Characterization of Polycrystalline Silicon-Germanium Film Deposition for Modularly Integrated MEMS Applications

The deposition of in situ boron-doped polycrystalline silicon-germanium (poly-SiGe) films in a conventional low-pressure chemical-vapor deposition reactor has been characterized using the design of experiments method. The dependencies of deposition rate, resistivity, average residual stress, strain gradient, and wet etch rate in hydrogen peroxide solution are presented. Structural layer requirements for general microelectromechanical system applications can be met within the process temperature constraint imposed by complementary metal-oxide-semiconductor (CMOS) electronics. However, residual stress and strain gradient requirements for inertial sensor applications will be difficult to meet with a single homogeneous layer of poly-SiGe that is about 2 mum thick. By correlating stress depth profile measurements with cross-sectional transmission electron microscopy images, we conclude that the large strain gradient is due to highly compressive stress in the lower (initially deposited) region of the film. For films deposited at very low temperature (near the range of amorphous film deposition), in situ boron doping enhances film crystallinity and reduces the strain gradient

[1]  Roger T. Howe,et al.  Optimization of Poly-SiGe Deposition Processes for Modular MEMS Integration , 2003 .

[2]  Roger T. Howe,et al.  Study of Poly-SiGe Structural Properties for Modularly Integrated MEMS , 2006 .

[3]  M. Strasser,et al.  Miniaturized Thermoelectric Generators Based on Poly-Si and Poly-SiGe Surface Micromachining , 2002 .

[4]  Jason C. S. Woo,et al.  Symmetric CMOS in fully-depleted silicon-on-insulator using P/sup +/-polycrystalline SiGe gate electrodes , 1993, Proceedings of IEEE International Electron Devices Meeting.

[5]  Characterization of KrF excimer laser annealed PECVD SixGe1−x for MEMS post-processing , 2006 .

[6]  S. Sedky,et al.  Pulsed-laser annealing, a low-thermal-budget technique for eliminating stress gradient in poly-SiGe MEMS structures , 2004, Journal of Microelectromechanical Systems.

[7]  Sherif Sedky,et al.  Characterization and optimization of infrared poly SiGe bolometers , 1999 .

[8]  S. Senturia.  Microsystem Design , 2000 .

[9]  A. Kiureghian,et al.  Analysis of Microfabricated Textured Multicrystalline Beams: I. Homogenization Approach , 1992 .

[10]  Fan Chen,et al.  Silicon-Germanium Heterojunction Bipolar Transistors , 2002 .

[11]  K. Saraswat,et al.  Polycrystalline silicon-germanium thin-film transistors , 1994 .

[12]  Jean-Pierre Celis,et al.  Effect of deposition parameters on the stress gradient of CVD and PECVD poly-SiGe for MEMS applications , 2004, SPIE MOEMS-MEMS.

[13]  P. Garone,et al.  Developing a manufacturable process for the deposition of thick polysilicon films for micromachined devices , 2000, 2000 IEEE/SEMI Advanced Semiconductor Manufacturing Conference and Workshop. ASMC 2000 (Cat. No.00CH37072).

[14]  J. M. Mora,et al.  Processing of MEMS gyroscopes on top of CMOS ICs , 2005, ISSCC. 2005 IEEE International Digest of Technical Papers. Solid-State Circuits Conference, 2005..

[15]  P. Houtte,et al.  Effect of in situ boron doping on properties of silicon germanium films deposited by chemical vapor deposition at 400 °C , 2001 .

[16]  S. Sedky,et al.  Pulsed Laser Deposition of Boron Doped Si 70 Ge 30 , 2006 .

[17]  Robert Mertens,et al.  Structural and mechanical properties of polycrystalline silicon germanium for micromachining applications , 1998 .

[18]  Roger M. Sauter,et al.  Introduction to Statistical Quality Control (2nd ed.) , 1992 .

[19]  Stress Stability of Poly-SiGe and Various Oxide Films in Humid Environments , 2004 .

[20]  D. Harame,et al.  SILICON:GERMANIUM HETEROJUNCTION BIPOLAR TRANSISTORS: FROM EXPERIMENT TO TECHNOLOGY , 1994 .

[21]  A. Witvrouw,et al.  Optimisation of PECVD poly-SiGe layers for MEMS post-processing on top of CMOS , 2005, The 13th International Conference on Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05..

[22]  R. Howe,et al.  Polycrystalline silicon-germanium films for integrated microsystems , 2003 .

[23]  Robert Mertens,et al.  Thin-film boron-doped polycrystalline silicon70%-germanium30% for thermopiles , 1996 .

[24]  C. W. Low,et al.  Hydrogen peroxide etching and stability of p-type poly-SiGe films , 2004, 17th IEEE International Conference on Micro Electro Mechanical Systems. Maastricht MEMS 2004 Technical Digest.

[25]  G. Patton,et al.  Silicon-germanium base heterojunction bipolar transistors by molecular beam epitaxy , 1988, 1987 International Electron Devices Meeting.

[26]  Ann Witvrouw,et al.  Determination of stress profile and optimization of stress gradient in PECVD poly-SiGe films , 2005 .