Measurement of the rotational temperature of the second positive system of N 2 was used as a diagnostic of the gas temperature in low-pressure inductively coupled Ar, Kr and N 2 plasmas. The rotational temperatures determined from the rovibrational bands (ν , ν ) = (0, 0), (1, 0), (0, 2) and (4, 2) of the N 2 C 3 u → B 3 g system differ by about 300 K depending on the operating gas pressure in the 0.4-20 mTorr range. Important discrepancies exist between the temperatures found from each of the rovibrational bands of N 2 . This shows that the method has important intrinsic uncertainty that may be due either to errors in the transition probabilities of N 2 C 3 u → B 3 g or to inefficient thermal coupling between translational and rotational temperatures. In the case of argon, the population of the emitting C 3 u states by energy transfer from Ar 3 P 0,2 metastable atoms is also considered as a possible factor influencing the rotational structure of some rovibrational bands. Based on these measurements, it is shown that, in the range of experimental conditions studied herein, the uncertainty of the method should be carefully accounted before considering one of the rotational temperatures of the N 2 second positive system equal to the gas temperature.

No abstract

The influence of surface chemistry in plasma etching of multicomponent oxides was investigated through measurements of the ion energy dependence of the etch yield. Using pulsed-laser-deposited CaxBa(1−x)Nb2O6 (CBN) and SrTiO3 thin films as examples, it was found that the etching energy threshold shifts toward values larger or smaller than the sputtering threshold depending on whether or not ion-assisted chemical etching is the dominant etching pathway and whether surface chemistry is enhancing or inhibiting desorption of the film atoms. In the case of CBN films etched in an inductively coupled Cl2 plasma, it is found that the chlorine uptake is inhibiting the etching reaction, with the desorption of nonvolatile NbCl2 and BaCl2 compounds being the rate-limiting step.