Cluster ion beam smoothing of SiC and YBCO surfaces

Optimization of the surface topography, especially in high-temperature supe rconductor (HTS) and silicon carbide is crucial for device processing. Surf ace smoothing in these materials was investigated using gas cluster ion bea ms (GCIB) capable of delivering cluster ions of greater than or equal to 20 00 Ar atoms with energies of up to 30 kV. Examination of the surface topogr aphy after cluster ion irradiation was done using cross-sectional transmiss ion electron microscopy (TEM) and atomic force microscopy (AFM). The result s indicate that typical as-deposited YBCO films on MgO substrates have an a verage roughness of the order of 40 m and interpeak distance between 300 an d 600 nm. Application of GCIB to the surface planarization reduces the roug hness to only 10 nm. Also, power handling and microwave surface resistance of the YBCO film and its relationship to surface smoothness are reported. S imilar observations using bulk SiC are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.