Semiconductor diode and method of manufacture
A diode ( 200 ) is disclosed having improved efficiency, smaller form factor, and reduced reverse biased leakage current. Schottky diodes ( 212 ) are formed on the sidewalls ( 210 ) of a mesa region ( 206 ). The mesa region ( 206 ) is a cathode of the Schottky diode ( 212 ). The current path through the mesa region ( 206 ) has a lateral and a vertical current path. The diode ( 200 ) further comprises a MOS structure ( 214 ), p-type regions ( 220 ), MOS structures ( 230 ), and p-type regions ( 232 ). MOS structure ( 214 ) with the p-type regions ( 220 ) pinch-off the lateral current path under reverse bias conditions. P-type regions ( 220 ), MOS structures ( 230 ), and p-type regions ( 232 ) each pinch-off the vertical current path under reverse bias conditions. MOS structure ( 214 ) and MOS structures ( 230 ) reduce resistance of the lateral and vertical current path under forward bias conditions. The mesa region ( 206 ) can have a uniform or non-uniform doping concentration.
1. A semiconductor device comprising:
a substrate of a first conductivity type;
a mesa region of the first conductivity type formed in or overlying the substrate having a major surface and sidewalls;
a first MOS structure overlying the major surface of the mesa;
a Schottky diode comprising an anode and a cathode where the anode of the Schottky diode overlies a portion of a sidewall of the mesa region and where the cathode of the Schottky diode is the mesa region; and
a first diode comprising a first region of a second conductivity type a first predetermined distance from the major surface of the mesa region and adjacent to the sidewall of the mesa region where the first region couples to the anode of the Schottky diode.
2. The device of claim 1 where a gate of the first MOS structure couples to the anode of the Schottky diode.
3. The device of claim 1 where the anode of the Schottky diode comprises a barrier metal formed adjacent to major surface of the mesa.
4. The device of claim 3 where a portion of the anode of the Schottky diode overlies a portion of the first region of the second conductivity type.
5. The device of claim 1 further including a second MOS structure overlying a portion of the sidewall of the mesa region where the second MOS structure is formed at a second predetermined distance below the major surface of the mesa region.
6. The device of claim 5 where the gate of the second MOS structure couples to the anode of the Schottky diode.
7. The device of claim 5 further including a second diode comprising a second region of the second conductivity type a third predetermined distance from the major surface of the mesa region.
8. The diode of claim 7 where the first predetermined distance is above the second predetermined distance and the second predetermined distance is above the third predetermined distance.
9. The diode of claim 1 where the mesa region is uniformly doped.
10. The diode of claim 1 where the mesa region is non-uniformly doped.
11. A semiconductor device comprising:
a substrate or a first conductivity type;
a mesa region of the first conductivity type formed in or overlying the substrate having a major surface and sidewalls;
a Schottky diode comprising an anode and a cathode where the anode of the Schottky diode overlies a portion of a sidewall of the mesa region, where the cathode of the Schottky diode comprises the mesa region;
a first MOS structure overlying the major surface of the mesa region; and
a second MOS structure overlying a portion of the sidewall of the mesa region where the MOS structure is formed at a second predetermined distance below the major surface of the mesa.
12. The device of claim 11 further including a first diode comprising a first region of a second conductivity type a first predetermined distance from the major surface of the mesa region and adjacent to the sidewall of the mesa region where the first region is coupled to the anode of the Schottky diode.
13. The device of claim 12 where a gate of the first and second MOS structures couple to the anode of the Schottky diode.
14. The diode of claim 13 further including a second diode comprising a second region of the second conductivity type a third predetermined distance from the major surface of the mesa region and adjacent to the sidewall of the mesa region where the first predetermined distance is above the second predetermined distance and where the second predetermined distance is above the third predetermined distance.