R.F. SPUTTERING DEPOSITION OF BUFFER LAYERS FOR Si/YBCO INTEGRATED MICROELECTRONICS

Abstract

The aim of the present work is the optimization of the Si /buffer-layer/YBCO multilayer deposition process so as to grow superconducting films of quality suitable for device applications. The structural properties of the Si/CeO 2 system, obtained by RF magnetron sputtering of CeO 2 targets in Ar atmosphere, have been studied. More than 50 films have been deposited and some of them submitted to post-deposition annealing treatments both in N 2 and O 2 atmospheres. The presence of an unwanted amorphous SiO 2 layer at the Si/CeO 2 interface compromises the YBCO c-axis orientation, and therefore the sharpness of the R versus T transition. A newly designed deposition system has been realized: it has been specially conceived for obtaining bi- and tri-layers, adopting two targets in YSZ and CeO 2, respectively. Results on YSZ/Si and CeO 2/ YSZ/Si systems obtained with the new machine are presented and discussed: (100) oriented YSZ films with nominal thickness of 40 nm have been obtained. The CeO 2 film subsequently deposited has the desired (100) orientation. The YBCO film, in the final YBCO/YSZ/CeO 2/ Si configuration, is c-axis oriented.