INDUCTIVELY-COUPLED PLASMA FOR POLYMER ETCHING OF 200 MM WAFERS

An inductively coupled plasma etcher has been developed which uses a l ow aspect ratio, helical coil placed atop a planar vacuum window. The geometry of the inductive coupling element results in strongly peaked radio frequency power absorption around the periphery of the plasma. I n addition, capacitive coupling and sputtered contaminants are signifi cantly reduced by electrically grounding the turn of the inductor whic h is adjacent to the vacuum window. The radially resolved ion saturati on current indicates that, in spite of the locally intense induction f ields, the uniformity is only marginally better than expected from a d ischarge with a uniform ionization frequency, This is due to the nonlo cal nature of the electron energy distribution. Etching of photoresist from 200 mm wafers using O-2 is shown to be 2.5% uniform for operatin g conditions of 5 mTorr, 50 seem, and 500 W radio frequency induction power. (C) 1996 American Vacuum Society.