Method for non-contact xyz position sensing

• US 4,724,322 A
• Filed: 03/03/1986
• Issued: 02/09/1988
• Est. Priority Date: 03/03/1986
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Lindfors, administrator, by P. J. C., Pantzar, deceased, Jan E. G., Knowles, James L.
• Primary Examiner(s): Howell, Janice A.
• Assistant Examiner(s): Hannaher, Constantine
• Application Number:
  US06/835,397
• Time in Patent Office: 708 Days
• Field of Search: 250/341, 250/340, 250/360.1, 250/359.1, 250/358.1, 250/572, 250/571, 356/371
• US Class Current: 250/341.4
• CPC Class Codes: H01L 21/681 using optical controlling means

Abstract

A method for detecting and precisely locating features such as susceptor surfaces, wafers and surface depressions and elevations, is disclosed. A modified high angle, infrared, crossed-optics-pair sensor unit is used, as well as both perpendicular and parallel scanning.

Claims

1. In a method of detecting essentially specularly reflecting and partially specularly reflecting, partially diffuse regions or components of a surface, the steps comprising:

(1) mounting an infrared beam emitter having a focal length and an infrared beam detector having a focal length along respective output beam and input beam axes oriented at an angle of about 45°

-90°

therebetween and spaced apart a distance selected to provide coincident emitter and detector foci;

(2) confining the output beam at the emitter and the input beam at the detector to relatively small diameters;

(3) positioning the emitter and detector at different angles relative to the normal to the surface; and

(4) scanning the positioned emitter and detector along the surface at the focal distance therefrom to provide reflected emitter beam intensity levels at the detector representative of at least one of (1) substantially purely specular reflection and partially specular reflection and (2) at least one of elevations and depressions in the partially specularly reflecting region or component of the surface.

2. The method of claim 1 wherein the emitter and detector beam diameters are approximately 5 mm.

3. The method of claim 1 wherein the angular difference between the orientation of the emitter and the detector is about 16°

.

4. In a method of detecting the distance between a crossed optics pair sensor unit and a partially specularly reflecting surface, the steps comprising:

(1) mounting an infrared beam emitter having a focal length and an infrared beam detector having a focal length along respective output beam and input beam axes oriented at an angle of about 45°

-90°

therebetween and spaced apart a distance selected to provide coincident emitter and detector foci;

(2) confining the output beam at the emitter and the input beam at the detector to relatively small diameters;

(3) positioning the emitter and detector at different angles relative to the normal to the surface; and

(4) scanning the detector along an axis substantially perpendicular to the surface and through the focal distance of the unit to provide reflected emitter beam intensity levels at the detector representative of the distance between the detector and the surface along the perpendicular axis.

5. The method of claim 4 wherein the emitter and detector beam diameters are approximately 5 mm.

6. The method of claim 4 wherein the angular difference between the orientation of the emitter and the detector is about 16°

.

7. A method of controlling the relative position of an object and a depressed or elevated feature in a partially specular reflecting, partially diffuse reflecting surface, along a direction generally parallel to the surface, using a sensor including a light beam emitter having a focal length and a light beam detector having a focal length, comprising:

(A) positioning the sensor by mounting the light beam emitter and the light beam detector along respective output beam and input beam axes oriented with an angle of about 45°

-90°

therebetween and spaced apart a distance selected to provide substantially coincident emitter and detector foci, and orienting the emitter and detector at different angles relative to the normal to the surface;

(B) scanning the positioned emitter and detector along the surface at the focal distance therefrom to provide reflected emitter beam intensity levels representative of spaced edges of the feature, and determining the position of the feature relative to the position of the sensor from said representative signals; and

(C) using the position information to control the relative position of the object and the feature.

8. A method of controlling the position of an object along an axis transverse to a partially specular reflecting, partially diffuse reflecting surface using a sensor means including a light beam emitter for reflecting the light beam off said surface and a light beam detector means for providing an output signal representative of the reflected light intensity received at the light beam, the light beam emitter and the light beam detector means each having a focal length, comprising:

(A) positioning the light beam emitter and the light beam detector means along respective output beam and input beam axes oriented with an angle of about 45°

-90°

therebetween and spaced apart a distance selected to provide coincident emitter and detector foci, positioning the light beam emitter and the light beam detector means at different angles relative to the normal to the surface, and mounting the object a known distance along the axis relative to the sensor means;

(B) scanning the positioned sensor along the axis through the focal distance of the positioned sensor unit to provide equal valued output signals on opposite sides of said focal distance representative of the detector being spaced an equal distance from the focal distance, and determining the maximum side signals and using the focal distance to determine the associated distance between the object and the surface; and

(C) using the associated distance information to control the position of the object relative to said surface.

9. A method of controlling the position of an object along an axis transverse to a partially specular reflecting, partially diffuse reflecting surface using a sensor means including a light beam emitter for reflecting the light beam off said surface and a light beam detector means for providing an output signal representative of the reflected light intensity received at the light beam detector means, the light beam emitter and the light beam detector means each having a focal length, comprising:

(A) positioning the light beam emitter and the beam detector means along respective output beam and input beam axes oreinted with an angle of about 45°

-90°

therebetween and spaced apart a distance selected to provide coincident emitter and detector foci, positioning the light beam emitter and the light beam detector means at different angles relative to the normal to the surface, and mounting the object a known distance along the axis relative to the sensor means.

(B) determining the position of the object relative to the surface by scanning the positioned sensor means along the axis and through the focal distance of the positioned sensor unit to provide at least several output signals on opposite sides of said sensor focal distance representative of the distance between the detector means and the surface, determining the positive and negative slopes of the signal curve associated with the opposite side signals, extrapolating the two slopes to obtain the location of the maximum signal and associated focal distance, and using the focal distance to determine the associated distance between the object and the surface; and

(C) using the associated distance information to control the position of the object relative to said surface.