Magnetron sputter coating of microspherical substrates

Abstract

The fabrication of laser fusion targets requires the deposition of various metal and dielectric layers on microspherical substrates (100–500 μm diameter). The continuous motion for uniformly coating these spherical substrates has been accomplished for rf sputtering applications. In one approach, the spheres being coated are bounced and laterally swept across a table as the frequency of vibration of the table is changed continously. In another approach, the sputtering gas is also a levitation gas. The argon is fed through a collimated hole structure and keeps the microsphere both levitated and rotating during the sputter deposition. The uniformity and surface quality of the deposited films obtained by these two techniques are compared.