RTP requirements to yield uniform and repeatable ultra-shallow junctions with low energy boron and BF 2 ion implants

Ion implants of 2.0 and 5.0 keV 11B+ and 2.2, 5.0, and 8.9 keV 49BF 2 + at a dose of 1E15/cm2 were investigated. Anneal conditions were developed which produced highly activated yet shallow junctions. The effects of oxygen were studied previously by us1–12 and found to be an important variable to control in order to produce uniform and repeatable sheet resistance and junction depths. A purge procedure and integrated oxygen sensor were developed to measure and control the oxygen background concentration for each anneal to assure repeatable results. “Shelf-life,” that is dwell time between implant and anneal, was investigated. It was found that, for low energy implants, the amount of native oxide grown affects retained dose, sheet resistance (Rs), and uniformity. Controlled oxygen level repeatability and shelf life results are presented and equipment designs are discussed.