Thermally induced wrinkling in thin-film stacks on patterned substrates
by K. Srinivasan
S. Goyal
T. Siegmund
G. Subbarayan
and Q. Lin
Thermally induced film wrinkling is a fabrication and reliability
challenge for thin-film stacks consisting of a compliant film capped
by a stiffer film. The current understanding of film wrinkling is
largely restricted to thin-film stacks on blanket substrates. An
understanding of wrinkling in thin-film stacks on patterned
substrates is of greater practical relevance to the microelectronic
industry. Toward this goal, a numerical technique based on a
spectral method is employed to simulate wrinkling in a stiff-film/
compliant-film system on a rigid patterned substrate. A coupling
term in the Fourier space is introduced to capture the interaction
between wrinkling amplitudes above patterned regions and
surrounding regions. This coupling in wrinkling amplitudes
suppresses wrinkling above patterned regions. Wrinkling
amplitudes for a thin-film stack on a patterned substrate are shown
to be dependent on the size of the patterns and their relative
spacing.
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