METHOD AND APPARATUS FOR ALIGNING A MASK AND A SUBSTRATE USING INFRARED RADIATION

• US 3,588,347 A
• Filed: 03/13/1969
• Issued: 06/28/1971
• Est. Priority Date: 03/13/1969
• Status: Expired due to Term

• Current Assignee: AT&T Technologies Inc (Nokia Corporation)
• Original Assignee: Donald C. Walls, Liber J. Montone
• Inventors: Montone, Liber J., Walls, Donald C.
• Application Number:
  US04/806,919
• Time in Patent Office: 837 Days
• US Class Current: 348/164
• CPC Class Codes: G03F 9/70 for microlithography measuring printed patterns for monitoring overlay G03F7/70633 or focus G03F7/70641; projection system adjustment G03F7/70258; position control G03F7/70775
• CPC Class Codes: H01L 21/00 Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
• CPC Class Codes: Y10S 438/975 Substrate or mask aligning feature

Abstract

MASK AREAS ARE ALIGNED ON AN UNTREATED SURFACE OF A SEMICONDUCTIVE WAFER WITH ELEMENTS FORMED ON THE OPPOSITE SIDE OF THE WAFER BY IMPINGING INFRARED RADIATION ONTO BOTH THE TOP AND BOTTOM SURFACES OF THE SUPERIMPOSED MASK AND WAFER AND VIEWING THE SUPERIMPOSED REFLECTED IMAGES AND SHADOW IMAGES OF THE ELEMENTS AND MASK AREAS ON A TELEVISION SCREEN. INFRARED RADIATION PASSING THROUGH THE BOTTOM SURFACES PROJECT SHADOW IMAGES OF THE ELEMENTS AND THE MASK AREAS ON THE TELEVISION SCREEN. INFRARED RADIATION IMPINGED FROM BELOW PENETRATES THE WAFER TO ISOLATE THE ELEMENT AREAS ON THE SCREEN AND VISIBLE LIGHT IMPINGED FROM ABOVE ISOLATES THE MASK AREAS AND TOGETHER THE ISOLATED AREAS EMPHASIZE THE LINES OF DEMARCATION BETWEEN THE SHADOWS OF THE MASK AREAS

AND THE ELEMENT AREAS TO PRODUCE CLEARLY DISTINGUISHABLE LIGHT IMAGES AND PERMIT SHIFTING AND ALIGNMENT OF THE MASK AREAS WITHIN THE ELEMENT AREAS.

Claims