Silicon/Porous Silicon (Si/PS) composite membranes can be fabricated by converting a part of the silicon membrane thickness into porous silicon (PS) with electrochemical etching in HF based electrolyte. In this paper we discuss the performance of composite membranes with MacroPS for pressure sensors. The sensitivity of the composite membrane is found to be higher compared to silicon and improves with the increase in the porosity due to the drastic reduction in Young's Modulus of PS with porosity. The sensor response is found to be linear for pressures below 1 bar. PS formation produces stress in the membrane raising the offset voltage in the pressure sensors. © 2007 IEEE.

Enakshi Bhattacharya

Department of Electrical Engineering

electric conductivity

Membranes

Molecular beam epitaxy

Nonmetals

Optical design

Porous silicon

Pressure sensors

PRESSURE TRANSDUCERS

Semiconducting Silicon Compounds

Semiconductor device manufacture

Semiconductor device models

Semiconductor devices

Semiconductor materials

Semiconductor switches

Sensors

Silicon

MEMS

Offset voltage

POROUS SILICON (PS)

Pressure sensor

PS FORMATION

Sensor responses

SILICON MEMBRANES

Stress

Young's Modulus

Composite membranes

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Sensitivity and stress in pressure sensors with composite silicon/macroporous silicon membranes

Proceedings of the 14th International Workshop on the Physics of Semiconductor Devices, IWPSD

Porous silicon (PS) has many interesting and unique properties that make it a viable material in the field of MEMS. In this paper, we investigate the application of PS in improving the sensitivity of bulk micromachined piezoresistive pressure sensors. The property of a low Young's modulus of PS and its dependence on porosity have been exploited to obtain a higher sensitivity compared to pressure sensors with single crystalline silicon membranes. Simulation was carried out to represent the Si/PS composite membrane by two layers with Young's modulus corresponding to silicon and PS. The behavior of this membrane was studied for various values of porosity and thickness of the PS layer. Composite Si/PS membranes were fabricated by converting a part of the silicon membrane thickness into PS by electrochemical etching in an HF-based electrolyte. Polysilicon piezoresistors were formed on the membrane in the form of a Wheatstone bridge for the measurement of sensitivity. When compared to membranes of silicon, the sensitivity of the composite Si/PS membrane is found to be higher showing improvement with an increase in the porosity and thickness of the PS layer. © 2007 IOP Publishing Ltd.

Journal of Micromechanics and Microengineering

Enhancement of the sensitivity of pressure sensors with a composite Si/porous silicon membrane

Materials Science and Engineering: R: Reports

Formation and application of porous silicon

Thin Solid Films

Lattice-mismatch induced-stress in porous silicon films

Journal of Porous Materials

10.1023/a:1009690521403

Journal	Proceedings of the 14th International Workshop on the Physics of Semiconductor Devices, IWPSD
Open Access	No