A method for fabricating an electron device stack structure includes preparing plural substrates, each having a corresponding one of plural vias; sputter-depositing plural metal layers on the plural substrates to form plural electron device layers, each of the plural metal layers being sputter-deposited on a corresponding one of the plural substrates and including a part straying into a corresponding one of the plural vias as a corresponding one of plural stray metal portions; stacking the plural electron device layers to construct the electron device stack structure having a conductive path formed by connecting the plural vias; and injecting a conductive material into the conductive path to form a vertical electrical connection among the plural stray metal portions.