Open AccessReactive ion beam etching of piezoelectric ScAlN for bulk acoustic wave device applications
Author(s) -
Richard D. James,
Yannick Pilloux,
Hemant Hegde
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1407/1/012083
Subject(s) - materials science , etching (microfabrication) , photoresist , surface acoustic wave , reactive ion etching , scandium , optoelectronics , piezoelectricity , surface roughness , nanotechnology , optics , composite material , physics , layer (electronics) , metallurgy
Etching piezoelectric Scandium Aluminum Nitride (ScAlN) films containing a high concentration of Scandium with controllable feature profile angle and smooth surface is needed for next-generation Bulk Acoustic Wave (BAW) RF filter applications. This paper reports the facile etching of ScAlN with Scandium concentration of up to 15% using Reactive Ion Beam Etching (RIBE) with a very smooth surface of less than 5 nm average roughness and profile angle between 60 to 80 degrees. Recent studies show that doping AlN with a high concentration of Sc increases the piezoelectric response by five times and the bandwidth of RF filters also improved. However, etching ScAlN with a high concentration of Sc using traditional RIE and ICP based methods are extremely difficult and often results in low etch rate and rough surface. We have developed RIBE processes using a mixture of Reactive Gas and Ar with highly controllable profile angle from 60 to 80 degrees, improved etch rate (~ 36nm/min) and selectivity to photoresist mask (0.7:1), in comparison to conventional IBE. This work has positive implications in fabricating ScAlN based BAW RF filters for next-generation mobile and wireless applications.