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:
Aug. 08, 1989
Filed:
May. 01, 1987
Werner Zapka, Gaertringen-Rohrau, DE;
Jurgen Kempf, Gechingen, DE;
Joachim Keyser, Wildeberg, DE;
Karl Asch, Herrenberg-Gultstein, DE;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A mask for radiation beam lithography is formed from a semiconductor wafer by thinning a region into a membrane with a hole pattern defining the pattern of the mask. The membrane is doped with a tensile stress-generating material so that minimum doping exists at the periphery of the membrane with the maximum at its center. The difference in doping between the periphery and the center is chosen so that when the mask is irradiated with a given beam current intensity, the membrane is tension-free. To make a mask in the wafer, a hole pattern is formed by etching holes in the membrane or by depositing a layer on the membrane. The wafer is thinned from the opposite surface until the holes in the hole pattern are throughholes or until the desired thickness is reached. The membrane is doped with tensile-stress-generating material using ion implantation or diffusion proportionally to the temperature distribution existing in the membrane during irradiation with exposure beams.