Journal of Vacuum Science & Technology B, Vol.14, No.2, 732-737, 1996
Inductively-Coupled Plasma for Polymer Etching of 200 mm Wafers
An inductively coupled plasma etcher has been developed which uses a low 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. In addition, capacitive coupling and sputtered contaminants are significantly reduced by electrically grounding the turn of the inductor which is adjacent to the vacuum window. The radially resolved ion saturation current indicates that, in spite of the locally intense induction fields, the uniformity is only marginally better than expected from a discharge with a uniform ionization frequency, This is due to the nonlocal nature of the electron energy distribution. Etching of photoresist from 200 mm wafers using O-2 is shown to be 2.5% uniform for operating conditions of 5 mTorr, 50 seem, and 500 W radio frequency induction power.
Keywords:LANGMUIR PROBE