Fabrication Process for Full Rox Isolation Without a Bird's Beak
Original Publication Date: 1980-Apr-01
Included in the Prior Art Database: 2005-Feb-13
Conventional fabrication processes for fully-recessed silicon dioxide isolation (full ROX) lead to the formation of an oxide ridge in the shape of a bird's head with a crest and a beak . This "bird's beak" is undesirable because it reduces the available active surface area and hence the device packing density. The "bird's crest" can also cause discontinuities in thin films covering the ROX boundary. When the oxide is grown in steam, a Kooi pinch effect has also been observed near the ROX edge and has been attributed to the diffusion of NH(3) to the Si surface near the edge of the Si(3) N(4) diffusion mask .