STUDY OF STI ETCHING DEFECTS FOR O.18m AND BEYHOND TECHNOLOGY

摘要

Shallow Trench Isolation (STI) is the preferred isolation choice for quarter-micron and beyond CMOS technology due to its near zero field encroachment, high density, better planarity, latch-up immunity and low junction capacitance. While CMOS technology moves to 0.1 um device region, stringent photolithography and CD control requirements ask for high performance STI plasma etch process. Etch must possess excellent CD control with minimal CD loss, superior trench profile with minimal microloading, smooth edge-rounding with low stress and leakage, good trench depth uniformity with minimal etch rate microloading, high selectivity to resist and low etch defects. In this paper, the interaction between etch defects and etch chemistry will be examined from a Decoupled Plasma Source (DPS) reactor from Applied Material. Process characterization of inline CD, trench profile and trench depth uniformity along with preliminary yield will be also presented. Our experiment indicates that improper control of gas-phase polymer formation during nitride mask opening is the main reason for having high number of cone-shaped defects.