JPH028706A - Surface shape measuring apparatus - Google Patents

Abstract

PURPOSE:To enable measurement of a surface shape at a very high accuracy in a fine order by moving a Z table so that a difference is down to zero between a value of a height signal of a surface to be measured and a value stored and set to add a movement value thereof to the height signal. CONSTITUTION:An object to be measured mounted on an X-Y table is irradiated with a light beam from a light source 61, reflected light thereof is received with a photodetector 64 of a photosensor 6 and signals i1 and i2 are outputted to a computation 65 to compute the Z-wise moving table of the surface of an object to be measured. The height signal is compared with a fixed value stored and set previously and a Z-way moving table is driven with a motor 14 in such a direction that the resultant difference approaches zero. As the Z-wise movement value is added to the height signal with a signal processor 12, the photosensor 6 follows irregularities of the object to be measured. This enables the use of a highly sensitive photosensor 6 to measure a surface shape at a very high accuracy in a fine order.

Description

[Detailed Description of the Invention] Industrial Application Field of the Present Invention The present invention uses an optical sensor to measure the surface shape (i.e. surface irregularities) of a measured object over a wide area with extremely high precision and at high speed. The present invention relates to a surface shape measuring device capable of performing measurements.

<Prior art> As a conventional method for measuring the surface shape (surface irregularities) of a measured object in a non-contact manner, Japanese Unexamined Patent Publication No. 124944/1983 discloses a method in which a light beam is directed by an X orthogonal beam to the surface of the measured object.
A method has been proposed in which the object is irradiated while moving in the -Y direction and the reflected light spots are measured.

The same publication also proposes a technique in which a light emitting/receiving device is moved back and forth in accordance with the unevenness of the surface of the object to be measured, and the amount of movement of the mouth is detected as the height of the unevenness.

Problems to be Solved by the Present Invention> However, in such conventional methods, the detection device is moved back and forth in accordance with the unevenness of the surface of the object to be measured, and this amount of movement is used as the measurement value of the unevenness. When it is desired to measure on an extremely minute order, there is a problem in that it is difficult to control this minute amount of advance and retreat so that it perfectly matches the unevenness (that is, makes the difference zero).

In addition, measurements on extremely small orders can be made with high precision.
In order to do this, the sensitivity of the detection device must be extremely high, and the amount of unevenness that can be measured (distance in the Z direction) becomes extremely narrow. Since the unevenness extends outside the measurement range, there is a problem in that the measurable range is significantly narrowed.

An object of the present invention is to provide a device that solves the above problems.

Means for Solving the Problems> In order to solve the problems described above, the surface shape measuring apparatus of the present invention includes (1) an X-direction moving table for moving the object to be measured in the X-direction; and the X-direction moving table. X direction movement to detect the amount of movement #
J-suspended detector, and Y that moves the object to be measured in the Y direction orthogonal to the X direction.
a direction movement table; and a Y direction movement table for detecting movement 11Jffi of the Y direction movement table.
a directional movement amount detector; an optical sensor that outputs a height signal of the surface of the object to be measured by irradiating a light beam onto the surface of the object to be measured and detecting the position of a reflected light point; A Z-direction moving table that moves in two directions perpendicular to the X-Y plane, and a Z-direction moving table that detects the amount of movement of the Z-direction moving table.
lJ hanging detector, the X-direction movement amount detector and Y-direction movement! When the shift 0 suspension signal output from the lJ suspension detector changes, the corresponding shift! a storage device that stores the height signal from the optical sensor before the lJm signal changes; a storage device that stores the height signal from the optical sensor before the lJm signal changes; an X-direction movement control 611 that compares the height signal from the optical sensor after the II suspension signal has changed and outputs a control signal to move the X-direction movement table in a direction in which the difference between the two approaches zero;
and a summing device that adds the height signal from the optical sensor and the moving signal from the Z-direction moving field detector.

(2) an X-direction moving table for moving the object to be measured in the X-direction; and an X-direction moving table for detecting the amount of movement of the X-direction moving table.
vJ suspension detector, and Y that moves the object to be measured in the Y direction orthogonal to the X direction.
a directional movement table; a Y-direction movement amount detector that detects the movement IJffl of the Y-direction movement table; an optical sensor that outputs a surface height signal; an X-direction movement table that moves the optical sensor in the X direction perpendicular to the X-Y plane; and a Z-direction movement that detects the lifting of the X-direction movement table. When the quantity detector and the object to be measured are optically flat,
A moving table shift hanging window device in which a height signal outputted from the optical sensor is stored and set in advance in association with the amount of movement outputted from the X-direction movement lJl hanging detector and the Y-direction movement amount detector. and a storage device for storing the height signal from the optical sensor before the movement amount signal changes when the movement 11Jffi signal output from the X-direction movement amount detector and the Y-direction movement amount detector changes. and comparing the height signal stored in the storage device with the height signal from the optical sensor after the change in the movement amount signal, and moving the X-direction moving table in a direction in which the difference between the two approaches zero. A Z-direction movement control device that outputs a control signal for moving the m The amount of deviation set on the table deviation amount setting device,
The X-direction movement 1) includes an arithmetic device that performs subtraction in association with the movement field output from the lffi detector and the Y-direction movement amount detector.

In this way, in (1) above, the optical sensor is controlled to move in seven directions so as to follow the irregularities on the surface of the object to be measured, and this Z direction movement! 1
Since lffi and the optical sensor output are added, even if the optical sensor's tracking movement does not perfectly match the irregularities on the surface of the object to be measured, this mismatch will be added, so the output will be accurate. .

In addition, in (2) above, the movement in the X-Y direction! Both the Il error and the Z-direction follow-up movement y4 difference are eliminated.

Examples of the present invention> Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 to 5 show an embodiment of the present invention.

In the figure, reference numeral 1 denotes a flat base on which the object to be measured W is installed, and this base 1 is movable in the x direction on a table 2 in the horizontal direction (X-axis direction) by a pulse motor 3. This X-direction moving table 2 is movable by a pulse motor 5 in the vertical direction (Y-axis direction) on a Y-direction moving table 4 perpendicular to the X direction.

Since the base 1, the X-direction moving table 2, and the X-direction moving table 4 are set vertically, the object W to be measured is installed on the surface of the base 1 in a vertical state.

In front of the base 1, an optical sensor 6 is fixedly installed on a fixed base 7.

As shown in FIG. 2, the optical sensor 6 includes a light source 61 that emits a light beam with good directionality, an irradiation lens 62 that narrows down this light beam and irradiates it onto the surface of the object W to be measured, and an optical axis of the irradiation lens 62. is shifted at a certain angle from the optical axis of
An imaging lens 63 that forms an image of a reflected light spot on the light-receiving surface 64a of 4, and a case where the reflected light spot changes due to displacement of the surface of the object W in 7 directions <direction orthogonal to the X-Y plane). The light-receiving surface 64a is arranged so as to match the locus of the light-receiving surface 64a, and two signals i1, iz
It is composed of a light receiving element 64 which outputs , and a computing unit 65 which calculates a change z1 in the height of the surface of the object W from the two outputs jl and 12 of the light receiving element 64.

As shown in FIG. 3, the surface of the object W to be measured is
If there is a displacement (in a direction perpendicular to the Y plane) (i.e. surface unevenness), the light beam from the irradiation lens 62 is reflected on the surface, and the reflected light spot is imaged by the imaging lens 63.
Q is displaced in the Z direction corresponding to the displacement in the Z direction.

In order to detect the IQ displacement of the reflected light spot in the 2' direction, the light receiving surface 64a of the light receiving element 64 is
The direction of the force, ie, the locus of the image Q of the reflected light spot, is made to match.

As the light receiving element 64, for example, as shown in FIG.
One-dimensional diffused PI that converts displacement in one direction into electrical signals
N diodes are used. This light-receiving element 64 has a ratio of light-receiving currents i+ and iz flowing through load resistors R and R connected to terminals 64b and 64c provided at both ends in the 2' direction, respectively, due to a change in the position of the reflected light spot in 90 directions. The distance Zo in one direction from the center line 0 to the image Q of the light spot is determined as follows.

Note that the optical sensor 6 shown in FIG. 3 shows an optical system of the type used for measurement when the object W to be measured is a scattering surface, and when the object W to be measured is a mirror surface, , a type of optical sensor is used in which the irradiated light beam and the reflected light beam are symmetrical with respect to the normal to the surface of the object W because of specular reflection.

X by the X-direction moving table 2 and the Y-direction moving table 4
8 movement amounts X and Y in the direction and Y direction are determined by an X-direction movement amount detector 10 and a Y-direction movement amount detector 11 that receive drive outputs of an X driver 8 and a Y driver 9, respectively, which drive a pulse motor 3.5. detected by.

The signal processor 12 is configured as shown in FIG.

121 indicates the X-direction movement amount detector 10 and the Y-direction movement v when the object to be measured is an optical flat.
This is a moving table shift suspension setting device in which the height @#z1 outputted from the optical sensor 6 is stored in advance in association with the movement ff1X, Y outputted from the J amount detector 11.

That is, the output of the optical sensor 6 when measuring the optical flat indicates the deviation in seven directions for each movement position in the X and Y table movements.

This offset is set in advance for the entire X-Y plane.

122 outputs the displacement amount set in the moving table displacement suspension setting K@12 from the height signal Z1 from the optical sensor 6 from the X-direction movement amount detector 10 and the Y-direction movement amount detector 11. This is a subtraction device that subtracts in correspondence with the amount of movement.

Reference numeral 123 denotes a control device that controls the setting of the moving table shift indicating device @121, the operation of the subtraction device @122, and the operation of the X and Y drivers 8.9.

Since the surface shape measuring device is configured as described above, it is possible to measure the surface shape! Ill! Install IW on base 1 and move it in the X direction V
While the base 1 is moved in the XY plane by the table 2 and the Y-direction moving table 4, a light beam from the light source 61 of the optical sensor 6 is directed onto the surface of the object W to be measured 9A.

The light receiving element 64 outputs signals i1 and iz, and the computing unit 65 receives the signals i1 and iz and calculates the
Calculate the height Zl in the direction. This is output to subtraction device 122.

Output Z1 of optical sensor 6 and X and Y direction movement amount detector 10
．． 11 in the X and Y directions are output to the setting device 121 and the subtraction device 122.

i! Under the control of the i-control device 123, the displacement corresponding to the position on the XY plane set in the moving table displacement setting value 121 is subtracted from the output of the optical sensor 6. As a result, surface measurements can be made without errors due to movement in the X-Y directions.

FIG. 6.7 t shows a case where the optical sensor 6 is installed movably on the seven-direction moving table 13 in the Z-axis direction perpendicular to the X-Y plane by the motor 14. This Z
Seven direction movement vJ of optical sensor 6 by direction movement table 13
ffiZ is l-113-N which is not frequency stabilized.
Interference α to detect movement of optical sensor 6 using e-laser
This is carried out by a Z-direction movement detector 15 consisting of one device.

The signal processor 12 shown in FIG. 7 is constructed as shown in FIG.

In FIG. 8, reference numeral 124 indicates the amount of movement from the optical sensor 6 before the movement effi signal changes when the movement amount A8 output from the X-direction movement detector 10 and the Y-direction movement amount detector 11 changes. This is a storage device that stores height signals.

125 compares the height signal stored in the storage device 124 with the height signal from the optical sensor 6 after the shift 1ffi signal change, and moves the Z direction in a direction in which the difference between the two approaches zero. Z outputs a control signal to move the table 13
It is a directional movement controlled tS device.

Reference numeral 126 denotes an adding device that adds the height signal from the optical sensor 6 and the moving part from the seven-direction movement amount detector 15.

127 is a control device that controls each of these early springs.

With this configuration, when the surface height of the object to be measured changes due to movement in the X-Y direction, the height signal Z1 of the optical hinge 6 changes, but this change does not occur at a certain point before. The height signal stored in the storage device 124 is compared with the two-direction movement control device @125, and a control signal is output to the 7 driver 16 so that the difference between the two approaches zero. As a result, the optical sensor 6 is moved by the table 7 in a direction that follows the unevenness of the surface. (For this reason, the image Q of the reflected light spot is always made to approach near the center line J!O of the light receiving surface 64a of the light receiving element 64 in FIG. 4.) At this time, the movement from the two detectors 15 in seven directions The amount and the height from the optical sensor 6 are added by addition 8 and 126.

Therefore, even if the tracking of unevenness does not match perfectly, this addition will measure accurately, making it possible to measure with high precision.
It becomes possible to determine j. Moreover, even if the amount of change in surface irregularities is large, the optical image is always controlled to approach the center 10 of the PIN diode, so it will not go outside the measurement fi area, and the measurement range will be significantly expanded. .

Furthermore, if the subtraction of the misalignment due to the X-Y direction movement shown in Fig. 5 is added to the configuration of Fig. 8, the advantages of both Fig. 5 and Fig. 8 can be weighted, and - high layer accuracy and Become.

Note that when the object to be measured is fixed to the base 1, it may shift from its vertical fixed position.

Therefore, the signal processor 12 stores the heights of three points on the surface of the object W in two directions based on the output of the optical sensor 6, and the heights of these three points in seven directions become equal values. 7 of any other arbitrary point when the measured object W is virtually replaced as shown in FIG.
If the calculation is performed so as to output the directional height), the accuracy will be even higher.

Note that it can also be configured to output the positions of contour lines in seven directions from the height in the Z direction.

Effects of the Present Invention> As explained above, according to the present invention, it is possible to measure the surface shape on the minute order with extremely high degree of precision and at high speed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the gate structure of a surface profile measuring device according to an embodiment of the present invention, FIG. 2 is a block diagram of its circuit section, and FIG.
FIG. 4 is an explanatory diagram showing an example of a light-receiving bundler, and FIG. 5 is a block diagram showing a specific configuration of the signal processor shown in FIG. 2. FIG. 6 is a perspective view showing another embodiment of the present invention, FIG. 7 is a block diagram of its circuit section, and FIG. 8 is a block diagram showing the specific configuration of its signal processing section. W...Object to be measured, 1...Base, 2...
...X-direction moving table, 4...Y-direction moving table, 6... Optical sensor, 10...
・X-direction movement amount detector, 11...Y-direction movement vJ
ffi detector, 12... Signal processor, 13...
...Z-direction moving table, 15...2-direction moving sensor. Patent applicant: Anritsu Corporation

Claims (2)

[Claims] (1) An X-direction movement table that moves the object to be measured in the X direction; an X-direction movement amount detector that detects the amount of movement of the X-direction movement table; and an X-direction movement amount detector that moves the object to be measured in the Y direction orthogonal to the X direction. Move Y
a directional movement table; a Y-direction movement amount detector for detecting the movement amount of the Y-direction movement table; an optical sensor that outputs a height signal of the surface of the object to be measured; a Z-direction moving table that moves the optical sensor in the Z direction perpendicular to the X-Y plane; and a Z-direction moving table that detects the amount of movement of the Z-direction moving table. When the movement amount detector, the movement amount signal output from the X-direction movement amount detector and the Y-direction movement amount detector change, the height signal from the optical sensor before the movement amount signal changes is determined. The height signal stored in the storage device is compared with the height signal from the optical sensor after the movement amount signal has changed, and the height signal is adjusted in the direction in which the difference between the two approaches zero. A surface comprising: a Z-direction movement control device that outputs a control signal for moving a Z-direction movement table; and an addition device that adds a height signal from the optical sensor and a movement amount from the Z-direction movement amount detector. Shape measuring device. (2) an X-direction movement table that moves the object to be measured in the X direction; an X-direction movement amount detector that detects the amount of movement of the X-direction movement table; and an X-direction movement amount detector that moves the object to be measured in the Y direction orthogonal to the X direction. Move Y
a directional movement table; a Y-direction movement amount detector for detecting the movement amount of the Y-direction movement table; an optical sensor that outputs a height signal of the surface of the object to be measured; a Z-direction moving table that moves the optical sensor in the Z direction perpendicular to the X-Y plane; and a Z-direction moving table that detects the amount of movement of the Z-direction moving table. When using a movement amount detector and an optical flat object to be measured,
a moving table deviation amount setting device in which a height signal output from the optical sensor is stored and set in advance in association with the movement amount output from the X-direction movement amount detector and the Y-direction movement amount detector; a storage device that stores the height signal from the optical sensor before the movement amount signal changes when the movement amount signal output from the X-direction movement amount detector and the Y-direction movement amount detector changes; Comparing the height signal stored in a storage device with the height signal from the optical sensor after the change in the movement amount signal, and moving the Z-direction moving table in a direction in which the difference between the two approaches zero. a Z-direction movement control device that outputs a control signal; a height signal from the optical sensor and a movement amount from the Z-direction movement amount detector; The amount of deviation set to
A surface shape measuring device comprising: an arithmetic unit that performs subtraction in association with the movement amount output from the X-direction movement amount detector and the Y-direction movement amount detector.