JP2899884B2 - Shape measurement method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a shape measuring method, and more particularly to a shape measuring method for inspecting the surface undulation and thickness of a ceramic substrate or the like by optical means.

(Prior Art and Problems) It is required that the surface of a ceramic substrate on which electronic components are deposited or an electric circuit is printed be completely flat. As the inspection method, conventionally, an attempt has been made to illuminate the surface of an object to be measured and to grasp the surface state by the reflected light.

For example, Japanese Patent Application Laid-Open No. 62-36511 discloses that a reference shape, which is spot-likely projected on an object to be measured, is input as an image to a two-dimensional sensor, and the input characteristic amount of the reference shape and a pass stored in advance. It has been proposed to determine the pass / fail of the measured object by extracting the difference between the characteristic amount of the reference shape on the measured object and the apparent deviation based on a predetermined formula.

However, with this conventional method for measuring an object to be measured, although large undulations of the entire ceramic substrate can be detected,
Since the deviation from the reference shape is detected and pass / fail is determined,
For example, such a substrate cannot detect a partial undulation or flatness of a portion to which an extremely important electronic component is attached, an accurate flatness of a surface portion, or a degree of undulation.

On the other hand, JP-A-58-111708 and JP-A-61-40503 propose to measure the flatness of the surface of an object to be measured by projecting a laser beam. The measurement method assumes that the thickness of the measured object is uniform because it detects the amount of displacement of the reflected light from the device and converts it into an electric signal to determine the flatness of the surface of the measured object. Only the degree of flatness according to the distance from can be grasped. That is,
When the object to be measured is placed on the stage and the flatness is measured by a conventional method, the object to be measured is tilted due to the inclination of the stage itself or a partial thickness difference of the object to be measured. In such a case, the distance from the light source itself differs, and it was impossible to measure the flatness and thickness accurately.

The present invention has been devised in view of such problems of the conventional method, and accurately detects the flatness of the surface of the measured object and also detects the partial flatness of the surface of the measured object. It is another object of the present invention to provide a shape measuring method capable of detecting the thickness of an object to be measured very accurately.

(Means for Solving the Problems) According to the first invention, the reflected light is received by the photoelectric conversion device by relatively moving the projected light beam onto the measured object, and the displacement of the reflected light on the photoelectric conversion device is changed. A shape measuring method for measuring the flatness of the surface of an object to be measured by quantifying an amount, forming a virtual reference line by connecting two points on the scanning line of the projection light beam, and forming an irregularity from the virtual reference line. A shape measuring method is provided, wherein a flatness of a surface of a measured object is measured by detecting a value.

According to the second invention, the object to be measured is placed on the stage, the projected light beam is relatively moved on the object to be measured, the reflected light is received by the photoelectric conversion device, and the reflected light is reflected by the photoelectric conversion device. A method for measuring the thickness of a copy portion of an object to be measured by quantifying the amount of displacement of light, wherein the projection light is projected onto the stage from an actually measured value obtained by quantifying the amount of displacement of the reflected light. A shape measuring method is provided, wherein a thickness corresponding to a pull measurement object is measured by subtracting a value corresponding to a tilt of a stage obtained by relative movement.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of an apparatus used for a shape measuring method according to the present invention, wherein 1 is a sensor head, 2 is an XY stage, 3 is an arithmetic and control unit, and 7 is an object to be measured.

The sensor head 1 includes an irradiating section 1a for projecting light B such as a laser beam, and a light receiving section 1b for receiving reflected light B 'of the projected light B, and a light receiving section for receiving the reflected light B'. 1b is composed of, for example, a photoelectric conversion device. The shape of the object to be measured 7 is detected by a so-called optical triangulation method in which the displacement of the reflected light B 'on the photoelectric conversion device is detected and plotted. The sensor head 1 is fixed to the fine adjustment stage 1c so that it can be manually changed in the Z-axis direction.

The XY stage 2 is configured to move in the X-axis and Y-axis directions by driving the pulse motors 2a and 2b. Therefore, the projected light beam B of the sensor head 1
Moves relatively on the XY stage 2. This stage 2 is, as shown in FIG.
A plurality of through holes 2d are formed in 2c, and the lower part of the plate 2c is formed in a hollow shape. In fixing the measured object 7 to the plate 2c, the measured object 7 is fixed at a predetermined position by a knock pin 2d provided at an end of the plate 2c.
A work guide 2e having a larger through-hole formed therein is fixed, the object 7 to be measured is positioned in the through-hole of the work guide 2e, placed on the stage 2, and then a suction machine 4 (see FIG. 1). ) Is fixed by suctioning the hollow portion. This XY
The stage 2 is driven via a driver 6 based on an operation of the arithmetic and control unit 3.

A controller 5 is connected to the arithmetic and control unit 3, and the controller 5 controls the amount of displacement of the reflected light beam B 'displaced by the irregularities on the surface of the measured object 7 in the photoelectric conversion device by a gain set in advance. The function of calculating based on is performed.

The arithmetic and control unit 3 is mainly composed of a microcomputer, and the arithmetic result is recorded by a printing device 3a.

FIG. 3 is a diagram showing the relationship between the detected surface state of the measured object 7 and the reference line X.

By moving the XY stage 2 in the X-axis and Y-axis directions to scan the projection light beam B on the object 7 to be measured, the projection light beam B includes an uneven portion with respect to a reference line X equidistant from the light source of the projection light beam B. It is plotted as a scanning line A. This reference line X
Is merely an equidistant line from the light source, and does not take into account the tilt X ′ of the stage 2 itself or the tilt X ″ of the measured object 7 itself due to a partial difference in the thickness of the measured object 7.
Even if the amount of unevenness from the reference line X is detected, an accurate amount of unevenness cannot be detected. Therefore, by connecting the scanning start point L _S and the scanning end point L _E of the projection beam B "and, the virtual reference line X" imaginary reference line X by detecting the amount of irregularities from exact surface itself of the object to be measured 7 The amount of unevenness can be detected.

FIG. 4 is a diagram for explaining a method of measuring flatness according to the present invention.

First, all data (h _{1 to} hn, L _{1 to} Ln) of each point of the measurement location detected by the sensor head 1 are calculated and processed by the arithmetic and control unit 3.
Take in. At this time, the distance from the scanning line A to the reference line X
hm is calculated.

Next, the scanning start point (h ₁ , L ₁ ) and the scanning end point (hn,
By connecting ln) "pull the virtual reference line X with respect to the reference line X" imaginary reference line X excursion amount Xm of, obtained by _{Xm = Lm / L · X E} .

Next, of the perpendiculars from the scanning line A to the reference line X,
The distance H'm from the scanning line A leading to a virtual reference line X ", obtained by h'm = hm-Lm / L · X E.

Next, of the perpendiculars from the scanning line A to the virtual reference line X ", the distance h" m from the scanning line A to the virtual reference line X "
To Ask for.

Similarly, the distance h ″ m of each measurement point from the virtual reference line X ″ is obtained.

Among the respective distances from the scanning line A to the virtual reference line X ″ obtained in this way, h ″ m (max) −h ″ m (min) = W is the swell amount W.

Therefore, the inclination of the stage 2 and the variation of the thickness of the measured object 7 can be eliminated, and the unevenness amount on the surface of the measured object 7 can be accurately detected.

In the above embodiment, the description has been given of connecting the scanning start point and the scanning end point of the projection light beam B as a virtual reference line.
The present invention is not limited to this embodiment. For example, similar effects can be obtained by extracting and connecting any two points on the scanning line of the projected light beam and forming a virtual reference line.

FIG. 5 is a diagram showing the relationship between the inclination of the stage 2 and the thickness of the measured object.

The projection light B is scanned on the plate 2c without placing the object 7 to be measured and the work guide 2e on the plate 2c, and the distance (reference line X) from the light source of the projection light B to one point on the stage 2 is determined. The inclination X 'of the stage 2 itself is obtained in advance.

Then, all data points for each measurement point detected by the sensor head _{1 (h 1 ~hn, L 1} ~Ln) an arithmetic and control unit 3
Take in. At this time, the distance from the scanning line A to the reference line X
hm is calculated.

Then, the value h _S corresponding to the tilt amount X _S, determined by _{h S = X S / L ·} Lm, it is possible to obtain an accurate thickness h "m Citations measurement object 7 by pulling from the measured value hm.

(Effect of the Invention) As described above, according to the shape measuring method according to the present invention, two points on the scanning line of the projected light are connected to form a virtual reference line, and the unevenness value from the virtual reference line is calculated. By detecting and measuring the flatness of the surface of the object to be measured, the flatness of the surface of the object to be measured can be detected extremely accurately, for example, only the portion of the ceramic substrate on which the semiconductor device is mounted, such as the portion on which the semiconductor device is mounted. The present invention can provide an extremely excellent shape measurement method capable of accurately detecting even the partial flatness of the object, and accurately detecting the flatness even when the surface of the measured object is inclined.

Also, from the measured value obtained by quantifying the amount of displacement of the reflected light, the value corresponding to the inclination of the stage obtained by relatively moving the projected light beam on the stage is subtracted to measure the thickness of the measured object. In addition, it is possible to provide a shape measuring method capable of measuring an extremely accurate thickness of an object to be measured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus used for a shape measuring method according to the present invention, FIG. 2 is a cross-sectional view of a stage portion, and FIG. 3 shows a relationship between a detected surface state of a measured object and a reference line. FIG. 4 is a view for explaining the measurement method, and FIG. 5 is a view showing the relationship between the inclination of the stage 2 and the thickness of the object to be measured. DESCRIPTION OF SYMBOLS 1 ... Sensor head, 2 ... Stage 3 ... Calculation control device, 7 ... Measured object A ... Scanning line B ... Projection ray B '... Reflected light X ... Reference line X "... Virtual reference line

Claims (2)

(57) [Claims] A light beam projected on an object to be measured is relatively moved, a reflected light is received by a photoelectric conversion device, and a displacement amount of the reflected light on the photoelectric conversion device is quantified to obtain a flatness of a surface of the object to be measured. A virtual reference line connecting the scanning start point and the scanning end point on the scanning line of the projected light beam, and detecting the unevenness value from the virtual reference line to obtain the surface measurement object surface. A shape measuring method characterized by measuring flatness. 2. An object to be measured is placed on a stage, a light beam projected on the object to be measured is relatively moved, and reflected light is received by a photoelectric conversion device. A shape measurement method for quantifying the amount of displacement and measuring the thickness of a plurality of portions of the measured object, from an actual measurement value obtained by quantifying the amount of displacement of the reflected light,
A shape measuring method characterized in that the thickness of an object to be measured is measured by subtracting a value corresponding to the inclination of the stage obtained by relatively moving the light beam projected on the stage.