New low-stress PECVD poly-SiGe layers for MEMS

C.R. Rusu, Sherif Sedky, Brigette Parmentier, Agnes Verbist, Olivier Richard, Bert Brijs, Luc Geenen, Ann Witvrouw, Franz Lärmer, Frank Fischer, Silvia Kronmüller, V. Leca, A.M. Otter

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34 Citations (Scopus)


Thick poly-SiGe layers, deposited by plasma-enhanced chemical vapor deposition (PECVD), are very promising structural layers for use in microaccelerometers, microgyroscopes or for thin-film encapsulation, especially for applications where the thermal budget is limited. In this work it is shown for the first time that these layers are an attractive alternative to low-pressure CVD (LPCVD) poly-Si or poly-SiGe because of their high growth rate (100-200 nm/min) and low deposition temperature (520/spl deg/C-590/spl deg/C). The combination of both of these features is impossible to achieve with either LPCVD SiGe (2-30 nm/min growth rate) or LPCVD poly-Si (annealing temperature higher than 900/spl deg/C to achieve structural layer having low tensile stress). Additional advantages are that no nucleation layer is needed (deposition directly on SiO/sub 2/ is possible) and that the as-deposited layers are polycrystalline. No stress or dopant activation anneal of the structural layer is needed since in situ phosphorus doping gives an as-deposited tensile stress down to 20 MPa, and a resistivity of 10 m/spl Omega/-cm to 30 m/spl Omega/-cm. With in situ boron doping, resistivities down to 0.6 m/spl Omega/-cm are possible. The use of these films as an encapsulation layer above an accelerometer is shown.
Original languageEnglish
Pages (from-to)816-825
Number of pages10
JournalJournal of microelectromechanical systems
Issue number6
Publication statusPublished - 2003


  • METIS-217565
  • IR-104476


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