JPH0626842A - One-dimensional scanning type surface displacement meter - Google Patents

Abstract

PURPOSE:To perform the measurement of one-dimensional surface displacement at a high speed by scanning the surface of a sample with an optical beam with a rotary mirror and light projecting lens, and focusing the image of moving scattered light on the light receiving part of a position detecting element. CONSTITUTION:The emitting angle of a rotary plane mirror 9 with respect to the laser beam from a semiconductor laser 7 is changed in response to the rotation of the plane mirror 9. The emitted light of a light projecting lens 10 is cast orthogonally into a sample 6 with respect to an optical beam, which is appllied from any direction. Namely, the projected light 11 of the light projecting lens 10 performs the scanning for the sample 6 in the direction of an arrow in response to the rotation of the rotary plane mirror 9. Scattered light 12 is also moved into the same direction together with the projected light 11 and cast into a condenser lens 14 through a reflecting mirror 13. The emitted light is reflected toward the same point on the rotary plane mirror 9 regardless of the incident angle of the incident light. Since the rotary plane mirror 9 is rotated, the laser beam from a condenser lens 14 is always emitted toward a position detecting element 16. The surface displacement of the sample 6 is detected based on the movement of the image on the position detecting element 16. The adequate one-dimensional surface displacement can be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring a one-dimensional surface displacement, and more particularly to a technique effective for scanning a surface of a sample with a laser beam and measuring the surface displacement. .

[0002]

2. Description of the Related Art As surface displacement meters for measuring the surface displacement of a sample (for example, a semiconductor wafer, a disk, etc.) in a non-contact manner, all those currently on the market perform spot measurement.

Therefore, in order to measure the one-dimensional or two-dimensional surface state, a mechanical slide mechanism is required.

FIG. 3 is a perspective view showing a schematic structure of a conventional surface displacement meter.

The surface displacement meter 1 is attached to one end of an L-shaped arm 2, and the other end is fixed to an XY stage 3. This XY stage 3 includes motors 4, 5
The surface displacement meter 1 can be moved in two orthogonal directions by being driven by. Immediately below the surface displacement meter 1, a sample 6 as an object to be measured is arranged.

At the time of measurement, the sample 6 is fixed,
The XY stage 3 is driven by the motors 4 and 5, and the surface displacement meter 1 is positioned on the measurement start point of the sample 6. Here, a light beam is emitted from the surface displacement meter 1 to irradiate the surface of the sample 6, and the reflected light is made incident on the photodetector of the surface displacement meter 1. In this state, the surface displacement meter 1 is continuously moved in one direction (for example, the X direction) by the XY stage 3 to perform one-dimensional scanning. When the scanning from one end to the other end of the sample 6 is completed, the surface displacement meter 1 is moved in the Y direction by a predetermined pitch, and the surface displacement meter 1 is again moved in the X direction. Thereafter, the surface displacement is measured by scanning the entire surface of the sample 6 in the same manner.

[0007]

According to the study by the present inventor, the surface displacement measuring technique for mechanically moving the surface displacement meter to measure the displacement requires a slide mechanism, so that the time required for the measurement is small. However, there is a problem that the device becomes large in size and heavy in weight (that is, the speed cannot be increased).

Therefore, an object of the present invention is to provide a technique capable of measuring one-dimensional surface displacement at high speed.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0010]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, a rotating mirror that reflects the light beam at an emission angle according to the rotation, a scanning lens that irradiates the sample with the light beam from the rotating mirror, and a scattering of the irradiation light from the lens from the surface of the sample. A reflecting member that reflects light or specularly reflected light in the direction of the rotating mirror, has the same focal length as the scanning lens, and connects scattered light or specularly reflected light from the reflecting member to the same point on the rotating mirror surface. A condensing lens for forming an image and a position detecting means for detecting the emitted light from the rotary plane mirror with respect to the incident light from the condensing lens are provided.

[0012]

According to the above-mentioned means, the rotating mirror and the scanning lens irradiate the light beam so as to move on the surface of the sample to perform the scanning, and at the time, it moves with the movement of the irradiation light. The scattered light or the specularly reflected light again enters the rotating mirror by the condenser lens, and the emitted light is imaged on the light receiving portion of the position detecting means. Therefore, the one-dimensional surface displacement measurement can be performed at high speed, and the size and cost of the device can be reduced.

[0013]

1 is a perspective view showing the schematic construction of an embodiment of a one-dimensional scanning type surface displacement meter according to the present invention.

A collimator lens 8 and a rotating plane mirror 9 as a rotating mirror are sequentially arranged on an emission optical path of a laser beam (light beam) of a semiconductor laser 7 which is a measuring light source.
A light projecting lens 10 (scanning lens) for irradiating the sample 6 with a projection light 11 from a direction perpendicular to the scanning light from the rotating flat mirror 9 is disposed on the reflected light path of the rotating flat mirror 9.

The scattered light 12 is generated by irradiating the sample 6 with the projected light 11. The scattered light 12 has an optical path (this embodiment assumes an angle of 20 ° to 45 °).
A reflecting mirror (planar mirror) 13 as a reflecting member is arranged horizontally in the horizontal direction. A condenser lens 14 (convex lens) having the same focal length as that of the light projecting lens 10 is arranged on the outgoing optical path of the reflecting mirror 13. This condenser lens 1
The outgoing light of No. 4 is incident on the rotary plane mirror 9, and the outgoing light becomes the optical axis 15 of the scattered light collected, and the position detecting element 16 (position detecting means) is arranged to receive the outgoing light. The position detection element 16 detects the position from the image formation position of the received light spot.

In the above structure, the laser beam emitted from the semiconductor laser 7 is collimated by the collimator lens 8 and then incident on the rotating plane mirror 9. The light emitted from the rotary plane mirror 9 with respect to this incident light is incident on the light projecting lens 10, and the emitted light (projected light 11) is sent out perpendicularly to the sample 6. When the projection light 11 is incident on the surface of the sample 6 from the projection lens 10, scattered light 12 is generated, and the scattered light 12 is incident on the reflecting mirror 13. Reflector 1
The emitted light of 3 enters the condenser lens 14, and the incident light is reflected on the rotating plane mirror 9.

In the above description, the rotating plane mirror 9 is not rotated for the sake of convenience of explanation, but it is actually rotating in the direction of the arrow, and the emitting angle of the rotating plane mirror 9 with respect to the laser beam from the semiconductor laser 7 is as follows. It changes according to the rotation of the rotating plane mirror 9. The light projecting lens 10 reflects light emitted from any direction so that the emitted light is vertically incident on the sample 6. That is, the emitted light (= projected light 11) of the light projecting lens 10 continuously moves, that is, scans the sample 6 in the direction of the arrow in accordance with the rotation of the rotary plane mirror 9. Therefore, the scattered light 12 also moves in the same direction as the projected light 11 moves, enters the condenser lens 14 via the reflecting mirror 13, and the emitted light is on the rotating plane mirror 9 regardless of the incident angle of the incident light. Reflect toward the same point. Since the rotating plane mirror 9 is rotating, the condenser lens 14
The laser beam from is always emitted toward the position detecting element 16. The surface displacement of the sample 6 is detected from the movement of the image on the position detecting element 16, and the one-dimensional surface displacement in a predetermined length in the linear direction can be measured.

As described above, according to the above embodiment, since it is not necessary to mechanically move the surface displacement meter, it is possible to measure the one-dimensional surface displacement inline at high speed. Further, the size can be reduced, and the slide mechanism such as the table is not required, so that the cost can be reduced.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in order to further increase the scanning speed, a rotary polygon mirror 17 may be used instead of the rotary plane mirror 9 as shown in FIG. If you do this,
Whereas the rotary flat mirror 9 scans twice per rotation, the rotary polygon mirror 17 scans N times per rotation, where N is the number of mirror surfaces, so (N / 2) times faster. Can be achieved.

Further, in the above-mentioned embodiment, the projected light 1
Although 1 is projected from the direction perpendicular to the sample 6, the projected light 11 may be projected from an oblique direction. In this case, not the scattered light but the specularly reflected light is collected by the condenser lens 1.
The light is condensed at 4 and guided to the position detection element 16. The configuration for projecting light in an oblique direction can be achieved by placing a reflecting mirror in the optical path between the light projecting lens 10 and the sample 6, for example.

Further, instead of the position detecting element 16, a CCD
(Charge coupled device) can be used.

In the above description, the case where the invention made by the present inventor is mainly applied to the measurement of the surface displacement of a semiconductor wafer, which is the field of use of the invention, has been described. However, the invention is not limited to this and, for example, traveling. Measurement of runout of tape inside, measurement of runout of motor shaft and wheels, measurement of warpage of LCD glass, IC lead inspection, line printer head inspection, metal plate such as printed board and aluminum board The present invention can be applied to the measurement of the thickness and width of the rolled plate, the measurement of the vibration of the speaker and the mechanism during operation, the highly accurate positioning system, and the like.

[0024]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

That is, a rotating mirror that reflects the light beam at an emission angle according to the rotation, a scanning lens that irradiates the sample with the light beam from the rotating mirror, and a scattering of the irradiation light from the lens from the sample surface. A reflecting member that reflects light or specularly reflected light in the direction of the rotating mirror, has the same focal length as the scanning lens, and connects scattered light or specularly reflected light from the reflecting member to the same point on the rotating mirror surface. Since the condensing lens for forming an image and the position detecting means for detecting the emitted light from the rotating plane mirror with respect to the incident light from the condensing lens are provided, the one-dimensional surface displacement can be measured at high speed. It is possible to reduce the size and cost of the device.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment of a one-dimensional scanning type surface displacement meter according to the present invention.

FIG. 2 is a perspective view of a main part showing a modified example of the embodiment of FIG.

FIG. 3 is a perspective view showing a schematic configuration of a conventional surface displacement meter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Surface displacement meter 2 Arm 3 XY stage 4,5 Motor 6 Sample 7 Semiconductor laser 8 Collimating lens 9 Rotating plane mirror 10 Projection lens 11 Projection light 12 Scattered light 13 Reflective mirror 14 Condenser lens 15 Optical axis 16 of scattered light Position detector 17 Rotary polygon mirror

Claims (3)

[Claims] 1. A rotating mirror for reflecting a light beam at an emission angle according to rotation, a scanning lens for irradiating the sample with the light beam from the rotating mirror, and scattering of light emitted from the lens from the surface of the sample. A reflecting member that reflects light or specularly reflected light in the direction of the rotating mirror, has the same focal length as the scanning lens, and connects scattered light or specularly reflected light from the reflecting member to the same point on the rotating mirror surface. A one-dimensional scanning type surface displacement meter comprising: a condenser lens for forming an image; and position detection means for detecting the light emitted from the rotary plane mirror with respect to the light incident from the condenser lens. 2. The one-dimensional scanning surface displacement meter according to claim 1, wherein the rotating mirror is a rotating plane mirror or a polygon mirror. 3. The one-dimensional scanning type surface displacement meter according to claim 1, wherein the position detecting means is a position detecting element or a charge coupled element.