9:30 AM - 11:30 AM
▲ [15a-PB3-9] Fabrication and Characterization of N-MOSFET-based Cantilever Sensors for Molecular Detection
Keywords:Microcantilever, MOSFET, Sensor
MOSFET (metal oxide semiconductor field effect transistor)-based cantilevers offer improved performance of cantilever-based sensor due to their sensitivity to local stress at the channel surface and their better noise properties. The basic principle of MOSFET-based cantilever detection is based on the change of surface stress due to molecular adsorption, resulting in strain in the MOSFET channel and change of drain current.
In this work, two types of N-MOSFET were designed on the top of identical cantilevers (400 x 95 um), i.e., U-shaped channel (width/length ratio of 10 um/5 um) with parallel direction to the cantilever (MEC 1) and single-channel (width/length ratio of 50 um/5 um) with non-parallel direction to the cantilever (MEC 2). The N-MOSFET-based cantilevers were fabricated on a 500 nm SOI wafer by combining CMOS standard process and bulk micromachining process whereas a drain current-drain voltage (ID-VD) characteristic of the MOSFETs was measured using semiconductor characterization system integrated with a probe station to make direct contacts to Al pads on the wafer. A micrograph of the N-MOSFET-based cantilever devices is shown in Fig. 1.
The deflection of the N-MOSFET-based cantilever was observed by ethanol vapor exposure. As a result, the drain current of both MOSFET types decreased, indicating the cantilever deflection when exposed by ethanol. The higher drain current change was reached by MEC 2 (Fig. 2) which indicated the higher sensitivity for MEC 2.
A part of this research is based on the Cooperative Research Project of Research Center for Biomedical Engineering.
Fig. 1. A micrograph of N-MOSFET-based cantilever devices. MEC 1 and MEC 2 indicate U-shaped and single-channel type of MOSFET, respectively. Fig. 2. ID-VD characteristic of the MEC 2 before (black line) and after (red line) ethanol exposure.
In this work, two types of N-MOSFET were designed on the top of identical cantilevers (400 x 95 um), i.e., U-shaped channel (width/length ratio of 10 um/5 um) with parallel direction to the cantilever (MEC 1) and single-channel (width/length ratio of 50 um/5 um) with non-parallel direction to the cantilever (MEC 2). The N-MOSFET-based cantilevers were fabricated on a 500 nm SOI wafer by combining CMOS standard process and bulk micromachining process whereas a drain current-drain voltage (ID-VD) characteristic of the MOSFETs was measured using semiconductor characterization system integrated with a probe station to make direct contacts to Al pads on the wafer. A micrograph of the N-MOSFET-based cantilever devices is shown in Fig. 1.
The deflection of the N-MOSFET-based cantilever was observed by ethanol vapor exposure. As a result, the drain current of both MOSFET types decreased, indicating the cantilever deflection when exposed by ethanol. The higher drain current change was reached by MEC 2 (Fig. 2) which indicated the higher sensitivity for MEC 2.
A part of this research is based on the Cooperative Research Project of Research Center for Biomedical Engineering.
Fig. 1. A micrograph of N-MOSFET-based cantilever devices. MEC 1 and MEC 2 indicate U-shaped and single-channel type of MOSFET, respectively. Fig. 2. ID-VD characteristic of the MEC 2 before (black line) and after (red line) ethanol exposure.