Direct and dry micro-patterning of nano-particles by electrospray deposition through a micro-stencil mask

A new micro-pattern formation method for thin films of organic or bio-macromolecules is proposed. The method combines an electrospray deposition process with a micro-fabricated stencil mask made of a silicon nitride membrane. The highest resolution of 2 µm line and space is possible using 50 nm fluorescent latex beads. The deposited nano-structure consists of clusters of particles ranging from 100 to 200 nm, which indicates that nanometer resolution is potentially achievable. The surface roughness of the deposit is about 3.6 nm on average, and thickness uniformity is about 10 nm with 76 nm film thickness over 72 µm. Size uniformity of the 5 µm dots reaches 5.2% in the coefficient of variation (CV) value. These results indicate that the resolution and uniformity of the proposed method are high. In addition, the charged particles on the micro stencil mask of electrical insulation are proved to induce a focusing effect, which suggests that the size of the deposited pattern can be smaller than the mask aperture size