Semiconductor device and manufacturing method of same
View Patent ↗The characteristic of the semiconductor device of this invention is that the device has a piercing hole 10 formed in the semiconductor layer to touch a first metal film 18 , a insulating film 12 formed on the side wall of the piercing hole 10 , a second metal film 13 disposed on the first metal film 18 at the bottom of the piercing hole 10 where the insulating film 12 has not been formed and on the semiconductor layer, a barrier metal film 14 formed on the insulating film 12 in the piercing hole 10 and on the first metal film 18 , and a wiring layer 15 formed inside the piercing hole 10 through the barrier metal film 14.
1. A semiconductor device comprising:
a semiconductor substrate of a first general conductivity type having a piercing hole piercing the substrate from a front surface thereof to a back surface thereof;
a source layer formed in the front surface of the substrate;
a drain electrode disposed on the front surface of the substrate to cover the piercing hole;
a metal film disposed on the back surface of the substrate so as to make a direct contact with the back surface of the substrate; and
a drain wiring disposed inside the piercing hole and electrically connected with the drain electrode, the drain wiring covering the metal film,
wherein the drain wiring comprises a wiring layer and a barrier metal film disposed between the wiring layer and a sidewall of the piercing hole, the barrier metal film covers the metal film, the wiring layer is physically in contact with the barrier metal film, the metal film is disposed on the back surface of the substrate so that the barrier metal film is not in contact with the back surface of the substrate, and part of the metal film is disposed between the drain electrode and the drain wiring so as to be physically in contact with the drain electrode.
2. The semiconductor device of claim 1 , further comprising a first insulating film disposed on the sidewall of the piercing hole.
3. The semiconductor device of claim 2 , wherein the semiconductor substrate comprises an epitaxial layer formed on a silicon substrate, an impurity diffusion layer of a second general conductivity type formed in the epitaxial layer, a trench extending from a surface of the impurity diffusion layer into the epitaxial layer, a gate electrode comprising a conduction layer buried in the trench and a second insulating film disposed between the conduction layer and a wall of the trench, and the source layer is formed in the impurity diffusion layer adjacent the trench.
4. The semiconductor device of claim 1 , wherein the drain wiring does not completely fill the piercing hole.
5. The semiconductor device of claim 1 , wherein the metal film is a metal film formed by a sputtering method or an evaporation method.
6. The semiconductor device of claim 1 , wherein the barrier metal is titanium nitride, tungsten nitride or tantalum nitride.
7. The semiconductor device of claim 6 , wherein the metal film comprises titanium, chromium, vanadium, tantalum, tungsten or zirconium.
8. The semiconductor device of claim 1 , wherein the drain wiring and the metal film extend on the back surface of the substrate so as to overlap the source layer so that a current path from the source layer to the drain wiring is the shortest.