Significant Improvement of Copper Dry Etching Property of a High-Pressure Hydrogen-Based Plasma by Nitrogen Gas Addition

[Image: see text] The characteristics of copper (Cu) isotropic dry etching using a hydrogen-based plasma generated at 13.3 kPa (100 Torr) were improved dramatically by simply introducing a moderate amount of N(2) gas into the process atmosphere. A maximum Cu etch rate of 2.4 μm/min was obtained by nitrogen addition at a H(2) mixture ratio (C(H(2))) of 0.9 and an input power of 70 W. The etch rate for the optimally N(2)-added plasma was 8 times higher than that for the pure H(2) plasma. The Cu etch rate increased with increasing input power. The maximum etch rate reached 3.1 μm/min at an input power of 100 W and a C(H(2)) of 0.9. The surface roughness of the etched copper decreased as a result of optimum N(2) addition. Furthermore, N(2) addition also improved the etch selectivity between Cu and SiO(2) such that the selectivity ratio reached 190. Finally, selective etching of a trench-patterned Si wafer with an electroplated Cu layer was demonstrated.