Low stress atomic layer deposited alumina for nano electro mechanical systems

A new fabrication process, test structures, and measurements of material properties are presented for atomic layer deposited (ALD) alumina (Al₂O₃) nanoelectromechanical systems (NEMS). ALD Al₂O₃ has similar electrical and mechanical properties to silicon nitride (Si_xN_y) and can be used in many of the same applications. Yet ALD Al₂O₃ is an advantageous material to use over Si_xN_y due to the low deposition temperature, which allows for integration with CMOS processing. Also, ALD Al₂O₃ has a high chemical resistance to Si etchants. In this work the stress in ALD Al₂O₃ is measured to be σ=401±32 MPa and σ=445±66 MPa for 100 nm and 50 nm thick Al₂O₃ films, respectively. The measured Young´s modulus is in the range of 110-120 GPa.