Cryogenic Bolometer Array Technology Development on 150 mm Wafers

The number of polarization sensitive detectors deployed in CMB experiments has been growing steadily from 1,000 of stage-II to 10,000 stage-III and projected detectors of approximately 500,000 for CMB-S4 experiments.The Particle Physics Project Prioritization Panel (P5) outlined a strategic plan for US particle physics research over the coming decade in 2014.The panel recommended, "support CMB experiments as part of the core particle physics program.The multidisciplinary nature of the science warrants continued multiagency support." In response to the recommendation, CMB community started planning for Stage IV CMB experiment called CMB-S4.CMB-S4 aims to make definitive measurement of the early universe with ~500,000 detectors.Such a task will involve the fabrication of over 500 science grade wafers within a relatively short period.It has increasingly been clear that the next phase of development of detectors for CMB experiments will require well maintained with controlled environments micro-fabrication facilities.SeeQC-HYPRES’ fabrication facility fits this requirement very well.SeeQC-HYPRES is the premier commercial superconductor electronics company in the US equipped with 150 mm wafer processing equipment.Furthermore, the decades of experience with low temperature superconducting electronics fabrication processes makes SeeQC-HYPRES an ideal foundry to deliver wafers for the CMB experiments.SeeQC-HYPRES have been collaborating with LBNL to develop path to commercially manufacture detectors for CMB experiment since late 2015.The main goal was to combine know-how of detector fabrication process from academia and know-how of high throughput fabrication from industry to overcome challenges of next generation CMB experiment.Through the collaboration we have been able to transfer know-how from the institutions to our foundry and implement a modular fabrication process for making antenna coupled Transition Edge Sensor (TES) bolometer array through an SBIR phase-I project of the project.During eight months of the phase-I project, we fabricated prototype detector array for Simons Observatory successfully.The run was fully executed at SeeQC-HYRRES fabrication facility, as such, were able to track the progress of the fabrication flow very closely and were able generate a fabrication model that could be used fabricate 100s of wafers a year that are required for the CMB-S4 project.We also identified the bottle necks of the process flow.Moreover, we were able to quantify the fabrication yield and factors that affected the yield and some steps taken to alleviate them.We are excited to push commercial fabrication of CMB detector to full maturity through SBIR.LBNL will provide overall project direction, detector design, fabrication process consulting, and test results with a tight feedback loop with SeeQC-HYPRES.We have already established robust fabrication steps to make detector array.With the SBIR Phase-2, we will work on removing two fabrication bottle necks we identified during Phase-I (e-beam evaporation and silicon nitride deposition) by incorporating high throughput e-beam evaporator that already exists at SeeQC-HYPRES and by changing nitride deposition sequence.We will then demonstrate an increase in production throughput with a goal of further improving cost and schedule of detector production towards CMB-S4.LBNL will perform a cryogenic evaluation of fabricated CMB detector.This includes cryogenic yield, detector linearity, noise performance, antenna beam profile, and polarization purity.