JP2008304413A - Shape measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shape measurement method which enables the easy correction of an attachment angle error of an angle detector detecting a tilt of a stylus. <P>SOLUTION: An angle error estimation value such that contact point position coordinate data calculated by scanning a measurement surface of an object to be measured in a first direction agree with contact point position coordinate data calculated by scanning it in a second direction antithetical to the first direction is calibrated as the attachment angle error of the angle detector to perform the shape measurement. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shape measuring method for measuring a three-dimensional shape of an object having an arbitrary shape with high accuracy.

  Patent Document 1 discloses a three-dimensional shape measurement technique that makes it possible to measure the side surface shape of an object to be measured by tilting a stylus from a vertical direction to an arbitrary direction.

  FIG. 13 shows the configuration of the three-dimensional measuring apparatus described in Patent Document 1. In the measuring apparatus 100, follow-up control for bringing a stylus attached to the side of the object 200 to be measured into contact with the tip of the probe 102 so as to have a substantially constant measurement force, and positioning control for performing scanning in the measurement direction. Performed by the X-axis stage 112, the Y-axis stage 113, and the Z-axis stage 114. Further, the relative position coordinates of the stylus are measured using the measurement laser beam generated from the laser light source 101 and the reference mirror 115 (the Z-axis reference mirror is shown. The same applies to the XY axes).

FIG. 14 shows the configuration of the measurement point information determination unit of the measurement apparatus 100. A stylus 103 that can tilt in an arbitrary direction from the vertical direction is attached to the probe 102, and a sphere (stylus tip sphere) 104 having a high sphericity is attached to the tip (lower end in FIG. 14) of the stylus 103. Installed. A mirror attached to the base end (upper end in FIG. 14) of the stylus 103 by using an optical system 90 including a reflection mirror 91 and a semi-transmission mirror 92 for measuring laser light L ₁ generated from the laser light source 101. irradiated 105, the reflected light L ₂ by measuring the relative position of the stylus 103 in the position coordinate measuring section 108 by using the optical system 90, obtains the stylus position data. Further, the stylus 103 can be tilted in an arbitrary direction around a fulcrum (meaning the center of rotation) by an external force, and a stylus tilt angle of a part of the reflected light L ₂ is transmitted by the semi-transmissive mirror 92 of the optical system 90. The light is incident on the detection unit 106, and a change (change amount) in the stylus inclination is detected from the displacement (displacement amount) of the spot position of the laser beam on the surface of the stylus inclination angle detection unit 106. The stylus tip displacement calculator 107 connected to the stylus tilt angle detector 106 uses the tilt of the stylus 103 detected by the stylus tilt angle detector 106 to detect the stylus tip sphere 104 generated by the tilt of the stylus 103. A displacement, that is, a stylus displacement amount is calculated. In the adding unit 109 connected to the position coordinate measuring unit 108 and the stylus tip displacement calculating unit 107, the stylus position coordinate data acquired by the position coordinate measuring unit 108 and the stylus displacement calculating unit 107 are calculated. The relative position coordinates of the tip of the stylus 103 are acquired by adding the stylus displacement amount.

An angle detection method when the stylus 103 is brought into contact with the side surface of the DUT 200 will be described below with reference to FIG. In FIG. 15, a mirror 116 is added to the configuration of the optical system 90 of FIG. 14 for easy understanding. FIG. 15 describes only the laser optical axis in order to avoid complicated notation. When the stylus 103 is not inclined, the light spot center of the reflected light L ₂ coincides with the center position 300a of the angle detector 106. In contrast, when the tip of the stylus 103 is pressed in the X-axis + direction (right direction in FIG. 15), the irradiation position of a light spot center of the reflected light L ₂ reflected light L ₂ is, from the center position 300a Move to position 300b, which is off to the left.

Similarly, by the stylus 103 is inclined in any direction, as shown in FIG. 16, in accordance with the direction and magnitude of the slope, the light spot position of the reflected light L ₂ is two-dimensionally varied. Position 301b is a state where the stylus 103 is contacted toward the X axis + side, position 301c is a state where the stylus 103 is contacted toward the X axis − side, and position 301d is a state where the stylus 103 is contacted toward the Y axis + side. The position 301e indicates the state in which the stylus 103 is brought into contact with the Y axis minus side. The angle detector 106 can acquire the inclination of the stylus 103 by detecting the amount of displacement of the light spot position. The angle detection unit 106 is applicable as long as it can detect the light spot position two-dimensionally, such as a four-division photodiode or a two-dimensional PSD. Hereinafter, the sensors applied to the angle detector 106 are collectively referred to as “angle detectors”.

In the prior art, follow-up control is performed in order to make the measurement force substantially constant. For example, the inclination of the X-axis direction of the stylus 103 as shown in FIG. 15 is the X-axis stage 112 is controlled to a substantially constant value theta _x. This control is performed when the measurement laser light L ₁ is reflected by the mirror 105 at the base end of the tilted stylus 103 and the reflected light L ₂ is irradiated on the light receiving surface of the angle detector 106. center is realized by configuring the control system to follow on a straight line position 300b at a distance X _t from the center of the light receiving surface. Here, corresponding to the distance X _t, the target value X _t on angle detector 106 corresponds to the inclination target value theta _x of the stylus 103 in the measuring coordinate system.

  Hereinafter, the positional relationship between the measurement object 200 and the stylus 103 and the relationship between the angle detector 106 and the light spot position when the measurement surface of the measurement object 200 is measured using the conventional technology will be described.

  In order to facilitate the following description, simple notations are shown in FIGS. 19A and 19B. FIG. 19A is an explanatory view including a top view and a front view of a state in which the stylus 103 is brought into contact with the object to be measured 200 so that the pushing amount becomes the target value 120, and FIG. The light spot center 302 and the control target value 119 are shown. In the top view of FIG. 19A, only the object 200 to be measured, the fulcrum 117 and the contact point 118 of the stylus 103 are indicated by a triangular mark and a star mark, respectively, and the stylus 103 is omitted. Hereinafter, description will be made using the top view of FIG. 19A and the notation of FIG. 19B.

  20A to 20F show the positional relationship between the fulcrum 117 and the contact point 118 of the stylus 103 when scanning in the Y-axis direction while bringing the stylus 103 into contact with the X-axis + side of the DUT 200 with a substantially constant measurement force. Show. 20A to 20C show a state from the state in which the stylus 103 is stationary with respect to the Y-axis direction until the stylus 103 starts to move relative to the Y-axis + side. FIGS. 20D to 20F show the stylus 103 in the Y-axis direction. This shows a state from a state where it is stationary with respect to the direction until it starts to move relative to the Y-axis minus side. 20A to 20F, the upper diagram shows the positional relationship between the fulcrum 117 of the stylus 103 and the contact point 118 when the DUT 200 and the stylus 103 contact each other, and the lower diagram shows the angle detector 106. 2 shows the positional relationship between the light spot centers 300a to 303f.

  In the state of FIG. 20A where the stylus 103 is stationary in the Y-axis direction, the vector connecting the fulcrum 117 of the stylus 103 and the contact point 118 is parallel to the X-axis, and the stylus 103 does not tilt in the Y-axis direction. Next, in the state of FIG. 20B, which is the state at the moment when the stylus 103 starts to move in the Y-axis + direction, the drag from the DUT 200 acts on the contact point 118 of the stylus 103, so that friction is generated in the scanning direction. Force is generated. When the static frictional force is larger than the moment in the tilt direction of the stylus 103, the contact point 118 of the stylus 103 tends to stay in place, so that only the fulcrum 117 of the stylus 103 is displaced in the Y axis + direction. . The contact point 118 of the stylus 103 begins to move at the moment when the relative distance between the fulcrum 117 of the stylus 103 and the contact point 118 increases in the Y-axis direction, and the moment in the tilt direction of the stylus 103 becomes greater than the static friction force. Switching from static friction force to dynamic friction force. This state is shown in FIG. 20C. Since dynamic friction force ≦ static friction force, when the inclination of the stylus 103 in the X-axis direction is constant, after the contact point 118 starts to move once, the fulcrum 117 of the stylus 103 and the Y-axis direction of the contact point 118 The stylus 103 is tilted and moved so that the relative distance is constant. At this time, the positional relationship between the angle detector 106 and the light spot center is as shown in the lower diagram of FIG. 20C. 20D to 20F showing the transition of the state when the stylus 103 scans in the Y axis-side can be described in the same manner as described above, and thus are omitted.

  Finally, a technique will be described in which the stylus 103 is brought into contact with the side surface of the device under test 200 and the coordinate value of the contact point 118 between the device under test 200 and the stylus 103 is acquired in a state where the stylus 103 is tilted in an arbitrary direction.

  First, for the sake of simplicity, it is assumed that measurement can be performed without tilting the stylus 103 when the measurement is performed with the stylus 103 in contact with the DUT 200 as shown in FIG. 17A. Under this assumption, the relative position coordinates (X, Y, Z) of the stylus tip position can be acquired by a conventional three-dimensional measurement technique.

Next, as shown in FIGS. 17B to 17D, it is assumed that the stylus 103 is measured tilted from the vertical direction around the fulcrum 117 of FIG. 17A. Here, it is assumed that the inclination θ _x on the X axis and the inclination θ _y on the Y axis with respect to the vertical direction of the stylus 103 can be detected without including an error. As described above, the relative position coordinates (X, Y, Z) of the tip position 104a of the stylus 103 when it is assumed that the stylus 103 is not tilted can be acquired by a conventional three-dimensional measurement technique. Hereinafter, the coordinate value (X, Y, Z) of the center of the tip sphere 104 of the stylus 103 when it is assumed that the stylus 103 is not inclined is referred to as “relative position coordinate data”.

Actually, since the stylus 103 is tilted, the relative position coordinate data (X, Y, Z) is the coordinate value (X ′, Y ′, Z ′) of the contact point 104b between the DUT 200 and the stylus 103. It turns out that it is not what shows. Hereinafter, the coordinate values (X ′, Y ′, Z ′) of the contact point are referred to as “contact point position coordinate data”. Therefore, the contact point position coordinate data (X ′, Y ′, Z ′) is obtained using the relative position coordinate data (X, Y, Z) and the inclination data (θ _x , θ _y ) of the stylus 103. Necessary. The contact point 118 between the stylus 103 and the device under test 200 refers to the center point of the stylus tip sphere 104 in a state where the stylus 103 and the device under test 200 are in contact. When the stylus 103 is tilted by (θ _x , θ _y ) from the initial state where the stylus 103 is stationary in the vertical direction, the tip of the stylus 103 is obtained from the initial position (X, Y, Z) by the following formula (Equation 1). (Δ _x , δ _y , δ _z ).

In the above equation, the variable L represents the length from the fulcrum 117 of the stylus 103 to the center of the stylus tip sphere 104. As described above, by adding the displacement (δ _x , δ _y , δ _z ) of the stylus tip due to the inclination of the stylus 103 to the relative position coordinate data (X, Y, Z), the contact point position coordinate data (X ′, Y ', Z') is obtained.

JP 2006-284410 A

Technique disclosed in Patent Document 1, a premise by irradiating a laser beam L ₂ reflected from the mirror 105 of the base end of the stylus 103 in the angle detector 106 is the inclination of the stylus 103 that determined the expected However, in order to realize submicron measurement accuracy, the angle formed by the length measurement coordinate system and the angle detector 106 (hereinafter referred to as “mounting angle error”) is a problem that cannot be ignored. Hereinafter, this problem will be described.

As described above, when the contact point position coordinate data (X ′, Y ′, Z ′) is obtained with high accuracy, the relative position coordinate data (X, Y, Z) with high accuracy in the length measurement coordinate system and the length measurement are used. Highly accurate tilt data (θ _x , θ _y ) of the stylus 103 in the coordinate system is required. In order to calculate the inclination (θ _x , θ _y ) of the stylus 103 in the length measurement coordinate system from the displacement amount of the light spot position on the angle detector 106 as used in Patent Document 1, FIG. As described above, the coordinate axes θ _x and θ _y of the angle detector 106 need to be parallel to the length measurement coordinate system. However, actually, as shown in FIG. 18, the coordinate axes θ _x and θ _y of the angle detector 106 are not necessarily parallel to the length measurement coordinate system, and rotate around the origin of the angle detector 106. The angle detector 106 is attached to the length measurement coordinate system. Therefore, the inclination of the stylus 103 detected from the angle detector _{106 (θ x ', θ y} ') and the inclination of the stylus 103 in the measuring coordinate system to be obtained originally (θ _x, θ _y) be not match Is clear. Also, considering that the length measurement coordinate system is optically configured, it is very difficult to adjust the mounting angle of the angle detector 106 with respect to the length measurement coordinate system.

Next, the influence of the mounting angle error of the angle detector 106 when acquiring the contact point 104b between the DUT 200 and the stylus 103 will be described with reference to FIGS. 17B to 17D as examples. It is assumed that the inclination of the stylus 103 in the measurement coordinate system is (θ _x , θ _y ) in a state where the stylus 103 is in contact with the DUT 200.

Now, it is assumed that the angle detector 106 is attached with an error (attachment angle error) by an angle γ with respect to the length measurement coordinate system. At this time, the inclination data (θ _{x ′} , θ _{y ′} ) detected from the angle detector 106 is expressed by the following (Equation 2) with respect to the inclination (θ _x , θ _y ) of the stylus 103 in the length measurement coordinate system. It becomes relation of expression.

Further, the displacement amount (δ _{x ′} , δ _{y ′} , δ _{z ′} ) of the tip of the stylus 103 estimated from (θ _{x ′} , θ _{y ′} ) is expressed by the following equation (equation (Equation 3)).

That is, when the inclination (θ _x , θ _y ) of the original stylus 103 is used when obtaining the contact point position coordinate data (X ′, Y ′, Z ′) from the relative position coordinate data (X, Y, Z). And the inclination data (θ _{x ′} , θ _{y ′} ) detected from the angle detector 106, the error of (δ _{x ′} −δ _x , δ _y −δ _{y ′} , δ _z −δ _{z ′} ) is I can see what happens.

For example, the length L of the stylus 103 is 20 mm, the mounting angle error γ of the angle detector 106 is = 1 °, the amount of pushing the stylus 103 into the DUT 200 is δ _x = 10 μm, and δ _y When = 0 μm, δ _{x ′} = 9.998 μm and δ _{y ′} = 0.175 μm, and it is apparent that it cannot be ignored in order to obtain submicron measurement accuracy.

  Next, a description will be given of the follow-up control for making the measurement force substantially constant using the conventional technique when the angle detector 106 has the mounting angle error γ.

FIG. 18 shows a state in which the angle detector 106 includes a deviation of the mounting angle error γ. As described above, the X-axis stage 112 is controlled so that the light spot center 300c is aligned with the target position 119 of the angle detector 106. At this time, since the angle detector 106 is inclined by the mounting angle error γ, the control result is such that the inclination of the stylus 103 becomes substantially constant not at the original target angle θ _x but at the slightly shifted angle θ _{x ′.} .

  While performing this follow-up control, the positional relationship between the fulcrum 117 and the contact point 118 of the stylus 103 and the angle detector 106 and the light spot when the stylus 103 is scanned on the Y axis relative to the object 200 to be measured. The positional relationship between the centers 304a to 304h is shown in FIGS. 21A to 21H.

  21A to 21D show a state from the state where the stylus 103 is stationary with respect to the Y-axis direction until the stylus 103 starts to move relative to the Y-axis + side, and FIGS. 21E to 21H show the stylus 103 as the Y-axis. This shows a state from a state where it is stationary with respect to the direction until it starts to move relative to the Y-axis minus side. In the state of FIG. 21A in which the stylus 103 is stationary in the Y-axis direction, the vector connecting the fulcrum 117 of the stylus 103 and the contact point 118 is parallel to the X-axis, and the stylus 103 does not tilt in the Y-axis direction. Next, FIG. 21B shows a state at the moment when the stylus 103 starts to move in the Y axis + direction. Drag from the DUT 200 acts on the contact point 118 of the stylus 103 to generate a frictional force in the scanning direction. When the static friction force is greater than the moment of inclination of the stylus 103, the contact point 118 of the stylus 103 tries to stay in place, so that only the fulcrum 117 of the stylus 103 is displaced in the Y axis + direction. In addition, the stylus 103 is also inclined in the Y-axis direction. At this time, the light spot in the Y-axis direction is displaced. However, since the mounting angle error of the angle detector 106 is included, an error from the control target position 119 in the X-axis direction on the angle detector 106 occurs. At this time, as shown in FIG. 21C, the fulcrum 117 of the stylus 103 in the X-axis direction moves in a direction to reduce the pushing of the stylus 103 in order to follow the target position of the angle detector 106 by the follow-up control in the X-axis direction. To do. At the moment when the moment in the tilt direction of the stylus 103 becomes larger than the static friction force, the contact point 118 of the stylus 103 starts to move, and the static friction force is switched to the dynamic friction force. This state is shown in FIG. 21D. After the contact point 118 starts to move once, the contact point 118 is inclined and moved so that the relative distance between the fulcrum 117 of the stylus 103 and the contact point 118 in the Y-axis direction is constant. At this time, the positional relationship between the angle detector 106 and the light spot center is as shown in the lower diagram of FIG. 21D. FIGS. 21E to 21H showing the transition of the state when the stylus 103 is stationary in the Y-axis direction to scan in the Y-axis direction are basically the same as those described above. Since the generation direction of the frictional force due to the scanning is reversed, the fulcrum 117 of the stylus 103 is displaced in a direction in which the stylus 103 is pushed further.

The influence of the above phenomenon on the measurement result will be described. The first relative position coordinate data (X, Y, Z) and the first inclination data (θ _x , θ) acquired at least at two or more locations when the stylus 103 scans the measurement surface of the DUT 200 in the Y axis + direction. _y ) and the second relative position coordinate data (X, Y, Z) and the second inclination data acquired by scanning the stylus 103 in the Y-axis direction in the Y axis-direction at a position that roughly matches the measurement position. Using (θ _x , θ _y ), contact point position coordinate data of the object 200 and the stylus 103 when the stylus 103 scans in the Y axis + direction, and an object to be measured when the stylus 103 scans in the Y axis direction. FIG. 22 shows the result of calculating the contact point position coordinate data of 200 and the stylus 103. In FIG. 22, the contact point position coordinate data 121a that is the contact point estimation result at the time of scanning in the Y-axis + direction with respect to the object to be measured 200 matches the contact point position coordinate data 121b that is the result of contact point estimation at the time of scanning in the Y-axis-direction. do not do.

  This is a measurement error caused by the mounting angle error of the angle detector 106, and the stylus 103 is tilted with respect to the length measurement coordinate system even though it is tilted in the X axis and Y axis directions of the length measurement coordinate system. This is nothing but the result of calculating the contact point using the detection result of the angle detector 106.

  The object of the present invention is to solve the above-mentioned problems by easily correcting the mounting angle error of the angle detector that detects the stylus inclination, and detecting the stylus inclination with high accuracy to detect the relative position coordinates. An object of the present invention is to provide a shape measuring method for obtaining a contact point of a stylus from data with high accuracy and measuring the shape of a surface to be measured with high accuracy.

  In order to achieve the above object, the present invention is configured as follows.

According to the first aspect of the present invention, the measuring force is controlled by controlling the moving device that moves the relative position between the object to be measured and the stylus by bringing the stylus into contact with the surface to be measured of the object to be measured. While controlling the relative position of the object to be measured and the stylus so as to be substantially constant, the relative position of the stylus with respect to the object to be measured is moved in the direction substantially perpendicular to the direction of the measurement force acting on the stylus. The relative position coordinates of the laser beam are measured by the position coordinate measuring unit, and the light spot position displacement amount of the laser light is detected by the angle detector, thereby obtaining the stylus tilt by the stylus tilt angle detecting unit, and by the obtained tilt. The amount of displacement of the stylus tip due to the tilt of the stylus is calculated by a stylus tip displacement calculation unit, and the stylus tip is converted into the relative position coordinate. In the shape measuring method of calculating the contact point of the said object to be measured stylus by an adder by adding the amount of displacement,
The relative position between the object to be measured used for calibration and the stylus is moved in the first direction, and the first relative position coordinate data and the first inclination data of the stylus are transferred to the position coordinate measuring unit and the position at at least two positions. Obtained by each angle detector,
The relative position between the object to be measured and the stylus is moved in a second direction opposite to the first direction, and the position approximately coincides with the position where the first relative position coordinate data and the first inclination data are acquired. The second relative position coordinate data and the second inclination data of the stylus are respectively determined by the position coordinate measurement unit and the angle detection unit,
Calculating the first contact point position coordinate data of the object to be measured and the stylus from the first relative position coordinate data and the first inclination data by the adding unit;
The addition unit calculates second contact point position coordinate data of the object to be measured and the stylus from the second relative position coordinate data and the second inclination data,
The first contact point position coordinate data and the second contact point position coordinate data are compared to calibrate the mounting angle error γ of the angle detector that detects the light spot position displacement amount by a γ calibration unit,
The relative position between an arbitrary object to be measured and the stylus is moved in an arbitrary direction to obtain third relative position coordinate data and third inclination data of the stylus by the position coordinate measurement unit and the angle detection unit, respectively. The third inclination correction data is calculated by correcting the error due to the mounting angle error γ of the angle detector included in the third inclination data by the stylus tip displacement calculation unit,
From the third relative position coordinate data of the stylus and the third inclination correction data, the third contact point position coordinate data of the object to be measured and the stylus is calculated by the adding unit, and the shape of the object to be measured is calculated. A shape measuring method characterized by measuring

According to the second aspect of the present invention, in the operation of calibrating the mounting angle error γ of the angle detector,
The first tilt correction data is calculated by the stylus tip displacement calculation unit by transforming the first tilt data by an arbitrary angle γ ′ around the origin of the coordinate system where the light spot position displacement is detected,
The second tilt correction data is calculated by the stylus tip displacement calculation unit by transforming the second tilt data by the angle γ ′ around the origin of the coordinate system,
Calculating the first contact point position coordinate data of the object to be measured and the stylus from the first relative position coordinate data and the first inclination correction data by the adding unit;
Calculating the second contact point position coordinate data of the object to be measured and the stylus from the second relative position coordinate data and the second inclination correction data,
By repeating these series of operations while changing the value of the angle γ ′, the difference between the first contact point position coordinate data and the second contact point position coordinate data is smaller than a predetermined determination value. An angle γ ′ is calculated by the γ calibration unit, and an operation for calibrating the mounting angle error γ of the angle detector is performed.

According to the third aspect of the present invention, the object to be measured used for the calibration is a known shape object, and the difference between the first contact point position coordinate data and the second contact point position coordinate data is used. Instead of calibrating the mounting angle error γ,
Comparing the first contact point position data with the known shape data representing the known shape object, and calculating the first error data in the comparison unit;
The second contact point position data and the known shape data are compared and second error data is calculated by the comparison unit,
By repeating these series of operations while changing the value of the angle γ ′, an angle γ ′ in which both the first error data and the second error data are smaller than a predetermined determination value is set to the γ There is provided a shape measuring method according to the second aspect, characterized in that an operation of calibrating is performed by using a calibrating unit and calibrating with the mounting angle error γ of the angle detector.

  As described above, when the first contact point position coordinate data and the second contact point position coordinate data are directly compared, it is not necessary to know the shape of the object to be measured. Is also possible.

  The condition determination value used when calibrating the mounting angle error of the angle detector can be input in advance by the measurer from the input device.

  When calibrating the mounting angle error of the angle detector, the relative position coordinate data and the tilt data are obtained by the reciprocating measurement realized by continuously performing the measurement scanning in the first direction and the measurement scanning in the second direction. And separating the relative position coordinate data and inclination data into first relative position coordinate data and first inclination data in a first direction, and second relative position coordinate data and second inclination data in a second direction, It can also be used in the measurement method.

  The measurement range can be obtained by measuring the first relative position coordinate data and the first inclination data obtained by measuring the entire circumference of the side surface of the object to be measured in the first direction, and making one measurement in the second direction. The second relative position coordinate data and the second inclination data can be used in the measurement method.

  In addition, the measurement range is obtained by measuring the first relative position coordinate data and the first inclination data obtained by measuring the entire circumference of the object to be measured two or more times in the first direction and two or more turns in the second direction. The reliability can be improved by using the obtained second relative position coordinate data and second inclination data and using the second relative position coordinate data and the second inclination data.

  In addition, an appropriate value determined by the measurer can be input from the input device as the mounting angle error of the angle detector.

  In addition, since the mounting angle error of the angle detector is not changed unless the mounting adjustment of the angle detector is performed, once the mounting angle error calculated by the measurement method is held, any post-calibration arbitrary error can be obtained. It is also possible to use that value in the measurement. However, since it is possible that the housing of the three-dimensional shape measuring apparatus to which the angle detector is attached has changed over time due to a temperature change or the like, it is preferable to perform periodic calibration.

  According to the measurement method of the present invention, the mounting angle error of the angle detector can be easily calibrated, and the measurement error due to the mounting angle error of the angle detector can be reduced. In addition, regarding the provision of an angle adjustment reference that becomes difficult when the length measurement coordinate system is composed of an optical system, numerically indicate how much the angle detector is inclined with respect to the length measurement coordinate system. Therefore, adjustment using a relative angle becomes possible, and it becomes easy to provide an angle adjustment reference. Further, it is not necessary to repeatedly adjust the mounting angle of the angle detector.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  A three-dimensional shape measuring apparatus capable of performing a three-dimensional shape measuring method according to an embodiment of the present invention is an improvement of the three-dimensional shape measuring apparatus described in Patent Document 1, and has a basic structure and operation. Since it is similar to the three-dimensional shape measuring apparatus described in Patent Document 1, the three-dimensional shape measuring method according to the embodiment will be described after briefly describing them.

  FIG. 1 shows a configuration of a three-dimensional shape measuring apparatus 100G capable of performing the three-dimensional shape measuring method according to the embodiment of the present invention.

  The three-dimensional shape measuring device 100G is a device that can measure holes, outer shapes, and arbitrary side shapes that have not been measured with high accuracy in the past with high accuracy on the order of nanometers and with low measuring force in a short time. . The object to be measured is, for example, a hole shape in a motor bearing, an ink jet printer nozzle, a fuel injection nozzle in an automobile engine, etc. that require extremely high precision, and is formed in a fluid bearing and contains a lubricant. The shape of the groove portion to be formed, the inner diameter of the micro air slide provided in the three-dimensional shape measuring apparatus, the cylindricity, and the like. Moreover, the trench part in a semiconductor circuit pattern can also be included in a measuring object. The surface to be measured that can be measured by the three-dimensional shape measuring apparatus provided with the probe for the three-dimensional shape measuring apparatus is from 0 degree to the maximum at the intersection angle θ between the tangential direction and the vertical direction on the surface to be measured. A surface having an angle of up to about 30 degrees.

  FIG. 2A shows a configuration of the measurement point information determination unit 80G of the three-dimensional measurement apparatus 100G.

  First, the three-dimensional shape measuring apparatus probe 102G will be described. A probe 102G for a three-dimensional shape measuring apparatus shown in FIG. 1 is an object provided in the three-dimensional shape measuring apparatus 100G and having a portion that comes into contact with the measured surface 200Ga of the measured object 200G to be measured. Then, the arm 122 can be tilted in any direction regardless of the X and Y axis directions. The probe 102G includes a mounting member 110, a swinging member 120 corresponding to an example serving as a measurement surface contact portion, a stylus 103G, and a coupling mechanism 130, and the stylus 103G can be arbitrarily set in the vertical direction. It is possible to tilt in the direction of

The mounting member 110 is a block member that is fixed to or detachably attached to the three-dimensional shape measuring apparatus 100G, and is a non-moving portion while the swinging member 120 swings, and the three-dimensional shape measuring apparatus 100G. The laser beam for measurement (for example, oscillation frequency stabilized He—Ne laser beam) LL ₁ irradiated from the laser light source 101G of the laser beam 101G can be passed, and the laser beam opening 111 penetrating the mounting member 110 is provided in the center portion. .

Swinging member 120, the stylus 103G in contact with the measured surface 200Ga of the object 200G erected downward, and a mirror 105G for reflecting the measurement laser beam LL ₁ which has passed through the mounting member 110 of the stylus 103G It is a member that is provided at the upper end and swings with respect to the mounting member 110 in accordance with the displacement of the stylus 103G according to the shape of the measurement target surface 200Ga. A sphere (stylus tip sphere) 104G having a high sphericity is attached to the tip (lower end in FIG. 3) of the stylus 103G, and this portion contacts the surface to be measured 200Ga of the object to be measured 200G.

  In this embodiment, the stylus tip sphere 104G of the stylus 103G is, for example, a spherical body having a diameter of about 0.3 mm to about 2 mm, and the arm 122 has a thickness of about 0.7 mm as an example, From the lower surface of the moving member 120 to the center of the stylus tip sphere 104G is a rod-like body having a length L of about 10 mm as an example. These values are appropriately changed depending on the shape of the measurement target surface 200Ga. Further, the shape of the swing member 120 is not limited to a disk shape.

Coupling mechanism 130, the swing member 120 also tilt the swing member 120 in any direction intersecting the optical axis 211a of the measurement laser beam LL ₁ to be irradiated on the mirror 105G and the swingable This is a mechanism that is supported by the mounting member 110. As long as it has such a function, the form of the connection mechanism 130 is not limited. However, in this embodiment, the connection mechanism 130 includes the connection member 131 and the fulcrum member 132. In the present embodiment, the optical axis 211a coincides with the Z-axis direction, which is the vertical direction.

  The connecting member 131 is a rod-shaped member that supports the swinging member 120 facing the mounting member 110, for example, in a suspended form with or without the member, and the stylus 103G is measured. Restoration that restores the swinging member 120 to the neutral position in the initial state perpendicular to the optical axis 211a, which is a force that generates a pressing force to press the measured surface 200Ga of the object 200G. It is a member that generates force. An example of such a connecting member 131 is a suspension member made of an elastic material that can be expanded and contracted. For example, a coil spring can be used. When a coil spring is used, the spring constant may be 40 μN / mm, the measurement force may be 0.2 mN, and the mass of the rocking member 120 may be 60 mg in relation to the measurement force and the like. For example, the upper end of the coil spring may be attached to the attachment member 110 and the lower end may be attached to the swing member 120. Further, a plurality of coil springs may be used, and the lower end portion of each coil spring may be attached to the peripheral portion of the swing member 120 at equal intervals. In the present embodiment, as an example, three coil springs arranged at approximately equal intervals around the optical axis 211a are used, but four or more may be provided. Moreover, it is preferable that the said restoring force in each coil spring is the same.

  Further, the connecting member 131 is not limited to a member made of a material that can be expanded and contracted, such as the coil spring described above. Any member that generates the restoring force as described above may be used.

  The fulcrum member 132 is disposed between the mounting member 110 and the swinging member 120, contacts the mounting member 110 and the swinging member 120 by the restoring force of the coil spring, and swings with respect to the optical axis 211a. This is a member that becomes a fulcrum of swinging of the swinging member 120 when the member 120 is tilted. In the present embodiment, the fulcrum member 132 is a ring-shaped member having a triangular cross section, and is fixed to one of the lower surface of the mounting member 110 and the upper surface of the swing member 120 and is also rocked. When the moving member 120 is inclined, the moving member 120 has a pointed point that makes point contact with either the lower surface of the mounting member 110 or the upper surface of the swinging member 120, and the pointed end serves as a supporting point for the swinging of the swinging member 120. Configure the fulcrum part. The height of the tip is preferably constant over the entire circumference of the ring-shaped member of the fulcrum member 132.

  As described above, in this embodiment, the fulcrum member 132 is fixed to the upper surface of the swing member 120, and the tip is disposed so as to contact the lower surface of the mounting member 110. The fulcrum member 132 is fixed to the upper surface of the swing member 120 so that the center point thereof coincides with the center point of the mirror 105G. In the present embodiment, the fulcrum member 132 is configured, for example, as a fulcrum at the pointed end of the fulcrum member 132. However, the oscillating member 120 can be freely tilted in any direction. As long as it is satisfied, it is not limited to the continuous formation, and the fulcrum portion may be constituted by a set of a plurality of tips.

  In the present embodiment, the misalignment preventing portion 112 for preventing the swinging member 120 from being displaced in the horizontal direction is formed on the lower surface of the mounting member 110 with which the fulcrum member 132 contacts. Has been. In this embodiment, the misregistration prevention portion 112 has a concave shape formed on the lower surface of the mounting member 110, and corresponds to the flat surface 112a on which the laser beam opening 111 is formed, and the side wall of the concave portion. It is formed by a conical slope 112b with the optical axis 211a as the center, and the tip of the fulcrum member 132 is disposed to face the flat surface 112a. Therefore, since the slope 112b becomes a barrier, the misalignment prevention unit 112 functions to always position the optical axis 211a at a fixed point of the mirror 105G, for example, the center point, and the fulcrum member 132 is shifted in the horizontal direction. Can be prevented. Further, in order to minimize the amount of displacement of the fulcrum member 132 on the flat surface 112a, the fulcrum member 132 may be configured such that the tip of the fulcrum member 132 is located at the boundary between the flat surface 112a and the inclined surface 112b. In addition, if the inclination angle of the inclined surface 112b is made gentler than the inclination angle of the inclined surface of the fulcrum member 132 that forms the tip of the fulcrum member 132 so as not to prevent free oscillation of the oscillating member 120. Good. The formation of the misalignment prevention unit 112 is optional and may not be formed.

  The probe 102G in the three-dimensional shape measuring apparatus of the present embodiment configured as described above is operable as follows.

  That is, the swing member 120 suspended from the attachment member 110 by the coil spring coupling member 131 is pulled toward the attachment member 110 by the restoring force of the coil spring. Therefore, the fulcrum member 132 fixed to the swing member 120 is sandwiched between the lower surface of the mounting member 110 and the upper surface of the swing member 120, and the point of the fulcrum member 132 is placed on the lower surface of the mounting member 110. In contact. As described above, since the restoring force in each coil spring is the same, when the swing member 120 is not inclined with respect to the mounting member 110, that is, when the swing member 120 is in the initial state, it is for the fulcrum. The tip end of the entire circumference of the member 132 is in contact with the lower surface of the mounting member 110. In this initial state, in this embodiment, the arm 122 included in the swing member 120 is positioned along the vertical direction.

  On the other hand, as will be described later, the three-dimensional shape measurement of the measurement target surface 200Ga of the measurement target 200G is performed by pressing the stylus 103G attached to the swing member 120 against the measurement target surface 200Ga with a predetermined pressing force. The pressing force is obtained by slightly moving the mounting member 110 to the measured object 200G side in a state where the tip sphere 104G of the stylus 103G is in contact with the measured surface 200Ga, as shown in FIG. Is inclined. Due to the inclination, the restoring force of the coil spring which is the connecting member 131 acts on the swing member 120, and as a result, the stylus 103G is pressed against the surface to be measured 200Ga with a predetermined pressing force, that is, a substantially constant measuring force. become. When the oscillating member 120 is inclined, the pointed tip contacts the lower surface of the mounting member 110 at one point of the entire circumference of the fulcrum member 132, and the pointed end serves as a fulcrum to allow the oscillating member 120 to be inclined. Therefore, the tip other than the portion serving as the fulcrum is not in contact with the lower surface of the mounting member 110. Further, according to the direction of the force acting on the stylus 103G, the position serving as a fulcrum can be freely moved over the entire circumference of the fulcrum member 132 by the restoring force of the coil spring of each connecting member 131. Therefore, the stylus 103G and the arm 122 are swingable like a joystick with the point of contact with the lower surface of the mounting member 110 as a fulcrum, that is, swing and rotate in any direction of 360 degrees. Is possible. Further, even when the swing member 120 is displaced so that the optical axis 211a is shifted in the horizontal direction from a fixed point on the mirror 105G due to such swing of the swing member 120, in the present embodiment, Since the misalignment prevention unit 112 is formed, the position of the swing member 120 is automatically corrected so that the optical axis 211a returns to a fixed point on the mirror 105G.

  In addition, the DUT 200G is fixed on the surface plate 292. On the other hand, an X-axis stage 112G and a Y-axis stage 113G that are independently movable in the X-axis and Y-axis directions orthogonal to each other on a plane are placed on a surface plate 292, and the laser light source 101G is placed on the Y-axis stage 113G. A measurement point information determination unit 80G and a Z-axis stage 114G are arranged. Further, by providing the probe 102G below the Z-axis stage 114G, the probe 102G can be independently moved in all directions of the X-axis, Y-axis, and Z-axis. The X-axis stage 112G, the Y-axis stage 113G, and the Z-axis stage 114G are driven and controlled by the control device 111G. Accordingly, the stylus 103G of the probe 102G is advanced and retracted in the X-axis direction by the X-axis stage 112G and advanced and retracted in the Y-axis direction by the Y-axis stage 113G with respect to the object 200G fixed on the surface plate 292, Drive control is performed by the control device 111G so that the Z-axis stage 114G moves forward and backward in the Z-axis direction.

  In the three-dimensional shape measuring apparatus 100G having such a configuration, the stylus 103G attached to the tip of the probe 102G is brought into contact with the surface to be measured 200Ga that is the side surface of the object to be measured 200G so as to have a substantially constant measuring force. Tracking control and positioning control for scanning in the measurement direction (scanning direction) are independently driven under control of the control device 111G for the X-axis stage 112G, the Y-axis stage 113G, and the Z-axis stage 114G. This can be done. At this time, when scanning the surface to be measured 200Ga of the object to be measured 200G with the probe 102G, the control device 111G does not incline the swing member 120 in the probe 102G only in a specific direction, but swings in any direction. In addition, the X-axis stage 112G, the Y-axis stage 113G, and the Z-axis stage 114G can be driven and controlled independently to control the movement amounts of the probe 102G in the X, Y, and Z axis directions, respectively.

  Further, the measurement laser light generated from the laser light source 101G and a reference mirror 115G (a Z-axis reference mirror (a reference mirror having a reference surface in the Z-axis direction) are shown (the same applies to the XY axis). Is used to measure the relative position coordinate of the stylus 103G.

  The measurement point information determination unit 80G uses the laser beam 211 generated by the laser beam generation unit 210 to obtain position information of the measurement point (contact point) 200Gb on the measurement target surface 200Ga of the measurement target 200G. And a laser length measuring unit that measures the length based on interference between the laser light from each reference plane in the X-axis, Y-axis, and Z-axis directions and the laser light from the measurement point 200Gb. Yes. As an example, the laser length measurement unit includes a position coordinate measurement unit 108G and an angle detection unit 106G.

The optical system 90G includes a reflection mirror 91G and a semi-transmission mirror 92G. The measurement laser beam LL ₁ generated from the laser light source 101G, by using the optical system 90G, the base end of the stylus 103G is irradiated to the mirror 105G attached to (the upper end in FIG. 3), an optical reflection light LL ₂ Using the system 90G, the relative position of the stylus 103G is measured by the position coordinate measuring unit 108G to obtain stylus position data. Also, stylus 103G, the (mean center of rotation) fulcrum by an external force as it is possible to tilt in any direction about the semi-transparent mirror of the optical system 90G part of the reflected light LL ₂ described above 92G makes it incident on the stylus tilt angle detection unit 106G, and detects the change (change amount) in the tilt of the stylus 103G from the displacement (displacement amount) of the spot center position of the laser beam on the surface of the stylus tilt angle detection unit 106G. The control device 111G drives and controls the X-axis stage 112G, the Y-axis stage 113G, and the Z-axis stage 114G using the change (change amount) in the inclination of the stylus 103G detected by the stylus inclination angle detection unit 106G. ing.

A method for detecting the tilt angle of the stylus 103G when the tip sphere 104G of the stylus 103G is brought into contact with the surface to be measured 200Ga of the object to be measured 200G will be described below with reference to FIG. In FIG. 3, in order to facilitate understanding, a mirror 116G is added to the configuration of the optical system 90G in FIG. 2A. In FIG. 3, only the laser optical axis is described in order to avoid complicated notation. When the stylus 103G is not inclined, the light spot center of the reflected light LL ₂ coincides with the center position 300Ga of the angle detection unit 106G. In contrast, when the tip of the stylus 103G is pressed in the X-axis + direction (right direction in FIG. 3), the irradiation position of the reflected light LL ₂ is a light spot center of the reflected light LL ₂ is from the center position 300Ga Move to position 300 Gb, which is off to the left.

Similarly, by the stylus 103G inclines in any direction, as shown in FIG. 4, in accordance with the direction and magnitude of the slope, the center of the light spot position of the reflected light LL ₂ is two-dimensionally varied. The position 301Gb is a state in which the tip sphere 104G of the stylus 103G is in contact with the DUT 200G toward the X axis + side, and the position 301Gc is a state in which the tip sphere 104G of the stylus 103G is in contact with the DUT 200G toward the X axis − side. In a state where the tip sphere 104G of the stylus 103G is in contact with the object to be measured 200G with the position 301Gd facing the Y axis + side, the tip 301G of the stylus 103G is measured with the position 301Ge facing the Y axis − side. The state which contacted the thing 200G is each shown. By detecting the amount of displacement of the light spot center position in the angle detector 106G, the inclination of the stylus 103G can be acquired. The angle detection unit 106G is applicable as long as it can detect the center position of the light spot two-dimensionally, such as a four-division photodiode or a two-dimensional PSD. Hereinafter, the sensors applied to the angle detection unit 106G are collectively referred to as “angle detectors”.

Further, in order to make the measuring force of the stylus 103G substantially constant, the control device 111G uses the difference in the light spot center position with respect to the tracking target value determined in advance by the control device 111G, and the X-axis stage 112G and the Y-axis stage 113G and Z By controlling the drive of the shaft stage 114G, the same follow-up control as in the conventional technique can be performed. For example, as shown in FIG. 3, the inclination of the X-axis direction of the stylus 103G is such that the substantially constant value theta _x, X-axis stage 112G is driven and controlled by the controller 111G. This control is measurement laser beam LL _1, inclined has been reflected light LL ₂ becomes reflected by the mirror 105G to the proximal end of the stylus 103G, its reflected light LL ₂ a light receiving surface of the angle detector 106G time, the light spot center is realized by configuring the control system to follow the straight line position 300Gb at a distance X _t from the center of the light receiving surface.

Here, since the light spot center as described above to follow the straight line position 300Gb at a distance X _t from the center of the light receiving surface, wherein the control system is configured as follows.

  First, a state in which the stylus 103G is in contact with the measurement surface 200Ga of the measurement object 200G is considered as an initial state. At this time, if the X-axis stage 112G or the Y-axis stage 113G is slightly moved, the inclination of the stylus 103G slightly changes according to the movement amount of the X-axis stage 112G or the Y-axis stage 113G, and the mirror 105G at the upper end of the stylus is also the same. Lean on. When the tilt of the mirror 105G changes, the direction of the reflected light from the mirror 105G also changes slightly, and the spot center position on the angle detector 106G changes slightly. The spot center position can be detected by an output (voltage value) from the angle detector 106G, and a voltage value corresponding to the spot center position and a preset tracking target position (straight line 119G in FIG. 3). Can be compared by the control device 111G. From the comparison result, when the spot center position 300Gb is far from the origin O of the angle detector 106G with respect to the target position 119G, the X-axis stage 112G or the Y-axis stage 1132G is moved in the direction toward the origin O. To do. The same applies to the reverse case. By repeating this operation, the spot center position follows the target position 119.

Here, corresponding to the distance _{X t,} the target value _{X t} on angle detector 106G corresponds to the inclination target value theta _x of the stylus 103G in measurement coordinate system.

  Further, in the arithmetic processing unit 109G connected to the position coordinate measuring unit 108G and the angle detecting unit 106G, the relative position coordinate data of the stylus 103G obtained by the position coordinate measuring unit 108G and the stylus obtained by the angle detecting unit 106G. The contact point position coordinate data between the stylus 103G and the object to be measured 200G is calculated using the inclination data of 103G.

  The configuration of the arithmetic processing unit 109G will be described with reference to FIG. 2B. The relative position coordinate data of the stylus 103G obtained by the position coordinate measurement unit 108G and the inclination data of the stylus 103G obtained by the angle detection unit 106G are stored in the storage units 400 and 401, respectively. The tilt data stored in the storage unit 401 is corrected by a stylus tip displacement calculation unit 403 using a mounting angle error γ of an angle detector 106G described later stored in the storage unit 402, and tilt correction data is calculated. The The relative position coordinate data stored in the storage unit 400 and the inclination correction data obtained by the stylus tip displacement calculation unit 403 are added by the addition unit 404, and contact point position coordinate data between the stylus 103G and the DUT 200 is calculated. Is done. In the first and second embodiments, the comparison unit 406 scans in the first scanning direction and, as described above, calculates the first contact point position coordinate data calculated by the addition unit 404 and the like in the second scanning direction. As described above, it is possible to compare the second contact point position coordinate data calculated by the adding unit 404 or the like as described above, and to calculate error data of the two, in the third embodiment of the present invention. , The known shape data input in advance by the input device (eg, keyboard, touch panel, mouse, voice input device, etc.) 411 and stored in the storage unit 405 and the contact point calculated by the addition unit 404 as described above It is also possible to compare the position coordinate data and calculate error data. The error data is stored in the storage unit 407, output to the display device 413, and displayed on the display device 413. Further, when the mounting angle error γ of the angle detector 106G is calibrated, the error data stored in the storage unit 407 and the calibration completion determination value input in advance to the comparison unit 407H by the input device 411 are used. When the comparison is not completed in the comparison unit 407H, the mounting angle error γ of the angle detector 406G is calibrated in the γ calibration unit 407G. The mounting angle error γ of the angle detector 106G used in the stylus tip displacement calculation unit 403 is a value input in advance to the storage unit 402 by the input device 411 or a γ calibration unit 407G and is stored in the storage unit 402. Is the value stored in

  Hereinafter, the positional relationship between the measured object 200G and the stylus 103G and the relationship between the angle detector 106G and the light spot center position when measuring the measured surface 200Ga of the measured object 200G will be described.

  In order to facilitate the following description, simple notations are shown in FIGS. 7A and 7B. FIG. 7A is an explanatory view including a top view and a front view of a state in which the tip sphere 104G of the stylus 103G is brought into contact with the object to be measured 200G so that the pushing amount becomes the target value 120G, and FIG. 7B is an angle with respect to the inclination of the stylus 103G. The detector 106G, the light spot center 302G, and the control target value 119G are shown. In the top view of FIG. 7A, only the fulcrum 117G and the contact point 118G of the DUT 200G and the stylus 103G are indicated by triangular marks and star marks, respectively, and the stylus 103G is omitted. Hereinafter, description will be made using the top view of FIG. 7A and the notation of FIG. 7B.

  While the tip sphere 104G of the stylus 103G is brought into contact with the X axis + side of the object 200G with a substantially constant measuring force, it is in the Y axis direction (for example, the two opposite directions, the Y axis + direction and the Y axis − direction). The positional relationship between the fulcrum 117G and the contact point 118G of the stylus 103G when scanning is shown in FIGS. 8A to 8C show a state from when the stylus 103G is stationary with respect to the Y-axis direction until the stylus 103G starts to move relative to the Y-axis + side. FIGS. This shows a state from a state where it is stationary with respect to the direction until it starts to move relative to the Y-axis minus side. 8A to 8F show the positional relationship between the fulcrum 117G of the stylus 103G and the contact point 118G when the object 200G to be measured and the tip sphere 104G of the stylus 103G are in contact with each other. The positional relationship between the light spot centers 303Ga to 303Gf in the angle detector 106G is shown.

  In the state of FIG. 8A where the stylus 103G is stationary in the Y-axis direction, the vector connecting the fulcrum 117G of the stylus 103G and the contact point 118G is parallel to the X-axis, and the stylus 103G does not tilt in the Y-axis direction. Next, in the state of FIG. 8B, which is the state at the moment when the stylus 103G starts to move in the Y-axis + direction, the drag from the object to be measured 200G acts on the contact point 118G of the stylus 103G, so that friction occurs in the scanning direction. Force is generated. When the static friction force is greater than the moment of inclination of the stylus 103G, the contact point 118G of the stylus 103G tries to stay there, so that only the fulcrum 117G of the stylus 103G is displaced in the Y axis + direction. . Then, at the moment when the relative distance between the fulcrum 117G of the stylus 103G and the contact point 118G increases in the Y-axis direction and the moment in the tilt direction of the stylus 103G becomes larger than the static friction force, the contact point 118G of the stylus 103G starts to move, Switching from static friction force to dynamic friction force. This state is shown in FIG. 8C. Since dynamic friction force ≦ static friction force, when the inclination of the stylus 103G in the X-axis direction is constant, after the contact point 118G starts to move once, the fulcrum 117G of the stylus 103G and the Y-axis direction of the contact point 118G The stylus 103G is tilted and moved so that the relative distance of is constant. At this time, the positional relationship between the angle detector 106G and the light spot center 303Gc is as shown in the lower diagram of FIG. 8C. 8D to 8F showing the transition of the state when the stylus 103G scans in the Y axis-side can be described in the same manner as described above, and thus are omitted.

  Finally, the tip sphere 104G of the stylus 103G is brought into contact with the side surface of the device under test 200G that is the surface to be measured 200Ga, and the device under test 200G and the tip sphere 104G of the stylus 103G are in contact with the stylus 103G tilted in an arbitrary direction. A technique for acquiring the coordinate value of the point 118G will be described.

  First, for the sake of simplicity, it is assumed that measurement can be performed without tilting the stylus 103G when the tip sphere 104G of the stylus 103G is brought into contact with the device under test 200G as shown in FIG. 5A. In this assumption, the relative position coordinate data (X, Y, Z) of the stylus tip position can be acquired using a conventional three-dimensional measurement technique.

Next, as shown in FIGS. 5B to 5D, it is assumed that the stylus 103G is measured tilted from the vertical direction around the fulcrum 117G of FIG. 5A. Here, it is assumed that the inclination θ _x on the X axis and the inclination θ _y on the Y axis with respect to the vertical direction of the stylus 103G can be detected by the stylus inclination angle detection unit 106G without including an error. As described above, the relative position coordinate data (X, Y, Z) of the tip position 104Ga of the stylus 103G when it is assumed that the stylus 103G is not tilted is obtained by using the conventional three-dimensional measurement technique. It can be acquired at 108G.

Actually, since the stylus 103G is inclined, the relative position coordinate data (X, Y, Z) is the contact point position coordinate data (X ′) of the contact point 104Gb between the object 200G to be measured and the tip sphere 104G of the stylus 103G. , Y ′, Z ′). Therefore, using the relative position coordinate data (X, Y, Z) and the inclination data (θ _x , θ _y ) of the stylus 103G, the contact point position coordinate data (X ′, Y ′, Z ′) of the contact point 118G. Needs to be obtained by the position coordinate measuring unit 108G. The contact point 118G between the tip sphere 104G of the stylus 103G and the object 200G to be measured refers to the center point of the stylus tip sphere 104G in a state where the tip sphere 104G of the stylus 103G and the object 200G to be measured are in contact with each other. When the stylus 103G is tilted by (θ _x , θ _y ) from the initial state where the stylus 103G is stationary in the vertical direction, the tip sphere 104G of the stylus 103G has the following calculation formula (several numbers) with respect to the relative position coordinate data (X, Y, Z): It will be displaced by (δ _x , δ _y , δ _z ) obtained in 4).

  In the above equation, the variable L represents the length from the fulcrum 117G of the stylus 103G to the center of the stylus tip sphere 104G.

As described above, by adding the displacement amount (δ _x , δ _y , δ _z ) of the stylus tip due to the inclination of the stylus 103G to the relative position coordinate data (X, Y, Z) by the adding unit 404, the contact point position coordinate data ( X ′, Y ′, Z ′) is obtained by the adding unit 404.

Up to this point, but in which the inclination of the stylus 103G is assumed that the obtained as expected by irradiating a laser beam LL ₂ reflected from the mirror 105G of the base end of the stylus 103G angle detector 106G, sub In order to achieve micron measurement accuracy, as described above, the angle formed by the length measurement coordinate system and the angle detector 106G (hereinafter referred to as “mounting angle error”) cannot be ignored. This is solved by the three-dimensional shape measurement method according to the embodiment.

As described above, when the contact point position coordinate data (X ′, Y ′, Z ′) is obtained with high accuracy, the relative position coordinate data (X, Y, Z) with high accuracy in the length measurement coordinate system and the length measurement are used. Highly accurate tilt data (θ _x , θ _y ) of the stylus 103G in the coordinate system is required.

In order to calculate the inclination (θ _x , θ _y ) of the stylus 103G in the length measurement coordinate system from the displacement amount of the light spot center position on the angle detector 106G, as shown in FIG. 3, the coordinate axes of the angle detector 106G It is necessary that θ _x and θ _y be parallel to the length measurement coordinate system. However, actually, as shown in FIG. 6, the coordinate axes θ _x and θ _y of the angle detector 106G are not always parallel to the length measurement coordinate system, and rotate around the origin of the angle detector 106G. The angle detector 106G is attached to the length measurement coordinate system. For this reason, the inclination (θ _{x ′} , θ _{y ′} ) of the stylus 103G detected from the angle detector 106G does not match the inclination (θ _x , θ _y ) of the stylus 103G in the length measurement coordinate system to be originally obtained. Is clear. Further, considering that the length measurement coordinate system is optically configured, it is very difficult to adjust the mounting angle of the angle detector 106G with respect to the length measurement coordinate system.

Next, the influence of the mounting angle error of the angle detector 106G when acquiring the contact point 118G between the object 200G to be measured and the tip sphere 104G of the stylus 103G will be described using FIG. 5B as an example. It is assumed that the inclination of the stylus 103G in the length measurement coordinate system is (θ _x , θ _y ) in a state where the tip sphere 104G of the stylus 103G is in contact with the object 200G.

Now, it is assumed that the angle detector 106G is attached to the length measurement coordinate system with an error (attachment angle error) by an angle γ. At this time, the inclination data (θ _{x ′} , θ _{y ′} ) detected from the angle detector 106G is the following (Equation 5) with respect to the inclination data (θ _x , θ _y ) of the stylus 103G in the length measurement coordinate system. The relationship of

Further, the displacement amount (δ _{x ′} , δ _{y ′} , δ _{z ′} ) of the tip sphere 104G of the stylus 103G estimated from (θ _{x ′} , θ _{y ′} ) is expressed by the following equation (equation (Equation 6)). .

That is, when the original inclination (θ _x , θ _y ) of the stylus 103G is used when obtaining the contact point position coordinate data (X ′, Y ′, Z ′) from the relative position coordinate data (X, Y, Z). And the inclination data (θ _{x ′} , θ _{y ′} ) detected from the angle detector 106G, the error of (δ _{x ′} −δ _x , δ _y −δ _{y ′} , δ _z −δ _{z ′} ) is You can see what happens.

The above-mentioned error is, for example, the length L of the stylus 103G = 20 mm, the mounting angle error γ = 1 ° of the angle detector 106G, and the amount by which the tip sphere 104G of the stylus 103G is pushed into the object to be measured 200G is δ _x = 10 μm. When δ _y = 0 μm, δ _{x ′} = 9.998 μm and δ _{y ′} = 0.175 μm, which are clearly not negligible in order to obtain submicron measurement accuracy.

  Next, a description will be given of the follow-up control for making the measuring force substantially constant using the conventional technique when the angle detector 106G has the mounting angle error γ.

FIG. 6 shows a state where the angle detector 106G includes a deviation of the mounting angle error γ. As described above, the X-axis stage 112G is controlled so that the light spot center 300Gc is aligned with the target position 119G of the angle detector 106G. At this time, since the angle detector 106G is inclined by the mounting angle error gamma, rather than the stylus 103G slope original target angle theta _x, the control result such that substantially constant at slightly offset angle theta _{x '} .

  While performing this tracking control, the positional relationship between the fulcrum 117G and the contact point 118G of the stylus 103G and the angle detector 106G and the light spot when the stylus 103G is scanned on the Y axis relative to the object 200G. The positional relationships between the centers 304Ga to 304Gh are shown in FIGS. 9A to 9H.

  9A to 9D show a state from when the stylus 103G is stationary with respect to the Y-axis direction until the stylus 103G starts to move relative to the Y-axis + side, and FIGS. This shows a state from a state where it is stationary with respect to the direction until it starts to move relative to the Y-axis minus side. In the state of FIG. 9A where the stylus 103G is stationary in the Y-axis direction, the vector connecting the fulcrum 117G of the stylus 103G and the contact point 118G is parallel to the X-axis, and the stylus 103G does not tilt in the Y-axis direction. Next, FIG. 9B shows a state at the moment when the stylus 103G starts to move in the Y axis + direction. A drag force from the object to be measured 200G acts on the contact point 118G of the stylus 103G, and a frictional force is generated in the scanning direction. When the static frictional force is larger than the moment of inclination of the stylus 103G, the contact point 118G of the stylus 103G tries to stay there, so that only the fulcrum 117G of the stylus 103G is displaced in the Y-axis + direction, resulting in In addition, the stylus 103G is also inclined in the Y-axis direction. At this time, the center of the light spot in the Y-axis direction is displaced. However, when the mounting angle error of the angle detector 106G is included, an error from the control target position 119G in the X-axis direction on the angle detector 106G occurs. At this time, as shown in FIG. 9C, in order to follow the target position of the angle detector 106G by follow-up control in the X-axis direction, the fulcrum 117G of the stylus 103G in the X-axis direction pushes the tip sphere 104G of the stylus 103G. Move in the direction of decreasing. At the moment when the moment in the tilt direction of the stylus 103G becomes larger than the static friction force, the contact point 118G of the stylus 103G starts to move and switches from the static friction force to the dynamic friction force. This state is shown in FIG. 9D. After the contact point 118G starts to move once, the contact point 118G is inclined and moved so that the relative distance between the fulcrum 117G of the stylus 103G and the contact point 118G in the Y-axis direction is constant. At this time, the positional relationship between the angle detector 106G and the light spot center 304Gd is as shown in the lower diagram of FIG. 9D. FIGS. 9E to 9H showing the transition of the state when the stylus 103G is stationary in the Y-axis direction to the Y-axis-side are basically the same as described above, but are in the Y-axis direction. Since the generation direction of the frictional force due to the scanning is reversed, the fulcrum 117G of the stylus 103G is displaced in a direction in which the tip sphere 104G of the stylus 103G is pushed further.

The influence of the above phenomenon on the measurement result will be described. The first relative position coordinate data (X, Y, Z) and the first inclination data (θ _x ) acquired at least at two or more positions when the stylus 103G scans the measurement surface 200Ga of the measurement object 200G in the Y axis + direction. , Θ _y ) and the second relative position coordinate data (X, Y, Z) acquired at least at two or more positions by scanning the stylus 103G in the Y-axis-direction at a position that roughly matches the measurement position, and the second Using the tilt data (θ _x , θ _y ), the contact point position coordinate data of the object 200G to be measured and the tip sphere 104G of the stylus 103G during the Y axis + direction scanning of the stylus 103G, and the Y axis minus direction of the stylus 103G FIG. 10A shows the result of calculating the contact point position coordinate data of the object 200G to be measured and the tip sphere 104G of the stylus 103G during scanning. In FIG. 10A, contact point position coordinate data 121a which is a contact point estimation result at the time of Y-axis + direction scanning with respect to the object to be measured 200G coincides with contact point position coordinate data 121b which is a contact point estimation result at the time of Y-axis-direction scanning. do not do.

  This is a measurement error due to the mounting angle error of the angle detector 106G, and the stylus 103G is inclined with respect to the length measurement coordinate system even though it is inclined in the X axis and Y axis directions of the length measurement coordinate system. This is nothing but the result of calculating the contact point using the detection result of the angle detector 106G.

  In the three-dimensional shape measurement method according to the present embodiment, the measurement error is reduced by correcting the attachment angle error by the following procedure.

  The correction process is performed by the stylus tip displacement calculator 403.

First, the coordinate axis of the mounting angle error-free angle detector 106G and theta _x-axis and theta _y-axis as shown in FIG. 11A, the mounting angle error γ the angle detector around the origin O of 106G as shown in FIG. 11B Assuming that the coordinate axes of the angle detector 106G when rotated only by θx _′ axis and θy _′ axis.

Assume that the light spot center 305G is irradiated at the position shown in FIGS. 11A and 11B. In the case where the mounting state of the angle detector 106G is shown in FIG. 11B, the angle detection result is detected in the first quadrant in the θ _{x ′} θ _{y ′} coordinates, but there is no ideal mounting angle error shown in FIG. 11A. As a result of a typical angle detection, it exists on the _θx axis. If the isotropicity of the two-dimensional space of the angle detector 106G is obtained, the angle detection result is shown in FIG. 11B by performing coordinate conversion as shown in the following equation (Equation 7) by the stylus tip displacement calculation unit 403. It is possible to convert from θ _{x ′} θ _{y ′} coordinates to θ _x θ _y coordinates shown in FIG. 11A.

  In order to realize this conversion, the mounting angle error γ of the angle detector 106G is required.

The mounting angle error γ is calculated as follows. First, the stylus 103G is scanned in the first direction, and the first relative position coordinate data (X, Y, Z) and the first are detected by the position coordinate measurement unit 108G and the angle detection unit 106G, respectively, at at least two positions. 1 Inclination data (θ _{x ′} , θ _{y ′} ) is obtained. In addition, the position coordinate measuring unit 108G and angle detection are performed at a position that approximately matches the position at which the first relative position coordinate data and the tilt data are obtained by scanning the stylus 103G in a second direction opposite to the first direction. The second relative position coordinate data (X, Y, Z) and the second inclination data (θ _{x ′} , θ _{y ′} ) are obtained by the unit 106G, respectively. Further, by inputting the initial value of the mounting angle error γ from the input device 411 in advance, the coordinate conversion formula shown in (Expression 7) is realized. The coordinate conversion formula is implemented in the stylus tip displacement calculator 403. The first tilt data (θ _{x ′} , θ _{y ′} ) and the second tilt data (θ _{x ′} , θ _{y ′} ) are converted by the stylus tip displacement calculator 403 using the coordinate conversion formula of the stylus tip displacement calculator. First inclination correction data (θ _x , θ _y ) and second inclination correction data (θ _x , θ _y ) are obtained. Next, the first relative position coordinate data (X, Y, Z) and the first inclination data (θ _{x ′} , θ _{y ′} ) obtained respectively and the second relative position coordinate data (X, Y, Z) are obtained. , Second inclination data (θ _{x ′} , θ _{y ′} ), the converted first inclination correction data (θ _x , θ _y ), and second inclination correction data (θ _x , θ _y ). Are used to add the first contact point position coordinate data (X ′, Y ′, Z ′) and the second contact point position coordinate data (X ′, Y ′, Z ′) of the stylus 103G and the object 200G to be measured. ) Is calculated. Then, the optimum mounting angle error γ is searched by the γ calibration unit 407G to calibrate the mounting angle error of the angle detector 106G. Hereinafter, a method of calibrating the mounting angle error of the angle detector 106G by the arithmetic processing unit 109G will be described.

  As described above, the contact point position obtained by scanning the surface to be measured 200Ga of the object to be measured 200G with the stylus 103G in the two opposite directions (for example, the Y axis + direction and the Y axis-direction). When there is an attachment error of the angle detector 106G, the coordinate data 121a and the contact point position coordinate data 121b do not match both the contact point position coordinate data 121a and the contact point position coordinate data 121b as shown in FIG. 10A. . However, when the mounting angle error of the angle detector 106 becomes small, as shown in FIG. 10B, the difference between the contact point position coordinate data 121a and the contact point position coordinate data 121b becomes small, and there is a mounting angle error of the angle detector 106G. If not, as shown in FIG. 10C, the contact point position coordinate data 121a and the contact point position coordinate data 121b match within the range of measurement accuracy.

  Therefore, one index for searching for the optimum mounting angle error γ by the γ calibration unit 407G is defined by the γ calibration unit 407G as follows.

10A to 10C, the difference between the contact point position coordinate data 121a and the contact point position coordinate data 121b obtained by scanning the stylus 103G in two opposite directions (for example, the Y axis + direction and the Y axis-direction) is shown. As an index to be expressed, in the first and second embodiments of the present invention, contact point estimation data (X _{a ′ [i]} , Y _{a ′ [i]} , Z _{a ′ [i]} ) with respect to the first scanning direction, When the contact point position coordinate data (X _{b ′ [i]} , Y _{b ′ [i]} , Z _{b ′ [i]} ) with respect to the second scanning direction is shown in the first three lines of the following (Equation 8). In this way, the comparison unit 406 performs comparison, and the final row distance d is defined by the γ calibration unit 407G. However, the subscript i is i = 1, 2,..., N, where N is an arbitrary number of data.

In the third embodiment of the present invention, when the device under test 200G has a known shape, another index shown below for searching for the optimum mounting angle error γ by the γ calibration unit 407G is expressed as γ This is defined by the calibration unit 407G. First contact point position coordinate data (X _{a ′ [i]} , Y _{a ′ [i]} , Z _{a ′ [i]} ) and first known shape data (X _{Da ′ [i]} , Y) with respect to the first scanning direction _{Da ′ [i]} , Z _{Da ′ [i]} ), and second contact point position coordinate data (X _{b ′ [i]} , Y _{b ′ [i]} , Z _{b ′ [i]} ) with respect to the second scanning direction. And second known shape data (X _{Db ′ [i]} , Y _{Db ′ [i]} , Z _{Db ′ [i]} ), the last of (Equation 9) is used as an index representing the difference between the two contact point position coordinate data The row distance d is defined by the γ calibration unit 407G. It should be noted that items other than the last line in (Equation 9) are realized by the comparison unit 406. The first and second known shape data are input by the input device 411, and may be a large number of three-dimensional coordinate data groups. For example, if the known shape is a sphere, a radius value may be input. Thus, it is possible to calculate known shape data corresponding to the contact point position coordinate data.

  The angle at which the two indices of the distance d of the last row in (Equation 8) and the distance d of the last row in (Equation 9) are smaller than the judgment value for completion of calibration input in advance by the input device, respectively. γ is calibrated by searching by the arithmetic processing unit 109G, and the mounting angle error of the angle detector 106G is set to the calibrated angle γ in the stylus tip displacement calculating unit 403, whereby the stylus tip displacement calculating unit 403 The mounting angle error γ of the angle detector 106G can be corrected. Note that the calibrated mounting angle error γ can also be applied to the third relative position coordinate data and the third inclination data of the stylus 103G obtained by scanning in an arbitrary direction after calibration, and the arithmetic processing unit 109G. Then, the contact point position coordinate data of the stylus 103G and the object 200G to be measured can be calculated from the third relative position coordinate data and the third inclination data.

  Further, when the measured object 200G has a known shape and the known shape data can be used, and the error between the contact point position coordinate data and the known shape data is used as an index, the calculation processing unit 109G receives the contact point. It is preferable to calculate an error between the contact point position coordinate data aligned with the known shape data by the comparison unit 406 and the known shape data by adding a processing unit for aligning the position coordinate data with the known shape data. As an example of this alignment method, after obtaining the coordinate conversion amount that minimizes the mean square sum of the difference between the contact point estimation data and the known shape data, the contact point estimation data is subjected to coordinate conversion using the coordinate conversion amount. It ’s fine.

Furthermore, in the third embodiment of the present invention, when the γ calibration unit 407G uses the distance d shown in the last row of (Equation 9) as an index, the first error data is dx _a = dy _a = dz _a When d = 0 and the second error data is dx _b = dy _b = dz _b = 0, the distance d = 0 is guaranteed. That is, the γ calibration unit 407G expands to the index of the following formula (Equation 10), thereby scanning in the first scanning direction to obtain the relative position coordinate data of the stylus 103G and scanning in the second scanning direction. Thus, the measurement position for obtaining the relative position coordinate data of the stylus 103G does not have to coincide with each other, and the γ calibration unit 407G can calibrate the mounting angle error even if the two measurement data numbers are different. Become.

This state is shown in FIGS. 10D to 10F. In FIG. 10D, contact point position coordinate data (X _{da [i]} , Y _{da [i]} , Z _{da [i]} ) when the stylus 103G is scanned to the Y axis + side corresponds to the contact point position coordinate data. The known shape data to be performed is (X _{Dda [i]} , Y _{Dda [i]} , Z _{Dda [i]} ). The subscript i is i = 1, 2,. Similarly, the contact point position coordinate data (X _{db [j]} , Y _{db [j]} , Z _{db [j]} ) when the stylus 103G is scanned to the Y axis-side corresponds to the contact point position coordinate data. The known shape data is _assumed to be (X _{Ddb [j]} , Y _{Ddb [j]} , Z _{Ddb [j]} ). The subscript j is j = 1,2,3. Index _{d d} in FIG. 10D is obtained by the in γ correction unit 407G by the equation (11) as follows.

Similarly, in FIG. 10E as well, the contact point position coordinate data ( _{Xea [i]} , _{Yea [i]} , _{Zea [i]} ) when the stylus 103G is scanned to the Y axis + side is the same. The known shape data corresponding to the position coordinate data ( _{XDea [i]} , _{YDea [i]} , _{ZDea [i]} ), and the contact point position coordinate data when the stylus 103G is scanned to the Y axis-side (X _{eb [j]} , Y _{eb [j]} , Z _{eb [j]} ), and known shape data corresponding to the contact point position coordinate data (X _{Deb [j]} , Y _{Dev [j]} , Z _{Dev [j]} ) And In this case, the index _{d e} is obtained in by the γ correction unit 407G as (number 12).

Similarly, in FIG. 10F as well, contact point position coordinate data (X _{fa [i]} , Y _{fa [i]} , Z _{fa [i]} ) when the stylus 103G is scanned to the Y axis + side is the contact point. The known shape data corresponding to the position coordinate data (X _{Dfa [i]} , Y _{Dfa [i]} , Z _{Dfa [i]} ), and the contact point position coordinate data when the stylus 103G is scanned to the Y axis-side (X _{fb [j]} , _{Yfb [j]} , _{Zfb [j]} ), and known shape data corresponding to the contact point position coordinate data ( _{XDfb [j]} , _{YDfb [j]} , _{ZDfb [j]} ) And In this case, the index _{d f} is obtained in by the γ correction unit 407G as (number 13).

  As is clear from the relationship between the contact point position coordinate data shown in FIGS. 10D to 10F and the known shape data corresponding to the contact point position coordinate data, the following equation (Formula 14) is established.

  Finally, the flow of the three-dimensional shape measurement method according to the embodiment of the present invention will be described with reference to the flowchart shown in FIG. 12A.

  First, in step S1, under the control of the control device 111G, the measurement surface 200Ga of the measurement object 200G used for calibration is scanned with the stylus 103G in the first direction, and the first at at least two positions. Relative position coordinate data and first inclination data are obtained by the position coordinate measurement unit 108G and the angle detection unit 106G, respectively. Specifically, the stylus tip sphere 104G of the stylus 103G is brought into contact with the surface to be measured 200Ga of the object to be measured 200G with a substantially constant measurement force, and the first relative position coordinate data and the first data are scanned in the first direction. One inclination data is obtained by the position coordinate measuring unit 108G and the angle detecting unit 106G, respectively, at two or more points, and stored in the storage units 400 and 401, respectively.

  Next, in step S2, under the control of the control device 111G, the surface to be measured 200Ga of the object to be measured 200G used for the calibration is scanned with the stylus 103G in the second direction opposite to the first direction. The second relative position coordinate data and the second inclination data at the position that approximately matches the position at which the first relative position coordinate data and the first inclination data are obtained are respectively obtained by the position coordinate measurement unit 108G and the angle detection unit 106G. Ask. Specifically, the second relative position coordinate data is scanned in the second direction opposite to the first direction while bringing the stylus 103G into contact with the measurement surface 200Ga of the measurement object 200G with a substantially constant measurement force. And the second inclination data are respectively obtained by the position coordinate measurement unit 108G and the angle detection unit 106G at positions substantially coincident with the positions at which the first relative position coordinate data and the first inclination data are obtained, respectively. The data are stored in the storage units 400 and 401, respectively.

  Next, in step S3, the stylus tip displacement calculation unit 403 obtains the stylus tip displacement corresponding to the tilt amount from the first tilt data stored in the storage unit 401, and the first relative position coordinates stored in the storage unit 400 are obtained. The adder 404 adds the data and the stylus tip displacement to calculate the first contact point position coordinate data. Similarly, in step S4, second contact point position coordinate data is calculated from the second relative position coordinate data and the second inclination data.

  In step S5, the first contact point position coordinate data and the second contact point position coordinate data are compared by the comparison unit 406 to calculate error data. The error data is stored in the storage unit 407, output to the display device 413, and displayed on the display device 413. Further, when the mounting angle error γ of the angle detector 106G is calibrated, the error data stored in the storage unit 407 and the calibration completion determination value input in advance to the comparison unit 407H by the input device 411 are used. If the comparison is not completed in the comparison unit 407H, the mounting angle error γ of the angle detector 106G is calibrated by the calibration unit 407G. The flow relating to the calibration will be described later.

  Next, in step S6, the third relative position coordinate data and the third inclination data are obtained by replacing the measurement object with an arbitrary object to be actually measured and moving the relative position of the stylus in an arbitrary direction. Is obtained by the position coordinate measuring unit 108G and the angle detecting unit 106G and stored in the storage units 400 and 401, respectively.

  Next, in step S7, the mounting angle error of the angle detector 106G included in the third inclination data stored in the storage unit 401 is converted into the stylus tip displacement using the mounting angle error γ calibrated by the calibration unit 407G. By correcting by the calculation unit 403, third inclination correction data is calculated.

  Next, from the third relative position coordinate data and the third tilt correction data, the adder 404 calculates third contact point position coordinate data of the device under test 200G and the stylus 103G.

  Finally, the known shape data of the measurement object input in advance by the input device 411 and the third contact point position coordinate data are compared by the comparison unit 406 to calculate third shape error data, and the storage unit 407 And then displayed on the display device 413.

  A flow relating to the operation of calibrating the mounting angle error γ of the angle detector 106G according to the second embodiment of the present invention will be described with reference to the flowchart shown in FIG. 12B.

  First, in step S11, an initial value γ ′ for obtaining the mounting angle error γ of the angle detector 106G by iterative processing and a determination value for judging completion of calibration by the iterative processing are obtained from the input device 411 from the comparison unit 407. Enter and set.

  Next, in step S12, the mounting angle error of the angle detector 106G included in the first inclination data obtained by measuring the measured object 200G used for the calibration in the stylus tip displacement calculation unit 403 is calculated as an angle. By correcting using γ ′, first inclination correction data is calculated. Similarly, in step S13, the mounting angle error of the angle detector 106G included in the second inclination data obtained by measuring the measured object 200G used for the calibration in the stylus tip displacement calculation unit 403 is calculated as an angle. By correcting using γ ′, second inclination correction data is calculated.

  Next, in step S14, after the first stylus tip displacement amount is calculated from the first tilt correction data by the stylus tip displacement calculator 403, the first object obtained by measuring the object 200G used for the calibration is obtained. By adding the relative position coordinate data and the obtained first stylus tip displacement amount by the adding unit 404, the first contact point position coordinate data is calculated. Similarly, in step S15, the second stylus tip displacement amount is calculated from the second tilt correction data by the stylus tip displacement calculator 403, and then the second object obtained by measuring the object to be measured 200G used for the calibration. By adding the relative position coordinate data and the obtained second stylus tip displacement amount by the adding unit 404, the second contact point position coordinate data is calculated.

  Next, in step S16, the first contact point position coordinate data and the second contact point position coordinate data are compared by the comparison unit 406, and whether the difference is smaller than the determination value set in step S11 is compared. Judge at 407H. This utilizes the fact that a difference appears in the comparison result when the angle γ ′ used in steps S12 and S13 does not appropriately represent the actual mounting angle error γ.

In step S16, when the comparison result is smaller than the determination value, the angle γ ′ at that time becomes the actual mounting angle error γ of the angle detector 106G as shown in step S18. On the other hand, if the comparison result is larger than the determination value, there is a difference between the angle γ ′ and the actual mounting angle. Therefore, in step S17, the minute amount δγ is calibrated to the angle γ ′. After adding in the section 407G, the angle γ ′ is optimized by repeating steps S12 to S16. Incidentally, the determination of the minute change amount [delta] _gamma required during optimization may be applied to the bisection method or the like.

  A flow relating to the operation of calibrating the mounting angle error γ of the angle detector 106G according to the third embodiment of the present invention will be described with reference to the flowchart shown in FIG. 12C.

  First, in step S21, an initial value γ ′ for determining the mounting angle error γ of the angle detector 106G by iterative processing, a determination value for determining completion of calibration by the iterative processing, and an object 200G to be used for calibration. Because of the known shape, the known shape data is input from the input device and set.

  Next, in step S22, the mounting angle error of the angle detector 106G included in the first inclination data obtained by measuring the measurement object 200G used for the calibration in the stylus tip displacement calculation unit 403 is expressed as an angle γ. The first tilt correction data is calculated by correcting using '. Similarly, in step S23, the mounting angle error of the angle detector 106G included in the second inclination data obtained by measuring the measured object 200G used for calibration in the stylus tip displacement calculation unit 403 is expressed as an angle γ. The second inclination correction data is calculated by correcting using '.

  Next, in step S24, after calculating the first stylus tip displacement amount from the first tilt correction data by the stylus tip displacement calculation unit 403, the calculated first stylus tip displacement amount and the measurement object used for the calibration. The first contact point position coordinate data is calculated by adding the first relative position coordinate data obtained by measuring 200G by the adding unit 404. Similarly, in step S25, after calculating the second stylus tip displacement amount from the second inclination correction data by the stylus tip displacement calculator 403, the calculated second stylus tip displacement amount and the object 200G to be used for the calibration are calculated. The second contact point position coordinate data is calculated by adding the second relative position coordinate data obtained by measuring the value by the adding unit 404.

  Next, in step S <b> 26, the first error data is calculated by comparing the known shape data corresponding to the first contact position coordinate data by the comparison unit 406 and stored in the storage unit 407. Similarly, in step S <b> 27, second error data is calculated by comparing the known shape data corresponding to the second contact position coordinate data with the comparison unit 406, and stored in the storage unit 407.

  Next, in step S28, the comparison unit 407H determines whether or not the evaluation index obtained from the first error data and the second error data stored in the storage unit 407 is smaller than the determination value set in step S21. Judge by comparison. This utilizes the fact that a difference appears in the comparison result when the angle γ ′ used in steps S22 and S23 does not appropriately represent the actual mounting angle error γ.

  In step S28, if the comparison result is smaller than the determination value, the angle γ 'at that time becomes the actual mounting angle error γ of the angle detector 106G as shown in step S30. On the contrary, if the comparison result is larger than the determination value, there is a difference between the angle γ ′ and the actual mounting angle. Therefore, in step S29, the minute amount δγ is calibrated to the angle γ ′. After adding in the unit 407G, the angle γ ′ is optimized by repeating steps S22 to S28.

Finally, a calculation formula for calculating the contact point between the stylus 103G and the DUT 200G from the relative position coordinate data (X, Y, Z) and the inclination data (θ _{x ′} , θ _{y ′} ) by the adding unit 404 is as follows. (Equation 15) Here, the mounting angle error of the angle detector 106G is γ, and the distance from the fulcrum of the stylus 103G to the center of the tip sphere 104G is L.

  As described above, according to the shape measurement method of the present invention, the mounting angle error of the angle detector 106G can be easily calibrated, and the measurement error due to the mounting angle error of the angle detector 106G can be reduced. It becomes. Further, it is not necessary to repeatedly adjust the mounting angle of the angle detector 106G.

  In addition, when the first contact point position coordinate data and the second contact point position coordinate data are directly compared as described above, it is not necessary to know the shape of the object to be measured. It is also possible to use it.

  In addition, it can be made to show the effect which each has by combining arbitrary embodiment or modification of the said various embodiment or modification suitably.

  The shape measuring method according to the present invention acquires the position of the center of the light spot with a two-dimensional sensor in order to detect the inclination of the stylus when measuring the three-dimensional shape of the side surface of the arbitrary shape of the object to be measured with high accuracy. However, the present invention can be applied to a shape measuring method that performs the three-dimensional shape measurement of the side surface with high accuracy.

The block diagram of the three-dimensional shape measuring apparatus concerning one Embodiment of this invention 1 is a configuration diagram of a measurement point information determination unit in the three-dimensional shape measurement apparatus of FIG. 1 is a configuration diagram of an arithmetic processing unit in the three-dimensional shape measuring apparatus of FIG. 1 is a configuration diagram of an angle detection optical system in the three-dimensional shape measuring apparatus of FIG. Explanatory drawing regarding the angle detector of the said three-dimensional shape measuring apparatus of FIG. FIG. 1 is a relationship diagram of relative position coordinate data, inclination data, and contact points when a three-dimensional shape measuring method is performed using the three-dimensional shape measuring apparatus of FIG. FIG. 1 is a relationship diagram of relative position coordinate data, inclination data, and contact points when a three-dimensional shape measuring method is performed using the three-dimensional shape measuring apparatus of FIG. The side view which shows the relationship between relative position coordinate data and inclination data, and a contact point when implementing the three-dimensional shape measuring method using the said three-dimensional shape measuring apparatus of FIG. The side view which shows the relationship between relative position coordinate data and inclination data, and a contact point when implementing the three-dimensional shape measuring method using the said three-dimensional shape measuring apparatus of FIG. Illustration about the issue When measuring the measurement surface of the measurement object, the target is the amount of stylus pushed into the measurement object to briefly explain the relationship between the measurement object and the stylus and the relationship between the angle detector and the light spot center position. Explanatory drawing including a top view and a front view in a state of contact with each other An angle detector and a light spot with respect to the stylus inclination for simply explaining the positional relationship between the measured object and the stylus and the relationship between the angle detector and the center position of the light spot when measuring the measurement surface of the measured object. A representation that simply shows the center and control target values FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector Illustration of the effect of angle detector mounting angle error Illustration of the effect of angle detector mounting angle error Illustration of the effect of angle detector mounting angle error Illustration of the effect of angle detector mounting angle error Illustration of the effect of angle detector mounting angle error Illustration of the effect of angle detector mounting angle error Explanatory drawing regarding the shape measuring method according to the embodiment of the present invention. Explanatory drawing regarding the shape measuring method according to the embodiment of the present invention. The flowchart of the three-dimensional shape measuring method according to the embodiment of the present invention. The flowchart regarding the operation | movement which calibrates the attachment angle error (gamma) of an angle detector in the three-dimensional shape measuring method concerning 2nd Embodiment of this invention. The flowchart regarding the operation | movement which calibrates the attachment angle error (gamma) of an angle detector in the three-dimensional shape measuring method concerning 3rd Embodiment of this invention. Configuration diagram of a conventional three-dimensional shape measuring apparatus Configuration diagram of measurement point information determination unit in FIG. Configuration diagram of the tilt detection optical system in FIG. Illustration of the angle detector and the displacement direction of the light spot center Relationship diagram of relative position coordinate data and inclination data and contact point Relationship diagram of relative position coordinate data and inclination data and contact point Side view showing relationship between relative position coordinate data and inclination data and contact point Side view showing relationship between relative position coordinate data and inclination data and contact point Explanatory drawing about problems of conventional technology In order to simply explain the positional relationship between the object to be measured and the stylus and the relationship between the angle detector and the center position of the light spot when measuring the measurement surface of the object to be measured using conventional technology, Explanatory drawing including a top view and a front view of a state in which the stylus is brought into contact so that the pushing amount becomes a target value For measuring the measurement surface of the object to be measured using conventional technology, the positional relationship between the object to be measured and the stylus and the relationship between the angle detector and the light spot center position are simply described with respect to the inclination of the stylus. An expression diagram showing the angle detector, light spot center and control target value in a simple manner FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 7 is an explanatory diagram of a measurement operation when the mounting angle error of the angle detector is not included, and the upper diagram is an explanatory diagram showing the positional relationship between the stylus fulcrum and the contact point when the object to be measured and the stylus contact each other. Yes, the lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector FIG. 6 is an explanatory diagram of a measurement operation when an angle detector mounting angle error is included, and the upper diagram is an explanatory diagram showing a positional relationship between a stylus fulcrum and a contact point when the object to be measured contacts the stylus. The lower figure is an explanatory diagram showing the positional relationship of the light spot center in the angle detector Illustration of the effect of angle detector mounting angle error

Explanation of symbols

100G three-dimensional shape measuring apparatus 101G laser light source 102G probe 103G stylus 104G stylus tip sphere 104Ga to 104Gb stylus tip sphere center 105G mirror 106G stylus tilt angle detector (angle detector)
108G Position coordinate measuring unit 109G Arithmetic processing unit 111G Control unit 112G X-axis stage 113G Y-axis stage 114G Z-axis stage 115G Z-axis reference mirror 116G Mirror 117G Stylus rotation center (fulcrum)
118G Contact point between measured object and tip sphere of stylus 119G Control target position on angle detector 120G Control target position on length measurement coordinate system 121Ga to 121Gb Contact point position coordinate data calculated from relative position coordinate data and inclination data 200G object to be measured 200Ga surface to be measured 300Ga to 300Gc, 301Ga to 301Ge, 302G, 303Ga to 303Gf, 304Ga to 304Gh, 305G Light spot center 400 storage unit 401 storage unit 402 storage unit 403 stylus tip displacement calculation unit 404 addition unit 405 storage Unit 406 comparison unit 407 storage unit 407G gamma calibration unit 407H comparison unit 411 input device 413 display device

Claims (3)

By controlling a moving device that moves the relative position of the object to be measured and the stylus by bringing the stylus into contact with the surface to be measured of the object to be measured, the measurement force is approximately constant. While controlling the relative position of the object and the stylus, the relative position coordinate of the stylus is moved by the position coordinate measuring unit by moving the relative position of the stylus with respect to the object to be measured in a direction substantially perpendicular to the direction of the measurement force of the stylus. In addition to measuring, the angle detector detects the light spot position displacement amount of the laser beam by the stylus tilt angle detector, and the stylus tip tilts due to the stylus tilting according to the obtained tilt. The displacement is calculated by the stylus tip displacement calculator, and the displacement of the stylus tip is added to the relative position coordinates before In the shape measuring method of calculating the adding section contact point of the stylus and the object to be measured,
The relative position between the object to be measured used for calibration and the stylus is moved in the first direction, and the first relative position coordinate data and the first inclination data of the stylus are transferred to the position coordinate measuring unit and the position at at least two positions. Obtained by each angle detector,
The relative position between the object to be measured and the stylus is moved in a second direction opposite to the first direction, and the position approximately coincides with the position where the first relative position coordinate data and the first inclination data are acquired. The second relative position coordinate data and the second inclination data of the stylus are respectively determined by the position coordinate measurement unit and the angle detection unit,
Calculating the first contact point position coordinate data of the object to be measured and the stylus from the first relative position coordinate data and the first inclination data by the adding unit;
The addition unit calculates second contact point position coordinate data of the object to be measured and the stylus from the second relative position coordinate data and the second inclination data,
The first contact point position coordinate data and the second contact point position coordinate data are compared to calibrate the mounting angle error γ of the angle detector that detects the light spot position displacement amount by a γ calibration unit,
The relative position between an arbitrary object to be measured and the stylus is moved in an arbitrary direction to obtain third relative position coordinate data and third inclination data of the stylus by the position coordinate measurement unit and the angle detection unit, respectively. The third inclination correction data is calculated by correcting the error due to the mounting angle error γ of the angle detector included in the third inclination data by the stylus tip displacement calculation unit,
From the third relative position coordinate data of the stylus and the third inclination correction data, the third contact point position coordinate data of the object to be measured and the stylus is calculated by the adding unit, and the shape of the object to be measured is calculated. A shape measuring method characterized by measuring In the operation of calibrating the mounting angle error γ of the angle detector,
The first tilt correction data is calculated by the stylus tip displacement calculation unit by transforming the first tilt data by an arbitrary angle γ ′ around the origin of the coordinate system where the light spot position displacement is detected,
The second tilt correction data is calculated by the stylus tip displacement calculation unit by transforming the second tilt data by the angle γ ′ around the origin of the coordinate system,
Calculating the first contact point position coordinate data of the object to be measured and the stylus from the first relative position coordinate data and the first inclination correction data by the adding unit;
Calculating the second contact point position coordinate data of the object to be measured and the stylus from the second relative position coordinate data and the second inclination correction data,
By repeating these series of operations while changing the value of the angle γ ′, the difference between the first contact point position coordinate data and the second contact point position coordinate data is smaller than a predetermined determination value. The shape measuring method according to claim 1, wherein the angle γ ′ is calculated by the γ calibration unit, and the operation of calibrating the mounting angle error γ of the angle detector is performed. Instead of the operation of calibrating the mounting angle error γ of the angle detector using the difference between the first contact point position coordinate data and the second contact point position coordinate data, with the measured object used for the calibration being a known shape object In addition,
Comparing the first contact point position data with the known shape data representing the known shape object, and calculating the first error data in the comparison unit;
The second contact point position data and the known shape data are compared and second error data is calculated by the comparison unit,
By repeating these series of operations while changing the value of the angle γ ′, an angle γ ′ in which both the first error data and the second error data are smaller than a predetermined determination value is set to the γ The shape measuring method according to claim 2, wherein an operation of calculating by a calibration unit and calibrating using the angle detector mounting angle error γ is performed.

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