Method for fabricating a transformer integrated with a semiconductor structure
View Patent ↗A substrate is provided and a top interconnection metal layer and a primary winding layer are formed thereon. Then a passivation layer having a plurality of via exposed parts of the top interconnection metal layer is formed on the substrate. A secondary winding layer and at least a bonding pad are formed on the passivation layer. The bonding pad electrically connects to the top interconnection metal layer through the via.
1. A method for fabricating a transformer integrated with a semiconductor structure comprising:
providing a substrate;
simultaneously forming a top interconnection metal layer and a primary winding layer comprising a coil pattern on the substrate;
providing a space in between the top interconnection metal layer and the primary winding layer;
forming a passivation layer covering the top interconnection metal layer and the primary winding layer on the substrate, and the passivation layer further having a plurality of openings exposing parts of the top interconnection metal layer; and
simultaneously forming a secondary winding layer comprising a coil pattern and at least a bonding pad on the passivation layer, and the bonding pad being electrically connected to the top interconnection metal layer through the openings.
2. The method of claim 1 , wherein the substrate further comprises an active circuit and at least an interconnection metal layer.
3. The method of claim 1 , wherein the passivation layer has a thickness in a range of 100-500 angstroms.
4. The method of claim 1 , wherein the top interconnection metal layer and the primary winding layer are simultaneously formed by the copper interconnection technology.
5. The method of claim 1 , wherein the secondary winding layer comprises titanium, titanium oxide, aluminum, or alloys of the aforementioned metals.
6. The method of claim 1 , wherein the coil patterns of the primary winding layer and the secondary winding layer are partially overlapping.
7. The method of claim 6 , wherein the patterns of the primary winding layer and the secondary winding layer are preferably coaxial.
8. The method of claim 1 , wherein a width of the primary winding layer is smaller than a width of the secondary winding layer.
9. The method of claim 1 further comprising a step of forming a protection layer on the substrate, the protection layer covering the secondary winding layer and exposing the bonding pad.
10. The method of claim 9 , wherein the protection layer comprises silicon nitride.