RADICAL CONTROL BY WALL HEATING OF A FLUOROCARBON ETCHING REACTOR

The entire vessel of a RF diode etching reactor was heated to control the radical composition of a CF4/H-2 plasma. Appearance mass spectrome try revealed that the CF3 and CF2 densities are 2 to 3 orders of magni tude higher in the heated reactor at 230 degrees C, compared with the conventional reactor at 30 degrees C. On the other hand, the F atom de nsity monitored by an actinometry technique is almost unchanged. The t emporal variation of the CF3 and CF2 densities induced by H-2 addition is relatively smaller in the heated environment. A few mechanisms for the anomalous increase of the CFx radical are discussed in view of th e radical surface loss and the electron-impact radical production. As a consequence, wall heating is useful for controlling the etching proc esses by enhancing the carbon-containing radicals.