Inverse design has triggered great research interests in integrated photonic design. It can be  advantageous in discovering new photonic devices, because, unlike traditional device design (or forward design) where only a few parameters can be swept, a high-order multi-dimensional parameter space can be searched with an advance optimization algorithm for a global fitness that is often correlated with one or more performance metrics of the targeted device. Recently, such design concept has been applied to obtain ultra-compact photonic devices. They, however, suffer greatly from performance degradation due to large out-of-plane scattering from strong scattering processes. In this talk, we utilize the concept of inverse design and show that it is possible to design ultra-compact and highly performance silicon photonic devices that may have potential impact in future very large scale silicon photonic integrated circuits.