P1J-9 Aluminum-Nitride Manufacturing Solution for BAW and other MEMS Applications Using a Novel, High-Uniformity PVD Source

The growing number of Bulk Acoustic Wave (BAW) applications and the need to reduce the price per device drives equipment manufacturers to improve their related thin-film processes, lowering the cost of ownership of their tools by increasing overall device yield. In this paper, details of how the piezoelectric AlN film thickness uniformity and stress can be controlled over sputter target life are presented. Electrical measurements on single BAW resonators and filters fabricated on 150 mm and 200 mm wafers show that the presented solution yields frequency uniformities ²
> 6% and filter insertion losses of better than -2 dB over the entire wafer diameter with a very narrow edge exclusion. This work reports further on the piezoelectric activity of the deposited AlN layers both in terms of the d
_33,f
effective inverse piezoelectric coefficient and e
_31,f
effective transverse piezoelectric coefficient, with values equal to 5.2 pmmiddotV
^-1
and -1.35 C/m
²
respectively, at 2 mum AlN film thickness measured on a Mo underlayer