JPH04309804A - Device and method for measuring three dimensional contour - Google Patents

Abstract

PURPOSE:To carry out a measuring process in a short time even in the case of a wide measuring range in a three dimensional contour measuring method having a wide measuring range and highly accurate resolution by detecting the focusing position of a laser beam. CONSTITUTION:By detecting the moment when the focusing position of a laser beam 2, which is diaphragmed by an objective lens system 1 canned in its vertical direction, coincides with the surface of a test piece 3, and at that time by measuring the comparative height of the objective lens system 1 while scanning over the surface of the test piece 3 successively the three dimensional contour of the test piece 3 is obtained. The scanning range of the objective lens system 1 at a point to be measured is determined by presumably the position to be focused from a measuring point in its vicinity. As the result, the movement distance of the objective lens 1 can be made small, and therefore the measuring time can be shorten.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring a test piece, particularly suitable for measuring the amount of warpage of a plate.

0002

[Prior Art] As a method for measuring the surface shape of a test piece, light is focused on the surface of the test piece, the focal position is detected using a pinhole, and the focal position is determined from changes within the surface of the test piece. It has been known.

FIG. 3 shows its configuration. Laser light source 13
The surface of the test piece 3 is irradiated with a laser beam 2 generated by the laser beam 2 through an objective lens system 1, and the reflected light is guided to a pinhole 5 through a dichroic mirror 4. Furthermore, the distance between the objective lens system 1 and the test piece 3 can be changed. When the surface of the test piece 3 is in focus, the reflected light from the test piece can pass through the pinhole 5, so that the light hits the light receiver 6 and a signal can be extracted.

When the surface of the test piece 3 is not focused, most of the reflected light from the test piece 3 is reflected from the pinhole 5.
Since the light cannot pass through the light, almost no light hits the light receiver 6. The distance between the objective lens system 1 and the stage 7 on which the test piece 3 is placed is a wedge-shaped sliding surface 9, a ball screw 10,
It can be changed within a certain range by a servo motor 11, and an encoder 8 measures the distance between the objective lens system 1 and the stage 7 on which the test piece is placed when a signal indicating the focused point is received from the light receiver 6. Measured by CPU1
2, the relative height of the surface of the test piece 3 to the stage 7 is determined. By performing this measurement within the plane of the test piece 3, the surface shape of the test piece 3 with the stage 7 as a reference plane can be determined.

[0005]

[Problems to be Solved by the Invention] According to the above-mentioned conventional method, the distance between the test piece 3 and the objective lens system 1 is changed by a certain distance to detect the focal point position and to determine the relative position of a certain point on the test piece surface. The three-dimensional shape of the test piece 3 can be determined by determining the height of the test piece 3 and scanning the surface of the test piece. That is, after initially setting the upper and lower limits of the vertical scanning range of the objective lens system 1 so that the maximum and minimum height points on the surface of the test piece 3 can be measured, By scanning the objective lens system in the vertical direction, the position of the focal point can be detected and the relative height can be determined. By performing this over the entire surface of the test piece, the surface shape of the test piece 3 can be determined.

However, as shown in FIG. 4, while scanning the specimen surface and measuring the height at each point, the upper and lower limits of the vertical scanning range of the objective lens system 1 are always kept constant. there was. Therefore, when measuring the surface shape of the test piece 3 whose height changes greatly within the plane of the test piece 3, the vertical scanning range of the objective lens system 1 must be increased, resulting in a measurement time The disadvantage was that it was long. For this reason, it was impossible to measure changes over time in the surface shape of the test piece 3 whose height changes greatly within the plane of the test piece 3.

[0007] The present invention enables high-speed measurement of the surface shape of a test piece whose height varies greatly within the plane of the test piece.

[0008]

[Means for solving the problem] Estimate the height of the point to be measured, and change the upper and lower limits of the vertical scanning range of the objective lens system accordingly to calculate the height distribution within the surface of the test piece. The above problem can be solved by measurement.

[0009]

[Operation] According to the present invention, since the vertical scanning range of the objective lens system can be made smaller than that of conventional systems, the scanning time of the objective lens system can be shortened, and therefore the measurement time at each point can be shortened. can. Therefore, it becomes possible to measure the time dependence of the shape of a test piece even for a test piece whose height changes greatly within the plane of the test piece. This measurement method is particularly effective for measuring warpage and waviness of plates without large differences in level.

0010

[Example] As shown in Fig. 1, when starting the surface shape measurement of the test specimen 3, the upper and lower limits of the vertical scanning range of the objective lens system 1 are initially set, and the relative heights of several consecutive points on the surface of the test specimen are set. seek. The relative height of the test piece surface at the next measurement point is predicted from either the amount of change in height at these several points or the deformation form of the test piece, or both.

Then, the upper and lower limits of the vertical scanning range of the objective lens system 1 are automatically reset to be smaller than those at the start of the measurement, and the next point is measured using these set values. The height of the next measurement point is predicted again using the measurement result of this point and the measurement results of several points before, and the vertical scanning range of the objective lens system 1 is automatically set and measurement is performed.

Note that the present invention can be applied not only to the case where the objective lens system 1 is moved but also to the case where the stage 7 is moved.

A control method according to an embodiment of the present invention will be explained with reference to the flowchart shown in FIG. This example is 3mm x 34
The warpage in the longitudinal direction of a strip-shaped test piece of mm was measured.

Measurement points were set at intervals of 0.3 mm, and measurements were made sequentially from one end of the test piece in the longitudinal direction to the other end. In this example, the vertical scanning range of the objective lens system is arbitrarily set at the beginning of the measurement, and the vertical scanning range of the objective lens system is used to calculate the height of each point up to 0.9 mm from the end of the test piece. Measurements were taken.

[0015] Based on the actual measurement data of these three points, the height of the next point (0.3 mm ahead) is automatically predicted using the method of least squares,
± around the position of the objective lens system corresponding to this height.
The measurement was performed with a range of 5 μm as the vertical scanning range of the objective lens system.

Furthermore, to measure the next point, a range of ±5 μm centered on the position predicted by the least squares method from the measurement data of the previous three points is automatically set as the vertical scanning range of the objective lens system. went. This was repeated to obtain a relative height distribution of the surface of the test piece with respect to the stage.

The two-dimensional surface shape of the obtained test piece is shown in FIG. 5, which agrees with the data obtained by the conventional method in which the scanning range of the objective lens system is fixed. Also,
While it took 11 minutes to perform this measurement using the conventional method, the time could be shortened to 5 minutes by using the control method of the present invention. Therefore, it is now possible to obtain data on changes in the surface shape of the test piece over time.

FIG. 6 shows a flowchart for explaining a second embodiment of the present invention. In this example, a test piece with the same dimensions as the test piece in the above example, which was confirmed to have arc-shaped deformation, was used.

First, in the same manner as in the above example, the relative heights of three consecutive points on the surface of the test piece are measured to determine the radius of curvature of the arc, and from this the radius of curvature of the circular arc is determined by ±5μ around the predicted position.
The range of m was automatically set as the vertical scanning range of the objective lens system, and the next measurement point was measured.

Furthermore, to measure the next point, the vertical scanning range of the objective lens system is automatically set within a range of ±5 μm around the predicted position based on the radius of curvature obtained from the measurement data of the previous three points. went. Repeat this and
The relative height distribution of the specimen surface to the stage was obtained.

[0021] In addition, in the conventional method, 1
Although it required 1 minute, by using the control method of the present invention, it was possible to shorten the time to 5 minutes or less. Therefore, it is now possible to obtain data on changes in the surface shape of the test piece over time.

FIG. 7 shows a flowchart for explaining a third embodiment of the present invention. The test piece was prepared with the same dimensions and under the same conditions as the second embodiment of the present invention.

In this case, since the focal point position of the objective lens system at each measurement point can be predicted with reference to the second embodiment, the objective lens system can be scanned in the vertical direction within a range of ±2 μm around this point. The range was automatically set, and the relative height on the surface of the test piece was measured. While it took 11 minutes to perform this measurement using the conventional method, the time could be shortened to 3 minutes or less by using the control method of the present invention.

[0024]

[Effects of the Invention] The time required to measure the surface shape of a test piece is shortened, so throughput is improved. Furthermore, it becomes possible to measure changes in the shape of the test piece over time.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing the operation of an objective lens system during surface shape measurement in the present invention.

FIG. 2 is a flow diagram of a surface shape measuring method according to the present invention to explain an embodiment of the present invention.

FIG. 3 is a schematic diagram of the hardware of a measuring instrument to explain the prior art.

FIG. 4 is a schematic diagram illustrating the operation of an objective lens system during surface shape measurement to explain a conventional technique.

FIG. 5 is a diagram showing the measurement results of the surface shape of a test piece that is an example of the present invention.

FIG. 6 is a second diagram of the present invention for explaining an embodiment of the present invention.
It is a flowchart of the surface shape measurement method in the Example.

FIG. 7 is a third embodiment of the present invention for explaining an embodiment of the present invention.
It is a flowchart of the surface shape measurement method in the Example.

[Explanation of symbols]

1... Objective lens system, 2... Laser light, 3... Test piece, 4... Dichroic mirror, 5... Pinhole, 6... Light receiver, 7
...Stage, 8...Encoder, 9...Wedge-shaped sliding surface, 1
0...Ball screw, 11...Servo motor, 12...CPU,
13...Laser light source.

Claims (12)

[Claims] Claim 1: Detecting when the focal position of a laser beam narrowed down by an objective lens scanned in the vertical direction coincides with the surface of an object, and sequentially scanning the object surface to measure the relative height of the objective lens at this time. A method for obtaining a three-dimensional shape of an object by measuring the three-dimensional shape of an object surface, the scanning range of an objective lens at a certain measured point being determined from a focal point position estimated from nearby measurement points. How to measure shape. 2. The method for measuring a three-dimensional shape of an object surface according to claim 1, wherein a least squares method is used to estimate the scanning range of the objective lens. 3. Scan the stage in the vertical direction, find the relative height of the stage when the focal position of the laser beam focused by the objective lens coincides with the surface of the object, and repeat this operation within the object plane. A method for obtaining a three-dimensional shape of an object by sequentially scanning and measuring the object surface, characterized in that the scanning range of the stage at a certain point to be measured is determined from the focal point position estimated from nearby measurement points. How to measure the original shape. 4. A method for measuring a three-dimensional shape of an object surface according to claim 1, wherein a least squares method is used to estimate the scanning range of the stage. 5. Detecting when the focal position of the laser beam focused by the objective lens scanned in the vertical direction coincides with the surface of the object, and sequentially scanning the object surface to measure the relative height of the objective lens at this time. In a method of obtaining a three-dimensional shape of an object by measuring the shape of the object, the scanning range of the objective lens at a certain point to be measured is determined in advance by measuring the deformation of the specimen and/or the nearby measurement points. A method for measuring a three-dimensional shape of an object surface, characterized in that the three-dimensional shape of an object surface is determined from a focal point position estimated from. 6. Scan the stage in the vertical direction, find the relative height of the stage when the focal position of the laser beam focused by the objective lens coincides with the surface of the object, and repeat this operation within the object plane. In a method of obtaining a three-dimensional shape of an object by sequentially scanning and measuring, the scanning range of the stage at a certain point to be measured is determined in advance by measuring the deformation form of the test piece and the nearby measurement points. A method for measuring the three-dimensional shape of an object surface, characterized by determining from both. 7. Detecting when the focal position of the laser beam narrowed down by an objective lens scanned in the vertical direction coincides with the surface of the object, and sequentially scanning the object surface to determine the relative height of the objective lens at this time. A device for obtaining a three-dimensional shape of an object by measuring the three-dimensional shape of an object surface, characterized in that the scanning range of an objective lens at a certain point to be measured is determined from a focal point position estimated from nearby measurement points. Shape measuring device. 8. The apparatus for measuring a three-dimensional shape of an object surface according to claim 1, wherein a least squares method is used to estimate the scanning range of the objective lens. 9. Scan the stage in the vertical direction, find the relative height of the stage when the focal position of the laser beam focused by the objective lens coincides with the surface of the object, and repeat this operation within the object plane. A device for obtaining a three-dimensional shape of an object by sequentially scanning and measuring the object surface, characterized in that the scanning range of the stage at a certain point to be measured is determined from the focal point position estimated from nearby measurement points. Original shape measuring device. 10. The apparatus for measuring the three-dimensional shape of an object surface according to claim 1, wherein the least squares method is used to estimate the scanning range of the stage. 11. Detecting when the focal position of the laser beam narrowed down by an objective lens scanned in the vertical direction coincides with the surface of the object, and sequentially scanning the object surface to determine the relative height of the objective lens at this time. 3 of the object by measuring while
In a device that obtains a dimensional shape, the scanning range of an objective lens at a certain point to be measured is determined from the pre-measured deformation form of the specimen and the focal point position estimated from one or both of nearby measurement points. A device for measuring the three-dimensional shape of an object surface, characterized by: 12. Scan the stage in the vertical direction, find the relative height of the stage when the focal position of the laser beam focused by the objective lens coincides with the surface of the object, and repeat this operation within the object plane. In a device that obtains the three-dimensional shape of an object by sequentially scanning and measuring, the scanning range of the stage at a certain point to be measured is determined in advance by measuring the deformation of the specimen and one of the nearby measurement points. A device for measuring the three-dimensional shape of the surface of an object, characterized by determining the three-dimensional shape of the surface of an object.