Near-100% Quantum Efficiency of Delta Doped Large-Format UV-NIR Silicon Imagers

• Published in: IEEE transactions on electron devices 2008-12, Vol.55 (12), p.3402-3406
• Main Authors: Blacksberg, Jordana, Nikzad, Shouleh, Hoenk, Michael E., Holland, Stephen E., Kolbe, William F.
• Format: Article
• Language: English
• Subjects: Aluminum; Applied sciences; Back illuminated; Broadband; Charge coupled devices; Charge transfer devices; charge-coupled device (CCD); Chemical vapor deposition; Coating; delta doping; Deltas; Devices; Double layer; Electronics; Exact sciences and technology; fully depleted; high-purity silicon; Imaging devices; Metallization; Microelectronic fabrication (materials and surfaces technology); Quantum efficiency; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2008.2006779

We have demonstrated a back surface process for back-illuminated high-purity p-channel charge-coupled devices (CCDs), enabling broadband coverage from the ultraviolet to near infrared (NIR). The process consists of the formation of a delta layer followed by a double layer antireflection (AR) coating. The process is performed below 450 ^{\circ}\hbox{C} and is applied to fully fabricated CCDs with aluminum metallization. The delta doping process was demonstrated on 1 k \times 1 k and 2 k \times 4 k CCDs, which were found to exhibit low dark current and near reflection-limited quantum efficiency. Two broadband AR coatings were developed to cover the UV-visible and visible-NIR bands. These coatings consist of a double layer of \hbox{Si}_{x}\hbox{N}_{y} and \hbox{SiO}_{x} deposited by plasma enhanced chemical vapor deposition onto the back surface of a delta doped CCD. The thicknesses of the coating layers are adjusted for the desired bandpass.