Characterization and Control of Residual Stress and Curvature in Anodically Bonded Devices and Substrates with Etched Features

While anodic bonding is commonly used in a variety of microelectromechanical systems (MEMS) applications, devices and substrates that incorporate this processing technique are often subjected to significant residual stress and curvature that create post-processing and reliability issues. Here, using an anisothermal anodic bonding procedure, residual stresses and the resulting wafer curvature in these structures are controlled by varying the initial bond temperatures of the silicon and Pyrex wafers independently. Residual stresses are quantified by measuring bulk wafer curvature and, locally, stress concentrations are measured using infrared photoelasticity accompanied by 3-D thermomechanical finite element analysis. Based on the good agreement between numerical predictions and experimental results, this process can be used to determine the bulk post-bond wafer curvature and to reduce the likelihood of structural failure at these sites, by changing the residual stresses from tensile in nature, which may drive initiation and growth of cracks, to compressive, which can suppress such failures.

[1]  S. Spearing,et al.  Controlling and Testing the Fracture Strength of Silicon on the Mesoscale , 2000 .

[2]  M. Harz,et al.  Curvature changing or flattening of anodically bonded silicon and borosilicate glass , 1996 .

[3]  Green,et al.  Crack Arrest and Multiple Cracking in Glass Through the Use of Designed Residual Stress Profiles. , 1999, Science.

[4]  Kevin T. Turner,et al.  Modeling of direct wafer bonding: effect of wafer bow and etch patterns , 2002 .

[5]  M. Schmidt.  Wafer-to-wafer bonding for microstructure formation , 1998, Proc. IEEE.

[6]  David J. Green,et al.  Compressive surface strengthening of brittle materials , 1984 .

[7]  Zhiliang Zhang,et al.  Fracture of anodic-bonded silicon-thin film glass-silicon triple stacks , 2008 .

[8]  D. J. Green,et al.  Crack Stability and T‐Curves Due to Macroscopic Residual Compressive Stress Profiles , 1991 .

[9]  B. Puers,et al.  Characterization of the electrostatic bonding of silicon and Pyrex glass , 1995 .

[10]  Michael V. Swain,et al.  Microfracture beneath point indentations in brittle solids , 1975 .

[11]  S. Cunningham,et al.  Initiation toughness of silicon/glass anodic bonds , 2000 .

[12]  Removal of Photoresist Film Residues from Wafer Surfaces , 1979 .

[13]  M. Trinczek,et al.  Novel technique for high-precision Bragg-angle determination in crystal x-ray spectroscopy , 2005 .

[14]  Y. Chu,et al.  Detection and Quantification of Surface Nanotopography-Induced Residual Stress Fields in Wafer-Bonded Silicon , 2008 .

[15]  T Rogers,et al.  Considerations of anodic bonding for capacitive type silicon/glass sensor fabrication , 1992 .

[16]  Michael Harz,et al.  Stress Reduction in Anodically Bonded Silicon and Borosilicate Glass by Thermal Treatment , 1996 .

[17]  P. Barth,et al.  A monolithic silicon accelerometer with integral air damping and overrange protection , 1988, IEEE Technical Digest on Solid-State Sensor and Actuator Workshop.

[18]  Thomas J. Mackin,et al.  Trapped particle detection in bonded semiconductors using gray-field photoelastic imaging , 2005 .

[19]  M. Esashi,et al.  Vacuum packaging for microsensors by glass-silicon anodic bonding , 1994 .

[20]  T. Rogers,et al.  Selection of glass, anodic bonding conditions and material compatibility for silicon-glass capacitive sensors , 1995 .

[21]  Gavin P. Horn,et al.  Anisothermal Anodic Bonding: A Method to Control Global Curvature and Residual Stress , 2010 .

[22]  Jaydeep K. Sinha,et al.  Effect of wafer-scale shape variations and mounting in wafer bonding , 2005 .

[23]  W. Kern.  Cleaning solutions based on hydrogen peroxide for use in silicon semiconductor technology , 1970 .

[24]  W. Ludwig,et al.  X‐ray Diffraction Topography at a Synchrotron Radiation Source Applied to the Study of Bonded Silicon on Insulator Material , 2002 .

[25]  R B Roberts,et al.  Thermal expansion reference data: silicon 300-850 K , 1981 .

[26]  James G. Boyd,et al.  Improvements in MEMS gyroscope production as a result of using in situ, aligned, current-limited anodic bonding , 2005 .

[27]  Thomas J. Mackin,et al.  Infrared grey-field polariscope: A tool for rapid stress analysis in microelectronic materials and devices , 2005 .

[28]  H. Iwasaki,et al.  Roughening of the Si/SiO2 interface during SC1-chemical treatment studied by scanning tunneling microscopy , 2000 .

[29]  W. Kern.  The Evolution of Silicon Wafer Cleaning Technology , 1990 .

[30]  V. T. Srikar,et al.  Structural design considerations for micromachined solid oxide fuel cells , 2004 .