Influence of a ground shield on heat flux in parallel-plate plasma system

The influence of a ground shield on the heat flux to a substrate in a paral lel-plate plasma system was investigated experimentally using an original t emperature measurement technique. The evaluation of the temperature rise cu rve shows that the heat flux from the plasma towards the substrate increase s from 8% of the rf power to 26% by surrounding the powered electrode with the ground shield. The flux density on the powered electrode is 350 W m(-2) at an rf power of 50 W and pressure of 50 mTorr, and the value increases t o 1150 W m(-2) by shielding. However, the total power into the electrode is 23-26% of the rf power in both cases, after accounting for the larger plas ma facing surface area of the unshielded system. By shielding, a self-bias voltage decreases from 80% of the applied rf voltage to 73% due to a contra cted spatial distribution of the electron density between the electrodes by shielding. The ion Bur is smaller than the heat flux obtained from the sub strate temperature rise and it increases by shielding.