Process Variability in Top-Down Fabrication of Silicon Nanowire-Based Biosensor Arrays

Abstract

Silicon nanowire field-effect transistors (SiNW-FET) have been studied as ultra-high sensitive sensors for the detection of biomolecules, metal ions, gas molecules and as an interface for biological systems due to their remarkable electronic properties. “Bottom-up” or “top-down” approaches that are used for the fabrication of SiNW-FET sensors have their respective limitations in terms of technology development. The “bottom-up” approach allows the synthesis of silicon nanowires (SiNW) in the range from a few nm to hundreds of nm in diameter. However, it is technologically challenging to realize reproducible bottom-up devices on a large scale for clinical biosensing applications. The top-down approach involves state-of-the-art lithography and nanofabrication techniques to cast SiNW down to a few 10s of nanometers in diameter out of high-quality Silicon-on-Insulator (SOI) wafers in a controlled environment, enabling the large-scale fabrication of sensors for a myriad of applications. The possibility of their wafer-scale integration in standard semiconductor processes makes SiNW-FETs one of the most promising candidates for the next generation of biosensor platforms for applications in healthcare and medicine. Although advanced fabrication techniques are employed for fabricating SiNW, the sensor-to-sensor variation in the fabrication processes is one of the limiting factors for a large-scale production towards commercial applications. To provide a detailed overview of the technical aspects responsible for this sensor-to-sensor variation, we critically review and discuss the fundamental aspects that could lead to such a sensor-to-sensor variation, focusing on fabrication parameters and processes described in the state-of-the-art literature. Furthermore, we discuss the impact of functionalization aspects, surface modification, and system integration of the SiNW-FET biosensors on post-fabrication-induced sensor-to-sensor variations for biosensing experiments.

Silicon Nanowires Length and Numbers Dependence on Sensitivity of the Field-Effect Transistor Sensor for Hepatitis B Virus Surface Antigen Detection

“…The second type is the top-down method, in which photolithography and etching equipment for semiconductor manufacturing are used to define the dimensions and shape of the materials [ 13 ]. This process ensures control of the position of the nanowires, thereby facilitating mass production of nanowires of consistent quality [ 14 , 15 ]. However, because of the small size of nanowires, advanced photolithography equipment is required, which increases the fabrication costs [ 16 ].…”

Degradation Study of Thin-Film Silicon Structures in a Cell Culture Medium

“…In addition, micropatterned 1D, 2D, and 3D Si structures are attractive, label-free, and scalable sensing platforms, owing to their distinctive optical and/or electrical properties and high surface-to-volume ratio, which make them broadly interesting for biomedical applications in healthcare scenarios [ 2 , 3 , 4 ]. For example, Si pillars or nanowire field-effect transistors have been promisingly developed as potentiometric sensor devices for detecting a copious number of chemical and biological species, such as ions, DNA, proteins, and antibodies/antigens [ 5 , 6 , 7 ]. Other remarkable examples include the development of neural modulators [ 8 , 9 ], scaffolds [ 10 , 11 , 12 ], and implantable energy harvesters [ 13 , 14 ].…”

The Effect of Incubation Near an Inverted Pyramidal Structure on Adsorption Properties of an Enzyme

“…Single-molecule enzymology, focusing on studying single enzyme molecules instead of their large ensembles, becomes an increasing popularity [1,2]. This approach utilizes so-called molecular detectors, which allow the researchers to investigate enzymes with ultra-high sensitivity [3]: atomic force microscopes [4][5][6][7], nanoelectronic detectors [8][9][10][11], nanopore-based sensors [12][13], total internal re ection microscopes [2] etc.…”