JPH079367B2 - Shape measuring method and device - Google Patents

Description

The present invention relates to a shape measuring method and apparatus for measuring the surface shape of an object to be measured.

<Prior Art> (Fig. 12) In order to measure the warp, unevenness, etc. of the object surface, an object to be measured is placed on a moving table that moves in the XY directions, and the measurement points by the movement of the measuring surface 2. Description of the Related Art A shape measuring device that detects a change in height of a sensor with a sensor has been conventionally used.

FIG. 12 is a schematic view of a shape measuring apparatus using an optical sensor, in which the beam light output from the light source 2 of the sensor 1 is irradiated onto the surface 8a of the DUT 8 through the irradiation lens 3. Then, the image of this reflected light spot is formed on the light receiving surface of the light receiving element 5 by the imaging lens 4.

Since the light receiving element 5 is formed so as to output a light receiving signal according to a change in the image forming position of the reflected light point, the reflected light point (measurement point) is calculated by processing this light receiving signal.
The height in the Z direction can be measured.

Therefore, it is possible to determine the warp of the surface 8a, the degree of unevenness, and the like based on the height data measured by arbitrarily setting the position of the measurement point by moving the moving table 6.

Therefore, as described above, in the case of an apparatus that intends to measure the height of the measurement surface with high accuracy using an optical sensor,
As shown in the figure, if the displacement of the movable table 6 in the Z direction is small, a measurement error will occur.

In order to correct this error, in the conventional shape measuring device, an optically flat plate (optical flat) is placed on the moving table 6.
The movable table 6 is moved in a state of being mounted, and the displacement data measured in sufficient detail over the entire surface of the movable table 6 is stored in advance, and the measured height data is measured at the measurement of the measured object. The displacement data corresponding to the position of the measurement point is used for correction.

<Problems to be Solved by the Present Invention> However, as described above, the work of finely measuring the displacement data of the movable table in the Z direction over the entire surface has a problem that it takes a very long time.

Particularly, in order to correct the error due to the change with time of the mechanism for moving the movable table, this work is required periodically, and the efficiency of measurement is significantly reduced.

Further, there is a problem that a storage device capable of storing and holding a large amount of data for a long time is required to store the displacement data over the entire surface of the movable table.

<Means for Solving the Problems> In order to solve the problems, the shape measuring method of the present invention is a moving table on which an object having a flat surface lower than the movable range of the moving table is placed. Moving in the X-Y directions and measuring the displacement of the movable table in the Z direction at a predetermined pitch based on the detection signal from the sensor; storing the measured displacement data; and XY between the predetermined pitches. Direction, setting grid points subdivided in the interpolating pitch in the direction, calculating displacement data in the Z direction of the grid points by interpolation calculation of the measured displacement data, and calculating the displacement data of the grid points in the X direction. Storing the value corresponding to the Y coordinate value, calculating the height value in the Z direction of the measuring point of the object to be measured placed on the movable table based on the detection signal from the sensor, The height value of the measured point Correcting with the displacement data of the lattice point closest to the XY coordinate values.

Further, in order to realize the method, the shape measuring apparatus of the present invention comprises: a movable table on which an object to be measured is placed and moved in the XY direction; and a surface of the object to be measured placed on the movable table. A sensor for detecting the displacement of the measuring point in the Z direction, a moving means for moving the moving table to move the measuring point to a set XY coordinate position, and an XY coordinate for each predetermined pitch on the moving table. Pitch coordinate setting means for setting a value in the moving means, and displacement data in the Z direction for each of the predetermined pitches of the moving table itself, which is moved by the pitch coordinate setting means at a predetermined pitch, based on a detection signal from the sensor. Data calculating means for calculating, first storing means for storing displacement data calculated by the data calculating means, interpolation pitch setting means for setting an interpolation pitch smaller than the predetermined pitch, and the predetermined pitch Interpolation calculation means for calculating the displacement data in the Z direction of the grid points dividing the grid at the interpolation pitch from the displacement data stored in the first storage means, and the displacement data calculated by the interpolation calculation means are stored. And a second storage means for measuring the measurement point X- of the object to be measured placed on the movable table.
Measurement setting means for setting a Y coordinate value in the moving means; height calculation means for calculating the height in the Z direction of the measurement point set by the measurement setting means based on a detection signal from the sensor; Data reading means for reading the displacement data of the lattice point closest to the XY coordinate value of the measurement point calculated based on the result from the second storage means, and the height of the measurement point calculated by the height calculation means. Correction calculation means for correcting the height based on the displacement data read from the data reading means.

<Operation> Therefore, the measured height data of the measured object is the first
The displacement data of the lattice point closest to the XY coordinate of the measurement point is corrected by the displacement data of the lattice point calculated by the interpolation calculation from the displacement data of the lattice point stored in the storage means.

<Embodiment of the present invention> (Figs. 1 to 10) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an overall configuration of a shape measuring apparatus according to an embodiment.

In the figure, 10 is a measuring mechanism unit, 11 is a base, and 12 is an XY moving base provided on the base 11.

X is an optical sensor 15 to be described later attached to the base frame 11a.
It is a Z moving device for moving up and down in the Z direction orthogonal to the XY moving plane of the Y moving table 12.

14 is XY in response to a movement signal from the measurement control unit 30 described later.
An XYZ driving unit that drives the moving table 12 and the Z moving device 13.

Reference numeral 15 is an optical sensor attached to the Z moving device 13.

FIG. 2 is a diagram showing an optical configuration inside the optical sensor 15.

In FIG. 2, 16 is a laser light source, 17 is a laser light XY
It is an irradiation lens that irradiates the surface of the object to be measured along the Z direction orthogonal to the XY plane of the movable table 12.

Reference numeral 18 is an imaging lens that forms an image of the reflected light spot on the measurement surface, and 19 is a light-receiving surface that coincides with the locus of the imaging position that moves according to the change in the position of the reflected light spot (height in the Z direction). 19a is a position detecting element.

As shown in FIG. 3, the position detecting element 19 has a distance L from the center line C of the light receiving surface 19a to the image forming point Q and terminals 19 at both ends.
A light receiving element (for example, a one-dimensional diffusion type PIN diode) that has a relationship of L = K (I1−I2) / (I1 + I2) between the light receiving currents I1 and I2 flowing from b and 19c through the resistors R1 and R2. It is used (K is a constant), and the calculator 20 for performing this calculation calculates the distance L (displacement value) from the center line C to the image forming position Q.

Note that the optical axes of the irradiation lens 17 and the imaging lens 18 intersect at a point P, and the imaging position for the reflected light point from this point P is the light receiving surface.
It is set on the center line C of 19a, and the light receiving currents I1 and I2 at this time are equal and the displacement value L is zero.

Further, in FIG. 1, reference numeral 25 denotes an XY position detecting device for detecting the position on the XY plane of the reflected light point of the light beam with respect to a predetermined reference origin of the XY moving table 12 and outputting the position signal. The signal and the displacement signal from the optical sensor 15 are sent to the measurement control unit 30.

The measurement control unit 30 is composed of a computer as shown in FIG.

In FIG. 4, 31 is an input / output interface, 32 is an arithmetic processing unit, 33 is an external storage unit, 34 is an internal storage unit, 35 is an input operation unit such as a keyboard, and 36 is a display unit.

The measurement control unit 30 has a first mode in which displacement data in the Z direction when the movable table 20 is moved is measured and detected at a predetermined pitch.
It has a second mode for creating displacement data at a finer pitch based on the measured displacement data, and a third mode for correcting the measured data for the object to be measured with the displacement data.

In the first mode, as shown in FIG. 5, the height of the surface of the optical flat 40 previously placed on the moving table 12 is grid-shaped from the starting point (X1, Y1) to the ending point (Xm, Xn). To pitch Lp
Is a mode in which the displacement data of the heights Z (1,1) to Z (m, n) are measured.

FIG. 6 is a flow chart showing this processing procedure. In step 1, the start and end coordinates of the measurement, the measurement pitch Lp, and the height H of the optical flat are set by the input operation unit 35, and in step 2, the setting is made. The moving table 12 is moved so that the beam light from the optical sensor 15 is irradiated to the position (X1, Y1) of the designated starting point.

In step 3, the height value of the starting point (X1, Y1) is calculated based on the displacement signal L from the optical sensor 15.

In this calculation, the movement amount Z ₀ when the optical axis coincidence point P of the optical sensor 15 is moved by the Z moving device 13 from the reference origin on the XY moving table 12 to the reference point on the surface of the object to be measured is stored in advance. Every
The displacement signal L is converted into the actual displacement amount ZL of the reflected light spot, and Z ₀
The height data Z (1, 1) is calculated by subtracting (or adding) ZL from.

In step 4, a value d _{0 obtained} by subtracting the height H (true height data) of the optical flat 40 from the height data Z (1, 1) at the starting point is stored in a predetermined address of the internal storage device 33. .

In step 5, the coordinate position of the next measurement point is calculated according to the measurement route of FIG. 4 based on the starting point coordinates and the measurement pitch, and in step 6, the mobile station is moved to the calculated coordinate position.
12 is moved, and in step 7, the height of the measurement point is calculated as described above.

In step 8, the previously calculated height data is subtracted from the calculated height data to calculate the first difference data di, and in step 9, the sequentially calculated first difference data di is set to a predetermined address. It is stored in order from.

In step 10, it is determined whether or not the measurement of all the measurement points is completed. If not completed, the process returns to step 5,
When finished, move to step 11.

Step 11 is a step of calculating the second difference data Dk between the rows of the measurement route in FIG. 4, and the calculated second difference data Dk is sequentially stored in a predetermined address in step 12.

By this processing, the first and second difference data in the Z direction at the time of movement of the movable table 12 are stored in the internal storage table 34 at every predetermined pitch Lp, and this data is the true value of the starting point. It is stored in the external storage device 33 in step 13 together with the displacement data d ₀ .

The second mode is a mode in which the difference data stored in the first mode is read from the external storage device 33 at the start of measurement and displacement data at a finer pitch is calculated.

FIG. 7 is a flowchart showing the processing procedure of this mode. In step 1, the interpolation pitch Sp is set, and in step 2, the true displacement data d ₀ of the starting point measured in the first mode and the pitch The difference data between the four measurement points forming a quadrangle with Lp is read from the external storage device 33.

In step 3, displacement data of four measurement points and displacement data of grid points obtained by subdividing the intervals between Sp are calculated from this data and the interpolation pitch Sp.

As shown in FIG. 8, when the four displacement data h1 to h4 calculated from the difference data are represented as the height points in the Z direction of the measurement points as shown in FIG. XY that is regarded as a plane and is subdivided between pitches Lp by pitch Sp
The height hp of the (m, n) th grid point at the position is calculated by the linear interpolation of the following formula.

hp = [n · h2 + m · h4] Sp / Lp + [1- (m + n) · Sp / Lp] · h3 In step 4, the displacement data calculated by the interpolation calculation is the address corresponding to the XY coordinate of the internal storage device 34. Are sequentially stored in.

In step 5, it is judged whether or not the interpolation processing has been completed for all the surfaces formed by the four measurement points measured in the first mode, and if not completed, step 2
Return to. When all the interpolation processing is completed, the display of the measurement preparation completion is displayed on the display unit 36 in step 6.

Through the above processing, the displacement data hij of the lattice points are array-stored in the internal storage device 34, as shown in FIG.

The third mode is a mode in which the object to be measured placed on the movable table 12 is measured according to a predetermined measurement route, and in step 1, the measurement points R (I) to R (K) are input from the input operation unit 35.
When the XY coordinates and measurement method are set, n
Are initialized to 1.

In step 3, the XY coordinate value of the measurement point R (n) is compared with the XY coordinate value of the grid point, and the XY coordinate value of the measurement point R (n) is the XY coordinate value of the grid point ± Sp / 2. Search for grid point coordinates that fall within the range.

In step 4, the searched grid point coordinates (Xi, Yj) are stored in the address A, and in step 5, the displacement data hij of the grid point coordinates stored in the address A are read out and read in the address B.
It is stored in (n).

In step 6, n is incremented by 1, and in step 7, it is determined whether or not n has reached K-1.

If n does not reach K-1, the next measurement point R (n)
The absolute value of the difference between the XY coordinate of X and the previous coordinate of the grid point stored in the address A, that is, P = | X (n) -Xi |, Q = | Y (n) -Yj | is calculated.

In step 9, the values of P and Q are both at the grid point pitch Sp.
Whether it is 1/2 or less is determined. If Sp / 2 or less, the process returns to step 5, and if Sp / 2 or more, the process returns to step 3.

Therefore, the processing from step 2 to step 9 is performed for all the measurement points R (1) to R (k), and the displacement data of the nearest grid point to the measurement point is the address B.
(1) to B (k) will be stored.

When n reaches K-1 in step 7, n is initialized to 1 again in step 11 and the measurement operation is started.

In step 12, the moving table 12 is controlled to move to the coordinate position of the measuring point R (n), and in step 13, the height value Z (n) of the measuring point R (n) is calculated.

In step 14, from the measured value Z (n), the address B
The displacement data h (n) stored in (n) is subtracted, and the corrected height data H (n) is calculated.

In step 15, the height data H (n) is the address B
It is stored in (n), and n is incremented by 1 in step 16.

In step 17, it is judged whether or not n has reached K-1.
If not, return to step 12.

If n reaches K-1, addresses B (1) -B
Based on the height data H (1) to H (k) of the measurement points R (1) to R (k) stored in (k), the determination calculation by the preset measuring method is performed in step 18. .

The determination result is displayed on the display unit 36 in step 19.

<Other Embodiments of the Present Invention> In the above embodiment, the height displacement of the surface of the object to be measured was detected by the optical sensor 15. However, this does not limit the present invention and other non-existence may be performed. A contact type optical sensor or a contact type sensor may be used.

Further, in the above-described embodiment, the displacement data of the movable table in the Z direction measured in the first mode is stored in the external storage device 33, but it may be stored and held in a part of the internal storage device 34. Good.

Further, in this mode, the displacement data of the moving base 12 in the Z direction is detected so as to meander from the starting point at the upper right of the moving base 12 to the lower left, but this does not limit the present invention and the moving data can be moved from any direction. And can be detected.

Further, in the above embodiment, the movement command to the position corresponding to the measurement pitch is issued for each pitch, but only the command for continuously moving the movement table from the measurement start point to the measurement end point is issued. However, the same processing is possible.

That is, as shown in FIG. 11, an x sensor 41 and a Y sensor 42 for measuring the movement amount of the XY moving base 40 in the X and Y directions are provided to measure the moving coordinates. The pitch detector 46 compares the moving coordinates obtained from the X sensor 41 and the Y sensor 42 with the pitch coordinates from the pitch setting means 45, and outputs a signal from the optical sensor 43 every time the moving coordinates and the pitch coordinates match. Based on the above, the measurement value is output from the measurement control unit 50.

By doing so, the measurement can be performed at a higher speed than in the above-mentioned embodiment.

<Effects of the Present Invention> As described above, the shape measuring method and apparatus of the present invention stores displacement data in the Z direction of the movable table, which is measured and detected at a predetermined pitch, and further stores the displacement data based on the displacement data. Since the height of the measurement point is corrected by the displacement data of the grid points calculated by interpolation at a fine pitch,
It is not necessary to measure displacement data in detail as in the conventional case, and this required work can be performed on a regular basis in a short time, and the measurement efficiency is significantly improved.

In addition, the capacity of the storage device for storing the displacement data is
It is sufficient to store the displacement data measured at a predetermined pitch and the displacement data of the lattice points calculated from this displacement data, and the storage device can have a small storage capacity.

Further, when the surface surrounded by the four measurement points is approximated as a plane formed by the three points as described above, the interpolation calculation is very simple and the data of the grid points can be calculated in a short time.

Furthermore, when storing displacement data of the movable table in the Z direction,
When the difference data from the previous measurement value is stored as described above, sufficient resolution can be obtained with a small data length, and the storage capacity can be further saved.

Also, when reading displacement data for the coordinates of the measurement route, if the difference between the grid point coordinates of the previously read displacement data and the measurement point coordinates is less than a predetermined value, the same displacement data as the previous time is read. By correcting the measurement data by using it, there is an effect that the displacement data of the grid point coordinates with respect to the measurement point can be read in a short time.

[Brief description of drawings]

FIG. 1 is a diagram showing the overall configuration of an embodiment of the present invention, and FIG.
1 is a diagram showing an optical mechanism of a main part of FIG. 1, and FIG. 3 is a diagram showing a circuit of a main part of FIG. FIG. 4 is a block diagram of a main part of FIG. 1, and FIG. 5 is a plan view for explaining a measurement mode of one embodiment. FIG. 6 is a flow chart showing the first processing procedure of one embodiment, FIG. 7 is a flow chart showing the second processing procedure, and FIG.
The figure is a diagram for explaining the processing procedure of FIG. FIG. 9 is a memory diagram showing the data stored by the processing procedure of FIG. 7, and FIG. 10 is a flow chart showing the third processing procedure of the embodiment. FIG. 11 is a block diagram showing a main part of another embodiment of the present invention, and FIG. 12 is a schematic view showing a main part of a conventional device. 10 …… Measurement mechanism section, 12 …… Movement base, 13 …… Z movement device,
14 …… XYZ drive section, 15 …… Optical sensor, 25 …… XY position detector, 30 …… Measurement control section, 31 …… I / O interface,
32 ... Arithmetic processing device, 33 ... External storage device, 34 ... Internal storage device, 35 ... Input operation part, 36 ... Display part.

Claims (5)

[Claims] 1. A shape measuring method for measuring the height in the Z direction of a measurement point on the surface of an object to be measured by a sensor while moving the object to be measured placed on a moving table in the XY directions. The movable table on which an object having a flat surface, which is wider than the movable range of the table, is placed is moved in the XY directions, and the displacement of the movable table in the Z direction is displaced at a predetermined pitch based on a detection signal from the sensor. A step of measuring, a step of storing the measured displacement data, a step of setting grid points subdivided between the predetermined pitches in an XY direction at an interpolating pitch, and a step of measuring the displacement data of the grid points in the Z direction. The displacement data of the measured displacement data is interpolated, the displacement data of the grid points is stored in association with the XY coordinate values thereof, and the measurement points of the object to be measured mounted on the movable table are stored. The height value in the Z direction is measured by the sensor. A shape comprising: a step of calculating the measured height value based on the detection signal; and a step of correcting the measured height value by the displacement data of the lattice point closest to the XY coordinate value of the measurement point. Measuring method. 2. A movable table on which an object to be measured is placed and moved in the XY directions, and a sensor for detecting a displacement in the Z direction of a measurement point on the surface of the object to be measured placed on the movable table. A moving means for moving the moving table to move a measurement point to a set XY coordinate position; and a pitch coordinate setting means for setting an XY coordinate value for each predetermined pitch on the moving table in the moving means. Data calculation means for calculating displacement data in the Z direction for each of the predetermined pitches of the movable table itself, which is moved by the pitch coordinate setting means at a predetermined pitch, based on a detection signal from the sensor, and calculated by the data calculation means First storage means for storing the displaced displacement data, interpolation pitch setting means for setting an interpolation pitch smaller than the predetermined pitch, and Z direction of grid points dividing the predetermined pitch with the interpolation pitch in a grid pattern. Interpolation calculation means for calculating the displacement data in the direction from the displacement data stored in the first storage means, second storage means for storing the displacement data calculated by the interpolation calculation means, X- of the measuring point for the object to be placed
Measurement setting means for setting a Y coordinate value in the moving means; height calculation means for calculating the height in the Z direction of the measurement point set by the measurement setting means based on a detection signal from the sensor; Data reading means for reading the displacement data of the lattice point closest to the XY coordinate value of the measurement point calculated based on the result from the second storage means, and the height of the measurement point calculated by the height calculation means. A shape measuring device including a correction calculation unit that corrects the height based on the displacement data read from the data reading unit. 3. The interpolation calculation means linearly approximates displacement data in the Z direction of grid points in the plane by approximating a plane surrounded by four measurement points forming a quadrangle at the predetermined pitch. The shape measuring device according to the second item, which is calculated by interpolation. 4. The data calculating means uses the difference data between the displacement data calculated based on the detection signal from the sensor and the displacement data calculated immediately before for each predetermined pitch as the displacement data of the measurement point. The shape measuring device according to the second aspect, characterized in that the shape measuring device is stored in the first storage means. 5. The data reading means comprises XY coordinate values of measurement points of an object to be measured and X-Y values of grid points read immediately before.
When the difference from the Y coordinate value is less than half of the interpolation pitch, the same displacement data as the previous time is read out.
The shape measuring device according to the item.