Dry etching of via connections for GaAs monolithic microwave integrated circuits fabrication

Abstract

Through-the-wafer low-impedance via connections can improve characteristics of GaAs monolithic microwave integrated circuits (MMICs). A reactive ion etch process has been developed to etch via holes through 100-μm-thick substrates using SiCl4/Cl2 mixtures in a single-wafer, load-locked reactive ion etcher. The process satisfies the requirements of the via etch with regard to anisotropy, selectivity, profile, and surface morphology. In addition, the single-wafer system has low-overhead cycle times and a wide-process latitude. This process was used to fabricate a MMIC distributed amplifier with significant improvements in gain performance.