The effect of temperature and flow rate on aluminum etch rates in RF plasmas

The effect of sample temperature and etch gas flow rate on the etching of aluminum in BCl/sub 3//Cl/sub 2/ and CCl/sub 4//Cl/sub 2/ mixtures in a parallel-plate plasma etcher was investigated. Through the use of a thermally conductive epoxy to ensure good heat-transfer, sample heating due to exothermic chemical reactions and plasma heating was found to result in a temperature difference of more than 100/sup 0/C between bonded and unbonded samples. Thus, considerable increases in etch rate were observed for the unbonded samples. Etch nonuniformities during both the inhibition period and metal etching were studied, using different plasma conditions and a nozzle to deliver chlorine directly to the aluminum surface. Oxide etching depended upon ion flux and/or energy and upon the concentration of BCl/sub X/ or CCl/sub X/ species, while Cl/sub 2/ concentration at the sample surface determined the relative aluminum etch rates across the aluminum sample.