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:
Jan. 19, 1988
Filed:
Apr. 11, 1986
Helmut Keser, Birr, CH;
Jan Voboril, Nussbaumen, CH;
BBC Brown, Boveri & Company, Limited, Baden, CH;
Abstract
For the p-type doping of silicon, particularly for power semiconductor components, aluminum from an Al target is precipitated by cathode sputtering in an argon plasma on a major face (2) of a silicon wafer (1) by which means a comparatively high purity of the deposited aluminum is achieved. Before the aluminum deposition, the silicon water (1) is bombarded with argon ions for 10 min at an argon pressure of 20 .mu.bar which guarantees a uniform fusion of the aluminum with the silicon during later heating and, in particular, prevents the formation of droplets of the aluminum on the major face (2). The Al layer formed in this manner is photo-lithographically preferably structured in such a manner that several aluminum sources spaced apart from each other are allocated to one aluminum-doped zone (10). The subsequent diffusion occurs for 300 min at 1250.degree. C. in a gas mixture of nitrogen or argon (1 l/min) and oxygen (20 ml/min). During this process, the aluminum-doped zone (10) is produced. Subsequently, photoresist (13,14) is applied to the non-diffused regions. Residues (11') of the aluminum sources are then laterally etched by a silicon etchant and, as a result, removed. Following this, the photoresist (13,14) is removed.