A trench power transistor includes a semiconductor body having opposite first and second surfaces, and including at least one active region. Such region includes a trench electrode structure, a well, and a source. The trench electrode structure has an electrode trench recessed from the first surface, and includes first, second, and third insulating layers sequentially disposed over bottom and surrounding walls of the electrode trench, a shield electrode enclosed by the third insulating layer, a fourth insulating layer disposed on the first, second, and third insulating layers, and a gate electrode surrounded by the fourth insulating layer. The second insulating layer made of a nitride material and the fourth insulating layer are different in material. A production method of the transistor is also disclosed.