. The probe scanning path on the measurement surface 104 includes a first (stage) measurement path 105 indicated by a solid line, a second (stage) measurement path 106 indicated by an alternate long and short dash line, and a third (stage) measurement path 107 indicated by a broken line. It is divided into three stages. The first measurement path 105 has a first measurement path start point 105s and a first measurement path end point 105e. Similarly, the second measurement path 106 includes a second measurement path start point 106s and a second measurement path end point 106e, and the third measurement path 107 includes a third measurement path start point 107s and a third measurement path end point. 107e. When measuring the surface shape of the measurement surface 104, the probe 101 is scanned in the order of the first measurement path 105, the second measurement path 106, and the third measurement path 107. The probe scanning here is continuously performed without interruption between the measurement paths. Accordingly, the probe scan start point is the measurement path start point 105 s of the first measurement path 105, and the probe scan end point is the measurement path end point 107 e of the third measurement path 107.

  In this way, in the shape measuring method for measuring by scanning the probe with respect to the surface to be measured, the conventional method is to set the path from the probe scanning start point to the scanning end point as shown in FIG. In the shape measuring method according to the first embodiment, the measurement path is divided into three stages.

  In step S2, according to the first measurement path information, the surface to be measured is measured by scanning the probe 101 with respect to the surface to be measured 104. That is, the shape of the surface to be measured is measured by scanning the probe 101 from the first measurement path start point 105s to the first measurement path end point 105e.

  After step S2, the probe 101 moves from the first measurement path end point 105e to the measurement path start point 106s of the second measurement path 106 without interrupting the operation. In step S3, in the same manner as described above, the probe 101 is placed on the measured surface 104 according to the second measurement path information input as the measurement conditions to the control / analysis computer 210 in FIG. 1 or the control computer 310 in FIG. The surface to be measured is measured by scanning.

  After step S2, the measurement shape analysis (data analysis) is performed on the measurement data of the first measurement path 105 in step S4 simultaneously with step S3. The measurement shape analysis performed here is a calculation process generally called a curve fitting calculation. For example, an algorithm such as a least square method is applied to perform an estimation calculation that minimizes the shape error of the measurement shape with respect to the design shape of the measurement target surface 104. By performing this estimation calculation, a setting error (attachment error) with respect to the shape measuring device of the object 103 to be measured and a shape error with respect to the design shape in a state where the setting error is removed with respect to the measured shape of the measurement surface 104 are obtained. In general, in an optical element or a mold for molding an optical element that requires high precision in shape accuracy, the shape error is calculated in nm order.

  This measurement shape analysis is performed by shape analysis means (a computer program for shape analysis) which is a first calculation means installed in the control / analysis computer 210 of FIG. 1 or the analysis computer 311 of FIG.

  In the shape measuring apparatus according to the first embodiment, a program execution command is passed from the shape measuring program that controls the measurement of the shape of the surface to be measured being executed in steps S2 and S3 to the shape analyzing means after step S2 is completed. It has a function to perform measurement analysis automatically. In addition, after step S2 is completed, the measurement in step S2 is completed on the control / analysis computer 210 in FIG. 1 or the display device (display means) connected to the control computer 310 and the analysis computer 311 in FIG. A function for screen output may be provided. In this case, after the measurement operator confirms the output result, the measurement shape analysis in step S4 is executed.

  After step S4 is completed, measurement pass / fail determination processing based on the measurement shape analysis result of step S4 is performed (step S5). Specifically, the measurement pass / fail determination process is performed by the measurement pass / fail determination processing computing means (measurement success / failure automatic determination computer program) 211 shown in FIGS. Details of the arithmetic processing performed here are as follows.

  Among the various causes that cause the measurement failure described above, measurement failure due to dust adhering to the measurement surface 104 can be cited as a possible measurement success / failure determination based on the quantitative evaluation in step S5. Further, there are measurement failure caused by dust attached to the surface of the probe tip sphere 102 in the shape measuring apparatus having a contact type probe, and measurement failure related to a measurement region error caused by a setting error.

  Regarding the shape error with respect to the design shape of the surface to be measured 104, the PV value (the value obtained by subtracting the minimum value from the maximum value of the shape error in the surface to be measured) is expected to be within a range from several nm to several hundred nm. There is a case. In such a case, as a determination condition for measurement failure due to dust, for example, a value of 1 μm is set as a threshold, and this is set in the measurement pass / fail determination calculation means 211 before the measurement is started. In step S5, the PV value is calculated from the shape error calculated after the end of step S4 by the measurement pass / fail judgment calculating means 211. If the calculated PV value exceeds a set threshold value (here, 1 μm), the PV value is determined in step S2. It is automatically determined that the measurement made is a failure.

  The measurement area error can be immediately determined from the setting error calculated in the measurement shape analysis in step S4. That is, the outermost measurement point group that determines the measurement area is coordinate-converted based on the calculated setting error, and therefore, an area shifted from the measurement area specified as the measurement condition by the setting error is present on the measurement surface 104. On the other hand, it is calculated as a measurement region in which measurement is actually performed. Thus, for example, in FIG. 1B, the allowable error of the measurement area with respect to the XY coordinate system is set in the measurement pass / fail judgment calculation means 211 before the measurement as a threshold value within ± 10 μm with respect to the designated area. deep. In step S5, if the X-axis or Y-axis direction translational component of the setting error calculated after step S4 ends exceeds the allowable range, the measurement region after setting error correction is inevitably within the allowable error. Does not fit. Accordingly, it is automatically determined that the measurement target surface shape measurement performed in step S2 has failed.

  Heretofore, it has been described that the actual measurement region is shifted due to the influence of the setting error calculated in step S4. However, it is assumed that the shape of the surface to be measured can be measured without any setting error. The setting error calculated at this time is the position where the actual optical surface is deviated from the reference surface that defines the position and orientation of the optical surface to be measured 104 such as the optical element that is the measured object 103, and Indicates whether the shape is created in the posture.

  On the other hand, there is always a setting error. That is, among the setting errors obtained in step S4, the position and orientation errors of the surface to be measured 104 with respect to the reference surface in the object to be measured, the setting errors for the shape measuring device, and in many cases the object to be measured for the measuring jig. A mounting error of the object 103 is mixed. However, the problem to be solved here is that the measurement area of the optical surface which is the surface to be measured 104 is displaced with respect to the designated area, and as a result, the measurement shape evaluation of the end portion of the optical surface cannot be performed. Therefore, it is only necessary to grasp the positional deviation of the measurement region that occurs as a result of the combination of the actual setting error and the position and orientation error of the optical surface with respect to the reference surface, so that the measurement region based on the setting error calculated in step S4 is determined. The determination process is an appropriate and sufficient process.

  The above is the details of the measurement pass / fail determination calculation process performed in step S5. As described above, the problem to be solved here is to clarify the measurement failure of the surface shape to be measured in a short time and to shorten the surface shape measurement tact of the device to be measured 103 including remeasurement.

  Depending on the cause of the measurement failure, it is difficult to determine with the measurement pass / fail determination computing means 211 shown in FIGS. As described above, as the causes of the measurement failure when it is difficult to determine the success / failure of the measurement based on the quantitative evaluation, the instability of the measurement object 103, the instability of the surrounding environment of the measurement object 103, and the measurement region Setting mistakes can be mentioned. Below, the specific method of the measurement quality determination process in these cases is demonstrated.

  The measured surface shape after calculation of setting error correction calculated in step S4 (shape error with respect to the design shape) is output to the control / analysis computer 210 or a display device connected to the control computer 310 and the analysis computer 311. To do. At the same time, the calculation result of the measurement pass / fail judgment calculation means 211 is output on the screen.

  In step S5, it is difficult to quantitatively determine the attachment stability of the object to be measured 103 to the shape measuring apparatus, that is, whether or not the object to be measured 103 has moved in the measurement jig during measurement. Therefore, the measurement operator refers to the shape of the surface to be measured, which is the analysis result of step S4 output to the display screen, and determines whether or not the object 103 to be measured has moved in the measurement jig. It should be noted that quantitative evaluation regarding the mounting stability of the DUT 103 is possible in the measurement pass / fail determination process in step S11 described later.

  Similarly, it is difficult to quantitatively evaluate the presence or absence of the holding deformation of the object to be measured 103. Therefore, the measurement operator refers to the shape of the surface to be measured output on the display screen to determine whether the measurement has failed due to the holding deformation.

  In addition, the thermal deformation of the measurement surface shape caused by the temperature change around the object to be measured, which is cited as the instability of the measurement environment, is affected by the shape and material of the object 103 to be measured and the amount of temperature change around the object. The degree is different, and quantitative determination processing is still difficult. Accordingly, the measurement operator determines the measurement failure due to the temperature change around the object to be measured based on the shape of the surface to be measured output on the display screen.

  Note that, as described above, the measurement pass / fail determination computing unit 211 shown in FIGS. 1 and 2 determines the measurement failure caused by dust adhering to the measured surface 104 or the surface of the contact-type probe tip sphere 102. Is possible. However, for objects to be measured whose shape error with respect to the design shape of the surface to be measured is on the order of μm, if the PV value of the shape error is simply used, the abnormal shape due to dust is buried in the surface error of the surface to be measured. Disappear. For such an object to be measured, the measurement operator determines the success / failure of the measurement with reference to the shape of the surface to be measured output on the display screen, as in the case of the various measurement failures in which quantitative determination processing is difficult.

  In this way, based on the measurement pass / fail judgment result by the measurement pass / fail judgment computing means 211 output to the display device, and the measured surface shape (shape error with respect to the design shape) after the setting error correction calculated in step S4. In addition, the measurement operator determines the success / failure of the measurement. At this time, based on the determination result, the measurement operator informs the computer that is executing the shape measurement program whether to continue or end the measurement with respect to the shape measurement program that is controlling the shape measurement of the surface to be measured in step S3. input. If the measurement is unsuccessful according to the input measurement pass / fail judgment result, the flow proceeds to a yes flow in step S6, and the measurement ends abnormally (forced end) in step S7. On the other hand, if it is determined that the measurement is successful, the process proceeds to the no flow in step S6, and the measurement process for the second measurement path 106 is continued at that time (step S8).

  In addition, the shape measurement method in which the flow control in step S6 is performed only in accordance with the calculation result by the measurement pass / fail determination calculation means 211 shown in FIGS. In this case, the calculation result of the measurement pass / fail determination calculation means 211, that is, the measurement surface shape measurement success / failure determination information (signal) shown in step S2 is the shape measurement program that is controlling the measurement surface shape measurement in step S3. Automatically entered. In step S6, the program follows the input measurement pass / fail judgment information. If the measurement fails, the program proceeds to a yes flow and abnormally ends the measurement in step S7. On the contrary, if the calculation result input from the measurement pass / fail judgment calculation means 211 is information indicating the success of the measurement, the process proceeds to the no flow in step S6, and the probe scan along the second measurement path 106 is performed in step S8. Shape measurement continues.

  In the first embodiment, as measurement failure targets that can be calculated by the measurement pass / fail judgment calculation means 211, measurement failure caused by dust adhering to the surface to be measured or dust adhering to the probe tip sphere 102, and setting error are considered. It is limited to measurement failures related to the measurement area error caused. Measurement failures due to other causes were excluded from calculation. However, it is not necessary to limit the target of measurement failure. In general, even if it is difficult to determine the success / failure of a measurement based on quantitative evaluation, when it is possible to make a quantitative measurement pass / fail determination, the determination condition is immediately added to the measurement pass / fail determination computing means 211. be able to. As a result, an automatic determination process is performed in accordance with the calculation result of the measurement pass / fail determination calculation means 211 that does not require the determination of the measurement operator.

  Here, a case is considered in which it is determined in step S5 that the measurement of the surface shape to be measured in step S2 is unsuccessful and the measurement ends abnormally in step S7. In the conventional example, after the probe scans all the measurement paths on the surface to be measured, it was possible to determine whether or not the measurement was good based on the measurement shape analysis result performed in step S4 and step S5 of the present example. In this way, the measurement pass / fail determination that can be determined after the scanning of all the measurement paths is completed in the conventional technique can be determined at the time when only the first measurement path 105 is scanned in the present embodiment. Therefore, in the case of measurement failure, the measurement can be stopped without performing measurement of the surface shape to be measured for the remaining second and third measurement paths 106 and 107. After stopping the measurement, re-measure the conditions for the cause of the measurement failure.

  By repeating the loop of efficiently re-measuring the conditions for measurement failure, measurement of the measured surface shape for all the designated measurement paths succeeds in a short time, and the entire process is completed. As a result, the total time (measurement tact) until the measurement process is finally completed is greatly reduced as compared with the conventional technique.

  In the measurement surface shape measurement by probe scanning along the second measurement path 106 being measured in step S8, when the probe is scanned to the second measurement path end point 106e, the measurement surface shape measurement in step S3 and step S8. Ends. Thereafter, the probe 101 moves from the second measurement path end point 106e to the third measurement path start point 107s without interrupting the operation. After the movement is completed, the probe 101 is scanned on the surface 104 to be measured in accordance with the third measurement path information input as the measurement condition to the control / analysis computer 210 in FIG. 1 or the control computer 310 in FIG. The surface shape to be measured is measured (step S9).

  Further, after step S8 is completed, measurement shape analysis is performed on the measurement data of the second measurement path 106 in step S10 simultaneously with step S9. The measurement shape analysis performed here is the same as the calculation process (curve fitting calculation) performed on the measurement data of the first measurement path 105 in step S4. In step S10, coordinate point group data obtained by combining the measurement data for the first measurement path 105 obtained in step S2 and the measurement data for the second measurement path 106 obtained in steps S3 and S8 is also measured. The shape analysis may be performed similarly. After step S10, the measurement shape analysis result for the measurement data on the first measurement path 105, the measurement shape analysis result for the measurement data on the second measurement path 106, the measurement path 105, A measurement shape analysis result for the measurement data on 106 is obtained.

  The specific starting method of step S10 is the same as the starting method of step S4, and a program execution command is automatically sent from the shape measuring program executing step S9 to the measuring shape analyzing means after step S8 is completed. Passed to start the calculation. Alternatively, the display device described above is provided with a function of outputting the completion of step S8 on the screen, and after the measurement operator confirms the output result, the measurement shape analysis of step S10 is executed. The shape measuring apparatus according to the first embodiment has any function, and step S10 may be started by any of the above methods.

  After step S10 ends, measurement pass / fail determination processing based on all measurement shape analysis results obtained at this stage is performed (step S11). The specific measurement pass / fail determination process is substantially the same as the processing method described for step S5. The difference is that the measurement shape analysis result used in the measurement quality automatic determination process by the measurement quality determination calculation means 211 is the measurement shape analysis for all measured data up to the second measurement path end point 106e obtained in step S10. This is the result. Furthermore, it differs from step S5 in that it can be calculated in step S11 with respect to the determination relating to the mounting stability of the object 103 that has been difficult to quantitatively evaluate in step S5. Hereinafter, a specific calculation processing method will be described for the determination processing of whether or not the object 103 to be measured has moved relative to the shape measuring device during the measurement.

  When the attachment state of the object to be measured 103 to the shape measuring apparatus is stable, the attachment position of the object to be measured 103 to the shape measuring apparatus, that is, the setting error does not change. That is, the setting error obtained from the measurement shape analysis in step S4 and the setting error calculated in step S10 are approximately the same. Using this principle, it is possible to determine whether or not the object to be measured has moved in the measurement jig in the measurement of the surface shape to be measured until step S8 is completed. For example, a value of 1 μm is set as a threshold value as a measurement failure determination condition, and is set in the measurement pass / fail determination calculation means 211 before the measurement is started. Setting error X, Y, and Z axes for the X, Y, and Z axis direction translational components of the setting error obtained in step S4 and the measurement data on the second measurement path 106 calculated in step S10. Compare each translation component in the direction. When the difference exceeds a set threshold value of 1 μm, a determination result indicating that the measurement is unsuccessful is output because the DUT 103 is moving with respect to the shape measuring apparatus during the measurement. Similarly, an automatic determination function is also provided by comparing the setting error obtained in step S4 with the setting error obtained by measuring data on the first and second measurement paths 105 and 106 obtained in step S10. It may be. By making a determination based on one or both of the above functions, it is possible to automatically determine a measurement failure caused by the instability of attachment of the object to be measured 103 by an arithmetic process.

  Based on the measurement success / failure determination result in step S11, in the case of measurement failure, the flow proceeds to yes in step S12, and the measurement is abnormally terminated in step S13. On the other hand, if the measurement is successful, the flow proceeds to the no flow in step S12, and shape measurement by probe scanning along the third measurement path 107 is continued in step S14. The details of the branch processing from step S11 to step S12 are the same as those from step S5 to step S6 described above.

  Assuming that the measurement is failed and the measurement is abnormally terminated in step S13, it is possible to determine that the measurement has failed before the probe scan on the third measurement path 107 is completed. Compared to this, the measurement tact can be greatly shortened.

  If the probe is scanned from the third measurement path start point 107s to the third measurement path end point 107e in the measurement surface shape measurement by scanning the probe along the measurement path 107 in step S14, the process proceeds to step S15, and the measurement surface is measured. The surface shape measurement at 104 ends.

  Note that the probe scanning path by raster scanning shown in FIG. 1B, that is, the measurement path from the first measurement path start point 105s to the third measurement path end point 107e is merely an example, and the number of measurement lines and the like are illustrated. The number is not limited. Also, the probe scanning direction is not limited to the Y-axis direction in the figure, and may be a measurement path having the X-axis direction as the main scanning direction, for example.

  FIG. 4 shows a probe scanning path according to the second embodiment. In this case, instead of the raster scanning according to the first embodiment, the probe 101 is scanned in a radial manner so as to pass through the center of the measurement target surface 104. For the probe scanning path in this case, similarly to the first embodiment, the first (stage) measurement path 405, the second (stage) measurement path 406, and the third (stage) measurement path 407 are set. Then, the first measurement path start point 405s, the first measurement path end point 405e, the second measurement path start point 406s, the second measurement path end point 406e, the third measurement path start point 407s, and the third measurement path. Probe scanning is performed in the order of the end point 407e to measure the shape of the surface to be measured.

  FIG. 5 shows a probe scanning path according to the third embodiment. This scans the probe 101 concentrically with respect to the measurement region of the measurement surface 104. Also in this case, similarly to the first and second embodiments, the first (stage) measurement path 505, the second (stage) measurement path 506, and the third (stage) measurement path 507 are set. Then, the first measurement path start point 505s, the first measurement path end point 505e, the second measurement path start point 506s, the second measurement path end point 506e, the third measurement path start point 507s, and the third measurement path. Probe scanning is performed in the order of the end point 507e, and the shape of the surface to be measured is measured.

  In the above embodiment, the probe scanning path is divided into three stages from the first measurement path to the third measurement path, but the probe measurement path is not limited to three stages. If divided into at least two stages, the total measurement time is shortened as compared with the conventional technique.

  Further, the probe scanning pattern is not limited to the above-described raster scanning, radial scanning and concentric scanning, and any probe scanning pattern may be used. At this time, the probe scanning path is divided into at least two stages, and the shape of the surface to be measured is measured by the measurement flow shown in FIG. Compared to the case where the surface shape to be measured is measured by the conventional example for the same probe scanning pattern, the measurement tact time can be greatly shortened.

1A and 1B show a first embodiment, in which FIG. 1A is a schematic diagram illustrating a configuration of a shape measuring apparatus, and FIG. 2B is a plan view illustrating a probe scanning path. It is a schematic diagram which shows the shape measuring apparatus by one modification. 3 is a flowchart illustrating a shape measuring method according to the first embodiment. 6 is a plan view showing a probe scanning path according to Embodiment 2. FIG. 10 is a plan view showing a probe scanning path according to Embodiment 3. FIG. It is a flowchart which shows the shape measuring method by a prior art example. It is a top view which shows the probe scanning path | route by a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Probe 102 Probe tip sphere 103 Object to be measured 104 Surface to be measured 105, 405, 505 First measurement path 105s, 405s, 505s First measurement path start point 105e, 405e, 505e First measurement path end point 106, 406 , 506 Second measurement path 106s, 406s, 506s Second measurement path start point 106e, 406e, 506e Second measurement path end point 107, 407, 507 Third measurement path 107s, 407s, 507s Third measurement path Start point 107e, 407e, 507e Third measurement path end point 201 X-axis stage 202 Y-axis stage 203 Z-axis stage 209 Data sampling device 210 Control / analysis computer 211 Measurement pass / fail judgment computing means 310 Control computer 311 Analysis computer

Claims (5)

In a shape measuring method for measuring the shape of a surface to be measured by two-dimensionally scanning a contact or non-contact type probe with respect to the object to be measured,
A measurement process that sets at least three or more measurement paths, scans the probe according to the set measurement paths, measures the shape of the surface to be measured, and acquires measurement data of the measurement paths at each stage;
After measuring the shape of the measurement path of at least one stage that is not the last stage of the measurement process,
Comparison that compares at least two of the analysis results of data analysis of at least one measurement data acquired before the shape measurement or the analysis results of data analysis of multiple measurement data acquired before the shape measurement A selection step of selecting, based on the result, the measurement step if the analysis result or the comparison result is equal to or less than a predetermined threshold value, and forcibly terminating if the measurement result exceeds the threshold value. A shape measuring method characterized by the above.   2. The shape measuring method according to claim 1, wherein the data analysis of the acquired measurement data and the measurement of the shape of the surface to be measured at the next stage are performed simultaneously.   3. The shape measuring method according to claim 1, wherein each of the measurement paths is determined so as to measure the entire surface to be measured by raster scanning, and the measurement paths are different from each other. In a shape measuring apparatus for measuring the shape of a surface to be measured by two-dimensionally scanning a contact or non-contact type probe along the measurement path in at least three stages with respect to the object to be measured. During the scanning of the probe along the measurement path after the second stage, data analysis is performed on the measurement data obtained in the previous measurement path, and the shape error with respect to the design shape of the surface to be measured or its First calculation means for calculating a setting error of the object to be measured based on a comparison result obtained by comparing at least two analysis results obtained by performing data analysis of a plurality of measurement data obtained before the shape measurement;
Second calculation means for determining the quality of the measurement based on the shape error or setting error calculated by the first calculation means,
Based on the determination result by the second calculation means , select the measurement process if the analysis result or the comparison result is less than or equal to a predetermined threshold value, and forcibly terminate if it exceeds the threshold value A shape measuring apparatus characterized by that.   5. The shape measuring apparatus according to claim 4, further comprising display means for displaying a determination result by the second calculation means.

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