A 3-D-Silicon Nanowire FET Biosensor Based on a Novel Hybrid Process

Single-silicon nanowire field-effect transistor (SiNW-FET) devices are powerful tools for the detection and quantification of biochemical molecules. However, traditional SiNW-FET-based biosensors demonstrate low output signals and high fluctuation noises, which results from the tiny scale of a single channel and electrical property deterioration caused by the dry etching process. To improve the performance of the SiNW-FET biosensors, here we developed a 3-D-SiNW-FET by using a hybrid process of deep reactive ion etching and isotropic wet etching with HF, HNO3 and HAc (HNA) mixed solution. The 3-D-SiNW-FET that included 5 × 7 nanowire channels with a wire diameter of approximately 300 nm was successfully fabricated with the novel hybrid process. Compared with the performance of single-and 2-D-SiNW-FETs, the 3-D-SiNW-FET showed a fairly good ability to stabilize and enhance the source-drain current by parallelizing the signals of the multiple channels. With the fabricated 3-D-SiNW-FET, immunoglobulin G was detected at a concentration as low as 5 fM.