Browse Prior Art Database

Removing Impurities From Semiconductor Wafers

IP.com Disclosure Number: IPCOM000085670D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Bohg, A: AUTHOR [+2]

Abstract

As the integration density increases, the contamination of semiconductor wafers by rapidly diffusing metallic impurities presents a sizable problem, since on their own and/or in conjunction with crystal defects the materials lead to electric failure.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

Removing Impurities From Semiconductor Wafers

As the integration density increases, the contamination of semiconductor wafers by rapidly diffusing metallic impurities presents a sizable problem, since on their own and/or in conjunction with crystal defects the materials lead to electric failure.

The wafer is purified by diffusing the impurities under the influence of the gravitation field of a centrifuge, utilizing the fact that the atomic weights of the impurities in question are essentially higher than that of the semiconductor material, and that the impurities are highly mobile in the crystal lattice.

The wafers to be purified are placed in the centrifuge (acceleration about 100,000 g) in such a manner that the artificial gravitation forces the metal atoms to be removed in the direction of the rear side of the wafer. By a suitable heating step during centrifugation, the diffusion of the impurities is facilitated to such an extent that the purification process is completed within a reasonable time.

The process can be accelerated by purifying only the surface layer of several mu m depending on the type of structure. If required, the impurities can be removed from the rear side by suitable methods etching, sputtering or be left there.

1