Loading patent…
AssigneeSEH America, Inc.
InventorsWitawat Wijaranakula, Sandra A. Archer, Dinesh C. Gupta
Estimating the term…
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.
A method of producing a semiconductor wafer having a reduced quantity of light-scattering anomalies, the quantity of light scattering anomalies being characterized at a particular crystal-pulling rate by a graph of quantity of light scattering anomalies versus annealing temperature, the graph for a particular crystal-pulling rate having a local minimum corresponding to a preferred annealing temperature, the method comprising:
Dependencies are inferred from the claim text.