Etch Rates for Micromachining Processing

When designing a microfabrication process, the etch rate of each material to be etched must be known. Knowing the etch rates of other materials that will be exposed to the etch, such as masking films and underlying layers, enables an etch process to be chosen for good selectivity (high ratio of etch rate of the target material to etch rate of the other material)—if one exists. These two papers compare the etch rates of different materials in various etchants

K. R. Williams and R. S. Muller, "Etch rates for micromachining processing," in Journal of Microelectromechanical Systems, vol. 5, no. 4, pp. 256-269, Dec 1996.

K. R. Williams, K. Gupta and M. Wasilik, "Etch rates for micromachining processing-Part II," in Journal of Microelectromechanical Systems, vol. 12, no. 6, pp. 761-778, Dec. 2003.
doi: 10.1109/JMEMS.2003.820936

Etch rates for Micromachining Processing - Part 1

Etch rates for Micromachining Processing - Part 2

2D thermal MEMS accelerometer

A 2D thermal MEMS accelerometer uses a monolithic approach that integrates the sensor and electronics onto the IC which is then hermetically sealed in a package. The silicon die includes a heating element and thermopiles suspended over a cavity etched into the die. Instead of using capacitance to measure force, the thermal sensor uses the movement of the heated gas molecules to detect acceleration. With acceleration, the heated molecules move in the direction of acceleration, and with zero acceleration the heated gas is symmetrical above the heater. These devices have no flexing or moving parts, which make them more durable and delivers very high measurement repeatability.

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SiliconMicromachined Pressure Sensors - a Review

Silicon micromachining for realizing micro mechanical structures has received considerable interest due to the several advantages of this technology over the conventional machining techniques. Silicon pressure sensors were the first micro mechanical transducers developed. Since then the market for micromachined pressure sensors has grown in leaps and bounds and found application in all walks of life including defense and space applications. The relevant micromachining technology and the design considerations are reviewed in this paper. The paper also gives the latest developments in this area and gives the details of the polysilicon piezoresistor based pressure sensors with Silicon On Insulator (SOI) approach for integrating pressure sensor and associated electronics.

Prof. K.N. Bhat, IISC Bangalore

SiliconMicromachined Pressure Sensors

MEMS actuators and sensors: observations on their performance and selection for purpose

D J Bell, T J Lu, N A Fleck and S M Spearing

This paper presents an exercise in comparing the performance of microelectromechanical systems (MEMS) actuators and sensors as a function of operating principle. Data have been obtained from the literature for the mechanical performance characteristics of actuators, force sensors and displacement sensors. On-chip and off-chip actuators and sensors are each sub-grouped into families, classes and members according to their principle of operation. The performance of MEMS sharing common operating principles is compared with each other and with equivalent macroscopic devices. The data are used to construct performance maps showing the capability of existing actuators and sensors in terms of maximum force and displacement capability, resolution and frequency. These can also be used as a preliminary design tool, as shown in a case study on the design of an on-chip tensile test machine for materials in thin-film form.

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MEMS actuators and sensors: observations on their performance and selection for purpose