A new method of selectively patterning a silicon substrate with silicon dio
xide and silicon nitride is demonstrated. An oxide patterned silicon substr
ate is directly nitrided using a microwave generated nitrogen plasma. Upon
subsequent selective wet chemical etching using KOH, the oxide is removed a
nd etching proceeds into the silicon, revealing a contrast reversed pattern
of the oxide. The etch resistance of the nitrided surface is maximized by
increasing the microwave power, pressure, and nitridation duration. The etc
h rate of silicon dioxide is negligibly affected and its etch rate is nearl
y the same as before nitridation. Compositional analysis of the nitride and
the nitrided oxide using x-ray photoelectron spectroscopy confirms that mi
crowave plasma nitridation produces Si-N covalent bonds. (C) 2001 American
Vacuum Society.