The Role of the Sheath in Processing Plasmas

Abstract

Experimental results show that the sheath in a rf plasma processing discharge will expand and contract with the osicllating potential. Moreover, in SiHi discharges the surrounding plasma is by nature a dusty plasma containing negative ions. Computer simulation indicates that such negative ions alone will introduce a weak field throughout the plasma and a double layer at the sheath edge.The substrate etching rate is critically controlled by the ion injected through this sheath from the ‘plasma’ and thus a more complete understanding of this is essential for plasma processing technology.