Improvement of Zr film purity by using a purified sputtering target and negative substrate bias voltage

We report an improvement of the purity of Zr films using a purified sputtering target and a negative substrate bias voltage. The Zr films were deposited on Si (100) substrates using a non-mass separated ion beam deposition system. Glow discharge mass spectrometry (GDMS) was used for trace impurity analysis in the Zr films deposited on a low-purity or a high-purity target and with or without a negative substrate bias voltage. Results showed that the sputtering target purity noticeably affects impurity concentrations in deposited films, which suggests that purer films are obtainable by increasing the sputtering target purity. This study further established that by applying a negative substrate bias voltage, much purer films are obtainable through prevention of an influx of impurities into the films during deposition.