Effect of Laser Annealing on the Structure of Amorphous Porous SiCOH Materials
AM Raymunt and RT Bell and MO Thompson and P Clancy, JOURNAL OF PHYSICAL CHEMISTRY C, 119, 12616-12624 (2015).
The inherent trade-off of porosity and mechanical properties in ultralow dielectric constant SiCOH Materials is a Critical challenge in semiconductor processing. Numerous postdeposition processes have been studied to achieve simultaneous low-k materials with adequate mechanical rigidity, including thermal annealing. Typically, these thermal anneals are characterized by times On the order of seconds to minutes at relatively low temperatures (below 500 degrees C). In this work, we report on potential advantages of submillisecond time frame anneals at extreme temperatures up to 1200 degrees C. The effects of such processing on the structure of ultralow-k materials were studied using molecular dynamics Computer simulations employing a force field that facilitates the determination of bond rearrangements, coupled with direct experimental measurements during CO2 laser-induced spike annealing. Results show structural evolution with increasing temperature leading to densification of the SiOx network, reduction in the concentration of suboxides, and loss of remnant organic moieties from original SiCOH structures. In molecular dynamics simulations, organic structural units decompose at simulated temperatures above 850 degrees C, followed by an increase in Si-O networking at 900 degrees C. These observations are consistent with complementary experiments. These results provide atomic-scale structure and chemical intuition to guide the development of future low-k materials.
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