Polymer-Sandwich Ultra-Thin Silicon(100) Platform for Flexible Electronics

As a potential flexible substrate for flexible electronics, a polymer-sandwiched ultra-thin silicon platform is studied. SU-8 photoresist coated on the silicon membrane improves its flexibility as shown by an ANSYS simulation. Using the plasma enhanced chemical vapor deposited SiO₂/Si₃N₄ composite film as an etching mask, a 4 silicon- (100) wafer is thinned to 26μm without rupture in a 30 wt.% KOH solution. The thinned wafer is coated on both sides with 20 μm of SU-8 photoresist and is cut into strips. Then the strips are bent by a caliper to measure its bending radius. A sector model of bending deformation is adopted to estimate the radius of curvature. The determined minimal bending radius of the polymer-sandwiched ultra-thin silicon layer is no more than 3.3 mm. The fabrication process of this sandwich structure can be used as a post-fabrication process for high performance flexible electronics.