Kenneth J. Newton

Etching of dual-damascene oxide structures in a medium-density oxide etch reactor

This paper presents the work done to develop a self-aligned, dual-damascene etch in a medium-density (approximately X 1010 ion/cm3) oxide etch reactor. The systematic study of etch results was guided by the process performance criteria (See Table 1) and wafer material provided by Texas Instruments. This work was performed on a Lam Research Corporation 4520XLETM dual-frequency Reactive Ion Etch (RIE) tool. As shown in Figure 1, RF power applied to the upper electrode at a frequency of 27 MHz primarily serves to generate the medium-density plasma. RF applied to the lower electrode at a frequency of 2 MHz primarily controls the relative ion energy. The final process results indicate feasibility using a process with discrete steps for trench, via and nitride removal portions of the dual damascene structure. (See Figure 2)