The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 04, 1978
Filed:
Jan. 26, 1977
Robert Louis Hartman, Warren Township, Somerset County, NJ (US);
Wilbur Dexter Johnston, Jr, Holmdel, NJ (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
It has been discovered that plastic deformation of a wafer of light-emitting semiconductor material during processing creates areas of poor radiative efficiency known as large dark spot (LDS) defects. An improved technique for lapping is described which alleviates stress and substantially reduces the initiation and propagation of such defects. Conventionally, wafers are affixed to a mounting plate by coating the plate with wax or some other appropriate adhesive and then applying pressure. The improvement comprises interposing a spacer between the mounting plate and the wafer. The spacer is capable of accommodating surface irregularities and particulates while maintaining substrate planarity.