The effects of substrate bias on phase stability and properties of sputter-deposited tungsten carbide


The effects of substrate bias on phase formation and physical properties of rf magnetron sputter-deposited tungsten carbide films have been investigated in this work. Films were deposited at 275 degreesC using bias levels ranging from 0 to -150 V and at room temperature and -160 V At low bias levels, the films were primarily composed of the WC1-x/W-2(C,O) phases, both of which have the B1 structure, and the fraction of the hexagonal W2C phase increased with bias level. The increased substrate bias levels also correlated with a reduction in oxygen content, suggesting that reducing oxygen content promotes formation of the W2C phase. However, the film deposited at room temperature and -160 V bias had an oxygen content of only 3%, yet did not form the W2C phase, indicating a minimum level of thermal activation is also required to form W2C. Increasing the bias voltage also resulting in increases in film hardness, modulus and compressive residual stress, while reducing resistivity. (C) 2004 Elsevier B.V. All rights reserved.

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Materials Letters



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Copyright © 2004, Elsevier