Thin films of

were prepared on various substrated of MgO(100),

, and

by using off-axis magentron sputtering methods and annealing in-situ. The prarameters of film fabrication processes had been optimized through a "follow the lcoal maxima" strategy to yield good quality films in therms of the critical temperature

and the critical current density

. Optimizedproecsses employing a plane magndtron and an cylindrical magnetron yielded

>90K along with


A/

at 77K and > 2


A/

at 5K. The sampels, however, showed degradationinthe properties, after chemical etching for fabrication of microbridges with the line width of 2-10 mocrons. In particular, the value of

for the microbridges of 2microns was as small as 80%. The degradation was strongly dependent on the line width through a formula :

(e)=

)b) [1-a exp(-1000 bL)} where

(e) and

(b) are the values of

in the absolute scale measured after and before chemical etching, respectively and L is the line width in mm. By utilizing a best fitting technique, the proper constant values of a and to b were found as exp(-1.2) and 0.22, respectively. This formula was very useful in estimatiing the upper limit of the device operationtemperature.