Improvement of AlScN-Mo selectivity by adding hydrogen in combination with chlorine-based gases.

Abstract

The present invention provides an apparatus and method for plasma etching an additive-containing aluminum nitride film that includes an additive element selected from scandium (Sc), yttrium (Y), or erbium (Er). [Solution] The method includes the steps of: placing the workpiece 11 on the substrate support 13 in the plasma chamber 12; introducing BCl3 gas into the chamber 12 at a certain BCl3 flow rate (sccm); introducing H2 gas into the chamber 12 at a certain H2 flow rate (sccm); introducing an inert diluent gas into the chamber 12 at a certain inert diluent gas flow rate (sccm); and forming a plasma in the chamber 12 to plasma etch the additive-containing aluminum nitride film 11c exposed in the trench 11e. The ratio of the inert diluent gas flow rate to the BCl3 flow rate is 1:3 to 1:11, and the ratio of the BCl3 flow rate to the H2 flow rate is 11:1 to 2:1.

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