A new chemical mechanical planarization with the frozen chemical etchant as a polishing pad

Chemical Mechanical Planarization (CMP), a new technology have developed at IBM since the early 1980's, has remain fruitful and applicable to the global planarization of multilevel metallization of logic devices and interconnection of memory devices. However, the conventional CMP process incurs several difficulties such as unstable slurries, scratches on the surface, various metal contaminants, dishing and erosion phenomena, cleaning residues, low selectivities, and additional high processing cost due to using consumable slurries and urethane polishing pads. In our study, we propose the new method of Frozen Chemical Planarization (FCP). We have substitute the frozen chemical etchant pad for conventional urethane polymer polishing pads, slurries, and abrasives. The acidic frozen chemical etchant pad is frozen by a dilute polysilicon etching solution with the heat of vaporization of liquid nitrogen (LN2). From our experiments, we have verified the suitability of our new CMP process using a frozen polishing etchant pad.