Mesa etching characterization of InSb for high density image array applications

Abstract

The wet etching characteristics of InSb single crystal were investigated for highdensity focal plane array applications. Two different chemical systems were used to prepare the mesa structures using standard lithography. The wet etching characteristics corresponding to these chemical systems were measured and analyzed. The results can be used to identify the dominant control mechanisms during the etching process. The etching conditions such as the chemical concentration will influence the etching characteristics, the effects of which lead to our understanding the dominant control mechanism after optimizing different ratios of wet etching chemicals. Citric acid/peroxide has been shown to produce a practical etching rate at room temperature. The dominant control mechanism for InSb mesa etching in citric acid/peroxide is surface reaction rate-limit oriented, in that it depicts promising potential in morphology and sidewall profile control for InSb mesa type device applications. To verify the feasibility of these processes for device applications, a field emission scanning electron microscope was used to analyze the step coverage for dielectric deposition and metal layer coating. To meet the requirements of InSb high density array applications, a peroxide based chemical system with reaction rate-limit mechanism was concocted to bring to produce superior etching performance in comparison with a nitric acid based solution.