Design and fabrication of TES microcalorimeters for x-ray astrophysics in Japan

Our recent development of transition-edge sensor (TES) microcalorimeters for future X-ray astronomical missions such as DIOS is reported. In-house micromaching processes has been established aiming at prompt fabrication of TES devices. With a single-pixel TES microcalorimeter and an Au absorber, the energy resolution of 4.8 eV at 5.9 keV is achieved. 16×16 pixel arrays of TES microcalorimeters are successfully fabricated by using deep dry etching technique. The energy resolution is 11 eV and 26 eV with and without an Au absorber, respectively. The worse energy resolution than a single-pixel TES is due to large decrease of TES sensitivity and increase of transition temperature after etching. The reason for these phenomena is under investigation. In parallel, mushroom-type Au absorber structures are being tested. Furthermore, to precisely measure TES sensitivities and heat capacity, an experimental setup for impedance measurements is established.