The fracture strength of nitrogen doped silicon wafers

Materials Science and Engineering B (Impact Factor: 2.12). 01/1996; 836:246--250. DOI: 10.1016/0921-5107(95)01258-3

ABSTRACT With a specially designed double ring bending setup, we have studied the ro om temperature fracture strength of silicon wafers prepared by standard manufacturing methods with both (as) cut, (as) lapped. and (as) polished surfaces. Wafers from six different crystals have been tested, The differences between these crystals are related 10 growth method (float zone or Czochralski), concentration of light element impurities (nitrogen and oxygen). and further processing (neutron irradiation and thermal annealing), No significant differences in strength between crystal of different origin ean be revealed on wafers prepared with (as) cut and (as) lapped surfaces, Polished wafers generally show a fraeture strength of the order of l GPa, with a large scatter between single measurements. o differences between the strength of polished wafers from float zone (FZ) and Czochralski (CZ) crystals ean be detected, but the median strength of a FZ crystal with small concentration of both nitrogen and oxygen is observed to have a much higher value of 2.5 GPa.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents the development of a MEMS based capacitive tactile sensor intended to be incorporated into a tactile array as the core element of a biomimetic fingerpad. The use of standard microfabrication technologies in realising the device allowed a cost efficient fabrication involving only a few process steps. A low noise readout electronics system was developed for measuring the sensor response. The performance of both bare and packaged sensors was evaluated by direct probing of individual capacitive sensor units and characterising their response to load–unload indentation cycles.
    Sensors and Actuators A Physical 02/2011; 165(2):221–229. · 1.94 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The locking of dislocations by nitrogen impurities in nitrogen-doped FZ-grown (NFZ) silicon crystals was investigated as a function of time in the temperature range 550–830°C. It was found that nitrogen impurities induce a strong locking effect on stationary dislocations after a sufficiently long anneal. The locking is similar in magnitude to that observed for oxygen atoms in Czochralski-grown crystals (Cz), although the nitrogen concentration in the NFZ samples (2.2×1015cm−3) is two orders of magnitude lower than the usual oxygen concentration in Cz silicon. The unlocking stress initially increases with annealing time and then saturates to a value of approximately 50MPa for all the temperatures investigated. Information concerning nitrogen diffusion is deduced and by making certain physically realistic assumptions, data is inferred regarding the binding energy of nitrogen and the dislocation pinning force per nitrogen atom at the dislocation core.
    Physica B Condensed Matter 12/2003; 340:996-1000. · 1.28 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Specimens and fracture test methods for strength analysis of MEMS micromirrors were proposed. Bending and combined loading tests were performed, and torsion strength was estimated from those results. Two-parameter Weibull distribution was used to evaluate the fracture stresses estimated from the FEM model. The resulting scale and shape parameters were 787MPa and 7.77 for the bending test and 517MPa and 5.28 for the combined loading test. There was a difference in strength between the results of the bending and combined loading tests. From the load factor analysis, it was found that both geometry and stress distribution have to be considered to estimate the strength of MEMS since flaws are non-uniformly distributed. It was also found that torsional strength can be estimated on the safe side using the results of the combined loading test.
    Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A 11/2005; 72(17):2672-2685.


Available from
May 21, 2014