Abstract: An etching method for an In series compound semiconductor includes etching in a plasma etching of a flowing mixture of a halogen and nitrogen, the flow ratio of halogen to nitrogen being lower than 1, and at a gas pressure below 0.5 mTorr. An etching method for an In series compound semiconductor includes etching in a plasma etching apparatus and a mixture of halogen/inactive gas/nitrogen gas, the flow rate ratio of halogen/(halogen+inactive gas+nitrogen gas) being lower than 0.1, the flow rate ratio of nitrogen/(halogen+inactive gas+nitrogen gas) being above 0.1, and the gas pressure being below 0.5 mTorr. Etching at low ion energy produces good surface morphology, a vertical side surface configuration having an etched concave portion, and low damage.

Abstract: Polymer alloys which comprise (A) at least one cycloolefin polymer and (B) at least one polyaryl ether ketone, the amounts of (A) being 1 to 99% by weight and those of (B) being 99 to 1% by weight and relatively making up 100% by weight, with respect to the total alloy, are described. Such polymer alloys can be used as a matrix material for composite materials or for the production of shaped articles.