JPH0298618A - Positioning detector - Google Patents

Abstract

PURPOSE:To separate the movement of a laser spot caused by the positional deviation of a sample from that caused by the tilt of the sample by splitting a laser beam from a light source into two light beams by a beam splitter and conducting one light beam through a polarized light beam splitter and the other light beam through a reflecting mirror to the surface of the sample. CONSTITUTION:The laser beam 3 from the light source part 1 is splitted into a straight advancing light beam 5 and a reflected light beam 11 by the beam splitter 4 and the light beam 5 is conducted to the surface of the sample 2 through the polarized light beam splitter 6, a 1/4 wavelength plate 7 and a lens 8. Meanwhile, the light beam 11 is conducted to the surface of the sample 2 through the reflecting mirror 12. In the case of detecting the level of the surface of the sample 2, the reflected light beam 9 or 15 obtained by reflecting the light beam passing through the lens 8 on the surface of the sample 2 is conducted to a beam angle difference detector 10 so as to adjust the angle of the surface of the sample 2. In the case of detecting the height of the surface of the sample 2, the reflected light 13 or 16 obtained by reflecting the light beam passing through the reflecting mirror 12 on the surface of the sample 2 is conducted to a beam position detector 14 so as to adjust the height of the surface of the sample 2. Thus, the movement of the laser spot caused by the positional deviation of the sample can be separated from that caused by the tilt of the sample.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning detector, and in particular to a positioning detector for small electronic components.

[Conventional technology]

A conventional positioning detector will be described in detail with reference to the drawings.

FIG. 2 is an optical path diagram showing an example of a conventional positioning detector.

The positioning detector shown in FIG. 2 includes a light source unit 1 that irradiates a sample 17 with laser light, a one-dimensional position sensor 19 located on the reflected optical path from the sample 17, and a chip table 20 located below the sample 17. It consists of:

When the sample 17 becomes higher by ΔZ, a positional shift can be detected by the light receiving position signal output from the -dimensional position sensor 19.

FIG. 3 is an optical path diagram showing a case where the sample 17 in FIG. 2 is tilted.

In this case as well, a light reception position signal similar to that for positional deviation is output.

[Problem to be solved by the invention]

The above-mentioned conventional positioning detector had a drawback in that it was not possible to separate the movement of the laser spot due to positional deviation of the sample from the movement of the laser spot due to the tilt of the sample.

[Means to solve the problem]

The positioning detector of the present invention includes: (^) a light source section that outputs a first laser beam in a first optical path having a first polarization axis; (C) a beam splitter that splits the laser beam into a second laser beam that travels straight on an optical path and a third laser beam that travels on a second optical path that is perpendicular to the first optical path; passing a laser beam and having a second polarization axis different from the first polarization axis;
a polarizing beam splitter that refracts a second reflected light sent back from a direction opposite to the second laser beam into a third optical path; (D) rotating a polarization axis of the second laser beam that has passed through the polarizing beam splitter; (E) a quarter-wave plate that rotates the polarization axis of the first reflected light and sends it back to the polarizing beam splitter as the second reflected light; The laser beam is focused on the sample surface, and the reflected light from the sample surface is used as the first reflected light, and the 1/4
(F) a beam angle difference detector placed on the third optical path to determine the angular difference between the first optical path and the third optical path; (G) the second beam; a reflecting mirror that is placed on the road and reflects the third laser beam toward the sample surface as third reflected light; A beam position detector that detects the position of the fourth reflected light.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an optical path diagram showing an embodiment of the present invention.

The positioning detector shown in FIG. The second light beam goes straight on the optical path of the first light beam.
(C) a beam splitter 4 that splits the laser beam 5 into a third laser beam 11 that travels to a second optical path that is perpendicular to the first optical path; The laser beam 5 has a second polarization axis different from the first polarization axis.
(b) a polarizing beam splitter 6 that refracts the second reflected light 33 sent back from the opposite direction to a third optical path; (b) a fourth laser beam 41 that rotates the polarization axis of the laser beam that has passed through the polarizing beam splitter 6; (E) Focuses the laser beam 41 onto the sample surface 2, and rotates the polarization axis of the first reflected light 32 and sends it back to the polarizing beam splitter 6 as reflected light 33. A lens 8 that sends the reflected light 31 from the surface 2 as the first reflected light 32 to the quarter-wave plate 7, (F) is placed on the third optical path and connects the first optical path and the third Beam angle difference detector 1 for determining the angle difference with the optical path
0, (G) a reflecting mirror 1 placed on the second optical path and reflecting the laser beam 11 toward the sample surface 2 as third reflected light 51;
2. ()I) A beam position detector 14 that detects the position of the fourth reflected light 13 generated when the sample surface 2 is irradiated with the reflected light 51.

The present invention will be described in detail.

First, level the sample surface 2.

When the sample surface 2 is inclined, the laser beam 15 is incident on the beam angle difference detector 10, and when it is not inclined, the laser beam 9 is incident on the beam angle difference detector 10.

Therefore, the position of the laser beam on the beam angle difference detector 10 coincides with the optical path of the laser beam 9, that is, the laser beam 5 is placed at the position of the pixel of the beam angle difference detector 10 that detected the laser beam 9. Adjust the angle of the sample surface 2 so that the light is reflected.

Next, calculate the height of the sample surface 2.

When the sample surface 2 is low, the laser beam 16 is incident on the beam position detector 14, and when the sample surface 2 is at a normal height, the laser beam 13 is incident on the beam position detector 14.

Therefore, the position of the laser beam on the beam position detector 14 is
The height of the sample surface 2 is adjusted so that it matches the optical path of the laser beam 13, that is, so that the laser beam 11 is reflected at a certain position of the pixel of the beam position detector 14 that detected the laser beam 13. .

By providing the lens 8, the beam angle difference detector 10
Since the beam angle difference detector 10 can be placed after the back focal point of the lens 8, the distance between the sample surface 2 and the beam angle difference detector 10 can be increased, and the degree of freedom in the arrangement of the beam angle difference detector 10 can be increased.

〔Effect of the invention〕

By adding the second optical system, the positioning detector of the present invention has the advantage that movement of the laser spot due to positional deviation of the sample and movement of the laser spot due to tilt of the sample can be separated.

[Brief explanation of drawings]

FIG. 1 is an optical path diagram showing an embodiment of the present invention, FIG. 2 is an optical path diagram showing a conventional example, and FIG. 3 is an optical path diagram showing a case where the sample in FIG. 2 is tilted. 1...Light source section, 2...Sample surface, 4...
...Beam splitter, 6...Polarizing beam splitter, 7...1/4 wavelength plate, 8...
...Lens, 10...Beam angle difference detector, 1
2... Reflector, 14... Beam position detector. Agent: Susumu Uchihara, patent attorney! PJ1 map country most

Claims (1)

Scope of Claims: (A) a light source unit that outputs a first laser beam in a first optical path having a first polarization axis; (B) a light source unit that outputs a first laser beam having a first polarization axis; a beam splitter that splits the second laser beam into a second laser beam that travels straight on the road and a third laser beam that travels in a second optical path that is perpendicular to the first optical path; (C) the second laser beam; a polarizing beam splitter that allows the second laser beam to pass therethrough, has a second polarization axis different from the first polarization axis, and refracts the second reflected light sent back from the direction opposite to the second laser beam into a third optical path; (D) A fourth laser beam is created by rotating the polarization axis of the second laser beam that has passed through the polarizing beam splitter, and a fourth laser beam is created by rotating the polarization axis of the first reflected light. (E) focusing the fourth laser beam on the sample surface and using the reflected light from the sample surface as the first reflected light;
a lens that sends the light back to the wave plate; (F) a beam angle difference detector placed on the third optical path to determine the angular difference between the first optical path and the third optical path; (G) the second beam; a reflecting mirror placed on the road and reflecting the third laser beam toward the sample surface as third reflected light; A beam position detector for detecting the position of the reflected light of No. 4.