Low-temperature Junction Formation for Thinned High Energy Physics Sensors

Segal, J.; Kenney, C.; Rozario, Lisa; Blaj, G.; Chang, Chu-En; Hasi, J.; Kowalski, Jeffrey M.; Kowalski, Jeffrey E.

doi:10.1109/nssmic.2018.8824728

Cited by 3 publications

(2 citation statements)

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“…In addition to providing a shallow junction, microwave annealing for sensor dopant activation can add flexibility to the process integration. Because the substrate is not heated during the anneal, the technique can be used to post-process the backside of fully depleted monolithic CMOS sensors and CCD's, significantly simplifying the process [4].…”

Section: Resultsmentioning

confidence: 99%

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Thin-Entrance Window Process for Soft X-Ray Sensors

Segal

Kenney

Kowalski³

et al. 2021

Front. Phys.

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New free electron lasers, such as SLAC’s LCLS-II, will provide unique scientific imaging opportunities. In order to fully utilize these facilities, we need to develop detectors with shallow entrance windows that will enable detection of soft x-rays from 250 eV to 1.5 KeV. Achieving adequately shallow entrance windows is challenging because the high temperature anneal needed to activate the dopant also drives the dopant profile deeper, growing the region that is insensitive to soft x-rays. A new microwave annealing technology provides an efficient way to achieve shallow entrance windows in fully depleted high-resistivity silicon sensors. The microwave anneal technique can activate dopants at low substrate temperature, with minimal dopant diffusion, and can be used to fabricate both n-type and p-type entrance windows. SRP and SIMS measurements were used to verify dopant activation with negligible dopant diffusion. We then applied the microwave anneal process to a planar sensor wafer, using the new process to create the backside diode contact. Electrical test of the resulting sensors shows good reverse bias characteristics. The sensors have been bump-bonded to a read-out ASIC and used successfully to measure an Fe-55 x-ray spectrum. Process and device simulations were performed to characterize the quantum efficiency of the entrance window for soft x-rays. This technique is useful for other sensor applications requiring a shallow entrance window, including detectors for UV photons, low energy ions and low energy electrons.

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Section: Resultsmentioning

confidence: 99%

“…The dopants become polarized in the microwave chamber, allowing for dopant activation while the bulk silicon temperature remains at less than 500°C. The result is dopant activation with negligible dopant diffusion [3][4][5][6].…”

Section: Microwave Annealing For Dopant Activationmentioning

confidence: 99%

Thin-Entrance Window Process for Soft X-Ray Sensors

Segal

Kenney

Kowalski³

et al. 2021

Front. Phys.

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200 mm sensor development using bonded wafers

Alyari¹,

Bradford²,

Campanella³

et al. 2021

J. Inst.

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Sensors fabricated from high resistivity, float zone, silicon material have been the basis of vertex detectors and trackers for the last 30 years. The areas of these devices have increased from a few square cm to > 200m2 for the existing CMS tracker. High Luminosity Large Hadron Collider (HL-LHC), CMS and ATLAS tracker upgrades will each require more than 200 m2 of silicon and the CMS High Granularity Calorimeter (HGCAL) will require more than 600 m2. The cost and complexity of assembly of these devices is related to the area of each module, which in turn is set by the size of the silicon sensors. In addition to large area, the devices must be radiation hard, which requires the use of sensors thinned to 200 microns or less. The combination of wafer thinning and large wafer diameter is a significant technical challenge, and is the subject of this work. We describe work on development of thin sensors on 200 mm wafers using wafer bonding technology. Results of development runs with float zone, Silicon-on-Insulator and Silicon-Silicon bonded wafer technologies are reported.

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