MOVABLE-MASK REACTIVE ION ETCH PROCESS FOR THICKNESS CONTROL IN DEVICES

By moving the substrate relative to a shadow mask in a reactive ion et ching system, we are able to precisely tailor the thickness of critica l layers. To minimize disturbing the plasma, all the mechanical compon ents are kept below the anode. The system is highly reproducible, and can be programmed to yield arbitrary vertical profiles along one horiz ontal axis. Using silicon-on-insulator substrates, the resonance wavel ength was modified as a function of position with better than 1 nm con trol in the vertical dimension. This technique should prove useful for optical devices where the thickness of the layers controls the device characteristics. (C) 1996 American Institute of Physics.