Deformation characteristics of electroplated MEMS cantilever beams released by plasma ashing

The present study quantitatively examines the deformation characteristics of electroplated MEMS structures released by plasma ashing. This study investigates the thermal deformations due to the high temperature of ambient plasma, the changes in microstructures of the material during the deposition process, and the changes in material properties due to physical and chemical reactions between the film surface and the plasma particles. We conduct various experimental tests and introduce an analytical model to evaluate the residual stresses in MEMS structures when considering the three-dimensional anchor effect. The experimental results show that the high temperature of ambient plasma, the inhomogeneity of microstructures in the thickness direction, and the changes in the surface material properties may cause the deflections of MEMS structures after plasma ashing.

[1]  N. Kanani.  Electroplating: Basic Principles, Processes and Practice , 2005 .

[2]  Yong-Kweon Kim,et al.  Measurement of the mechanical properties of electroplated gold thin films using micromachined beam structures , 2005 .

[3]  R. Mclellan,et al.  High-temperature elastic constants of gold single-crystals , 1991 .

[4]  Daniel T. Schwartz,et al.  High-rate through-mold electrodeposition of thick (>200 /spl mu/m) NiFe MEMS components with uniform composition , 1999 .

[5]  Weng Hong Teh,et al.  Near-zero curvature fabrication of miniaturized micromechanical Ni switches using electron beam cross-linked PMMA , 2003 .

[6]  P. M. Zavracky,et al.  Electrostatically actuated micromechanical switches , 1997 .

[8]  P. Sarro,et al.  Improved thermal U-beam actuators for micro-assembly , 2008 .

[9]  D. Kwon,et al.  Film-thickness considerations in microcantilever-beam test in measuring mechanical properties of metal thin film , 2003 .

[10]  Y. S. Touloukian.  Thermophysical properties of matter , 1970 .

[11]  Ke-wei Xu,et al.  Hardness and elastic modulus of Au/NiCr/Ta multilayers on Al2O3 substrate by nanoindentation continuous stiffness measurement technique , 2005 .

[12]  W. G. Perdok,et al.  On the relations between structure and morphology of crystals. I , 1955 .

[13]  P. Hartman.  The effect of absorption on the face development of the equilibrium form , 1959 .

[14]  Jack W. Judy,et al.  Magnetic microactuation of polysilicon flexure structures , 1995 .

[15]  Horacio Dante Espinosa,et al.  Size effects on the mechanical behavior of gold thin films , 2003 .

[16]  G. Kovacs.  Micromachined Transducers Sourcebook , 1998 .

[17]  Jung-Mu Kim,et al.  Continuous anti-stiction coatings using self-assembled monolayers for gold microstructures , 2002 .

[18]  M. Madou.  Fundamentals of microfabrication , 1997 .

[19]  D. L. DeVoe.  Thermal issues in MEMS and microscale systems , 2002 .

[20]  K. Kondoh,et al.  Fabrication of new electrostatic linear actuator , 2000, Digest of Papers Microprocesses and Nanotechnology 2000. 2000 International Microprocesses and Nanotechnology Conference (IEEE Cat. No.00EX387).

[21]  Seok-jin Kang,et al.  Fabrication Of Flat RF MEMS Switch Membrane By Minimizing Of Stress Gradients In The Au Membrane Structure , 2002 .

[22]  F. Rudolf,et al.  Electrodeposition of 3D microstructures on silicon , 1993 .

[23]  Tadatomo Suga,et al.  Electroplating Ni micro-cantilevers for low contact-force IC probing , 2003 .

[24]  M. Gad-el-Hak.  The MEMS Handbook , 2001 .