US Patent 10573742 Oxygen inserted Si-layers in vertical trench power devices

A semiconductor device includes a gate trench extending into a Si substrate, a body region in the Si substrate adjacent the gate trench, a source region in the Si substrate above the body region, a contact trench extending into the Si substrate and filled with an electrically conductive material which contacts the source region at a sidewall of the contact trench and a highly doped body contact region at a bottom of the contact trench, a diffusion barrier structure formed along the sidewall of the gate trench, the diffusion barrier structure comprising alternating layers of Si and oxygen-doped Si and a Si capping layer on the alternating layers of Si and oxygen-doped Si, and a channel region formed in the Si capping layer and which vertically extends along the sidewall of the gate trench. Corresponding methods of manufacture are also described.