CMOS power sensor
A CMOS power sensor is disclosed in the present invention. The CMOS power sensor includes a current coil, a high voltage device circuit, and a Hall device. The current coil is fabricated during the process steps of forming gold bumps of a CMOS device. One end of the current coil is connected to a voltage source, and the other end of the current coil is connected to a load. The high voltage device circuit is connected to the voltage source. The Hall device is connected to the high voltage device circuit and induces a Hall voltage in response to the magnetic field generated by the current coil.
1. A process of forming a CMOS power sensor, wherein said CMOS power sensor is applied to detect a power magnitude of a given voltage source, comprising:
providing a semiconductor wafer with a Hall device and at least one CMOS device, wherein on the top of said semiconductor wafer is a passivation layer which covers at least one bonding pad;
opening a contact window over said at least one bonding pad by performing a photolithography process and an etching process;
coating a photo resist layer on said semiconductor wafer;
patterning said photo resist layer by using a photo mask during an exposure process, wherein said photo mask comprises patterns for forming at least one gold bump and a current coil; wherein said current coil is connected to said voltage source and able to induce a magnetic field which can induce said Hall device to generate a Hall voltage; and
Forming said at least one gold bump and said current coil by performing an electroplating process.
2. The process of claim 1 , further comprising forming a pad layer on said semiconductor wafer after performing said step of opening a contact window over said at least one bonding pad.
3. The process of claim 2 further comprising:
removing a residual photo resist by performing a stripping process; and
removing a part of said pad layer under said residual photo resist by performing an etching process.
4. The process of claim 3 , further comprising performing an anneal process.
5. The process of claim 1 , wherein said Hall device comprises:
a first terminal, which is connected to a high voltage device circuit;
a second terminal, which is connected to the ground;
a third terminal, which is connected to a first Hall probe; and
a fourth terminal, which is connected to a second Hall probe.
6. The process of claim 5 , wherein said Hall device is beneath said current coil, and said Hall device generates a Hall voltage in response to a magnetic field generated by said current coil.
7. The CMOS power sensor of claim 6 , wherein said Hall voltage is a voltage difference between said first Hall probe and said second Hall probe.
8. The process of claim 1 , wherein said current coil is made of gold having a thickness of between 4 μm and 20 μm.