Robust Pop-Up Shape Encapsulation Using Dual-Sealing

This letter presents pop-up-shaped (having a spherical top shape) thin film encapsulation (TFE) using two-step sealing method. The first sealing step seals the etch holes in the cap layer, whereas the second step provides the shape. A pop-up shape with 2.4-μm upward deformation is demonstrated using a negative pressure difference between the two sealing layers-0.5-μm SiN at 1100 mTorr followed by 3-μm SiO² at 390 mTorr on an aluminum nitride cap encapsulating 800-μm × 800-μm size cavities. Besides a deeper cavity, the pop-up shape has smaller downward deformation of the cap layer due to its sturdy design. The increase in the robustness of TFE with pop-up radius is verified through finite element method simulations and theoretical calculation.