Fabrication of Thick Metal Absorber With Overhanging Structure for TESs

In this report, we describe progress in fabricating thick metal absorbers with an overhanging structure for TES applications. First, a negative photoresist is photo-lithographed in order to define the stem of the mushroom structure. A thin seed layer of Au is sputtered over the photoresist pattern to provide an electrical contact for electroplating. Another layer of the photoresist is coated and patterned to form the cap of the structure. A thick layer of Au is then electro-deposited on the open part of the seed layer. Finally, the overhanging structure is completed after chemically releasing the photoresist and the unwanted seed layer. This absorber made on a Ti/Au bilayer whose sensitivity parameter alpha is about 350, is currently being developed to measure X-rays with high filling factor and high detection efficiency.