Characterization in Silicon Processing

shows

that

they are generated at various depths in the film by polysilicon grains

that

seem to be growing

radially

outward from a

point.

The source points are not

clearly

atypical in the TEM image. SIMS

analysis

of this hazy film showed a high

level

of chromium contamination of the film.

In many

cases,

the problem-solving process requires making many measure-

ments to look for across-wafer variations in important materials parameters, or even

wafer-to-wafer

variations.

This might come up, for example, in investigating source

gas

depletion effects in LPCVD tubes where the silicon in the source gas is depleted

by

deposition around the edges o