Epitaxial Deposition

Prime polished wafers are transferred to the epitaxial furnace area inside the clean room. Epitaxy is a process that grows a thin, ultra-pure layer of silicon on the polished surface of a silicon wafer substrate. Polished wafers are loaded into single slice, or multiple slice capacity, "epi" reactor. The recipe, or customer specification, is programmed for that machine's run (cycle). Trichlorosilane gas is injected at a high-temperature as the wafer spins in the reactor. The gas flows over the top resulting in the silicon atoms adhering to the crystalline wafer structure. This "epi" layer is designed to have different compositional and electrical properties from the underlying wafer, tailored to the specific demands of the device.

The epi layer is also free of imperfections that may cause device failure and it provides increased reliability during the fabrication process. In short, epi wafers provide our customers with a technically superior wafer on which to build the most complex and sophisticated devices in the world.

SunEdison Semiconductor played an integral role in the development of Epitaxy for CMOS applications in 1982 -- a major turning point in the semiconductor industry. By applying an epitaxial layer to the surface of a silicon wafer, this pioneering work by SunEdison Semiconductor made advanced applications possible.