Fabrication of antenna-coupled transition edge sensors for polarimeter applications

In this paper we describe the progress in the development of polarization sensitive superconducting, bolometric detector arrays targeted at cosmic microwave background (CMB) studies. Our implementation takes advantage of superconducting technology to reduce the complexity of the typical CMB bolometer focal plane by incorporating as many of the required elements as necessary on the detector itself. Each pixel in the array consists of a distributed dual-polarization beam forming antenna, a band pass filter, and power splitter/combiner delivering detected power to four separate superconducting transition edge sensors. This combination of elements detects the polarization of the incoming light uniquely while eliminating a large part of the cooled mass of the focal plane including feed horns, polarizers, and band pass filters. Of course this increases the fabrication complexity of the bolometric detector itself over previous implementations. We will describe our fabrication process consisting of eight front side mask levels and one back side layer designed to produce whole wafer array tiles suitable for CMB polarimeters.