Focused ion beam (FIB) probing attacks rely on advanced milling and deposition capabilities to significantly threaten the confidentiality of on-chip security assets such as private keys and device configuration. The existing countermeasures either suffer from the prohibitively high area overhead or low reliability, failing to serve as a perfect fit to address the issues. Recently, iPROBE framework has been proposed as a physical design flow enhancing the layout/device security against FIB attacks by adding additional shield nets at a minor cost. However, the parallel shielding methodology and metrics of iPROBE merely focus on the perpendicular FIB model instead of covering a more threatening one, tilted probing. In this paper, we present iPROBE-O to enable FIB-aware placement and routing using orthogonal shields to thwart both perpendicular and titled FIB intrusions. Besides, we extend the definition of shield coverage in the previous iPROBE work and propose the tilted shield security metric to comprehensively quantify the shield protection on every layer beneath the shield against tilted probing attacks. This metric allows users to choose the desired scheme such as shield layers and density accordingly for the optimal trade-off between overhead and security. Moreover, to alleviate the routing congestion risks from the orthogonal shields, we introduce keepout region between the shield drivers and target cells allowing more space and analytically assessing how the factors keepout region and a total number of gates jointly impact the overall protection strength. We demonstrate the effectiveness of iPROBE-O framework on a variety of benchmarks including AES, DES, and Simon by reducing up to 80% decrease on the exposed area can be achieved and the timing and area overhead is less than 3%.