Silicon Germanium as a novel mask for silicon deep reactive ion etching

This paper reports on the use of p-type polycrystalline Silicon Germanium (poly-Si1-xGex) thin films as a new masking material for cryogenic silicon deep reactive ion etching (DRIE). The proposed masking material can be deposited at CMOS backend compatible temperatures and demonstrates high etching selectivity towards silicon (>;1:270). Moreover, SiGe etches 37 times faster than SiO2 or SiN masks in SF6/O2 plasma resulting in a major reduction in the processing time without the need for a dedicated etcher. Selectivity tests revealed that the etching selectivity of the SiGe mask towards silicon strongly depends on the Ge content, boron concentration and etching temperature. This was attributed to chemical and thermodynamic stability of the SiGe film, as well as the electronic properties of the mask.

[1]  E. H. Wilson.  Origin , 1927, Bulletin of popular information - Arnold Arboretum, Harvard University..

[2]  Zhitang Song,et al.  Thermal annealing effects on the structure and electrical properties of Al2O3 gate dielectrics on fully depleted SiGe on insulator , 2006 .

[3]  Ann Witvrouw,et al.  Optimal conditions for micromachining Si1- xGex at 210 °C , 2007 .

[4]  J. Fluitman,et al.  A survey on the reactive ion etching of silicon in microtechnology , 1996 .

[5]  Ivo W. Rangelow,et al.  Critical tasks in high aspect ratio silicon dry etching for microelectromechanical systems , 2003 .

[6]  A. Scherer,et al.  Techniques of Cryogenic Reactive Ion Etching in Silicon for Fabrication of Sensors , 2009 .

[7]  G. Vaglio,et al.  Fourier transform-ion cyclotron resonance study of the gas-phase acidities of germane and methylgermane; Bond dissociation energy of germane , 1993, Journal of the American Society for Mass Spectrometry.

[8]  J. Koenderink.  Q… , 2014, Les noms officiels des communes de Wallonie, de Bruxelles-Capitale et de la communaute germanophone.

[9]  A. Bright,et al.  Doping effects in reactive plasma etching of heavily doped silicon , 1985 .

[10]  Sami Franssila,et al.  Mask material effects in cryogenic deep reactive ion etching , 2007 .

[11]  Miko Elwenspoek,et al.  Guidelines for etching silicon MEMS structures using fluorine high-density plasmas at cryogenic temperatures , 2002 .

[12]  I. Tittonen,et al.  The fabrication of silicon nanostructures by local gallium implantation and cryogenic deep reactive ion etching , 2009, Nanotechnology.

[13]  B.Y. Majlis,et al.  Deep Trenches in Silicon Structure using DRIE Method with Aluminum as an Etching Mask , 2006, 2006 IEEE International Conference on Semiconductor Electronics.

[14]  S. Retterer,et al.  Cryogenic Etching of Silicon: An Alternative Method for Fabrication of Vertical Microcantilever Master Molds , 2010, Journal of Microelectromechanical Systems.

[15]  Ilkka Tittonen,et al.  Atomic layer deposition enhanced rapid dry fabrication of micromechanical devices with cryogenic deep reactive ion etching , 2007 .

[16]  Ivo W. Rangelow,et al.  Dry etching-based silicon micro-machining for MEMS , 2001 .

[17]  Ivan Hotovy,et al.  Influence of gas composition and the mask materials on the etch profile of dry-etched structures in silicon , 1996, Photonics West - Micro and Nano Fabricated Electromechanical and Optical Components.

[18]  C. J. Mogab,et al.  Anisotropic plasma etching of polysilicon , 1980 .

[19]  A Scherer,et al.  Alumina etch masks for fabrication of high-aspect-ratio silicon micropillars and nanopillars , 2009, Nanotechnology.

[20]  Yong-Kweon Kim,et al.  Prevention method of a notching caused by surface charging in silicon reactive ion etching , 2005 .

[21]  M. Boufnichel,et al.  Origin, control and elimination of undercut in silicon deep plasma etching in the cryogenic process , 2005 .