Application of electrolytic in-process dressing (ELID) grinding and chemical mechanical polishing (CMP) process for emerging hard–brittle materials used in light-emitting diodes

In the light-emitting diode (LED) market, the market share for hard–brittle materials has increased. However, using the wafering process, the hard–brittle materials for LEDs are difficult to fabricate mechanically due to their hard–brittle characteristics. In addition, the hard–brittle materials are chemically stable. We propose a sequential process of electrolytic in-process dressing (ELID) grinding and chemical mechanical polishing (CMP) for hard–brittle materials used in LEDs, with applications to silicon carbide (SiC), sapphire and gallium nitride (GaN). The advantage of the ELID grinding–CMP process is to dramatically reduce process time and achieve high surface quality by adopting ELID grinding instead of general mechanical polishing, which has a low material removal rate and takes considerable process time. Finally, the surface of each material is smoothed using the CMP process with a mixed abrasive slurry (MAS) and a colloidal silica slurry.