Cryogenic bolometer array technology development on 150 mm wafers

Seeqc In 2015, the Cosmic Microwave Background CMB community started planning CMB Stage IV CMBS4, which aims to make definitive measurements of the early universe with ~500,000 detectors. To reach this number of detectors, the CMBS4 Concept Definition Task Force found that “Investment is needed in proving process uniformity and reproducibility in TES polarimeter fabrication. In addition, cost reduction could potentially be achieved…by exploring commercial fabrication options.” As part of this effort, Seeqc, Inc. began fabrication of antenna coupled transition edge sensor TES bolometers at Seeqc’s commercial Niobium foundry. PhaseI of the present SBIR was a study of the high throughput capability of our commercial fab. We successfully met out throughput goal by producing 10 sixinch antenna coupled detector wafers in 15 working days. During PhaseII, we have addressed these bottleneck steps by commissioning high throughput equipment electron beam evaporator and modifying detector designs to reduce required deposition times for both Pd and SiN. Commissioning of new equipment and development of the new designs were successful. Throughput the PhaseII we have been in close contact with CMBS4 project to update them on our progress. For example, CMBS4 have selected horn coupled antenna detector technology as their baseline. We have installed Deep Reactive Ion Etcher DRIE, and we have worked with the vendor, SPTS, and LBNL to develop backside Si etch process. We have successfully developed fabrication processes to fabricate a horn coupled detector. Having proven we can fabricate detectors in our facility, in PhaseIIa we plan to focus on inhouse characterization. Developing inhouse superconducting device characterization capability allow Seeqc to track the status of fabrication equipment, necessary for maintaining high throughput, as well as alleviate the testing burden at the National Laboratories, allowing them to focus on more demanding integrated tests. In addition, inhouse test addresses the following November 2019 CMBS4 Annual Review’s recommendations: R11: “It is a high priority that R&D resources are in place to demonstrate CMBS4 wafers for at least one site, preferably more, in time for CD1 2021. R14: “Incorporate expedited testing to validate “firsttype” and “firstsite” wafers early to retire the risk of new types.”. Seeqc, plans to develop test procedures for: Optical index of SiN at room temperature. Film stress of SiN, AlMn, Nb and Ti at room temperature. Sheet resistance of AlMn, Ti and Nb at room temperature and cryogenic temperatures, RRR. Superconducting transition temperature of AlMn and Nb. Loss of superconducting resonator at cryogenic temperature at 4~8 GHz as indicator of loss of SiN and any anomalous behavior of Nb at higher 30 GHz ~ 300 GHz frequencies. And other tests that may arise during the course of the PhaseIIa R&D. Phase IIa will allow us to bring our testing infrastructure in line with our fabrication capability, making us an independent commercial provider of TES detector arrays to CMBS4 and future superconducting sensor customers.