JPH0452505A - Measuring apparatus of stepped part - Google Patents

Abstract

PURPOSE:To enable continuous measurement of a stepped part on the surface of a substance to be measured, without having a contactor, by detecting a distance at which a lens for autofocus moves for focusing and a distance at which the substance to be measured is moved in one direction. CONSTITUTION:With the movement of an X-Y table 7, a recorder 16 operates and records the amount of movement of the table 7 obtained by a tachometer 4. At the same time, it is determined by phase comparison 14 whether or not an image formed in a detector of a detecting optical system is formed in the center of the detector included in the detecting optical system. Next, an output signal of the result of the comparison is subjected to a data processing by a control device 15 and commands are given therefrom to a servo motor 8 as to in which direction and in what degree it is to rotate. According to these commands, the motor 8 is made to rotate at a prescribed rotational angle, thereby a pinion 9 and a nut 10 are rotated, a ring 11 is moved in the direction of arrows and thereby the position of formation of the image is fixed. At the same time, an angle detector 1 detecting the rotational angle of the nut 10 detects a distance of movement of a lens 2 for autofocus to be recorded in the recorder 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a step measuring device for measuring steps on the surface of a material.

[Conventional technology]

Generally, there are various measuring instruments used to measure the level difference of wiring or the like formed on a semiconductor chip, but a roughness measuring instrument has been used as the easiest to handle measuring instrument.

FIG. 2 is a diagram schematically showing an example of a conventional level difference measuring device. As shown in the same figure, this level difference measuring device has an object to be measured 13
A stage 7a is mounted with a stage 7a that moves in one direction, a needle 6 that contacts the surface of the object to be measured 13, a detector (not shown) that detects the vertical movement of this needle 6, and a stage 7a that is moved in one direction. A detection meter 17 detects the amount of electricity generated.

In addition, when measuring the level difference of the object to be measured using this level difference measuring device, the needle 6 is brought into contact with the surface area on one end side of the object to be measured 13, and then the stage 7a is moved in the direction of the arrow to The unevenness of a linear region from one end side to the other end side of No. 13 was continuously measured.

[Problem to be solved by the invention]

The conventional level difference measuring instruments mentioned above place the needle on the surface of the object to be measured, so they may leave scratches on the surface of the object to be measured, and if the width of the recess on the surface is small, the needle may get into the recess. However, it had the disadvantage that it could not be measured.

An object of the present invention is to provide a step measuring device that eliminates such drawbacks.

[Means to solve the problem]

The level difference measuring device of the present invention is equipped with an object to be measured and
an XY child table that moves in the direction and the Y direction, an autofocusing lens that magnifies an image of a region of the object to be measured, a ring into which the autofocusing lens is fitted and a thread formed around the outer circumference; a nut into which a ring is screwed and a tooth profile is formed on the outer periphery; a servo motor that rotates the nut via a pinion that meshes with the tooth profile of the nut; an angle detector that detects the rotation angle of the servo motor; A detection optical system that detects the light passing through the autofocus lens, a phase comparator that compares the phase based on the light position obtained by this detection optical system,
and a control device that detects a focus shift using the phase comparator and controls the rotation of the servo motor.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a diagram schematically showing an embodiment of the level difference measuring device of the present invention. As shown in the same figure, this level difference measuring device has an object to be measured 13
an XY table 7 which is equipped with a drive motor 12 to rotate a feed screw and move in one direction, and an autofocus lens 2 which magnifies a spot image of a region of the object 13 to be measured.
Then, insert this autofocus lens 2 inside,
A ring 11 having a thread formed around its outer periphery, a nut 1o that is fitted into the thread of this ring 11 and having a tooth profile formed around its outer periphery, and a servo motor that rotates a pinion 9 that meshes with the teeth of this nut. 8 and this servo
An angle detector l that detects the rotation angle of the motor 8, two detection optical systems 5 that detect the light transmitted through the autofocusing lens, a phase comparator 14 that compares the phase using the detection optical system 5, and The control device 15 controls the rotation of the servo motor 8 by detecting a phase shift from the phase comparator 4. Further, the image magnified by the autofocus lens 2 is further magnified by the eyepiece lens 3. Furthermore, the digital signal is transmitted to the recorder by the angle detector.
It is continuously recorded as a step value along the Y child table traveling distance.

Next, the operation of this step measuring device will be explained. talented,
The object to be measured 13 is placed on the XY table 7. Next, a coaxial light source (not shown) is turned on to illuminate the area to be measured. Next, the XY table 7 is moved at low speed in the direction of the arrow. Here, for example, this moving speed is 50 mm/min.
The following shall apply. Along with this movement, the recorder 16 is activated, and the tachometer 4 records the amount of movement of the XY table 7.

Also, at the same time as this movement, whether or not the images formed on the detectors (not shown) by the two detection optical systems 5 are centered on the detector (not shown) included in the detection optical system. are compared by the phase comparator 14. Next, the control device 15 data-processes the output signal as a result of phase comparison by the phase comparator 14, and instructs the servo motor 8 how much to rotate in any direction. This command causes the servo motor 8, which is a pulse motor, to rotate to a predetermined rotation angle.

The rotation of the servo motor 8 causes the pinion 9 to rotate, and the rotation of the pinion causes the nut 10 to rotate, and the ring 11 for attaching the autofocusing lens moves in either direction of the arrow, keeping the imaging position always constant. Let it be. Simultaneously with this operation, an angle detector 1 detects the rotation angle of the nut 10, that is, the rotation angle of the servo motor 8.
The rotation angle, that is, the moving distance of the autofocusing lens 2 is detected by the recorder 16. Furthermore, the recorder l6 is
The moving distance of this autofocusing lens is recorded in correspondence with the above-mentioned XY child table moving distance.

By recording in this manner, the irregularities on the surface of the object to be measured (the moving distance of the autofocusing lens) can be continuously measured.

In addition, in order to measure irregularities of several micrometers or less, this step measuring device sets the focal length of the autofocusing lens to at least 10 mm or less, and the threads formed on the ring 11 and the nut 10 have 3 to 5 threads. A threaded thread was used, and the pitch was approximately 0.5 mm. This has made it possible to detect steps with a resolution of 1 μm or less.

〔Effect of the invention〕

As explained above, the present invention includes an autofocusing lens for enlarging the surface area of an object to be measured, a first means for detecting the distance traveled for focusing the lens, and a lens for moving the object to be measured in one direction. By providing a means for moving the object and a second means for detecting the distance traveled, it is possible to continuously measure the level difference on the surface of the object to be measured without having a contactor that comes into contact with the surface of the object to be measured. Therefore, it is possible to obtain a level difference measuring instrument that does not leave scratches on the surface regardless of the size of the recess of the object to be measured.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an embodiment of a level difference measuring device of the present invention, and FIG. 2 is a diagram schematically showing an example of a conventional level difference measuring device. DESCRIPTION OF SYMBOLS 1... Angle detector, 2... Lens for autofocus, 3... Eyepiece, 4... Tachometer, 5... Detection optical system, 6... Needle, 7... XY Child table 7a...
・Stage, 8... Servo motor, 9... Pinion, 10... Nut, 11... Ring, 13... Measured object, 14... Phase comparator, 15... Control device ,
16...Recorder.

Claims (1)

[Claims] An XY table that carries an object to be measured and moves in the X and Y directions, an autofocusing lens that magnifies an image of a region of the object, and an autofocusing lens that fits inside and has screws around the outside. a ring in which a ring is formed; a nut into which the ring is screwed and a tooth profile is formed on the outer periphery; a servo motor that rotates the nut via a pinion that meshes with the tooth profile of the nut;
An angle detector that detects the rotation angle of this servo motor,
a detection optical system that detects the light passing through the autofocus lens; a phase comparator that compares the phase based on the light position obtained by the detection system; and a phase comparator that detects a focus shift and detects the servo. A step measuring device comprising: a control device that controls rotation of a motor;