(470e) Evaporation Driven Assembly of on-Chip Nanothermite Devices

The fabrication and demonstration of nanothermite devices using evaporation driven assembly (EDA) of nanoparticles into micron-sized channels is demonstrated here. EDA of nanothermites features: the controlled delivery of material into micron-sized channels, minimal waste and hazard while making thick devices, and flexible substrate choice. These thermites may be used for on-chip thermal processing, welding, fuzing, MEMS actuation, etc. EDA may also be applied to thermites or other nanoenergetic material systems depending on whether heat, force, gases, etc. are desired.

In EDA, a volume of a solution is deposited into a reservoir connected to a trench. The solution is drawn into the trench by capillary action and the solution meniscus produces locally enhanced evaporation of the solution in the trench. The evaporation of the solution deposits the solute(s), and draws in more solution until the trench has been filled [S. S. Bedair, S. S., et al., IEEE Transactions on Magnetics, 46, 2198 (2010)].

The thermite suspension is a mixture of 80 nm Al and <50 nm CuO particles suspended in dimethyl formamide (DMF) and it is sonicated for 20 min immediately before use. Silicon wafers with 15, 25, or 50 µm wide, ~50 µm deep, and 10 mm long trenches were used. A few µl of thermite suspension are hand pipetted into a reservoir attached to the trench to be filled. The devices were ignited with a spark from a probe tip.

The nanothermite device morphologies were characterized using optical- and scanning-electron microscopy (SEM). The depth of the trench filling was measured with optical profilometry. The burning of the thermite devices were characterized using a Photron FAST-CAM SA5 high speed camera to measure the 1-15 m/s burn speeds and a FLIR Systems A40 infrared camera to measure the resulting temperature rise in the silicon die.

We have demonstrated that EDA is a suitable method for making nanothermite devices 10â??s µm thick, 10â??s of µm wide, and mmâ??s long while using a minimum of material.