Acta Mech Sin (2009) 25:197–203 DOI 10.1007/s10409-008-0193-7 RESEARCH PAPER Fracture mechanics analysis on Smart-Cut ® technology. Part 2: Effect of bonding flaws Bin Gu · Hongyuan Liu · Yiu-Wing Mai · Xi Qiao Feng · Shou Wen Yu Received: 16 April 2008 / Revised: 3 July 2008 / Accepted: 7 July 2008 / Published online: 16 September 2008 © The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH 2008 Abstract In Part 2 of the paper on the Smart-Cut process, the effects of bonding flaws characterized by the size and internal pressure before and after splitting are studied by using fracture mechanics models. It is found that the bon- ding flaws with large size are prone to cause severe devia- tion of defect growth, leading to a non-transferred area of thin layer when splitting. In a practical Smart-Cut process where the internal pressure of bonding flaws is very small, large interfacial defects always promote defect growth in the splitting process. Meanwhile, increasing the internal pres- sure of the bonding flaws decreases the defect growth and its deviation before splitting. The mechanism of relaxation of stiffener constraint is proposed to clarify the effect of bon- ding flaws. Moreover, the progress of the splitting process is analyzed when bonding flaws are present. After splitting, those bonding flaws with large size and high internal pres- sure are vulnerable for the blistering of the thin film during high-temperature annealing. The project supported by the Australian Research Council (ARC), the National Natural Science Foundation of China (10525210 and 10732050) and 973 Project (2004CB619303). BG, HYL, and YWM are, respectively, Postdoctoral Fellow, Research Fellow, and Federation Fellow supported by the ARC and tenable at the University of Sydney. B. Gu (B ) · H. Liu · Y.-W. Mai Centre for Advanced Materials Technology (CAMT), School of Aerospace, Mechanical and Mechatronic Engineering (AMME) J07, University of Sydney, Sydney, NSW 2006, Australia e-mail: bgu@usyd.edu.cn X. Q. Feng (B ) · S. W. Yu Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China e-mail: fengxq@tsinghua.edu.cn Keywords Smart-Cut technology · Fracture mechanics · Stress intensity factor · Interfacial defect 1 Introduction As stated in Part 1 of the paper, defect nucleation and growth induced by hydrogen ion implantation and high-temperature annealing in the Smart-Cut process have been research prio- rities in the past decade. Many experimental studies and a few theoretical and quantitative analyses were particularly conducted on these two aspects of the Smart-Cut technology [1–14]. Smart-Cut technique takes the advantages of ion implan- tation to split the thin film and of wafer bonding to com- bine the thin film with another substrate. However, so far few research efforts have been directed towards the effect of wafer bonding in the Smart-Cut process. Bruel [1] showed that the requirements for successful wafer bonding inclu- ded suitable hydrophilicity of both wafers to make the inti- mate contact possible at room temperature, and high bonding energy to sustain low/medium temperature annealing. Aspar and Maleville et al. [2, 15] found that depending on their sizes, the bonding flaws arising mainly from particle conta- mination could cause different damage to the SOI structure. Large interfacial defects induce the loss of local stiffeners and result in areas without any SOI transferred. Conversely, small interfacial defects will not fail the stiffener effect but may inflate during annealing thus leading to plastic deforma- tion on the SOI surface. Also, it was concluded by Bengtesson [16] that the quality of wafer bonding relied on the surface micro-roughness, wafer dimensions, ambient pressure and surface chemistry. Feng et al. [13] suggested using the ion cut method to directly carve three-dimensional surface mor- phology with the aid of a specialized metal mask. 123