Mechanical Characteristics and Temperature Effect of a Field-effect Transistor Microcantilever Sensor
Date Issued
2011
Date
2011
Author(s)
Cheng, Yung-Jen
Abstract
In recent year, with the development of biotechnology and microsystems, the aging society is gradually coming. Portable biosensors offer advantages over conventional instruments on miniaturization, label-free feature, portability, real-time rapid diagnosis, and potential low cost, showing the direction of research and development.
This study successfully utilized thin-film transistor(TFT) as a sensing transducer to convert induced stresses of a microcantilever(MCL) sensor. The thin-film transistor–based microcantilever(TFT-based MCL) was fabricated by semiconductor and micro-electromechanical system(MEMS) fabrication technology. Meanwhile, the mobility of the TFT device was measured to be 30~34 cm2/Vs, and the sensitivity of TFT-based MCL device was 0.034 μA/μm. For sensing purpose of the TFT-based MCL sensor, the device was very sensitive to temperature effect, which induced a result of a considerable current change. The sensitivity of the TFT-based MCL for temperature to saturation current was measured to be 0.6 μA/℃. In addition, the temperature effect induced changes of mobility and threshold voltage simultaneously. By the test of ID-VD with respect to temperature effect, five major factors were found to play considerable roles in the TFT-based MCL, including temperature coefficient of resistance of 74%, bimorph effect of about 1%, heat dissipation of 9%, and initial residual stress deformation-induced variation of temperature effect of 15%.
Finally, this study utilized a fixed TFT on a substrate as temperature sensor for thermal effect compensation to eliminate the temperature effect of the TFT-based MCL. The temperature feedback has been proved to demonstrate the device with a large scale of temperature variation. As a result, the TFT-based MCL sensor has been expected for biochemical detection with the elimination of temperature-sensitive effect.
Subjects
Microcantilever
Thin-film transistor (TFT)
Micro-electromechanical system (MEMS)
Temperature effect
Temperature coefficient of resistance (TCR)
surface stress
Type
thesis
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