EFFECTS OF TARGET EROSION ON THE GROWTH-RATE OF FILMS FABRICATED BY THE SPUTTERING METHOD

The sputtering method is a widely used technique for fabricating thin films by use of glow discharge plasma. A Monte Carlo simulation method for calculating the growth rate of films is proposed in a general form. The method is applicable not only to cases where atomic collisions play a dominant role, but also to cases where the target suffers from nonuniform erosion. The method is used to find an optimum erosion distribution for a typical sputtering condition. First it is shown that films of uniform thickness cannot be achieved with a uniform erosion distribution. Next, the effect of nonuniform erosion on the thickness distribution is examined by changing the location of the maximum erosion rate. The overall growth rate of films is shown to decrease upon moving the location of the maximum erosion rate outwards. At a given pressure there is a corresponding optimum erosion distribution that yields a uniform film. The depth of the eroded dent has only a small effect on the thickness distribution of films, in particular, at high pressure.