Contrast Enhancement of Wavelength-Selective Detection of Mid-Infrared Using Localized Atmospheric-Pressure Plasma Treatment

Abstract

A new processing method to enhance the signal contrast of a mid-infrared (MIR) detector integrated with a wavelength-selective function is studied. Using the hydrophilic characteristic of an IR absorber solution, an absorber material is selectively deposited onto a hydrophilically modified area over the hot junctions in the diaphragm of a thermopile detector. The hydrophilic modification of the chip-mounted detector is realized using localized atmospheric Ar + O2 plasma treatment through a stencil mask. Using a thermograph, we measured thermal distributions over a previously fabricated detector, whose absorber material is deposited using a manual manipulator without a position-selective mechanism, and the newly fabricated detector for comparison. The newly fabricated detector exhibited a larger temperature difference between hot and cold junctions than that of the previous detector. The detector has an increased signal contrast of 100% from the baseline at the absorption peak.