JPH11190616A - Surface shape measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify control processing for continuously measuring the surface shape of a measured object while copy-measuring it so as to measure the surface shape rapidly with high accuracy. SOLUTION: A contactless laser displacement gage 1 irradiates beams to a measured object W and outputs a displacement signal corresponding to surface shape. A Z-stage 5 moves the contactless laser displacement gage 1 in a Z- direction and outputs a displacement signal corresponding to the moving quantity. An automatic focusing unit 6 controls the movement of the Z-stage 5 for copy measurement, and adds the displacement signals from the contactless laser displacement gage 1 and the Z-stage 5 and outputs the added displacement signals as a displacement signal of the measured object W. A control means 20 controls the movement of X-, Y-stages 2, 3 and analyzes surface shape such as the height, width and sectional area of the measured object W on the basis of the displacement signal outputted from the automatic focusing unit 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface shape measuring device capable of measuring the surface shape of an object to be measured in a non-contact manner with high accuracy.

[0002]

2. Description of the Related Art As industrial products become smaller and higher in quality, inspection of shapes of materials and parts used in the products is indispensable for quality control of the products. By using a non-contact laser displacement meter as a sensor in these shape inspections, it has been used in a wide range of fields because it does not damage or deform the object to be measured, and it can measure with high accuracy and high speed. .

A surface shape measuring device using this non-contact laser displacement meter is used for measuring flatness of a magnetic disk or a wafer, for measuring warpage and thickness of a plate material such as a glass plate, and for measuring a shape such as a bump plating or a gimbal of a magnetic head. It is used for measurement and for measuring the warpage of an IC package and the height of an etched surface.

The non-contact laser displacement meter irradiates an object to be measured with a light beam and obtains the amount of displacement of the surface of the object to be measured based on the distance to the object to be measured. When measuring, the object to be measured or the non-contact laser displacement meter is moved in the same direction (X, Y axis directions). Further, when the unevenness of the surface is large, it is necessary to move in the same unevenness direction (Z-axis direction). A configuration in which the movement in the Z direction is controlled when moving in the X and Y directions is known as a technique called scanning measurement.

In the scanning measurement in the conventional surface profile measuring apparatus, a zero point of the displacement output of the non-contact laser displacement meter is detected, and the movement control in the Z-axis direction is performed so that the displacement output of the non-contact laser displacement meter becomes zero. However, since the value of the movement amount of the Z scale (for example, the output of the length measuring instrument) at this time is used as the displacement output, the measurement operation becomes discontinuous, and the scanning measurement cannot be speeded up.

In order to solve the above-mentioned problem, the present applicant has proposed FIG.
The inventors have invented a surface shape measuring device having the configuration shown in FIG. Explaining the configuration, the X stage 60 is movable in the X direction, and a Y stage 61 is provided thereon, and is movable in the Y direction. An object to be measured W is placed on the Y stage 61, and is movable in the X and Y directions by the X and Y stages 60 and 61. An arm 62a is provided on the base 62, and a non-contact laser displacement meter 50 is mounted via a Z stage 63 movable in the Z direction.

FIG. 5 is a diagram showing the principle of displacement detection of the non-contact laser displacement meter 50. The light beam (light projection beam) emitted from the light source 51 is converged by the light projection lens 52 and is irradiated on the surface of the object to be measured at a predetermined distance L0 from the end face 50a of the optical displacement sensor 50. to make. Light beam reflected or scattered from this irradiation point (reflected beam)
Are condensed by the imaging lens 53 and form an image of the irradiation point at a position K on the photodetector 54. The light beam and the reflected beam have a predetermined angle as shown in the figure and enter and exit from different places. This image moves on the light detection element 54 when the object to be measured moves up and down, and a displacement signal corresponding to the amount of movement is output from the light detection element 54. That is, when the irradiation point position of the light beam is at the position Q higher than the reference position P by ΔL, a signal corresponding to this displacement distance (+ ΔL) is output, and the irradiation point position is shifted to the position R lower by ΔL than the reference position P. When there is, a displacement signal corresponding to the displacement distance (-ΔL) is output.

The displacement signal output from the non-contact laser displacement meter 50 is output to the control means 70 via the display 64. The display unit 64 is provided with a sensor processing unit 64a, and performs display processing of a displacement signal. Also, the displacement amount of the Z stage 63 (the movement amount of the non-contact laser displacement meter 50 in the Z direction)
Is measured by the length measuring device 65 and output to the control means 70 via the processing section 66.

The movement amounts of the X, Y and Z stages 60 and 61 are detected by a movement amount detector (not shown) and output to the control means 70. The control means 70 is constituted by a personal computer,
F board (1) 71, I / F board (2) 72,
An F board (3) 73 is provided. Further, a CRT 75 for outputting a measurement result on a screen and a printer 76 for printing out are connected to the control means 70.

The amount of displacement of the Z stage is input to the I / F board (1) 71 via the processing unit 66, and the I / F board (2) 72 receives a displacement signal from the non-contact laser displacement meter 50. Is entered. The control means 70 synthesizes the displacement amount of the Z stage and the displacement signal from the non-contact laser displacement meter 50 based on the scanning measurement control program stored in the memory to thereby displace the object to be measured. An arithmetic operation for obtaining the quantity is performed. Also, the movement control of the X, Y, and Z stages 60, 61, and 63 necessary for scanning measurement in which the non-contact laser displacement meter 50 measures the surface shape of the object to be measured is performed. The movement signal for this is transmitted from the I / F board (3) 73 via the motor driver 77 to each of the X, Y, Z stages 6.
0, 61, 63.

[0011]

However, as the object to be measured is miniaturized and highly integrated, more accurate measurement is required. When performing high-precision shape measurement using the above-described non-contact laser displacement meter 50 as a sensor, the characteristics unique to the non-contact laser displacement meter 50 are as follows: ・ The measurement range is narrow ・ The beam spot diameter of the light beam on the projection side is measured・ Because the projecting beam is obliquely incident, the measurement location is displaced laterally due to the displacement to be detected.When detecting micron-level irregularities on the DUT, it is ignored in embodying the required accuracy. become unable. In order to solve these problems, the measurement is always performed while the sensor itself follows the surface shape of the object to be measured so that the beam spot diameter of the non-contact laser displacement meter 50 becomes as small as possible (close to the zero point). Copying measurement had to be performed.

However, in the apparatus having the above configuration, the single control means 70 is configured to execute both the calculation processing of the displacement amount of the object to be measured and the movement control for the scanning measurement. ) Becomes complicated, and the control process is a load on the control means 70. That is, the synthesis processing of the displacement amount of the Z stage 63 and the displacement signal from the non-contact laser displacement meter 50, and the X, Y, and Z stages 6 for scanning measurement
Since the movement control of 0, 61, and 63 must be performed in real time, these different control processes have to be performed by a single control means (CPU) 70. As a result, conventionally, high-speed movement control cannot be performed,
It took time to measure the entire surface profile.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can simplify a control process for continuously measuring the surface shape of an object to be measured while following the surface shape of the object. It is an object of the present invention to provide a surface shape measuring device capable of performing a complicated measurement at a high speed.

[0014]

In order to solve the above-mentioned problems, a surface shape measuring apparatus according to the present invention irradiates an object to be measured (W) with a light beam, receives light from the irradiated point, and receives a light from a light receiving position. Non-contact measuring means (1) for measuring the shape of the surface of the object to be measured and outputting a corresponding displacement signal in accordance with the change in the position of the object, and X for moving the object and the non-contact measuring means relatively in the X and Y axis directions. , Y moving means (2, 3), Z moving means (5, 7) for moving the non-contact measuring means in the Z-axis direction with respect to the object to be measured, and outputting a displacement signal corresponding to the moving amount; The displacement signal output from the non-contact measurement means and the Z movement means are added to output a displacement signal indicating the surface shape of the object to be measured. Change the output value of the displacement signal so that it is minimized on the surface of the DUT. An auto-focus unit (6) for controlling the movement of the Z-moving means on the basis of the above, and for controlling the movement of the X and Y-moving means along a preset measurement route, and Control means (20) for calculating and processing various surface shapes such as the height, width and cross-sectional area of the object to be measured based on the output displacement signal.

In the non-contact measuring means (1), the projected beam and the reflected beam have a predetermined angle, and are rotatable by a predetermined angle about a beam spot of the non-contact measuring means.
It is good also as a structure provided with the moving means (9).

When measuring the surface shape of the object W, the control means 20 controls the movement of the X and Y stages 2 and 3 along a predetermined measurement route to move the object W in the X and Y axis directions. Move. During this movement, the auto focus unit 6
Controls the movement of the Z moving means 5 in accordance with the surface shape such as the unevenness of the workpiece W, and moves the non-contact measuring means 1 in the Z-axis direction (scanning measurement). At this time, the autofocus unit 6 adds the outputs of the non-contact measuring means 1 and the Z moving means 7 and outputs a displacement signal indicating the displacement of the workpiece W. The control unit 20 associates the displacement signal output from the autofocus unit 6 with the X and Y coordinate axes, and calculates and outputs the surface shape such as the height, width, and cross-sectional area of the workpiece W based on the data of the entire measurement route. I do. As described above, the movement of the object to be measured W is controlled by separating and independently controlling the movement control and the surface shape calculation processing by the control means 20 and the movement control in the Z-axis direction for the scanning measurement by the autofocus unit 6.
Surface shape can be measured at high speed and continuously with high accuracy.

[0017]

FIG. 1 is an overall view showing a surface shape measuring apparatus according to the present invention. The non-contact laser displacement meter (non-contact measuring means) 1 outputs a displacement signal corresponding to the surface shape of the workpiece W by the same triangulation method as that of the configuration described in the related art, and has a predetermined measurement range. doing. Also, CCD
A camera is built-in, and a predetermined range is enlarged around the beam spot so that the surface of the object W can be observed on a monitor.

The object W and the non-contact laser displacement meter 1 are X,
By means of Y, Z, Θ, X, Y, Z,
It is movable in each axis direction of Θ. The X stage 2 is movable in the X direction, and the Y stage 3 is provided thereon, and is movable in the Y direction. An object to be measured W is placed on the Y stage 3 and is movable in the X and Y directions by the X and Y stages 2 and 3. Arm 4 on base 4
a is provided, and the Z stage 5 is movable in the Z direction.
The non-contact laser displacement meter 1 is attached via the.
The movement amounts of the X and Y stages 2 and 3 are measured by a length measuring device (not shown) and output to the control means 20.

A Θ stage 9 is provided between the Z stage 5 and the non-contact laser displacement meter 1, and holds the non-contact laser displacement meter 1 rotatably about a beam spot. The non-contact laser displacement meter 1 has a light emitting and receiving surface in terms of the measurement principle, and when measuring the cross-sectional shape, the light emitting and receiving surface is always orthogonal to the moving direction of the non-contact laser displacement meter 1 with respect to the workpiece W. . That is, the non-contact laser displacement meter 1 is rotatable.

The displacement signal output from the non-contact laser displacement meter 1 is input to the autofocus unit 6. The autofocus unit 6 includes a non-contact laser displacement meter 1
The sensor processing unit 6a adapted to the type and signal form of the sensor is mounted. The displacement amount of the Z stage 5 (the movement amount of the non-contact laser displacement meter 1 in the Z direction) is measured by the length measuring device 7 and input to the autofocus unit 6. Z moving means,
It comprises a Z stage 5 and a length measuring device 7. The non-contact laser displacement meter 1 and the length measuring device 7 are arranged so as to satisfy Abbe's principle in order to minimize a geometrical measurement error caused by the movement accuracy of the Z stage 5.

FIG. 2 is a block diagram showing the internal configuration of the autofocus unit 6. The autofocus unit 6 mainly performs the scanning measurement of the surface shape of the workpiece W by the non-contact laser displacement meter 1. The CPU 10 executes autofocus operation control and data processing, which are the contents of the scanning measurement (details will be described later). 11a,
Reference numeral 11b denotes an interface with the non-contact laser displacement meter 1 and the control means 20.

The displacement (displacement signal) output from the length measuring device 7 is input to the CPU 10 via the processing unit 12 and the I / F 13. The movement of the Z stage 5 and the 移動 stage 9 are controlled by motor drivers 15 and 16, respectively.モ ー タ The motor driver 16 of the stage 9 is the non-contact laser displacement meter 1
Is controlled to compensate for the characteristics of the non-contact laser displacement meter 1. By mounting this function in the autofocus unit 6, the control of the non-contact laser displacement meter 1 at the time of measuring the cross-sectional shape including the scanning measurement can be simplified.

The content of the autofocus operation control The displacement signal output from the non-contact laser displacement meter 1 is a sensor processing unit 6a built in the autofocus unit 6.
And sent to the CPU 10 as a digital signal. CP
When U10 receives the autofocus operation command from the control means 20, if the value of the displacement signal output from the non-contact laser displacement meter 1 exceeds a preset threshold,
The movement of the Z stage 5 is started so that the displacement signal becomes equal to or less than the threshold value. At this time, the moving speed of the Z stage 5 changes in proportion to the change amount of the displacement signal of the non-contact laser displacement meter 1. For example, the displacement of the non-contact laser displacement meter 1 is monitored at every predetermined cycle (for example, 16 kHz), and the moving speed is changed every one pulse output to the Z stage 5, and the vicinity of the center of the measurement range (outside the threshold near the threshold) The control is performed to move at a low speed when measuring at the speed, and at a high speed when measuring near both ends (points far from the threshold).

The contents of the data processing The autofocus unit 6 adds the displacement signal of the non-contact laser displacement meter 1 fetched by the CPU 10 and the displacement signal of the length measuring device 7 and outputs the added value to the control means 20. I do.

The control means 20 is constituted by a personal computer,
I / F with PU and memory such as ROM and RAM
A board (1) 21 and an I / F board (2) 22 are provided. The control means 20 is connected to a CRT 25 for outputting various settings and measurement results on a screen, and a printer 26 for printing out. The control means 20 takes in the displacement signal after addition output from the autofocus unit 6 via the I / F board (2) 22;
The movement control of the X and Y stages 2 and 3 is executed. The I / F board (1) 21 outputs a movement signal for this purpose to the X and Y stages 2 and 3 via the motor driver 27. The control means 20 includes an X, Y stage 2 indicating a current measurement point,
The coordinate position of No. 3 is associated with the displacement signal output from the autofocus unit 6, and the surface shape (height, width, cross-sectional area, etc.) of the workpiece W is calculated based on the data of the entire measurement.

Here, in the scanning measurement according to the present invention,
When the object to be measured W moves by the movement control of the X and Y stages 2 and 3 and the output of the non-contact laser displacement meter 1 changes, the autofocus unit 6 sets the displacement signal of the non-contact laser displacement meter 1 to 0 μm ( Z is adjusted so that the beam spot diameter applied to the measurement object W is minimized).
The stage 5 is moved (autofocus control).
The movement amount of the Z stage 5 is detected by the length measuring device 7. At this time, since the output of the non-contact laser displacement meter 1 does not exactly become 0 μm, the auto-focus unit 6 calculates the sum of the displacement signal of the non-contact laser displacement meter 1 and the displacement signal of the length measuring device 7 and receives the signal. The displacement of the measurement object W is output to the control means 20.

The above surface profile measuring apparatus is applied, for example, to a sealant profile inspection machine for quality control of a liquid crystal display. The manufacturing process of a liquid crystal display includes a cell assembly process in which two glass substrates are bonded with an adhesive called a sealant. Here, since the stress distribution at the time of bonding affects the gap accuracy, the cross-sectional shape of the sealant (the workpiece W) before bonding is measured, and the height,
It is necessary to calculate the width and the cross-sectional area to control the amount of the sealant applied. The device of the present invention measures the surface shape of the sealant.

The overall operation of the apparatus will be described. First, a glass substrate is placed on a setting base (Y stage 3), and a measurement route is set according to a route setting screen displayed on the CRT 25. The measurement route is defined by two coordinates, a start point and an end point. Start and end points are X and Y stages 2,
3 is moved so that the beam spot of the non-contact laser displacement meter 1 is aligned with the measurement location of the workpiece W, and the current coordinates (XY axes) of the non-contact laser displacement meter 1 at that time are input. These operations are performed by using a monitor provided in the non-contact laser displacement meter 1 together. You can register multiple measurement routes,
The route setting contents are saved in a file, and the same measurement can be performed by calling this file the next time the same measurement is performed.

Next, when "start" is selected on the measurement screen, the non-contact laser displacement meter 1 moves from the origin position to the starting point of the first route. At the same time, the stage 9 rotates so that the light emitting / receiving surface of the non-contact laser displacement meter 1 is orthogonal to the moving direction (scanning direction) in which the measurement is performed. Non-contact laser displacement meter 1
Performs an autofocus operation at the start point and starts scanning measurement in the end point direction. The control means 20 captures the displacement signal output from the autofocus unit 6 at the set pitch, and when the first route measurement is completed, the non-contact laser displacement meter 1 moves to the start point of the second route and performs the same measurement. I do. When the measurement of all routes is completed, the non-contact laser displacement meter 1 returns to the origin position.

After completion of the measurement, the control means 20 analyzes the measurement data and calculates and obtains the height, width and cross-sectional area of the measured object W (sealant). FIG. 3 is a waveform diagram showing the contents of this analysis processing. In each of (a) to (d), the horizontal axis represents the movement direction, and the vertical axis represents the signal corresponding to the shape of the DUT W in the height direction. (A) is a measured cross-sectional shape waveform, where a flat portion corresponds to a glass substrate and a convex portion corresponds to a sealant. (B) is a derivative of the cross-sectional shape waveform,
An inflection point is determined and the distance between the inflection points is calculated as the width of the sealant. (C) is obtained by obtaining a reference line from a cross-sectional shape waveform corresponding to the glass substrate, subtracting the reference line from the cross-sectional shape waveform, and correcting the inclination. The peak value of the peak is detected, and the height of the sealant is detected. Is calculated as (D) is obtained by integrating the waveform of (c), and the maximum value is calculated as the cross-sectional area of the sealant.

As described above, the function necessary for the scanning measurement for interpolating the characteristics of the non-contact laser displacement meter 1 is provided in the unitized auto-focus unit 6 and is separated from the control means 20. Control means 2 while performing high-precision, wide-range measurement by non-contact laser displacement meter 1
0 can be reduced. Further, since the autofocus unit 6 is formed as a unit separated from the control means 20, it is possible to easily mount the scanning measurement function itself on a surface shape measuring apparatus using the non-contact laser displacement meter 1 as a sensor.

[0032]

According to the present invention, the control for the scanning measurement is separately assigned to the autofocus unit, and the control means executes the movement control of the continuous measurement and the analysis processing of the surface shape of the object to be measured based on the measurement data. With this configuration, the processing load on the control means can be reduced, the surface shape can be measured with high accuracy, and the measurement operation can be performed at high speed without discontinuity.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing an internal configuration of an autofocus unit.

FIG. 3 is a diagram showing calculation contents of a control means.

FIG. 4 is an overall view showing a conventional surface shape measuring apparatus.

FIG. 5 is a diagram showing a non-contact laser displacement meter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Non-contact laser displacement meter, 2 ... X stage, 3 ... Y stage, 5 ... Z stage, 6 ... Autofocus unit, 7 ... Length measuring device, 9 ... Θstage, 10 ... CPU 20 ... Control means, 15, 16, 27 ... Motor driver.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiko Hara 5--10-27 Minamiazabu, Minato-ku, Tokyo Anritsu Corporation

Claims (2)

[Claims] An object (W) is irradiated with a light beam, receives light from the irradiated point, measures the shape of the surface of the object according to a change in a light receiving position, and outputs a corresponding displacement signal. Contact measuring means (1); X, Y moving means (2, 3) for relatively moving the object to be measured and the non-contact measuring means in the X and Y axis directions; Z movement means (5, 7) for moving the object in the Z-axis direction and outputting a displacement signal corresponding to the movement amount, and adding the displacement signals output from the non-contact measurement means and the Z movement means. While outputting a displacement signal indicating the surface shape of the object to be measured, always based on a change in the output value of the displacement signal so that the beam spot diameter irradiated from the non-contact measuring means is minimized on the surface of the object to be measured. Autofocus unit that controls the movement of the Z movement means ( 6) and controlling the movement of the X, Y moving means along a preset measurement route, and based on the coordinate position by the movement control and the displacement signal output from the autofocus unit, Control means (20) for calculating various surface shapes such as width and cross-sectional area. 2. The non-contact measuring means (1) includes a Θ moving means (9) which has a predetermined angle between a projected beam and a reflected beam and is rotatable by a predetermined angle around a beam spot of the non-contact measuring means. The surface shape measuring device according to claim 1, further comprising: