Residual stress study of thin films deposited by atomic layer deposition

Atomic layer deposition (ALD) has been widely used in microelectromechanical systems (MEMS) due to its unique advantages, e.g. precise film thickness control, high uniformity and superb conformality. The understanding of ALD film's mechanical properties is important for MEMS device design and fabrication. In this work, the studied thin films (Al<inf>2</inf>O<inf>3</inf> and Al<inf>2</inf>O<inf>3</inf>/TiO<inf>2</inf> laminates) were deposited by thermal ALD (THALD) and plasma-enhanced ALD (PEALD). The film growth behavior was determined by ellipsometry, and the residual stress was analyzed by wafer curvature measurements. We extracted a low residual stress near 100 MPa for Al<inf>2</inf>O<inf>3</inf> and Al<inf>2</inf>O<inf>3</inf>/TiO<inf>2</inf> laminates. A clear correlation was found between the film's process conditions (parameters and configurations) and residual stress.

[1]  Pascale Mazoyer,et al.  Evolution of materials technology for stacked-capacitors in 65 nm embedded-DRAM , 2005 .

[2]  G. Dingemans,et al.  Influence of the Deposition Temperature on the c-Si Surface Passivation by Al2O3 Films Synthesized by ALD and PECVD , 2010 .

[3]  Sun Jin Yun,et al.  Electrical Properties of Alumina Films by Plasma-Enhanced Atomic Layer Deposition , 2004 .

[4]  S. Yun,et al.  Investigation of a Two-Layer Gate Insulator Using Plasma-Enhanced ALD for Ultralow Temperature Poly-Si TFTs , 2004 .

[5]  Steven M. George,et al.  Atomic-layer deposition of wear-resistant coatings for microelectromechanical devices , 2003 .

[6]  T. Hecht,et al.  Mechanical stress in ALD-Al2O3 films , 2005 .

[7]  T. Sajavaara,et al.  Aluminum oxide/titanium dioxide nanolaminates grown by atomic layer deposition: Growth and mechanical properties , 2017 .

[8]  Wmm Erwin Kessels,et al.  Surface chemistry of plasma-assisted atomic layer deposition of Al2O3 studied by infrared spectroscopy , 2008 .

[9]  E. Cartier,et al.  Ultrathin high-K metal oxides on silicon: processing, characterization and integration issues , 2001 .

[10]  Helena Ronkainen,et al.  Aluminum oxide from trimethylaluminum and water by atomic layer deposition: The temperature dependence of residual stress, elastic modulus, hardness and adhesion , 2014 .

[11]  Hannu Kattelus,et al.  Implementing ALD Layers in MEMS Processing , 2007, ECS Transactions.

[12]  A. Krause,et al.  Successive reactions of gaseous trimethylaluminium and ammonia on porous alumina , 2001 .

[13]  G. D. Wilka,et al.  APPLIED PHYSICS REVIEW High- k gate dielectrics: Current status and materials properties considerations , 2001 .

[14]  Wmm Erwin Kessels,et al.  Plasma and thermal ALD of Al2O3 in a commercial 200 mm ALD reactor , 2007 .

[15]  S. Franssila,et al.  Fracture properties of atomic layer deposited aluminum oxide free-standing membranes , 2015 .

[16]  G. Stoney.  The Tension of Metallic Films Deposited by Electrolysis , 1909 .