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:
Dec. 11, 1990
Filed:
Aug. 23, 1989
John D Moran, Mesa, AZ (US);
Motorola Inc., Schaumburg, IL (US);
Abstract
Rectifiers of excellent characteristics may be more economically fabricated by a process in which a cavity is first etched in a non-epitaxial semiconductor wafer to a depth in the range of typically 15-25 percent of the initial wafer thickness. Simultaneous diffusion of N and P type dopants is used to provide (for an N type substrate) a P+ region in the bottom of the cavity and surrounding surface, and an N+ region on the opposite face of the wafer. A mask is then provided in the cavity bottom and the surrounding wafer regions etched to remove the P+ dopant outside the cavity thereby re-exposing the surrounding region of the original N type substrate. The P+ region may be level with or protrude slightly from the substrate surface. The junction formed between the P+ region in the cavity bottom and the N type substrate has a gradual contour where it intersects the surface thereby providing a more favorable field distribution. Passivation and metallization are provided in the conventional manner. The resulting devices may be fabricated in very thin wafers without significant mechanical breakage loss.