  A large diameter plasma over 300 mm in diameter is produced by electron
cyclotron resonance (ECR) discharges using a newly developed large diameter
chamber of 400 mm in inner diameter. It is found that the electron temperature
decreases as nitrogen gas is added to pure argon plasma, which is considered
that nitrogen molecules absorb the electron energy into the vibrational energy
and lead to the decrease of the electron temperature. Moreover, it is found
that the plasma uniformity is improved by adding nitrogen gas, suggesting that
the adjunction of nitrogen gas is effective for producing uniform and low
electron temperature plasma.
