Wafer-scale HfO₂ encapsulated silicon nanowire field effect transistor for efficient label-free DNA hybridization detection in dry environment

Abstract

Abatract Silicon nanowire (SiNW) charge based biosensors are attractive for DNA sensing applications due to their compactness and large surface-to-volume ratio. Small feature size, low production cost, repeatability, high sensitivity and selectivity are some of the key requirements for biosensors. The most common e-beam manufacturing method employed to manufacture sub-nm SiNWs is both cost and time intensive. Therefore, we propose a highly reproducible CMOS industry grade low-cost process to fabricate SiNW-based field effect transistors on 4″-wafers. The 60 nm wide SiNWs reported in this paper are fabricated using the sidewall transfer lithography process which is a self-aligned-double-patterning I-line lithography process that also facilitates encapsulation of the SiNW surface with a thin HfO2 layer on which DNA probes are grafted to finalize the biosensors. Upon DNA hybridization, SiNW devices exhibit threshold voltage shift larger than the noise introduced by the exposition to saline solutions used for the bioprocesses. More specifically, based on a statistical analysis, we demonstrate that 85% of the tested devices exhibit a positive threshold voltage shift after DNA hybridization. These promising results make way for the monolithic integration of SiNW biosensors and CMOS circuitry to realize a point of care device which can offer reliable real time electrical readout.

Optimization of GOPS-Based Functionalization Process and Impact of Aptamer Grafting on the Si Nanonet FET Electrical Properties as First Steps towards Thrombin Electrical Detection

“…For these reasons, extensive research work has been performed on Si NW–FETs for electrical detection of various charged biomolecules such as DNA. This is attested by reviews [ 1 , 2 , 3 ], summarizing advances on Si NW–FETs made of parallel Si NW arrays with NWs patterned by top-down techniques such as conventional photolithography, electron beam lithography [ 4 ], sidewall transfer lithography [ 5 ] and nano-imprinting approaches. In all these works, the resulting DNA detection limit varies between 0.1 fM [ 6 ] to 1 nM [ 7 ], depending on numerous parameters (Si NW size, NW doping, functionalization method, distance between DNA and NW surface, ionic medium, etc.).…”

Monolithic Wafer Scale Integration of Silicon Nanoribbon Sensors with CMOS for Lab-on-Chip Application

“…In particular, the SiRi-FETs described in this work can be functionalized using the process shown by Nguyen et al [ 5 ] and Jayakumar et al [ 11 ]. The first step in the DNA probe covalent grafting process is silanization.…”

“…In this step, the sensor surface is functionalized with single strand DNA using an organosilane such as (3-Aminopropyl)triethoxysilane (APTES) [ 5 ]. Later, the sensor can be used for the hybridization detection of target DNA that is complementary to the probe DNA [ 11 ]. At the same step, to verify the selectivity of the sensor, its surface is exposed to non-complementary DNA and saline buffer solution that is free of complementary DNA [ 11 ].…”

“…Later, the sensor can be used for the hybridization detection of target DNA that is complementary to the probe DNA [ 11 ]. At the same step, to verify the selectivity of the sensor, its surface is exposed to non-complementary DNA and saline buffer solution that is free of complementary DNA [ 11 ]. A well-behaved SiRi sensor is expected to not respond to the non-complementary DNA or the salt crystallization after drying and only exhibit V TH shifts because of the target complementary DNA [ 11 ].…”

“…At the same step, to verify the selectivity of the sensor, its surface is exposed to non-complementary DNA and saline buffer solution that is free of complementary DNA [ 11 ]. A well-behaved SiRi sensor is expected to not respond to the non-complementary DNA or the salt crystallization after drying and only exhibit V TH shifts because of the target complementary DNA [ 11 ]. Indeed, the sensing mechanism employed by works listed in Table 1 relies on the conductance changes in the SiRi channel.…”