A semiconductor structure includes a device region including field effect transistors located on a semiconductor substrate, and a planarization dielectric layer overlying the field effect transistors. A hydrogen-blocking structure can be formed to prevent subsequent hydrogen diffusion into the device region. A moat trench is formed through the planarization dielectric layer and into the semiconductor substrate around the device region. A ring-shaped hydrogen-diffusion-blocking material portion is formed within the moat trench. A horizontally-extending portion of a silicon nitride diffusion barrier layer is formed over the planarization dielectric layer. The ring-shaped hydrogen-diffusion-blocking material portion may include a vertically-extending annular portion of the silicon nitride layer, or may include an annular metal portion that is formed prior to formation of the silicon nitride diffusion barrier layer.