Method and structure for uniform contact area between heater and phase change material in PCRAM device

摘要

A PCM (phase change memory) cell in a PCRAM (phase change random access memory) semiconductor device includes a phase change material subjacently contacted by a heater film. The phase change material is formed over a surface that is a generally planar surface with at least a downwardly extending recess. The phase change material fills the recess and contacts the upper edge of the heater film that forms the bottom of the recess. After a planar surface is initially formed, a selective etching process is used to recede the top edge of the heater film below the planar surface using a selective and isotropic etching process.