JPH1151946A - Shape measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shape measuring device capable of measuring a minute three-dimensional shape. SOLUTION: A probe 1 comprises a tracing needle posture adjusting part 10, a fitting part 11 being the fixed end, a horizontal part 12, a curved part 13, a vertical part 14, and a region 15 being the releasing end, and an end part 16 sharpened in the vertical direction. A scanning device 2 is made up of an X-stage 21, a Y-stage 22, and a Z-stage 23, and carries out main scanning and auxiliary scanning. A contact detecting device 3 is made up of a microscopic optical system consisting of an objective lens 31, a revolver 32 for exchanging objective lens, a halogen light source 33, a coaxial falling-projection lighting mirror cylinder 34, an image pickup part 35 using a two-dimensional CCD camera, and an image processing device 9 connected to the image pickup part. A deflection is caused in the probe 1 when it is brought into contact with a measuring object 5. The contact detecting device 3 detects this deflection, so that the shape of the measuring object 5 can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring device, and more particularly to a shape measuring device suitable for measuring a fine three-dimensional shape.

[0002]

[Prior Art] With the advent of an advanced information society in which optical fibers are laid in homes, functional components used in image output equipment and optical communication are required to have higher resolution and higher density. The dimensions are required to be minute in units of μm, and the shape is required to be a three-dimensional shape including a free-form surface. For example, there is an ink jet printer as one of the image output devices. In a nozzle of a marking head used there, a pitch interval and a diameter are 100 μm to 10 μm, and the shape is based on a combination of linear shapes according to an ink ejection principle. Various shapes have been proposed, up to complex ones including free-form surfaces. As a manufacturing method, processing by molding is often performed from the viewpoint of productivity, and a resin material which is generally nonconductive is often used for this.

[0003] Observation of processing accuracy is mainly performed by visual observation using an optical microscope for this type of shape.
In this method, the accuracy of quantitative measurement is poor at present. On the other hand, several methods and apparatuses for non-contact measurement of a fine three-dimensional shape by combining optical devices have been proposed, and some of them are commercially available.

For example, Japanese Patent Application Laid-Open No. Hei 7-113617 discloses that a three-dimensional shape is obtained by measuring the distance from a sensor surface to an object to be measured by the principle of confocal and scanning the sensor itself in a two-dimensional plane. Technology has been proposed. In this method, a laser beam is projected onto a measurement object and received by a light receiving sensor through an objective lens. A pinhole is provided in front of the light receiving sensor, and only the reflected light from the focal position passes to detect the focal position. The distance to the object to be measured can be measured by changing the focal position by vibrating the objective lens at high speed. As another example, a technique has been proposed in which a focus position is detected by an astigmatism method, and a sensor itself is scanned in a two-dimensional plane to obtain a three-dimensional shape. In this method, the reflected light of the emitted laser beam is condensed by an objective lens, and is received by a sensor including a four-division light receiving element through a cylindrical lens. If the light is reflected from the in-focus point, the light is equally received by the four light receiving elements, but the light receiving ratio to the light receiving element differs between the front focus position and the rear focus position. By moving the sensor based on the information of the front focus and the back focus, the position can be controlled to the in-focus position. In these distance measuring means using laser beam light, reflected light can return to the light receiving element and be measured on a flat surface or an inclined surface having a gentle convex portion. On a surface having a tilt in the direction, the light beam does not return and measurement cannot be performed.

On the other hand, a method using a stylus is known for measuring a three-dimensional shape, and is widely used as a contour measuring instrument. However, due to the physical size of the stylus, it was not possible to measure a complex shape having a processing dimension of 100 μm or less or a slot having a high aspect ratio (groove depth to opening width). As a solution to this, for example, Japanese Patent Application Laid-Open No. 5-264215 discloses a method in which a fine stylus is vibrated to detect a position from a ratio of a conduction time with a contact surface. According to this method, it is possible to know the wall shape of the thin and deep groove, but it is not possible to measure a horizontal surface or a nonconductor, or a high electric field generated by applying a voltage to a minute gap. There is a problem of electrostatic attraction due to the above. To cope with this problem, for example,
Japanese Patent Application Publication No. 247743 proposes a method of detecting a contact by using a light path medium as a stylus and capturing a change in light amount, a change in frequency, and a change in polarization component. If this method is used, measurement of non-conductors becomes possible, but even if a commercially available thinnest single-mode optical fiber is used to form the optical path medium, the diameter is about 100 μm, which is assumed to be several tens μm. It is difficult to measure the surface shape of the microstructure.

Further, as a device for measuring a minute surface shape of a semiconductor or an optical component of several μm or less, a probe is bent by an atomic force generated when approaching the surface from a vertical direction using a minute probe, A scanning atomic force microscope (AFM) that knows the position by optically detecting the deflection is known. A method of measuring while imitating the surface so that the atomic force generated between the surface and the probe is constant, and 1
A method of measuring while detecting point-to-point contact is known. However, on a steeply inclined surface, slipping occurs when the probe approaches the vertical direction, and at present, sufficient resolution cannot be obtained on the inclined surface.

[0007] AFM tips are often manufactured using a semiconductor process. In such a process,
It is extremely difficult to make the tip of the probe long so that the inner surface of the deep groove of several tens of μm can be measured.
An example in which a tungsten wire is bent and formed as an initial probe of AFM is described in Apply. Physics.
Letter 53 (12), 19 September
r 1988 pp. Although it is reported in 1045-1047, it is not disclosed that the shape reaches a deep groove. On the other hand, "Preparation of Probe for Micro Profile Measuring Device by Micro Die-Sinking EDM", Proc. 1997 Spring Meeting of Japan Society for Precision Engineering, pp. 279-280, states that the tip of a fine stylus is horizontal and vertical. A method has been proposed in which a contact is formed in a vertical direction, and the contact is made to approach vertically in a horizontal plane and horizontally in a vertical plane, and the groove shape is measured by detecting a tunnel current. . In this method, since a tunnel current is used for contact detection, it is difficult to measure a nonconductor.

[0008]

As described above, many proposals have been made for the measurement of a fine shape. There is no satisfactory method for measuring a shape having a high aspect ratio including a steep inclination angle such as a side wall. As described above, the method using light cannot measure because reflected light does not return, and in the stylus method, the stylus physically interferes with the measurement object, cannot reach the measurement object, or is not measured. At present, there is a problem that a sufficient resolution cannot be obtained due to a failure to detect contact with an object and a practical method has not been shown at present.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a shape measuring device capable of measuring a fine three-dimensional shape.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide an elastic stylus having a horizontal portion, a bent portion, a vertical portion, and a tip portion, a detecting device for detecting the deflection of the stylus, This is achieved by a shape measuring device having a scanning device for making contact with and separating from an object to be measured.

Here, the scanning device performs main scanning and sub-scanning on the object to be measured. The main scanning direction was such that the stylus was inserted in the vertical direction for the roughly horizontal DUT surface, the horizontal direction for the roughly vertical DUT surface, and the approximate center position for the hole-shaped wall surface. Later in the horizontal direction.
When the main scanning direction is the horizontal direction, the object to be measured is sequentially rotated and scanned at regular intervals. Further, when performing the retraction operation from the stylus, the scanning device simultaneously performs the retraction operations in the horizontal direction and the vertical direction.

The tip of the stylus used here may be sharpened in a vertical direction or sharpened in a horizontal direction depending on the object to be measured. The tip sharpening means of the stylus is arranged near the stylus. Further, the stylus has a stylus posture adjusting unit for adjusting the tip so as to face a predetermined direction.
The tip position of the stylus is calibrated using the reference spherical surface. The shape of the stylus is a fillet shape in which a thin wire is formed into an L-shape and a semicircular arc, the diameter is 10 μm to 3 μm, the total radius of the horizontal portion and the bent portion is 10 mm to 0.5 mm, and the vertical portion is 0 mm. 0.5 mm to 2 mm, and the sharpened tip portion has a radius of curvature of 0.1 μm or more.

[0013] The detecting device has an image pickup section for picking up an image of the stylus and an image processing device for processing the image to detect the deflection of the stylus. An object to be imaged by the imaging unit of the detection device is a horizontal portion or a bent portion of the stylus. Deflection detection by the image processing device evaluates the degree of focusing of the stylus surface appearing in the captured image by a focus measurement function, and when the value of the focus measurement function exceeds a certain threshold, the deflection of the stylus is evaluated. Make a decision. The in-focus measure function is based on a luminance variation value or an average luminance value of individual partial images obtained by dividing an image into a plurality of partial images.
Alternatively, the sensing device can alternatively be constituted by a strain gauge and a resistance value change detector arranged on the horizontal portion of the stylus.

Further, the present device has a windshield box, and is arranged so as to cover the stylus, the detecting device and the scanning device.

[0015] In the shape measuring method according to the present invention, the horizontal portion,
A step of contacting an object to be measured with an elastic stylus having a bent portion, a vertical portion, and a tip, a step of detecting the contact state by deflection of the stylus, and a step of separating the stylus from the object to be measured. And measuring the shape of the object by repeatedly performing these steps. The detection of the deflection of the stylus is preferably performed at a horizontal portion or a bent portion of the stylus.

According to the present invention, when the stylus approaches the object to be measured having a fine shape including an inclined surface from the direction corresponding to the inclination direction and comes into contact with the object to be measured by the above configuration, the approaching direction is obtained. Regardless of the vertical deflection occurs, this deflection becomes a defocus amount in the microscope optical system and appears in the image, and it is detected that the stylus has been contacted by the determination criterion,
The position of one point is known from the position coordinates at that time, the feeding operation is sequentially performed, and finally the three-dimensional surface shape of the measured object is obtained.

According to the experiment of the present inventor, it is difficult to obtain the reflected light on the steeply inclined surface having the deep groove shape in the light receiver because it is necessary to devise the way of applying the light and the reflection direction, and it is difficult to obtain the reflected light. As described above, the contact type was selected. In order to perform measurement by inserting into a deep groove, a fine metal wire having a fine diameter such as a tungsten wire is used. Since the measurement of nonconductors is symmetric, the deflection of the stylus is used to detect contact. Further, it is preferable to approach the measurement surface from a horizontal direction to a measurement surface having a steep slope such as a side wall of a deep groove from the viewpoint of resolution, slip prevention, and the like.

The tip of the tungsten wire was bent to a length sufficient to reach the deep groove, and an L-shaped stylus formed by narrowing the tip was pressed against the bottom of the groove, and the behavior of the wire was observed with a microscope. From the experiment, it was found that the stylus in the horizontal portion was bent, and the stylus in the horizontal portion was similarly bent when pressed against the wall surface from the horizontal direction. From these, the shape measuring apparatus and method as described above have been obtained.

[0019]

FIG. 1 shows an embodiment of a shape measuring apparatus according to the present invention. As shown, the coordinate axes are defined as follows. The vertical direction is the Z direction, the horizontal width direction is the X direction, and the horizontal depth direction is the Y direction. The rotation about the X axis is the φ direction, and the rotation about the Y axis is the ψ direction.

In FIG. 1, a stylus 1 is a fillet-shaped cantilever in which a so-called linear cantilever and an arc-shaped cantilever are combined, and a stylus attitude adjusting unit 10 and a mounting end which is a fixed end. 11, a horizontal portion 12, a bent portion 13, a vertical portion 14, and a distal end region 15 which is an open end. Tip area 1
5 has a tip 16 sharpened in the vertical direction.

The scanning device 2 comprises an X stage 21, a Y stage 22, and a Z stage 23 having three axes orthogonal to each other, and performs main scanning and sub scanning. The contact detection device 3
It is arranged above the apparatus and is constituted by a microscope optical system.
The microscope optical system includes an objective lens 31, a revolver 32 for exchanging the objective lens, a halogen light source 33, a coaxial epi-illumination barrel 34, an imaging unit 35 using a two-dimensional CCD camera, and an image processing device connected to the imaging unit Consists of nine. The objective lens 31 includes one for contact detection and one for measurement position alignment.

The DUT 5 is set on a sample stage 24 on a stage. A reference spherical surface 6 is provided at a corner of the sample stage 24. A tip sharpening means 7 is provided at the right end of the apparatus. The main part of the present apparatus is installed in a wind shield box 4 arranged on an air base 8.

The stylus 1 functions as follows. When the tip 16 of the stylus 1 abuts on the object 5 in the vertical direction, the surface of the object 5 is slightly elastically deformed. When the stylus 1 receives an elastic force (load) generated by this elastic deformation, the stylus 1
In the horizontal portion 12 or the bent portion 13, bending occurs vertically upward. The stylus 1 may be considered as a cantilever spring member that bends under load. The deflection of this cantilever beam in the load direction was analyzed and the optimal shape was examined. The load direction is a direction in which the tip portion 16 contacts the workpiece 5. When analyzing the ratio of the bent portion as a parameter while keeping the sum of the length of the horizontal portion and the diameter of the bent portion constant, the smaller the ratio of the bent portion, the smaller the spring constant with respect to the load in the vertical direction, and the easier it is to bend in the vertical direction. all right. The easier the deflection, the more the displacement of the stylus 1 can be obtained with a small elastic force. Therefore, the present measurement technique can be applied to an object to be measured of a material having a low elastic limit such as a soft metal such as aluminum. On the other hand, for a load in the horizontal direction, when the ratio of the bent portion increases from 0 to about 50%, the spring constant decreases. Further, the spring constant is less than half of the load in the vertical direction as compared with the load in the horizontal direction, and is more easily bent. Therefore, if a shape that is more flexible is preferentially adopted in the horizontal load, the ratio of the bent portion is preferably about 50%.

The smaller the diameter of the stylus, the more suitable it can be applied to the object to be measured 5 having a fine shape. On the other hand, it is necessary to have a diameter of about several μm in order to recognize the behavior of the stylus on the image of the microscope optical system. Become. If the length of the horizontal portion and the bent portion of the needle is too long, plastic deformation of the mounting portion 11 occurs due to its own weight, and the needle is easily affected by airflow due to an increase in surface area. On the other hand, if the length is too short, the spring becomes hard, and the surface of the DUT 5 may be damaged. From the above, the optimal length range combining the horizontal part and the bent part diameter is about 10 mm to 3 mm when the stylus diameter is 10 μm, and about 2 mm to 0.5 mm when the stylus diameter is 3 μm. Further, it is preferable that the vertical portion is in the range of 500 μm to 2000 μm depending on the depth of the object to be measured, and the tip is sharpened in a radius of curvature of 0.1 μm or more. For example, using a commercially available tungsten wire, the diameter of the horizontal portion and the bent portion is 3 mm, and the radius of the bent portion is 1 mm.
It could be manufactured with a thickness of 00 μm, and it was confirmed that the bending operation was performed without damaging the surface of the aluminum surface as a soft metal.

In the scanning device 2, each of the stages 21, 2
Reference numerals 2 and 23 each have an optical scale for knowing the position coordinates. The X stage 21 is used when performing main scanning in the horizontal direction, and the Y stage 22 and Z stage 23 are used when performing sub-scanning. The Z stage 23 is used for main scanning in the vertical direction, and the X stage 21 and Y stage 22 are used for sub scanning.

The contact detecting device 3 is installed vertically above the stylus 1. This is because the deflection of the stylus 1 occurs in the vertical direction. The imaging unit 35 captures an image of the horizontal part 12 or the bent part 13 of the stylus 1 via the objective lens 31 and the illumination lens barrel 34. The deflection detection position is vertically above the stylus 1 regardless of whether the main scanning of the scanning device 2 is in the horizontal direction or the vertical direction. An observation point is set according to the main scanning direction. The displacement that appears most in the vertical direction due to the load generated in contact with the vertical direction is at the boundary 36 between the horizontal portion and the bent portion of the stylus 1.

FIG. 2 shows another embodiment of the shape measuring apparatus according to the present invention. The present embodiment differs from that of FIG. 1 in that, as shown, the distal end region 15 of the stylus 1 has a distal end portion 17 that is sharpened in the horizontal direction. In the present embodiment, the inner side surface of the deep groove is scanned using the tip portion 17. In the present embodiment, the displacement in the vertical direction due to the load generated by abutting in the horizontal direction appears at the boundary 37 between the tip of the bent portion of the stylus 1 and the vertical portion. Therefore, the observation point of the contact detection device 3 is set at this point.

FIG. 3 is a diagram for explaining the details of the stylus posture adjusting means 10. The adjusting means 10 adjusts the stylus tip portions 16 and 17 to be vertical and horizontal respectively. The adjusting means 10 includes a rotary stage 41 and a tilting stage 42, and the vertical portion 14 can be set in the vertical direction by an adjusting method described later. The rotary stage 41 can be adjusted in the φ direction around the X axis, and the tilt stage 42 can be adjusted in the ψ direction around the Y axis.

As shown in FIG. 1, the windshield box 4 is a box made of an acrylic resin having a thickness of, for example, 0.5 mm and having a closed upper surface and four side surfaces. By using this, it is possible to prevent the stylus 1 from bending due to a drag received from an airflow of 0.1 m or more per second. The stylus 1 does not bend in an airflow at a speed lower than this.

FIGS. 4A and 4B are flow charts showing the operation of the shape measuring apparatus shown in FIG. 1, wherein FIG. 4A shows a measuring operation and FIG. 4B shows a calibration operation. As a measurement operation, as shown in FIG. 3A, measurement position alignment is performed in step S1, and
2, a contact operation is performed, a contact detection is performed in step S3, a retreat operation is performed in step S4, and a feed operation is performed in step S5. In step S6, it is determined whether the measurement range has been completed, and steps S2 to S5 are repeated until the measurement range is completed. In the calibration operation, as shown in FIG. 3B, the tip of the stylus is sharpened in step S11, the stylus posture is adjusted in step 12, and the position of the stylus tip is calibrated in step 13.

In the measurement position alignment S1, a low-magnification objective lens 31 is selected by the revolver 32 of the contact detection device 3,
This is performed by adjusting the tip of the stylus 1 to the measurement position while observing the microscope image. After that, the objective lens 31 for contact detection is set.

The contact operation S2 is described with reference to FIGS.
This will be described with reference to FIG. The direction of the tip of the stylus 1 is selected according to the direction of the measurement surface of the DUT 5. For the substantially horizontal surface 51, a tip portion 16 sharpened in the vertical direction is used as shown in FIG. The object to be measured is scanned vertically upward 52 by the Z-axis stage 23 by a small distance. When the object to be measured comes into contact with the stylus 1 in the vertical direction, the stylus 1 bends as shown in FIG. For the approximately vertical surface 53, the tip 17 sharpened in the horizontal direction is used as shown in FIG. The object 5 is scanned by the X-axis stage 21 in the horizontal direction 54 by a small distance. When the object to be measured abuts on the stylus 1 in the horizontal direction, the stylus bends as shown in FIG. The minute distance is the measurement resolution of the present measuring device itself. In the present measuring apparatus, a stage having a measuring resolution of 0.1 μm or more is preferable. There are special cases in the vertical plane. The first is the shape inside the slot. In the measurement operation in this case, a stylus is first inserted near the center of the slot, and then scanning is performed by a minute distance in the horizontal direction. As another special case, there is a measurement of a cylindrical peripheral shape or the entire inner peripheral surface of a slot. The measurement operation in this case is shown in FIGS.
This will be described with reference to FIG. Since the stylus 1 used is sharpened in the horizontal direction, it is necessary to direct the surface of the object to be measured in this direction. For this purpose, a rotary table 91 having a rotation center at the intersection of the three-axis stages 21, 22, and 23 is set on the three-axis stage as shown in FIG. 90 degrees, 180 as shown in (c).
The degree may be set at a position of 270 degrees as shown in FIG.

In the contact detection S3, the contact between the stylus 1 and the object 5 is detected by the contact detection device 3 for each minute scan. The procedure of the contact detection S3 is as shown in FIG.
To capture an image, calculate the degree of focus in step S23, and determine contact in step S24. Image capture S22 records an image 71 of the stylus 1 as shown in FIG. 7A captured by the CCD camera through the microscope optical system in the image processing device 9. The focus degree calculation S23 divides this image 71 into a partial image 72 of n pixels × m pixels as shown in FIG. 7B. The values of n and m are suitably from 3 to 5.
An operator operates for each partial image 72 to determine the degree of focus. From the result of visual observation of the microscope image, it was
In the case of a stylus using a wire of about μm, it was found that the focused partial image 72 had a large variation in luminance for each pixel, and the unfocused partial image 72 had almost the same luminance for each pixel. . In the case of a stylus using a fine wire with a diameter of about 3 μm,
It was found that the change in the variation in the luminance for each pixel was small, and the absolute value of the luminance was changed. In other words, the focused partial image has a large luminance value for each pixel, and the out-of-focus partial image has a small luminance value for each pixel. Thus, it can be seen that the standard deviation of the pixel luminance values or the average value of the pixel luminance values may be used for each of the partial images 72 as a method of obtaining the degree of focus. These are defined as focus degree values. The greater the value of the degree of focusing, the closer to the focal point. FIG. 7C shows the data of the focus degree value with respect to the defocus amount when the numerical aperture of the microscope objective lens is changed from 0.2 to 0.7. If an objective lens having a numerical aperture of 0.7 and a magnification of 100 is used, a defocus amount of about 1 μm can be obtained with a half value width of the focusing degree value, and a measurement resolution of about 0.1 μm can be achieved from this result. Therefore, a numerical aperture of 0.
An objective lens of 7 or more and 100 times is suitable. The above is the operation of the focusing calculation S23. The value obtained by adding all the l partial images obtained by dividing the focus value calculated for each partial image 72 (hereinafter abbreviated as focus measure value) is the depth of the stylus on the microscope optical system. Direction, that is, a value related to the position in the Z direction. When the deflection due to the contact occurs, the focus measurement value changes to either larger or smaller than before the contact. Therefore, a change with respect to the focus measure value before the contact is obtained, and when the change width of the focus measure value exceeds a certain threshold value, it is determined that the deflection due to the contact of the stylus has occurred. The above is the operation of the contact determination S24. When the contact is detected, the minute scanning is completed, and the coordinate values for the three axes of the stage of the scanning device at this time are recorded.

In the retracting operation S4, the object to be measured is vertically downward (Z-direction) with respect to the substantially horizontal surface, and the object to be measured is horizontally opposite (X-direction) with respect to the substantially vertical surface. ) And the stylus separates from the surface of the object to be measured and returns to its original shape. At this time, the stylus once contacted may be adsorbed and may not be separated even if the measured object is retracted to a position immediately before the contact.
When a large force is applied to pull off the object to be measured, an elastic force is generated in the stylus in the separating direction, and the stylus separates from the surface of the surface to be measured. However, in the case of a thin slot, it may come into contact with the opposite side wall. This is shown in FIGS.
This will be described in detail with reference to FIG. First, when the contact is detected by the deflection of the stylus in FIG. 9A, the object to be measured moves in the opposite horizontal direction (X-direction) as shown in FIG. At this time, the contacted stylus may be adsorbed, and if the object to be measured is moved in the X-direction as it is, there is a possibility that the object will come into contact with the opposite side wall. So the DUT is
It moves largely in the Z-direction as shown in FIG. afterwards,
As shown in (e), it returned to the initial position. Relatively, by performing an operation of pulling out the stylus obliquely upward, collision with the side wall can be avoided.

In the feed operation S25, a feed operation for feeding a minute distance as a sub-scan by the X-axis stage 21 to the Y-axis stage 22 is performed within the measurement range.
Return to 2.

In the calibration operation, first, the tip of the stylus is sharpened S11. FIG. 1 shows the configuration of the sharpening means 7 for the tip of the stylus.
Explanation will be made using 0. The sharpening means 7 includes an electrolytic solution holding plate 101 installed on a stage sample stage instead of an object to be measured,
Electrolyte solution 102, copper wire 103 serving as a cathode electrode, DC power supply 104 capable of applying up to several tens of volts, and wiring 105
Consists of The sharpening method is a so-called electropolishing method, which utilizes the fact that the tip edge portion of the stylus 106 used as an anode is concentrated and deposited by electrolysis and consequently narrows in a conical shape. For example, as an electrolytic solution, a KOH aqueous solution, a distance between the anode and the cathode of about 1 mm, a depth of about 10 μm is immersed in the electrolytic solution, and a DC voltage of about 10 V is applied for only a few tens of minutes. It has been confirmed that the wire is thinned to a tip diameter of about 0.5 μm. After the stylus 106 is attached to the attachment portion, the sharpening is performed, so that the risk of breakage such as chipping of the tip due to attachment and detachment is reduced. It is also possible to regenerate the chipping of the tip portion 16 and to remove foreign substances such as attached dust.

The adjustment S12 of the stylus posture is performed as shown in FIGS.
This will be described with reference to FIG. The stylus tip portions 16 and 17 do not extend vertically or horizontally in terms of bending accuracy and mounting accuracy of the mounting portion. Therefore, horizontal and vertical are produced by the following adjustment procedure. First, a low-magnification objective lens for measuring position alignment is selected. The image of the stylus vertical portion 14 is observed from above vertically by a microscope optical system. When the angle φ in the rotation direction of the stylus is deviated from the downward vertical direction, FIG.
As shown in (a) and (c), the image 111 of the stylus vertical portion 14 looks oblique. This image 111 is the horizontal part 1
2. Adjust the rotating stage 41 so as to be aligned with the image 113 of the bending portion 13. Next, the angle φ of the inclination direction of the stylus
Is shifted from the downward vertical direction, an image 112 of the stylus vertical portion 14 can be seen as shown in FIG. FIG.
The tilt stage 42 is adjusted so that the image 112 of the stylus vertical portion 14 becomes invisible as shown in FIG. Thus, the vertical portion 14 can be set in the vertical direction.

In the calibration of the stylus tip position S13, the tip portion 17 of the stylus sharpened in the horizontal direction is subjected to three-dimensional position measurement at a plurality of at least six points with respect to the reference spherical surface 6. Next, three-dimensional position measurement is performed on the tip portion 16 of the stylus that is sharpened in the vertical direction at a plurality of at least six points with respect to the reference spherical surface 6. The following equation holds for each measured value. (X−X ₀ ) ² + (Y−Y ₀ ) ² + (Z−Z ₀ ) ² = r ² . . . . . (Equation _{1) ΔR = (X h -X} v, Y h -Y v, Z h -Z v). . . . . (Equation 2) Here, ΔR indicates a three-dimensional displacement of the tip. By measuring the diameter 2r of the reference spherical surface 6 in advance, (Equation 1) is solved from the three-dimensional position data of at least six or more points, and the center coordinates (X ₀ , Y ₀ , Z ₀ ) are obtained. Also the position measurement center coordinates Rh of the reference sphere 6 measured in the horizontal direction of the touch needle _{(X h, Y h, Z} h) and center coordinates Rv (X _v, measured in vertical direction touch the needle, Y _v, Z _v ) is obtained. As a result, ΔR shown in (Equation 2) is different between the tip portion 17 sharpened in the horizontal direction and the tip portion 1 sharpened in the vertical direction.
6 is obtained as the three-dimensional displacement.

FIGS. 12A and 12B show the results of measuring the cross-sectional shape of a φ50 μm drill hole as a sample measurement shape in order to confirm the means constituting the present invention and the operation procedure thereof. . FIG. 7A shows the results of measurement in the vertical direction, and FIG. 7B shows the results of measurement in the horizontal direction with the tip of the stylus in contact with the measurement surface. It can be seen that the inner surface shape of the narrow groove having an aspect ratio of 2 or more was successfully measured.

In this embodiment, as a method of contact detection, the movement of the stylus due to the deflection is detected by using the image defocus, but another conventionally known method may be used. FIGS. 13A and 13B show another embodiment according to the present invention. FIG. 13A is an overall view, and FIG. 13B is an enlarged view of a portion 137 in FIG. The deflection detecting means includes a strain gauge and a resistance value change detector arranged at a horizontal portion of the stylus. The operation detects the deflection of the stylus by the change in resistance due to the deflection of the strain gauge. As a strain gauge, a material using a thin metal wire such as manganin or advance, and a resistance change (piezoresistance effect) due to stress of silicon are known. For example, as a member of the bent portion 137 of the stylus in FIG. 13A, a silicon substrate 134 is used as shown in FIG. 13B, and an SiO 2 film 131 is formed on the surface.
A strain gauge 132 is formed by thermally diffusing or ion-implanting P-type silicon as a piezoresistive element. Finally, the aluminum wiring 133 is patterned. A voltage is applied from the DC power supply 136, and the change is detected by the voltmeter 135 to detect a change in the resistance value. In any case, additional processing for embedding the strain gauge structure in the stylus 1 is necessary. When the diameter of the stylus is reduced to several μm, additional processing becomes difficult. Therefore, the method for detecting the deflection shown in the previous embodiment is superior.

In the present invention, the deflection of the stylus having elasticity is detected and sequentially scanned by a three-axis linear stage to obtain the three-dimensional shape of the surface of the object to be measured. Three-dimensional shape measurement becomes possible. In addition, detection of the deflection for each minute scan, restoration of the stylus by the retracting operation,
Since scanning is performed from the feeding operation, three-dimensional shape measurement can be performed even on a surface having a property that cannot be measured if the surface is swept on a surface with steep irregularities.

The main scanning is performed in the vertical direction for a horizontal surface, the horizontal direction for a vertical surface, and the main scanning in the horizontal direction after inserting a stylus for a hole shape. And three-dimensional shape measurement of steeply inclined surfaces such as side walls. The provision of the rotary scanning device for sequentially rotating and scanning the object to be measured every 90 degrees enables the three-dimensional shape measurement of the cylindrical object to be measured. Since the retreat operation is performed simultaneously in the horizontal direction and the vertically upward direction, the three-dimensional shape measurement of the side wall having a particularly fine hole shape can be performed.

With respect to the shape of the stylus, one end is fixed horizontally, and the other end is vertically released and has a fillet-like shape, so that bending occurs at a horizontal portion or a bent portion, so that it can be achieved with a conventional scanning microscope. In addition to being able to measure a deep slot that was not present, the deflection can be detected only from vertically above, so that the device configuration can be simplified. Since the tip shape of the vertical portion of the stylus is sharpened in the horizontal direction and the vertical direction, three-dimensional shape measurement can be performed with high resolution not only on a flat surface but also on a steeply inclined surface. Since the sharpening of the stylus is held by the stylus main body and is performed on the shape measuring device with means for electrolytic polishing, the risk of breakage due to the attachment of the stylus is reduced, and the reliability is improved. Since it has a rotating and tilting stage that puts out the vertical part in the mounting part of the stylus,
The operability of the measuring device is improved, for example, the manufacturing accuracy of the stylus to be manufactured in advance can be reduced, the mounting can be facilitated, and the plastic deformation due to the collision of the stylus can be easily corrected. A common reference spherical surface is provided for the tip that is sharpened in the horizontal or vertical direction, so it is possible to calibrate the three-dimensional position of two contact points, from a horizontal plane such as a deep groove to a vertical plane. This makes it possible to measure a three-dimensional shape of an object.

As a method of detecting the deflection, the light is projected onto the stylus, the irradiated portion is observed with a microscope optical system, the light is received by a surface light receiver, and the deflection of the stylus is determined by image judgment. Therefore, the deflection can be detected in a non-contact manner without adding a special mechanism to the stylus, and the configuration of the apparatus can be simplified. The deflection detection position of the stylus is the horizontal portion or the bent portion of the stylus, and the positions of the light projecting means and the observation means are vertically above regardless of the main scanning direction, so that the device configuration can be simplified.

The degree of focusing on the surface of the stylus appearing in the image is evaluated by a focusing function, and if the value of the focusing function exceeds a certain threshold value, it is determined that deflection of the stylus has occurred. In addition, the deflection of the stylus can be obtained with high resolution, and the inspection accuracy is improved. Further, since the stylus only needs to be shown in the range of the microscope image, the adjustment accuracy of the optical system can be relaxed, and the device configuration can be simplified. The in-focus measure function is based on the luminance variation value or the average luminance value in each image block obtained by dividing an image into a plurality of image blocks, so it is a simple method and can be performed quickly even with an inexpensive processing board. Calculation can be performed, and the device configuration can be simplified.

As another method for detecting the deflection, a strain gauge and a resistance value change detector disposed at the horizontal portion of the stylus are provided, and the deflection of the stylus is detected by the resistance change due to the deflection of the gauge. Therefore, it is not necessary to use a high magnification microscope optical system, and the apparatus configuration can be simplified.

The shape of the stylus is an elongated rod-like fillet obtained by combining an L-shape and a semi-arc, and has a diameter of 10 μm to 3 μm.
m, the sum of the radii of the horizontal portion and the bent portion from 10 mm to 0.1 mm.
5 mm, the vertical portion is 0.5 mm to 2 mm, and the sharpening of the tip is assumed to have a curvature radius of 0.1 μm or more.
Even for materials with low elasticity limit, such as soft metals, it is possible to measure not only horizontal but also vertical measuring surfaces without damaging the measurement surface and without being affected by airflow below a certain level. . By providing a windshield box as an airflow suppressing means, it is possible to prevent the stylus from being bent by an airflow of 0.1 m / s or more in the vicinity of the stylus, thereby enabling highly accurate and highly reliable three-dimensional shape measurement. .

[0048]

According to the present invention, a three-dimensional shape such as a fine hole-shaped side wall or a surface inclination can be measured well.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a shape measuring apparatus according to the present invention.

FIG. 2 is a diagram showing another embodiment of the shape measuring apparatus according to the present invention.

FIG. 3 is a diagram for explaining details of a stylus posture adjustment unit;

FIGS. 4A and 4B are flowcharts showing the operation of the shape measuring apparatus according to the present invention, in which FIG. 4A shows a measuring operation and FIG. 4B shows a calibration operation.

FIGS. 5A to 5D are diagrams for explaining a contact operation of a stylus;

FIG. 6 is a diagram for explaining a procedure for detecting contact of a stylus;

7A is a diagram illustrating an image of a stylus, FIG. 7B is a diagram illustrating a partial image obtained by dividing the image, and FIG. 7C is a diagram illustrating a focus degree value with respect to a defocus amount.

FIGS. 8A to 8E are diagrams for explaining the retracting operation of the stylus.

9 (a) to 9 (d) are diagrams showing the measurement operation of the entire inner wall surface of the slot.

FIG. 10 is a view for explaining a configuration of a sharpening means for a tip of a stylus;

FIGS. 11A to 11D are diagrams for explaining adjustment of a stylus posture;

FIGS. 12 (a) and 12 (b) are diagrams each showing a result of measuring a sample shape.

FIG. 13 shows another embodiment according to the present invention.
(A) is an overall view, and (b) is a partially enlarged view.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 stylus 2 scanning device 3 contact detection device 4 windshield box 5 DUT 6 reference spherical surface 7 tip sharpening means 8 air surface plate 9 image processing device 10 stylus attitude adjustment unit 11 mounting unit 12 horizontal unit 13 bending Part 14 Vertical part 15 Tip area 16 Tip part 21 X stage 22 Y stage 23 Z stage 24 Sample table 31 Objective lens 32 Revolver 33 Halogen light source 34 Coaxial epi-illumination lens barrel 35 Imaging unit 36 Boundary between horizontal part and curved part

Claims (20)

[Claims] 1. An elastic stylus having a horizontal portion, a bent portion, a vertical portion, and a tip portion, a detecting device for detecting deflection of the stylus, and contact and separation between the stylus and an object to be measured. And a scanning device for performing the measurement. 2. The shape measuring apparatus according to claim 1, wherein the scanning device performs a main scan and a sub-scan on the object to be measured. 3. The main scanning direction is a vertical direction with respect to a substantially horizontal surface of the object, a horizontal direction with respect to a substantially vertical surface of the object, and a substantially central position with respect to a hole-shaped wall surface. 3. The shape measuring device according to claim 2, wherein the device is in a horizontal direction after inserting a stylus into the device. 4. The shape measuring apparatus according to claim 3, wherein when the main scanning direction is a horizontal direction, the object to be measured is sequentially rotated and scanned at a predetermined angle. 5. The measuring apparatus according to claim 1, wherein when the scanning device performs the retreat operation from the stylus, it performs the retraction operations in the horizontal direction and the vertical direction at the same time. 6. The shape measuring apparatus according to claim 1, wherein a tip portion of the stylus is sharpened in a vertical direction. 7. The shape measuring apparatus according to claim 1, wherein a tip portion of the stylus is sharpened in a horizontal direction. 8. The shape measuring apparatus according to claim 1, wherein the tip of the stylus is sharpened in the vicinity of the stylus. 9. The shape measuring apparatus according to claim 1, wherein the stylus has a stylus posture adjustment unit for adjusting the tip so as to face a predetermined direction. 10. The sample sphere according to claim 1, wherein a reference spherical surface for calibrating a tip position of the stylus is arranged on a sample stage.
The shape measuring device as described. 11. The shape according to claim 1, wherein the detection device includes an imaging unit that captures an image of a stylus, and an image processing device that processes the image and detects deflection of the stylus. Measuring device. 12. The shape measuring device according to claim 11, wherein an object to be imaged by the imaging unit of the detection device is a horizontal portion or a bent portion of the stylus. 13. The deflection detection by the image processing device evaluates a degree of focusing of a stylus surface appearing in a captured image by using a focus measure function, and when a value of the focus measure function exceeds a certain threshold value. The shape measuring apparatus according to claim 11, wherein it is determined that the stylus has a deflection. 14. The in-focus measure function is based on a luminance variation value or an average luminance value of individual partial images obtained by dividing an image into a plurality of partial images. 14. The shape measuring device according to claim 13. 15. The shape measuring device according to claim 1, wherein the detecting device comprises a strain gauge and a resistance change detector disposed at a horizontal portion of the stylus. 16. The stylus has a fillet shape in which a thin wire has an L-shape and a semicircular arc shape, and has a diameter of 10 μm to 3 μm.
m, the sum of the radii of the horizontal portion and the bent portion from 10 mm to 0.1 mm.
2. The shape measuring apparatus according to claim 1, wherein the shape is 5 mm, the vertical portion is 0.5 mm to 2 mm, and the sharpened tip portion has a radius of curvature of 0.1 μm or more. 17. A windshield box for covering the stylus, the sensing device and the scanning device.
The shape measuring device as described. 18. An object to be measured is brought into contact with an elastic stylus having a horizontal portion, a bent portion, a vertical portion, and a tip portion and having elasticity.
A shape measuring apparatus characterized in that the shape of an object to be measured is measured by detecting deflection of the stylus caused by the contact. 19. A step of contacting an object to be measured with an elastic stylus having a horizontal portion, a bent portion, a vertical portion, and a tip portion, a step of detecting the contact by the deflection of the stylus, Having a step of separating the stylus and the object to be measured,
A shape measuring method characterized by measuring the shape of an object to be measured by repeating these steps. 20. The shape measuring method according to claim 19, wherein the detection of the deflection of the stylus is performed at a horizontal portion or a bent portion of the stylus.