Thin Epitaxial Silicon by CVD

Abstract

Device applications for thin silicon epitaxy require sharp transition widths and uniform layers on wafers up to 200 mm diameter in production quantity. Uniform silicon epitaxy nominally 1 um thick deposited with transition widths of 0.2 – 0.3 µm over heavily doped buried layers using reduced pressure CVD technology are discussed. Both boron and arsenic buried layers can be accommodated in the 100 – 200 torr range. Thin selective epitaxy, with and without uniform polycrystalline silicon overgrowth on the oxide, is improved by reduced pressure deposition. Epitaxial lateral overgrowth is another technology based on thin epitaxy that is improved by reduced pressure CVD. Silicon-on-Sapphire requires very high growth rates at atmospheric pressure for very short times to achieve acceptable crystal quality. Some results for these thin epitaxy processes are reviewed.

Estimating negative binomial demand for retail inventory management with unobservable lost sales

“…Increased competition has made the retail inventory management system a key strategic weapon for large retailers such as supermarkets and department stores (see [6]). For high-priced durable goods such as furniture or appliances, unmet demand is typically backordered and thus can be observed; however, for low-cost, nondurable merchandise, sales are typically lost and not reported ' when the items are out of stock.…”