Polycrystalline silicon films of 300 nm thickness were deposited on oxidized
wafer surfaces, implanted with As, and annealed on a Varian IA 200 rapid
thermal annealer. Transmission electron microscopy was used to study
through-thickness and cross sectional views of grain size and morphology of
as-deposited and of transient annealed films. A bimoda] distribution of
grain sizes was present in as-deposited polycrystalline silicon films. The
first population was due to columnar growth of some grains to a final
average diameter of 20 rm. The second population of small equiaxed grains of
5 nm average diameter were formed early in the deposition process. During
transient annealing grains in the first population grew rapidly up to 280-nm
equiaxed grains. After this the growth rate decreased due to the grain size
reaching the thickness of the film. Grains in the second population grew
rapidly up to a size of 150 nm, after which the growth rate was lowered due
to grains impinging upon one another. The grain growth processes for both
populations have been described with a modified model for interfacially
driven grain growth. This model accounts for diffusion and grain growth
which occur with rapidly rising and falling temperatures during short
annealing times characteristic of transient annealing processes.