Highly Doped AlScN 3.5 GHz XBAW Resonators with 16% k2eff for 5G RF Filter Applications

Abstract

The authors report 3.5 GHz bulk acoustic wave resonators with an observed k<;span style="font-size: 14.5px;"> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <;/span> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> in the range of 14.2 to 16%, which the authors believe to be amongst the highest reported for a Sc mole fraction of 28%. The measured Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> is as high as 951 at 3.5 GHz, which is 3.8 times higher than recently reported for resonators at comparable Sc mole fractions. A high Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> of 1070 combined with the high k<;span style="font-size: 14.5px;"> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <;/span> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff </sub> achieves the highest reported FOM at 158 for a Sc mole fraction of 28%. Furthermore, randomly selected 3.5 GHz devices mounted on evaluation PCB boards were power tested and damaged at CW power levels between +40 dBm and +41.5 dBm, indicating high power performance capability.