Abstract: Perimeter material is removed from substrates by stacking the substrates and subjecting them to a plasma etch. In an exemplary application, the perimeter of a silicon wafer dielectric cap (typically silicon nitride) is removed by stacking the wafers in intimate contact, and etching the wafers in a barrel etcher. A well-controlled removal of the cap perimeter is obtained, allowing for a smooth epitaxial deposition at the water edge in a subsequent operation. An additional benefit is smoothing of the substrate edge contour, which reduces scratching of wafer cassettes and other handling equipment.

Abstract: An improvement in silicon wafer flatness is obtained by reducing the time spent in polishing the wafer. After a conventional lapping operation, the wafer is coated with an etch resistant coating, typically silicon nitride. A polishing step removes the nitride coating on the flat surfaces of the wafer, but leaves a nitride coating on the sides of pits that are formed in the lapping operation. The wafer is then etched, typically in KOH, to remove the silicon surface to below the depth of the pits. The undercutting of the nitride coating removes the pits, or leaves relatively small protrusions in their place. The protrusions may be removed by a short polishing operation. Other wafer types and etch-resistant materials are possible. Integrated circuits are typically formed on the wafers by lithography techniques that advantageously utilize the improved flatness.

Abstract: Sealing the backside of a semiconductor wafer prevents evaporation of the dopant (typically boron) when an epitaxial layer is grown on the front (active) side, thereby preventing autodoping of the epitaxial layer with excess dopant. The present technique deposits an oxide layer during the ramp-up of the furnace that also deposits the nitride cap, thereby avoiding an extra process step. It also avoids the higher temperatures required for the prior-art technique of growing the oxide layer, resulting in lower oxygen precipitation due to the capping process and a greater yield of usable wafers.

Abstract: A fluid (12), such as dichlorosilane, is stored in a pressure vessel (17) located at a site remote from a processing facility within the confines of a building (14). At such remote site the pressure vessel (17) is subject to climatic temperature variations over a range at the lower temperatures of which a vapor pressure of the fluid may be insufficient to generate a pressure within the pressure vessel to drive the fluid through a duct (36) toward the processing facility. A supply of an inert gas (34) is applied at a first predetermined pressure to the pressure vessel (17) to urge the fluid under such predetermined pressure through the duct (36) toward an evaporator vessel (38) located at the processing facility. The evaporator vessel (38) is maintained at a first predetermined elevated temperature at which the fluid at such first predetermined pressure is in a gaseous state.