Fabrication of Microstripline Wiring for Large Format Transition Edge Sensor Arrays

We are developing kilo-pixel arrays of TES microcalorimeters to enable high-resolution X-ray imaging spectrometers for future X-ray observatories and laboratory astrophysics experiments. Our current array design was targeted as a prototype for the X-ray Microcalorimeter Spectrometer proposed for the International X-ray Observatory, which calls for a 40x40-pixel core array of 300 micron devices with 2.5 e V energy resolution (at 6 keV). Here we present device characterization of our 32x32 arrays, including X-ray spectral performance of individual pixels within the ar.r:ay. We present our results in light of the understanding that our Mo/Au TESs act as weak superconducting links, causing the TES critical current (I c) and transition shape to oscillate with applied magnetic field (B). We show Ic(B) measurements and discuss the uniformity of these measurements across the array, as well as implications regarding the uniformity of device noise and response. In addition, we are working to reduce pixel-to-pixel electrical and thermal crosstalk; we present recent test results from an array that has microstrip wiring and an angle-evaporated Cu backside heatsinking layer, which provides Cu coverage on the four sidewalls of the silicon wens beneath each pixel.https://ntrs.nasa.gov/search

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“…In these close-packed arrays all thousand pixels are wired, using fine-line microstrip leads to achieve the required wiring density [10].…”

Section: Discussionmentioning

confidence: 99%

“…In addition, we can modify our field-coil geometry to provide a more uniform field across the array. 2 One other key result for array uniformity is presented in an accompanying paper [10]. In this experiment we measured the I c (B) pattern of one pixel with and without current through adjacent bias leads.…”

Section: Uniformitymentioning

confidence: 92%

Kilopixel X-ray Microcalorimeter Arrays for Astrophysics: Device Performance and Uniformity

et al. 2012

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“…It requires a minimum of eight pairs of wires between each pixel at the outer edge in order to wire out all of the pixels comprising a 32 × 32 array. [5] The previous generation utilized a microstrip structure with a 4 μm pitch. [1] The widths of the lower (Lead 1) and upper (Lead 2) conductors were 2.5 μm and 1.5 μm, respectively, with a gap between lines of 1.5 μm.…”

Section: Array Designsmentioning

confidence: 99%

Reduced-Scale Transition-Edge Sensor Detectors for Solar and X-Ray Astrophysics

Datesman

Adams

Bandler

et al. 2017

IEEE Trans. Appl. Supercond.

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We have developed large-format, close-packed X-ray microcalorimeter arrays fabricated on solid substrates, designed to achieve high energy resolution with count rates up to a few hundred counts per second per pixel for X-ray photon energies up to 8 keV. Our most recent arrays feature 31-micron absorbers on a 35-micron pitch, reducing the size of pixels by about a factor of two. This change will enable an instrument with significantly higher angular resolution. In order to wire out large format arrays with an increased density of smaller pixels, we have reduced the lateral size of both the microstrip wiring and the Mo/Au transition-edge sensors (TES). We report on the key physical properties of these small TESs and the fine Nb leads attached, including the critical currents and weak-link properties associated with the longitudinal proximity effect.

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“…Among them, Bi and Au are widely used because of the high stopping X-ray power (high atomic number Z = 83 and Z = 79) and low specific heat [ 2 , 17 ]. Although Bi shows a smaller X-ray absorptivity than Au (35% vs. 52%, 5 μm thickness, 20 keV) [ 15 ], the specific heat is two orders of magnitude smaller, allowing for much larger collection area, which is beneficial for the aerospace X-ray detection [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

Electroplating Deposition of Bismuth Absorbers for X-ray Superconducting Transition Edge Sensors

Chen

et al. 2021

Materials

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An absorber with a high absorbing efficiency is crucial for X-ray transition edge sensors (TESs) to realize high quantum efficiency and the best energy resolution. Semimetal Bismuth (Bi) has shown greater superiority than gold (Au) as the absorber due to the low specific heat capacity, which is two orders of magnitude smaller. The electroplating process of Bi films is investigated. The Bi grains show a polycrystalline rhombohedral structure, and the X-ray diffraction (XRD) patterns show a typical crystal orientation of (012). The average grain size becomes larger as the electroplating current density and the thickness increase, and the orientation of Bi grains changes as the temperature increases. The residual resistance ratio (RRR) (R300 K/R4.2 K) is 1.37 for the Bi film (862 nm) deposited with 9 mA/cm2 at 40 °C for 2 min. The absorptivity of the 5 μm thick Bi films is 40.3% and 30.7% for 10 keV and 15.6 keV X-ray radiation respectively, which shows that Bi films are a good candidate as the absorber of X-ray TESs.

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Fabrication of Microstripline Wiring for Large Format Transition Edge Sensor Arrays

Cited by 7 publications

References 8 publications

Kilopixel X-ray Microcalorimeter Arrays for Astrophysics: Device Performance and Uniformity

Kilopixel X-ray Microcalorimeter Arrays for Astrophysics: Device Performance and Uniformity

Reduced-Scale Transition-Edge Sensor Detectors for Solar and X-Ray Astrophysics

Electroplating Deposition of Bismuth Absorbers for X-ray Superconducting Transition Edge Sensors

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