화학적 부식을 이용한 실리콘 웨이퍼의 파쇄층 제거 및 거칠기 향상

Removal of Damaged Si Layer & Roughness Making of Fine Grinded Silicon Surface by Chemical Etching

In the manufacturing of semiconductor, devices are created within 20μm of surface, commonly called EPI layer. Generally, total thickness of silicon wafers varies from 200μm to 900μm. Therefore unnecessary thick backside of silicon must be removed by grinding and chip’s final thickness became 80∼400μm. When unnecessary backside is been removed by grinding, surface would covered with the damaged layer by mechanical treatment and it may be contain severe internal cracks that induce chip crack. If we consider the chip crack protecting, adhesion between back side metal and lead frame in packaging, it is essential that remove the damaged layer and making the backside of wafers to rough. Nowadays, there are several methods of using for this purposes. Traditional, very brief and cheap method is wet etching that using the mixture of HNO₃, HF and some diluents. By changing the composition of HNO₃, HF and diluents, silicon etching speed and surface geometry was varied widely In some area of chemical composition silicon surface became rough. Rough surface of silicon can be obtained by wet etching, and it elevate a adhesion between silicon and back metal film, and crack-free chip have strong die fracture strength.