JP2007327826A - Method of correcting force of stylus type step difference gage for measuring surface profile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of correcting force of a stylus type step difference gage for measuring a surface profile, capable of compensating dependency of the force to a probe position and a dispersion of a component dimension, in the stylus type step difference gage for measuring the surface profile. <P>SOLUTION: In this method of correcting the force of the stylus type step difference gage, the probe is provided in one end of a support body attached swingably to a fulcrum, a magnetic substance core of a displacement sensor is provided to detect a vertical directional displacement of the probe, and a magnetic substance core of a stylus pressure generator is attached to the support body to apply stylus pressure to the probe, and the surface profile of a sample captured by the probe is measured by the displacement sensor, based on a rotational motion around the fulcrum of the support body. In the method, a relation between a displacement component z of a stylus tip of the probe and the force in the stylus tip of the probe is measured preliminarily to find a relational expression so as to be programmed in a computer, the displacement component z of the stylus tip of the probe is monitored in real time when measuring the surface profile, and a change of the displacement component z of the stylus tip of the probe is compensated by controlling a current flowing in a force generating coil by the computer, using the relational expression. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for correcting the force of a stylus type step gauge for measuring the surface shape of a sample.

  In the present specification, the term “surface shape of the sample” is meant to include the concept of the step, film thickness, and surface roughness of the sample.

Conventionally, this type of step gauge has a probe whose tip contacts the sample surface, a needle pressure generator that contacts the sample surface with a constant load, and a probe that vibrates in a direction perpendicular to the load direction. Known to have a structure with a device that reciprocates the needle in parallel with the sample surface and a detection device that detects the magnitude of vibration corresponding to the frictional force of the probe against the sample when vibration is applied. (See Patent Document 1).
JP-A-3-87737

  The present inventor previously proposed a stylus-type step gauge for surface shape measurement in Japanese Patent Application No. 2005-199337. As shown in FIGS. 1 to 6 of the accompanying drawings, this stylus type step gauge has a rod-shaped first support member 1, and this first support member 1 is located in the left and right lateral directions at an intermediate portion thereof. A fulcrum needle attachment member 2 is provided, and two fulcrum needles 3 are attached to both ends of the fulcrum needle attachment member 2. These two fulcrum needles 3 are supported by two fulcrum receiving members 4 (FIG. 6), whereby the first support member 1 is supported by the fulcrum receiving member 4 in a freely swingable manner. . At one end of the first support member 1, a measuring element of the displacement sensor 5, that is, a core 6 is attached. The displacement sensor 5 comprises a differential transformer that generates an electrical signal in accordance with the vertical displacement of the probe, and includes a coil 7.

  The other end of the first support member 1 is provided with a core 9 of a needle pressure generator 8 that applies a needle pressure to the probe, and the needle pressure generator 8 includes a coil 10. The core 9 is made of a high magnetic permeability member arranged at a position shifted in the axial direction from the center of the coil 10.

  A holder in which two magnets 11 are embedded in the lower surface of the first support member 1 around the line connecting the two fulcrum needles 3 at both ends of the fulcrum needle mounting member 2 of the first support member 1. 12 is attached. As shown in FIG. 3, the holder 12 is provided with a longitudinal groove 13 having a trapezoidal cross section, and both side walls of the longitudinal groove 13 are tapered downward to form an inclined surface with respect to a horizontal plane. Yes. The two magnets 11 embedded in the holder 12 are arranged so that the polarities are opposite to each other as shown in FIG. The holder 12 containing the two magnets 11 is made of carbon in order to reduce the weight.

  In FIG. 1, FIG. 2, FIG. 4 and FIG. 6, reference numeral 14 denotes a rod-like second support member. A probe 15 is attached to the tip of the second support member, and the other end is formed of a high permeability member 16. Yes. Guide protrusions 17 extending upward are formed at both ends in the longitudinal direction of the high magnetic permeability member 16, and opposing side surfaces of these guide protrusions 17 are formed as inclined surfaces that open upward. The inclined surface of the high magnetic permeability member 16 and the inclined surfaces of both side walls of the longitudinal groove 13 in the holder 12 ensure the mutual positioning when the second support member 14 is attached to the first support member 1 and guide. Plays the role of The high permeability member 16 at the other end of the second support member 14 is fitted in the groove 13 of the holder 12 in the first support member 1, and at that time, the high permeability at the other end of the second support member 14. The member 16 is configured to contact the bottom surface of the groove of the holder 12 and not to contact the two magnets 11.

 The first support member 1 and the second support member 14 are made of light carbon in order to reduce the moment of inertia. On the other hand, the high permeability member 16 in the second support member 14 having a high density and a large mass and the magnet 11 in the holder 12 in the first support member 1 are close to the fulcrum in order to reduce the moment of inertia around the fulcrum. It is arranged.

  Further, as shown in FIG. 3, a plate-like member 18 is provided below the high-permeability member 16 in the second support member 14, and this plate-like member 18 has a high permeability material in order to enhance the magnetic field shielding effect. The plate-like member 18 allows the replacement part to be placed in the correct position even if it is tilted and brought close to the groove 13 of the holder 12 in the first support member 1.

 As described above, the magnet 11 embedded in the holder 12 in the first support member 1 is arranged so that the polarity is reversed, so that the magnetic field created in the place where the magnetic dipole is separated becomes small. 5. The magnetic field in the needle pressure generator 8 and the sample can be reduced. Further, due to this arrangement, the magnetic lines of force pass through the high permeability member 16 in the second support member 14 below the magnet 11, so that the magnetic field in the sample below and at the probe position is reduced.

  FIG. 5 shows an enlarged structure of the fulcrum receiving member 4 that receives the fulcrum needle 3. As shown in the drawing, the fulcrum receiving member 4 has a concave surface 4a for receiving the fulcrum needle 3. The concave surface is formed in an inverted conical shape so that the fulcrum needle 3 is positioned and received with high accuracy.

  FIG. 6 shows a state in which the stylus type surface shape measuring instrument shown in FIG. 1 is incorporated in the frame body 19, and the two fulcrum receiving members 4 are fixed to the lower frame members 19 a and 19 b of the frame body 19. The movable part on the fulcrum is housed in the frame body 19 and a panel (not shown) is attached to the outside of the frame body 19 so as to prevent the vibration and temperature change caused by the wind. The coil of the displacement sensor 5, the fulcrum receiving member 4, and the coil 10 of the needle pressure generator 8 are fixed to the frame body 19 in the frame body 19. In FIG. 6, the coil of the displacement sensor 5 and the coil 10 of the needle pressure generator 8 are omitted for easy viewing. These two types of coils are covered with the coils from above and fixed to the frame 19 with screws or the like. A portion including the displacement sensor 5 including the frame body 19 of FIG. 6, the needle pressure generator, and other movable parts on the fulcrum is referred to as a sensor head. In order to monitor the probe 15 obliquely from above with a camera, the probe 15 protrudes from the frame 19 and is a rod-shaped body that supports the probe 15, that is, a thin windbreak cover that is shaped along the second support member 14 (see FIG. (Not shown) is attached to the front of the frame 19. Stoppers (not shown) are provided above and below the tip of the second support member 14 to limit the range in which the probe 15 moves.

  The illustrated stylus type surface shape measuring instrument configured as described above includes a displacement sensor 5 and a needle pressure generating device 8 at both ends, and is supported by two fulcrum receiving members 4 via a fulcrum needle 3 so as to be swingable. The second support member 14 provided with the probe 15 and the high magnetic permeability member 16 at both ends is fixed to the holder 12 of the first support member 1 by magnet attracting force. In this case, the second support member 14 is formed by the inclined surfaces of both side walls of the longitudinal groove 13 in the holder 12 and the opposed inclined surfaces of the guide protrusions 17 in the high permeability member 16 of the second support member 14. The support member 1 can be easily positioned by being accurately positioned at a predetermined position with respect to the holder 12.

  Then, by applying a predetermined current to the coil 10 of the needle pressure generator 8, a force is generated according to the magnitude of the current, and the core 9 of the needle pressure generator 8 is drawn into the center of the coil 10 by this force. It is. As a result, the first and second support members 1 and 14 swing via the fulcrum needle 3 and press the probe 15 against the sample. By scanning the sample or the detection system, the probe 15 traces the surface of the sample, and the first and second support members 1 and 14 rotate slightly around the fixed fulcrum according to the surface shape. Then, the displacement of the core 6 of the differential transformer 5 is detected, and the displacement of the core 6 is converted into the displacement of the probe tip of the probe 15 to measure the surface shape and level difference of the sample.

  FIG. 7 shows an example of the positional relationship between the center of gravity of the movable part on the fulcrum and the fulcrum (fulcrum receiving member 4 that receives the fulcrum needle 3). The fulcrum is indicated by x, the center of gravity is indicated by ●, and the right end is the probe 15. FIG. 7A shows a case where the fulcrum and the z component of the center of gravity coincide, and FIG. 7B shows a case where the center of gravity is below the fulcrum. When the probe moves up, a change Δx occurs in the x component of the center of gravity as shown in FIG. As a result, the difference between the x component of the fulcrum and the center of gravity changes, and the force to raise the probe 15 changes. Since the dependence of the force on the probe position by the needle pressure generator 8 (coil current and core 9) trying to lower the probe 15 is small, a change in the x component of the center of gravity becomes a problem in the torque of the torque. If the force changes depending on the position of the probe 15 (z component), the surface shape (the z component of the probe 15 changes) cannot be measured with a constant force.

  As can be seen from FIG. 7, the change in the x component of the center of gravity is smaller as the difference between the fulcrum and the z component of the center of gravity is smaller. Therefore, in order to reduce the dependence of the force on the probe position, it is necessary to reduce the difference between the z component of the fulcrum and the center of gravity in the design and assembly of the movable part.

  In addition to the above-described problem of the center of gravity, there is also a problem of the radius of curvature of the needle tip of the fulcrum needle 3 constituting the fulcrum. Since the radius of curvature of the needle tip is not zero but limited, it is considered that the contact position between the needle tip of the fulcrum needle 3 and the fulcrum receiving member 4 moves with the rotation shown in FIG. As a result, the distance R between the fulcrum and the center of gravity changes, so that the force at the probe 15 changes. As shown in FIG. 7, when the probe 15 is raised, the fulcrum, which is the contact point, moves to the left, and the "force that the gravity acting on the center of gravity raises the probe" is reduced. The force to lower the needle 15 is increased. In order to reduce the movement of the fulcrum, the radius of curvature of the tip of the fulcrum needle 3 is made small. However, as the needle tip of the fulcrum needle 3 is worn and deformed as it is used, its radius of curvature is naturally limited.

  FIG. 8 shows a measurement example of the dependency of the force at the probe 15 on the probe position z, and the upward force is positive. A current of 25.4 mA is passed through the force generating coil 10, the time change of z is measured when the probe 15 descends from the position of the upper stopper, looks back and vibrates at the lower stopper, and the acceleration is obtained by second-order differentiation with time. In this example, the force is calculated and the force is calculated and plotted against z of the probe 15. FIG. 9 shows the time change of z of the probe 15 at that time, and FIG. 10 shows the time change of the force obtained from the acceleration obtained by second-order differentiation. The proportional constant between acceleration and force was obtained in advance by measuring the actual force with an electronic balance.

  In this example, no special fine adjustment (position of balance weight, fine adjustment of mass) for making z of the center of gravity close to that of the fulcrum is performed. The use range of z of this sensor head is assumed to be ± 0.15 mm, and in this range, there is a dependence of the force of −0.275 mgf / mm on z (see the broken line in FIG. 8). That is, in the use range of 0.3 mm, the force changes by 0.275 × 0.3 = 0.0825 mgf, and thus the surface shape cannot be measured with a constant force of 0.05 mgf.

  Even if the position and mass of the balance weight are finely adjusted by trial and error with a long time and effort, the actual limit is about -0.15 mgf / mm. The force changes by .15 × 0.3 = 0.045 mgf and is not always constant at 0.05 mgf. Alternatively, the range of z that can be said to be constant at 0.05 mgf is narrow.

  If the above-mentioned “slope of force with respect to z” is not negative, it may be considered that the probe 15 does not come down while it is raised when the probe 15 stops at the step portion during surface shape measurement. This is also one of the reasons why the inclination cannot be brought close to zero.

  Since the fulcrum needle 3 sharpens the tip of a 1φ rod by polishing, an error of about 0.1 mm is inevitable as an error in the total length of the part. In other words, even if manufactured under the same design, the difference between the fulcrum and the center of gravity z varies by about 0.1 mm, and fine adjustment that requires a long time for the position of the balance weight and mass for each sensor head is required.

  An example will be described with reference to FIG. The mass of the movable part is 4.3 g, and the distance r between the fulcrum and the probe 15 is 60 mm. Considering the speed at which the probe 15 returns to the upper stopper when the coil current is set to 0, if the force at the probe 15 is 2.5 mgf upward, the difference between the z component of the fulcrum and the center of gravity is R = 35 μm. At this time, if the difference Z between the fulcrum and the center of gravity z component is 0.1 mm, the geometrical consideration is that the 0.036 mgf force is different when the z component of the tip of the probe 15 is +0.15 mm and −0.15 mm. I understand. That is, an error of 0.1 mm in the overall length of the fulcrum needle part cannot be ruled out, and balance adjustment is required for each part. In the assembly of the fulcrum needle part, positioning must be performed at the upper part thereof, so that the error in the total length is reflected at the lower end, that is, the fulcrum part. However, even if fine adjustment is finished, the “relationship between the probe position and the force” changes due to wear of the tip of the fulcrum needle 3 that accompanies subsequent use.

In the balance adjustment (adjustment for reducing Z in FIG. 7), if the radius of curvature of the needle tip of the fulcrum needle 3 is sufficiently small, the movable part on the fulcrum is regarded as an actual pendulum, and the fulcrum and the center of gravity are determined from the cycle. The difference Z between the z components can be determined. After arranging the balance weight so that this period becomes longer, the weight may be shifted in the −x direction (left direction in FIG. 7) so that the probe 15 is raised by the coil current 0. In the example of the mass M = 4.30 g and the moment of inertia I = 740 gmm ² around the rotation axis (fulcrum), when the period T = 2π (I / MgoL) ^0.5 is 1 second, the distance L between the rotation axis and the center of gravity is 0. For .68 mm and T = 2 seconds, L = 0.17 mm is calculated. In the example of the fine adjustment result of −0.15 mgf / mm described above, Z in FIG. 7 is estimated to be 0.125 mm by geometrical consideration from the value of the slope of the dependency, and in that case at the time of balance (L = The period of 0.125 mm is calculated as 2.33 seconds. This coincides with the measurement value of 2.3 seconds at this time. The current may be passed through the coil 10 to be balanced, and the period may be measured.

  As described above, in this type of surface shape measuring stylus type step gauge, a slight shift of the z component between the fulcrum and the center of gravity is inevitable, and the radius of curvature of the needle point of the fulcrum needle is finite. When the z of the probe changes due to them, the force at the probe changes, and the surface shape cannot be measured with a constant force. Further, the difference between the z component of the fulcrum and the center of gravity, and the radius of curvature of the stylus tip of the fulcrum needle become larger due to wear of the stylus tip of the fulcrum needle, and the probe probe position z of the force at the probe is used as it is used. Dependence on becomes larger.

 Therefore, the present invention solves the problems associated with this type of surface shape measurement stylus profilometer and compensates for the dependency of the force on the probe position and the variation in component dimensions. It aims at providing the correction method of the power of a level difference meter.

In order to achieve the above object, according to the present invention, a probe is provided at one end of a support that is swingably attached to a fulcrum, and a magnetic core of a displacement sensor that detects vertical displacement of the probe is provided. A stylus type that provides a magnetic core of a needle pressure generator that applies needle pressure to the probe and attaches it to the support, and measures the surface shape of the sample captured by the probe with a displacement sensor by rotational movement around the fulcrum of the support In the method of correcting the force of the step meter,
The relationship between the displacement component z of the probe tip and the force at the probe tip is measured in advance and a relational expression is obtained and programmed in a computer, and when the surface shape is measured, the displacement component z of the probe tip is measured. Is monitored in real time, and the current flowing through the force generating coil is controlled by a computer using the relational expression to compensate for the change in the displacement component z of the probe tip.

  In the method for correcting the force of the stylus step meter according to the present invention, the displacement component z of the probe tip is monitored in real time, the force correction amount f (z) is calculated, and the probe tip displacement is calculated. The coil current to be output is obtained by a relational expression obtained by measuring in advance the relationship between the component z and the force at the probe tip.

  In addition, when the fulcrum needle tip is worn due to long-term use, the relationship between the displacement component z of the probe tip and the force at the probe tip is recalculated and the computer program is changed. The force is made constant by compensating for the change in the relationship between the probe position and the force.

  In the method of correcting the force of the stylus profilometer according to the present invention, the coil current value for generating the force to be output is measured in advance from the probe position monitored in real time. Since the output is based on "", the "dependence of force on the probe position", which has been unavoidable in the past, can be easily and reliably reduced. As a result, it is possible to save a large amount of time and effort to search for the position (x, z component) and mass of the balance weight according to the variation of the component dimensions, which has been conventionally performed.

  In addition, even if the z component of the center of gravity changes after the probe is changed, if the program is rewritten by recalculating the “relationship between the probe position and force”, the “dependence of force on the probe position” can be easily reduced. it can.

  Furthermore, even if the stylus tip is worn by long-term use and the “dependence of force on the probe position” changes, the change in “dependence of force on the probe position” can be changed just by changing the program as described above. Can be easily compensated.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 11 to 15 of the accompanying drawings. In addition, as a stylus type level difference meter, the thing of the structure shown previously in FIGS. 1-6 is used.

  FIG. 11 shows an example of the configuration of the measurement and control system. In FIG. 11, reference numeral 21 denotes a computer device. The computer device 21 is a drive device for a needle pressure generator power source 23 and a scanning stage 24 connected to the coil 10 in the needle pressure generator 8 via an analog input / output board 22. 25, respectively. The computer device 21 is connected to a detection circuit 27 having a digital lock-in amplifier and an oscillator via a general-purpose interface board 26. The detection circuit 27 is a primary coil and a secondary coil of a differential transformer 28 constituting the displacement sensor 5. Connected to the coil.

  In the present invention, the output voltage of the differential transformer 28 is measured by the lock-in amplifier of the detection circuit 27, and the analog output is read by the computer device 21 and converted into the displacement z. A current to be passed through the coil 10 in the needle pressure generator 8 is calculated from the value of the displacement z, and the power source 23 for the needle pressure generator is controlled. This control is performed every time the displacement z is read.

FIG. 12 shows the time flow of measurement and control. The relationship between the coil current X flowing through the coil 10 in the needle pressure generator 8 and the force F at the probe 15 fits well with F = aX ² + bX + c (a, b, c are constants), and a, b, c are set in advance. The coil current corresponding to the specified force is calculated from this formula and output.

First, when the force F0 at the probe 15 is designated and measurement is desired with this force F0, XO satisfying F0 = aX0 ² + bX0 + c is obtained and output. However, this relational expression is a relational expression when the displacement z = 0, for example. When the displacement z changes from 0, the force at the probe 15 changes to a value different from F0 if the coil current remains X0.

Therefore, in the method of the present invention, the displacement z is read, the force correction amount f (z) is calculated, and the coil current to be output is obtained by solving for F0 + f (z) = aX1 ² + bX1 + c and outputting X1. This is repeated at intervals of several ms. That is, since the force is corrected every time the displacement z is read, it is possible to generate a force that does not depend on the displacement z.

  The function form of the correction amount f (z) of the force F is determined in advance. When correcting the result of FIG. 8, since the broken line is F = −0.275z−0.075, the correction amount may be f (z) = 0.275z.

FIG. 13 shows an example of the relationship between the force, the tip displacement z of the probe 15, and the coil current X. The force FT (X, z) at the tip of the probe 15 is considered to be the sum of the force FG (z) due to gravity determined by the center of gravity, the fulcrum, and the position of the probe, and the force FC (X) due to the coil current. The total force is FT (X, z) = FG (z) + FC (X)
It is expressed. Since the dependence of FC (X) on the displacement z is considered to be sufficiently small, it is ignored.
Although FT (X, z) can be fitted with aX ² + bX + c, it is considered that FG (z) = c (z) and FC (X) = aX ² + bX. When z changes from 0 to z1 at X = X0, the total force changes from F0 to Fl as shown in FIG. 13B, and becomes smaller by f (z1) = c (0) −c (z1). (The absolute value of force increases). Therefore, it is necessary to correct this amount. Usually, the function FT (X, 0) at z = 1 is obtained. That is, a function form of FT (X, 0) = aX ² + bX + c (0) is obtained. Correcting the force at z = z1 is to obtain and output X1 such that FT (X, z1) = aX ² + bX + c (z1) = F0. As can be seen from FIG. 13, FT (X , 0) is the same as finding X1 such that FT (X, 0) = F0 + f (z1).
FT (X, z1) = aX ² + bX + c (z1) = F0
Against
FT (X, 0) = aX ² + bX + c (0) = F0 + f (z1)
The ^{aX 2 + bX + c (0} ) -f (z1) = aX 2 + bX + c (z1) = F0
And the same formula. This is because the function lines in FIG. From the above, X = X1 that satisfies aX ² + bX + c (0) = F0 + f (z1) may be obtained, which is consistent with the method described in FIG.

  The relationship between the displacement z and the force thus measured is shown in FIG. 14 on the same scale as FIG. 8 for comparison. As can be seen from the graph of FIG. 14, the dependence of the force on the displacement z can be made considerably small. The time change of the displacement z was measured in the same manner as in FIG. 8, and the acceleration was obtained therefrom to calculate the force. The force was plotted against the displacement z. In the “measurement of time change of the displacement z”, that is, the measurement as shown in FIG. 9, the above-described “control of force correction” was performed. The measurement time constant was 1 ms, the displacement z was read and the force was output every 2 ms.

  In this example, the correction amount is approximated linearly. However, if a more detailed correction amount is set, the dependence of the force on the displacement can be further reduced. Since the correction is a problem only for the program to the computer device 21, any correction is possible. In the example of the relationship between the displacement z and the force of the probe 15 shown in FIG. 8, what is expressed by the first order is considered to be due to the aforementioned “difference between the center of gravity and the z component of the fulcrum”. This is thought to be due to the movement of the fulcrum (contact point) due to the finite curvature of the tip of the fulcrum needle 3.

In the example of correction in FIG. 14, the vertical speed of the probe 15 when the displacement z is around 0 is about 2 × 10 ⁻³ m / s. In the actual surface shape measurement, when the measurement is performed with a weak force, the scanning speed of the head or the sample is about 1 × 10 ⁻⁴ m / s, and the vertical speed of the probe 15 is also about that level. Therefore, since the change of the displacement z is slower by one digit or more, real-time control is easier than the example of this experiment.

Since the range actually used is about ± 0.15 mm, detailed measurement of force correction in that range was performed. The control itself is the same as in the case of FIG. 14, but the amplification factor of the displacement measuring amplifier is increased five times. In addition, the vertical speed of the probe 15 when the displacement z was near 0 was reduced to about 1 × 10 ⁻³ m / s to bring it closer to the actual surface shape measurement state. The probe 15 was raised upward by the force of the coil 10 in the needle pressure generator 8, not by rebounding at the lower stopper. That is, when the displacement z is −0.2 mm or more, the force is corrected and the dependency of the force on the displacement z is reduced, but when the displacement z is −0.2 mm or less, the correction is not performed. The same power dependency. When the displacement z is thereby reduced, the force works upward and the probe 15 vibrates. Using the vibration, the time change of the displacement z was measured, the acceleration and the force were calculated, and the force was plotted against the displacement z. The displacement z of the measurement object was ± 0.15 mm, and it was vibrated as described above without being lowered to the lower stopper. FIG. 15 shows the result of making the force around −0.05 mgf in the range of about ± 0.15 mm. It shows that the surface shape can be measured in a wide range of about ± 0.15 mm with a force of about 0.05 mgf.

 By the way, in the illustrated embodiment, the first support member has been described based on an apparatus having a structure in which the first support member is supported at two points. can do. In addition, the present invention can be equally applied to a stylus type surface shape measuring instrument in which the positional relationship between the measuring element of the displacement sensor provided at both ends of the first support member and the core of the needle pressure generator is reversed.

The schematic of the structure of the stylus type surface shape measuring device which is implementing this invention. The schematic diagram which looked at the principal part of the stylus type surface shape measuring instrument in FIG. 1 from the bottom. The expanded partial sectional view which shows the structure of the holder part of the stylus type surface shape measuring device in FIG. The expanded partial sectional view which shows the structure of the holder part of the stylus type surface shape measuring device in FIG. The expanded sectional view which shows the structure of the fulcrum part of the stylus type surface shape measuring device in FIG. The schematic perspective view which shows the structure which incorporated the stylus type surface shape measuring device in the frame. The diagram which shows the positional relationship of a fulcrum and a gravity center. The graph which illustrates the relationship between the probe displacement z and the force. The graph which illustrates the time change of the displacement z of a probe. The graph which illustrates the time change of the force in a probe. The block diagram which shows the structure of a measurement and control system. The flow diagram which shows the method of the output of the force by the method of this invention. The graph which shows the relationship between force, displacement, and coil current. The graph which shows the result of having corrected force according to the method of the present invention. The graph which shows the detailed measurement example of the result of having corrected force according to the method of this invention.

Explanation of symbols

1: 1st support member 2: Needle mounting member for fulcrum 3: Needle for fulcrum 4: Support point receiving member 5: Displacement sensor 6: Core 7: Coil 8: Needle pressure generator 9: Core 10: Needle pressure generator 8 Coil 11: magnet 12: holder 13: longitudinal groove 14: second support member 15: probe 16: high permeability member 17: guide protrusion 18: plate member 19: frame 19a: lower frame member 21: Computer device 22: Analog I / O board 23: Needle pressure generator power supply 24: Scan stage 25: Drive device 26: General-purpose interface board 27: Detection circuit 28: Differential transformer

Claims (3)

A probe is provided at one end of a support that is swingably attached to a fulcrum, a magnetic core of a displacement sensor that detects vertical displacement of the probe is provided, and the magnetic force of a needle pressure generator that applies needle pressure to the probe In the method of correcting the force of the stylus type step gauge that attaches the body core to the support and measures the surface shape of the sample captured by the probe with a displacement sensor by the rotational movement around the fulcrum of the support,
The relationship between the displacement component z of the probe tip and the force at the probe tip is measured in advance and a relational expression is obtained and programmed in a computer, and when the surface shape is measured, the displacement component z of the probe tip is measured. A stylus step that compensates for a change in the displacement component z of the tip of the probe by controlling the current flowing through the force generating coil by a computer using the relational expression in real time How to correct the meter force.   The displacement component z of the probe tip is monitored in real time, the force correction amount f (z) is calculated, and the relationship between the displacement component z of the probe tip and the force at the probe tip is measured in advance. 2. The method of correcting a force of a stylus profilometer according to claim 1, wherein the coil current to be output is obtained by the relational expression obtained as described above. When the fulcrum needle tip wears due to long-term use, the probe is changed by recalculating the relational expression between the displacement component z of the probe tip and the force at the probe tip and changing the program in the computer. 2. The method of correcting a force of a stylus step meter according to claim 1, wherein the force is made constant by compensating for a change in the relationship between the position and the force.

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