Title:
AUTOMATIC FOCUSING DEVICE
Document Type and Number:
Japanese Patent JPH0636727
Kind Code:
A
Abstract:
PURPOSE: To correctly detect height or position of a sample or a body surface and their change by providing first and second optical beam focal point forming means, a servo Z-axis control electron system, etc. CONSTITUTION: A mirror 54, a lens 56, and a mirror 58 act on an optical beam 59 from a laser 52 to form a first optical beam focal point on a surface 20 of a wafer 22. A spherical mirror 62 collects radiation from the first optical beam focal point to form a second optical beam focal point close to it. In this case, change at a height or place of the surface along an axial line 16 of an electron beam 15 is generated by change of a place of the second focal point. Radiation from the second focal point is reflected by the mirror 58 to be inputted through the lenses 56, 64 to an image position-sensitive inspection instrument 66 to form an image on a instrument 66. Output of the instrument 66 is supplied to a servo Z-axis control electron system 68, so a DC correction voltage related to an error of the height or position of the surface 20 is outputted, thereby correct detection can be provided.
Inventors:
SHII CHIYAO RIN
Application Number:
JP12190293A
Publication Date:
February 10, 1994
Filing Date:
April 26, 1993
Export Citation:
Assignee:
AMRAY INC
International Classes:
G01B11/02; G02B7/198; G02B7/28; H01J37/21; H01J37/22; G01Q20/00; (IPC1-7): H01J37/21; G02B7/28; G02B7/198; H01J37/22
Attorney, Agent or Firm:
Kazuo Sato (3 others)
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