Performance Improvisation of Cantilever-type Silicon Micro Acceleration Sensors Using Stress Concentration Regions Technique

Acceleration sensors find applications in missile and competent munitions subsystems. Cantilever-type sensor's sensitivity and bandwidth are dependant on material properties of the cantilever and structure of proof mass. It is always desired to design a sensor as sensitive as possible but also maintaining higher bandwidth. In piezoresistive (cantilever-type) accelerometers, various techniques were employed by designers to enhance their sensitivity and bandwidth. Most of these techniques are usually focused on shape and size of either cantilever or proof mass. This paper presents a concept of creating stress concentration regions (SCRs) on the cantilever for enhancing its sensitivity. Five types of structures were simulated to study the behaviour of piezoresistive sensors with SCRs implementation. Use of SCRs results in substantial increase in the sensitivity, which is of the order of 1.85 times the nominal sensitivity. It was aimed at maximising sensor's performance factor, which is the product of sensor bandwidth and sensitivity. This study gives new dimension to the ways of improving performance of cantilevertype inertial piezoresistive sensor.

β

Piezoresistance doping factor (max. 1)

Nominal stress

Stress at section B

Poison's ratio

Longitudinal piezoresistive coefficient

Piezoresistive coefficients

Piezoresistive coefficient of silicon

Transverse piezoresistive coefficient

Change in current

Change in resistance

Longitudinal stress

Transverse stress

Major axis

Minor axis

Piezoresistor area

Applied acceleration

Current

Stress concentration factor

Resistance

Resistance of the piezoresistor

Sensitivity

Radius of curvature