Polycrystalline silicon films have been deposited on thermally oxidized wafers. The films have been implanted with As, B, or and annealed with a Varian IA‐200 rapid thermal annealer. The system uses infrared radiation from a resistively heated sheet of graphite to heat the entire wafer to temperatures in excess of 1000°C for times on the order of a few seconds. The effects on sheet resistance, sheet carrier concentration, and mobility due to exposure time, heater temperature, dopant species, and resultant grain size are discussed. Higher temperatures and longer exposure times produce the lowest sheet resistances. These results are compared to CW laser and conventional furnace‐annealed films. A substantial loss of As occurs during the anneal unless the films are capped with . Results on B and implanted films indicate no boron loss has occurred during the anneal. The As and B uniformly distribute throughout the film when exposed to anneal conditions that produce very little diffusion in single‐crystal Si. This implies that As and B diffusion is much faster in polycrystalline Si than in single crystal under these anneal conditions. The anneal causes both components of a bimodal grain size distribution to grow significantly until grain growth is slowed by geometrical constraints. Increased grain size results in a substantial increase in mobility. The grain growth has been modeled by an interfacial energy‐driven mechanism.
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Wilson et al. (1985) studied this question.