Highly Microcrystalline Phosphorous-Doped Si:H Very Thin Films Deposited by RF-PECVD

Fine-tuning the crystallinity and doping of the hydrogenated microcrystalline silicon thin films are the key points in obtaining high-quality devices for above-integrated circuit (above-IC) image sensors. This study focuses on the structural and electrical properties of radio-frequency plasma enhanced chemical vapor deposition (RF-PECVD) deposited microcrystalline silicon (mu c-Si:H) contact layers. Herein, phosphorus-doped mu c-Si:H is deposited by capacitively coupled plasma RF-PECVD (13,56 MHz) from a SiH4 + H-2 + PH3 gas mixture with varying phosphine concentrations. The influence of phosphine concentration on dopant concentration, active dopant concentration, and crystallinity is studied by secondary ion mass spectrometry, Hall effect measurement, and Raman spectroscopy, respectively. A high doping level is attained, reaching up to 1.7 x 10(20) cm(-3). Furthermore, low-power and high-power deposition conditions are studied which lead to incubation layers of different nature.

Automated summary

Fine-tuning the crystallinity and doping levels of hydrogenated microcrystalline silicon thin films is crucial for obtaining high-quality above-IC image sensors. This study investigates the structural and electrical properties of RF-PECVD-deposited microcrystalline silicon contact layers, focusing on the influence of phosphine concentration on dopant concentration, active dopant concentration, and crystallinity. A high doping level of 1.7 x 10(20) cm(-3) is achieved, and different incubation layers are obtained under different deposition conditions.