Patent ID: 7241632

Claim:
A process to manufacture a MTJ stack that is free of shorting problems that arise from MTJ cap protrusion after CMP, comprising: forming a MTJ stack, having sidewalls and a cap layer, on a substrate; using a first conformal deposition method, depositing a layer of silicon nitride on said MTJ stack and on said substrate; anisotropically etching said layer of silicon nitride until said cap layer is fully exposed, thereby forming spacers on said MTJ sidewalls; using a second conformal deposition method, depositing a layer of silicon oxide, having a surface, on all exposed surfaces to form a structure; and applying a CMP process that further comprises: using a high selectivity slurry containing an abrasive selected from the group consisting of ceria and silica at a pH between about 9 and 11, a polyurethane type pad, a slurry flow rate in the range of 150 to 250 ml/mm, a polishing pressure of 2 to 4 psi, a pad conditioning force of 6 to 8 pounds, and a platen speed of 30 to 50 rpm, selectively removing silicon oxide at a faster rate than silicon nitride and tantalum, thereby planarizing said structure until said cap layer and spacers protrude above said silicon oxide surface.