Visible to the public Single Crystalline Scandium Aluminum Nitride: An Emerging Material for 5G Acoustic Filters

TitleSingle Crystalline Scandium Aluminum Nitride: An Emerging Material for 5G Acoustic Filters
Publication TypeConference Paper
Year of Publication2019
AuthorsAnsari, Azadeh
Conference Name2019 IEEE MTT-S International Wireless Symposium (IWS)
Keywords5G acoustic filters, 5G mobile communication, 5G resonators, acoustic coupling, acoustic filters, acoustic resonators, AlN, aluminium compounds, Aluminum Nitride, bulk acoustic wave devices, bulk acoustic wave resonators, electromechanical coupling, emerging material, Film bulk acoustic resonators, film thickness, filter bandwidth, filtering applications, form factor, frequency 3.0 GHz to 10.0 GHz, high crystal quality, high electromechanical coupling, high-performance filters, high-quality single-crystalline, Human Behavior, III-V semiconductors, material candidate, next generation wireless communication devices, operation frequencies, Piezoelectric devices, piezoelectric material needs, piezoelectric materials, pubcrawl, Q-factor, quality factors, Resiliency, RF front-end, SC, Scalability, scandium, scandium compounds, Scandium Doping, semiconductor growth, Si, Single Crystalline, single-crystal, size 400.0 nm, sputter deposition, sputtering techniques, steep skirts, sub-micron ranges, surface acoustic wave devices, thin films, ultra-thin films, wide band gap semiconductors
AbstractEmerging next generation wireless communication devices call for high-performance filters that operate at 3-10 GHz frequency range and offer low loss, small form factor, wide bandwidth and steep skirts. Bulk and surface acoustic wave devices have been long used in the RF front-end for filtering applications, however their operation frequencies are mostly below 2.6 GHz band. To scale up the frequency of the filters, the thickness of the piezoelectric material needs to be reduced to sub-micron ranges. One of the challenges of such scaling is maintaining high electromechanical coupling as the film thickness decreases, which in turn, determines the filter bandwidth.Aluminum Nitride (AlN) - popular in today's film bulk acoustic resonators (FBARs) and mostly deposited using sputtering techniques-shows degraded crystal quality and poor electromechanical coupling when the thickness of AlN film is smaller than 1 mm.In this work, we propose using high-quality single-crystalline AlN and Scandium (Sc)-doped AlN epi-layers grown on Si substrates, wherein high crystal quality is maintained for ultra-thin films of only 400 nm thickness. Experimental results verify improved kt2 for 3-10 GHz resonators, with quality factors of the order of 250 and kt2 values of up to 5%based on bulk acoustic wave resonators. The experimental results suggest that single-crystal Sc-AlN is a great material candidate for 5G resonators and filters.
Citation Keyansari_single_2019