Ion energy control at substrates during plasma etching of patterned structures
Etch selectivity of OSG/SiC as a function of wafer self-bias voltage for (a) sinusoidal bias voltage wave form and (b) tailored bias voltage wave form for different feature widths. The experiment was repeated for self-bias voltages of and after several weeks to confirm reproducibility. Note that the vertical scales are different for the two cases.
OSG etch rate for (a) sinusoidal and (b) tailored bias voltage wave forms, measured at a depth of . Note that the vertical scales are different for the two cases.
SiC etch rate for (a) sinusoidal and (b) tailored bias voltage wave forms, measured at a depth of in OSG. Note that the vertical scales are different on the two plots.
OSG etch rate decreases with increasing feature aspect ratio. Etch rates are normalized to the etch rate in the open area, so that values less than 1 indicate suppression of etch rate due to aspect ratio effects.
Etch time was varied to determine the OSG etch rate at different etch depths.
While etch profiles are slightly different for tailored and sinusoidal bias voltage wave forms; both show smooth sidewalls. Nominal feature width is , and depth is . Remaining photoresist can be seen at feature tops.
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