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Title: Negative ion effects during magnetron and ion beam sputtering of YBa/sub 2/Cu/sub 3/O/sub x/

Conference · · AIP Conf. Proc.; (United States)
OSTI ID:6957556

The sputtering of YBa/sub 2/Cu/sub 3/O/sub x/ in both RF diode and magnetron systems has been plagued by negative ions effects. Negative ions are produced at the cathode surface during sputtering and are accelerated across the plasma sheath into the plasma. The dominant negative ion produced is O/sup -/. The negative ion attains energy by crossing the sheath and may bombard the depositing film at a high rate. The attached electron is usually stripped in the plasma and the energetic, now neutral atom travels through the plasma and bombards the substrate location in front of the cathode. The effect of this bombardment is to reduce the net deposition rate and to alter the film composition. The negative ion yields have been measured by both ion beam and magnetron techniques. In the former case, the negative ions were accelerated by a grid placed just over the sample. The particles were then energy analyzed and counted in a 4-grid energy analyzer. The spatial distribution was also measured. The magnetron diagnostic consisted of a differentially-pumped analyzer which shielded the charged particles from the detector. The energetic, now neutral O atoms were allowed to impact the collector, and the secondary electrons were collected. The negative ion yields were found to be dependant on the oxygen partial pressure in the discharge. However, there was sufficient oxygen in the target to produce a yield of 0.75 times the pure oxygen case. The yields often exceed 0.3, which in combination with the measured secondary electron yield implies that the actual incident positive ion current during sputtering is only 50--60% of the indicated current.

Research Organization:
IBM Watson Research Center, Yorktown Heights, NY 10598
OSTI ID:
6957556
Report Number(s):
CONF-871178-; TRN: 88-030188
Journal Information:
AIP Conf. Proc.; (United States), Vol. 165:1; Conference: Thin film processing and characterization of high temperature superconductors, Anaheim, CA, USA, 6 Nov 1987
Country of Publication:
United States
Language:
English