Board substrates, three-dimensional integrated circuit structures and methods of forming the same are disclosed. A board substrate includes a core layer, a first build-up layer, a second build-up layer, a first group of bumps, a second first group of bumps and at least one first underfill blocking wall. The first build-up layer and the second build-up layer are disposed on opposite sides of the core layer. The first group of bumps is disposed over the first build-up layer. The second first group of bumps is disposed over the first build-up layer. The at least one first underfill blocking wall is disposed over the first build-up layer and between the first group of bumps and the second group of bumps.