Aluminum scandium nitride thin-film bulk acoustic resonators for wide band applications

• Published in: Vacuum 2011-07, Vol.86 (1), p.23-26
• Main Authors: Moreira, Milena, Bjurström, Johan, Katardjev, Ilia, Yantchev, Ventsislav
• Format: Article
• Language: English
• Subjects: Acoustic microwave devices; Acoustics; Aluminum; Composite thin films; Engineering Science with specialization in Electronics; Joining; Piezoelectricity; Radio frequencies; Resonators; Scandium; TECHNOLOGY; TEKNIKVETENSKAP; Teknisk fysik med inriktning mot elektronik; Thin film devices; Thin films
• ISSN: 0042-207X; 1879-2715; 1879-2715
• DOI: 10.1016/j.vacuum.2011.03.026

Piezoelectric c-textured Al (1− x) Sc x N thin films, where the Sc relative concentration, x, varies in the range 0–0.15 have been studied in view of radio frequency (RF) electro-acoustic applications. Thin film bulk acoustic wave resonators (FBARs) employing these films were fabricated and characterized as a function of the Sc concentration for the first time. The measured electromechanical coupling is found to increase by as much as 100% in the above concentration range. The results from this work underline the potential of the c-textured Al (1− x) Sc x N based FBARs for wide band RF applications. ► Thin film bulk acoustic resonators (FBAR) employing highly c-textured Al (1− x) Sc x N thin films are found promising for radio frequency (RF) band applications. ► Electromechanical coupling increases by factor of two for relative Sc concentration up to 20%. ► Resonator figure of merit exhibit a maximum at relative Sc concentration of 9%. ► Accordingly wide bandwidth RF filters with low losses and steep skirts can be build using this technology.