R.F. sputtering deposition of buffer layers for Si/YBCO integrated microelectronics

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 axe 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)/S' configuration, is c-axis oriented.