John Francis Corboy

Reduced pressure silicon epitaxy; A review

Abstract As the critical dimensions of IC circuits are decreased, more demands are put on the characteristics of epitaxial silicon layers. Reduced pressure provides an additional control parameter to use in efforts to achieve the required characteristics in the epitaxial deposits. In this review we discuss the impact of reduced pressure epitaxial growth on: the growth temperature, arsenic autodoping, pattern integrity, thickness and resistivity uniformity, and deposition rate. Epitaxial growth has been achieved at temperatures well under 900°C at reduced pressures, but low temperature pre-epitaxial substrate surface conditioning methods still need to be developed. Very significant improvement in the control of arsenic autodoping, pattern integrity, and resistivity and thickness uniformity has been achieved at reduced deposition pressures. The impact of pressure on autodoping is, at least qualitatively, understood. A number of aspects of the impact of pressure on pattern integrity are not understood.

Relationship between crystallinity and electronic properties of silicon-on-sapphire

Abstract A comparative study of electronic properties (determined by photovoltage spectroscopy) and of the crystalline perfection (determined by UV reflection technique) was carried out on a series of silicon-on-sapphire wafers of different crystallinity. It was found that the improvement of crystallinity led to a significant reduction of the concentration of deep levels in the middle of the energy gap. Differences in the as-deposited crystalline quality can be related to differences in the electronic properties even after the deposits were ion implanted, oxidized and annealed. Recently discovered slight amorphization of silicon-on-sapphire was quantitatively analyzed in terms of the amorphization factor, η. It was found that η decreases with improvement of crystallinity and its value for SOS films was one to two orders of magnitude smaller than in a typical a-Si.