Characterization of polysilicon-encapsulated local oxidation

Abstract

Device isolation has been most commonly achieved through the use of local oxidation of silicon (LOCOS) or LOCOS derivatives. LOCOS is a highly dependable, low-defect isolation technique, which explains its continued extensive use. Unfortunately, the inherently large oxide encroachment associated with LOCOS is not compatible with 0.8- mu m design rules. Many alternative isolation techniques designed to reduce oxide encroachment have been proposed. These alternatives often result in an increase in defectivity and/or process complexity. Polysilicon-encapsulated local oxidation (PELOX) utilizes a polysilicon-filled cavity self-aligned to the nitride edge to achieve oxide encroachment reduction. The physical (scanning electron and transmission electron micrographs) and electrical (electrical channel width, diode leakage, and gate oxide integrity) characterization of PELOX isolation are reported. >