Strain Fields of a Buckled Silicon Nitride Membrane

Phase contrast image of a fabricated nanocalorimeter buckling under the tensile stress of a biaxially-oriented IBAD MgO film

David W. Cooke
Daniel R. Queen
Frances Hellman
Physics Department
University of California, Berkeley
Berkeley, California 94720

The device shown is a thin film nanocalorimeter based on a 50nm, 2mm-square silicon nitride membrane. An MgO film is deposited via ion beam assisted deposition (IBAD) to act as a crystalline template on the back side of the amorphous membrane. This thin crystalline layer allows subsequent deposited thin films to have a textured crystal orientation that would not naturally form on the amorphous substrate.

This picture was taken with a differential interference contrast microscope and the colors correspond to differences in height. We see that the stress induced in the deposition process results in a buckling of the nitride surface, leading to the ripple effect pictured. This effect can be controlled by pre-straining the surface prior to deposition, which is why the platinum leads appear to pin the strain field lines and remain flat.

References

D.R. Queen and F. Hellman, Rev. Sci. Instr. 80, 063901 (2009).

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Reporters may freely use this image as long as they include the following credit: "Image courtesy of D.Cooke/UC-Berkeley".

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