| 摘要 |
<p>A low-temperature (<200 DEG C) oxide etch process, particularly applicable to a bi-level contact structure, practiced in a high-density plasma etch reactor having both parallel electrodes (34,52) and an inductive coil (46) for coupling RF energy into the plasma. The top electrode (52) is composed of a fluorine scavenger, such as silicon, glass carbon, or silicon carbide. The RF bias power is split in a predetermined selectable ratio between the two electrodes. Up to 25% of the total RF power is applied to the scavenging electrode to achieve the desired selectivity with adequate margin against etch stop. The etch chemistry typically includes C2F6, CO, and Ar (or C4F8), and the entire chamber is kept below 180 DEG C. Etching TEOS-grown oxide with the inventive method produces center-point process results of an oxide etch rate of greater than 800nm/min and a selectivity to polysilicon of greater than 50:1. <IMAGE></p> |
