This paper demonstrates, for the first time, an integrated trench-based shielding for electromagnetic interference (EMI) isolation between components in an ultra-miniaturized radio frequency (RF) package. A novel component-level shielding structure is explored and developed using metallized trenches formed in the build-up layers of ultra-thin glass substrates. Through full-wave electromagnetic (EM) simulation, the coupling between different passive structures are compared. Additionally, the shielding effectiveness of trench-based structures are compared with traditional via-based shields. Further, the shield effectiveness of different magnetic and non-magnetic shield materials are compared through analytical modeling. Based on these modeling results, a representative shield structure is designed, fabricated and characterized to correlate its performance with simulations. It is observed through measurements, that package-integrated trench-based shields provide up to 25dB more lateral isolation than via-arrays.