Title :
Young´s Modulus Measurements in Standard IC CMOS Processes Using MEMS Test Structures
Author :
Marshall, Janet C. ; Herman, David L. ; Vernier, Thomas P. ; DeVoe, Don L. ; Gaitan, Michael
Author_Institution :
Nat. Inst. of Stand. & Technol., Gaithersburg
Abstract :
This letter1 presents a method to measure the Young´s moduli of individual thin-film layers in a commercial integrated circuit (IC) foundry process. The method is based on measuring the resonance frequency of an array of micromachined cantilevers and using the presented optimization analysis to determine the elastic modulus of each layer. Arrays of cantilever test structures were fabricated in a commercial CMOS IC process and were released using XeF2 as a postprocessing etch. A piezoelectric transducer placed under the test chip was used to excite the cantilevers to resonance, and the resonance frequency was measured using a laser Doppler vibrometer. It is reported that excellent agreement for values of Young´s modulus is observed for cantilevers between 200 and 400 mum in length, with average standard deviation being 4.07 GPa.
Keywords :
CMOS integrated circuits; Young´s modulus; cantilevers; micromechanical devices; optimisation; piezoelectric transducers; vibration measurement; xenon compounds; IC CMOS process; MEMS test structures; XeF2 - Binary; Young´s modulus measurements; elastic modulus; integrated circuit foundry process; laser Doppler vibrometer; micromachined cantilevers; optimization analysis; piezoelectric transducer; resonance frequency measurement; thin film layers; CMOS integrated circuits; CMOS process; Circuit testing; Frequency measurement; Integrated circuit measurements; Integrated circuit testing; Measurement standards; Micromechanical devices; Resonance; Resonant frequency; CMOS; MEMS; Young´s modulus; residual stress; resonance; test structures; thickness measurements;
Journal_Title :
Electron Device Letters, IEEE
DOI :
10.1109/LED.2007.906460
