Seh America, Inc.

Witawat Wijaranakula

Jallepally Ravi

Naoto Tate

Akihiko Tamura

Kiyoshi Mitani

Dinesh C Gupta

Sandra A Archer

A novel method of generating intrinsic gettering sites in epitaxial wafers employs co-implanting silicon and oxygen into a substrate of the wafer, annealing the substrate at a low temperature, and then depositing the epitaxial layer on a surface of the substrate. The epitaxial deposition acts as an in-situ anneal to form dislocation loops that act as gettering sites. Oxygen precipitate clusters form during the method, which clusters act to anchor the dislocation loops and prevent them from gliding to the wafer surface over time.

Silicon and oxygen ion co-implanation for metallic gettering in epitaxial wafers

Silicon and oxygen ion co-implantation for metallic gettering in

A semiconductor silicon wafer (10) useful as a calibration standard for measurement of a thickness (18) of a microdefect-free layer (16) is formed by depositing an epitaxial layer onto a substrate (12) having an interstitial oxygen concentration suitable for precipitating oxide. Large, uniform oxide microdefects (14) are formed in the substrate by maintaining the semiconductor silicon wafer at between 600.degree. C. and 900.degree. C. to nucleate oxide precipitates that are then grown at between 800.degree. C. and 1,200.degree. C. Because the epitaxial layer contains no oxide precipitate nuclei to form microdefects, the epitaxial layer remains a microdefect-free layer and has a relatively sharp, easily detectable boundary with the substrate. The epitaxial layer can be polished to a reduced thickness, if desired.

Method for manufacturing a wafer having a microdefect-free layer of a

An apparatus and method for growing large diameter silicon crystals using the Czochralski (Cz) method, wherein the neck section of the crystal is significantly strengthened to eliminate the risk of breakage in the neck section, by providing a heat shield assembly which is located adjacent to the neck section and ascends in conjunction therewith to force the cooling gas directly onto the neck section of the silicon ingot.

Method for improving mechanical strength of the neck section of

Apparatus for improving mechanical strength of the neck section of

A monitor wafer used to determine the cleanliness of a wafer fabrication environment requires a surface having a minimum of light scattering anomalies so that contamination deposited by the environment is not confused with light scattering anomalies initially on the monitor wafers. In the present invention, ingots of a single-crystal semiconductor are grown at a reduced pull rate and wafers produced from the ingot are annealed within a preferred temperature range that varies with the pull rate to produce wafers having reduced light-scattering anomalies on their surfaces. The number of light-scattering anomalies increases at a slower rate upon repetitive cleaning cycles than does the number of light-scattering anomalies of prior art wafers.

Method for producing semiconductor wafers with low light scattering

Method for manufacturing a calibration wafer having a microdefect-free

The present invention is a CMOS epitaxial silicon wafer (50) on which CMOS integrated circuits (16) can be manufactured, including such circuits that include bipolar components (referred to as 'BiCMOS' circuits). The CMOS wafer includes a lightly doped monocrystalline silicon substrate (56) having a major surface (54) that supports a lightly doped monocrystalline epitaxial silicon layer (52). The substrate includes a heavily doped diffused layer (58) extending a short distance (64) into the substrate from the major surface toward a lightly doped bulk portion (66) of the substrate. CMOS integrated circuits manufactured on the epitaxial layer of the CMOS wafer of this invention have a low susceptibility to latch-up. The low susceptibility is provided by the relatively low resistivity of the diffused layer. Since the diffused layer is relatively thin and the bulk portion is lightly doped, the oxygen content of the bulk can be readily measured and controlled.

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Vancouver, WA, United States of America

Witawat Wijaranakula