Silicon Deep-Trench Etching Using Freon 12 Plus Inert Gas Plasmas
Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18
This process includes the addition of an inert gas (either nitrogen or argon) to FREON* 12 etch (CCl2F2) for etching trenches in silicon semiconductors to eliminate sharp corners at the trench bottom and sidewall bowing. Sharp corners (Fig. 1) formed by etching trench structure cause defects in single crystal silicon. Fig. 2 shows trenches etched in CCl2F2 alone, which provided directional etching; however, unwanted sharp corners are apparent. Fig. 3 illustrates a trench etched with the addition of inert gas to the plasma. The addition of the inert gas is thought to provide the higher pressure necessary for removal of sharp corners (and bowing the trench) without changing the gas chemistry. This process has shown to be feasible with both argon and nitrogen gases, and both silicon and silicon dioxide reactor product plates.