IEC 62047-30:2017 pdf download

IEC 62047-30:2017 pdf download.Semiconductor devices – Micro-electromechanical devices – Part 30: Measurement methods of electro-mechanical conversion characteristics of MEMS piezoelectric thin film
1 Scope
This part of IEC 62047 specifies measuring methods of electro-mechanical conversion characteristics of piezoelectric thin film used for micro sensors and micro actuators, and its reporting schema to determine the characteristic parameters for consumer, industry or any other applications of piezoelectric devices. This document applies to piezoelectric thin films fabricated by MEMS process.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp 3.1 unimorph beam beam composed of piezoelectric thin film on substrate 3.2 direct transverse piezoelectric coefficient transverse piezoelectric coefficient of the piezoelectric thin film calculated from generated charge or voltage caused by strain or stress 3.3 converse transverse piezoelectric coefficient transverse piezoelectric coefficient of the piezoelectric thin film calculated from strain or stress caused by electric field or voltage
4 Test bed of MEMS piezoelectric thin film
4.1 General These measuring methods of the transverse piezoelectric properties apply to the unimorph beam. Symbols and designations of test bed are shown in Table 1 .4.2.4 Displacement meter The displacement meter measures the tip displacement of the cantilever. 4.2.5 Electric measurement instrument In measurements of direct piezoelectric effect, the thin film under testing generates electric output between electrodes. An electric measurement instrument (i.e. voltmeter, charge meter, ammeter, oscilloscope, or lock-in amplifier) measures the generated voltage, charge or current synchronizing with the displacement by the linear actuator. 4.2.6 Power source In measurements of converse piezoelectric effect, the power source applies an electric input signal between the top and bottom electrodes. The input sinusoidal signal from the function generator is amplified by the power amplifier.
5 Thin film under testing
5.1 General The top surface of the MEMS piezoelectric thin film is coated with a top electrode to measure output voltage in direct transverse coefficient measurement, or to provide input voltage in converse piezoelectric coefficient measurement. The thickness of the base material of the unimorph beam shall be much larger than that of the thin film under testing, typically at least 1 00 times, in order to approximate the neutral plane of the unimorph beam to be the half of the substrate thickness. The theoretical equation of the neutral plane is described in Clause A.5 (this approximation is used in the Stoney’s formula). Generally, the thickness of the electrodes should be much smaller than that of the thin film under testing. In the case of ferroelectric thin films, a poling treatment is indispensable to align the polar direction and maximize their piezoelectric characteristics.5.3 Measuring procedures of direct transverse piezoelectric coefficient The measuring procedures consist in the following steps: a) measure the ambient temperature and relative humidity; b) clamp one end of the unimorph beam with the thin film under testing to make a cantilever; c) set the linear actuator to the tip of the cantilever and vibrate the tip of the cantilever with triangular wave; d) measure the displacement of the tip of the cantilever; e) measure the output voltage of the thin film under testing. 5.4 Measuring procedures of converse transverse piezoelectric coefficient The measuring procedures consist in the following steps: a) measure the ambient temperature and relative humidity; b) clamp one end of the unimorph beam with the thin film under testing to make a cantilever; c) apply unipolar sinusoidal voltage to the thin film under testing to vibrate the cantilever; application voltage is in the same direction as for the poling treatment if poling treatment is done to the specimen; d) measure the input voltage to the thin film under testing; e) measure the displacement of the tip of the cantilever;