Mechanical Interfacing Using Suspended Ultrathin Films From ALD

Interlocking microstructures formed from suspended ultrathin films create a mechanical bond between heterogeneous microfabricated dies. Films approximately 34 nm in thickness have been fabricated using atomic layer deposition in conjunction with standard surface micromachining. Bonding surfaces consist of polyimide pillars with a pitch of 19.8-29 μm that support nanofilm cantilevers, with an areal density of 9.52 × 10
³
joints/mm
²
for square surface tiling and 4.14 × 10
³
joints/mm
²
for triangle tiling. Cantilevers 2.2 and 3.1 μm in length provide length-to-thickness aspect ratios of 65:1 and 91:1, respectively. Bonding of complementary mating surfaces has been observed optically through transparent flexible substrates.