| 摘要 |
Disclosed is a method of isotropically dry etching a current conducting runner comprising polysilicon material which is formed on a silicon substrate wafer containing integrated semiconductor circuits. The method employs a parallel plate reactor which is controllable to provide intermittent pulses of power over the parallel plates. Gases are injected to within the reactor to provide a reactive gas mixture at a preselected pressure. Preselected intermittent pulses of power are applied to ionize the reactive gas mixture into a plasma state. Such intermittent pulses are defined by an RFon period, an RFoff period, and an RFrepeat period. The ratio of RFon:RFrepeat is preferably from about 0.35 to 0.60. The wafer is subjected to the intermittent pulses and reactive gas mixture at the preselected pressure for a preselected amount of time to selectively isotropically etch the current conducting runner. The invention has specific application to isotropically dry etching a WSix/polysilicon sandwich structure. With such a structure, the preferred reactive gas mixture is SF6, Cl2, O2, and an inert carrier gas in approximate respective volume ratios of 10.0+/-5%:2.0+/-5%:3.0+/-5%:15.0+/-5%.
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