Choice Stop Material for Chemical/Mechanical Polish Planarization
Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18
The process uses an amorphous carbon film as a stop layer for silicon wafer chemical/mechanical polishing. The carbon film has a lower polish rate than polysilicon and silicon nitride films, conventionally used, and provide a more effective barrier against unwanted sodium ion migration into device regions. Silicon wafers are never truly flat and limitations of polishing machines make it necessary to depend on a stop layer, under the material to be removed, to halt the polishing action on some regions of the wafer, while overburden is still being removed in other regions. The stop material must have a much lower polishing rate than the material to be removed. This process uses amorphous, diamond-like carbon films that have a very low polish rate and therefore make an excellent stop layer.