High-efficiency Schottky rectifier and method of manufacturing same
View Patent ↗A rectifier device ( 10 ) comprising a multi-layer epitaxial film ( 12 ) and a rectifier and a transistor manufactured in the film ( 12 ), wherein the transistor is oriented vertically relative to the plane of the rectifier. The rectifier and transistor are separated by a transition zone of inverted bias. The rectifier is a Schottky barrier rectifier, and the transistor is a JFET. More specifically, the device ( 1 ) comprises the film ( 12 ), a trench ( 16 ), a first region ( 18 ) associated with an upper portion of the trench ( 16 ), and second region ( 20 ) associated with a lower portion. The interface between the p+ material of the second region ( 20 ) and the n material of the film ( 12 ) creates a p+/n junction. The device ( 10 ) has use in high frequency, low-loss power circuit applications in which high switching speed and low forward voltage drop are desirable.
1. A semiconductor device comprising:
a substrate;
a multi-layer epitaxial film overlaying a top surface of the substrate,
wherein a first layer of the multi-layer epitaxial film, includes a first dopant providing a breakdown voltage of at least approximately 30 volts, a second layer includes a second dopant providing an area of reverse-direction electric field when the device is reverse-biased, and a third layer comprises a resistivity less than resistivities of the first and second layers;
a trench in the multi-layer epitaxial film;
a first region associated with an upper portion of the trench; and
a second region associated with a lower portion of the trench,
wherein the first and second regions operate to create a zone of inverted electric field.
2. The semiconductor device as set forth in claim 1 , wherein the substrate includes n-type silicon and has a wafer resistivity of approximately between 0.002 Ohm-cm and 0.005 Ohm-cm.
3. The semiconductor device as set forth in claim 1 , wherein the multi-layer epitaxial film includes n-type material.
4. The semiconductor device as set forth in claim 3 , wherein the multi-layer epitaxial film is doped with phosphorus.
5. The semiconductor device as set forth in claim 4 , wherein the multi-layer epitaxial film includes:
a first layer having a thickness of approximately 2 micrometers and a resistivity of approximately 0.35 Ohm-cm;
a second layer having a thickness of approximately 3.0 micrometers and a resistivity of approximately 0.5 Ohm-cm; and
a third layer 30 having a thickness of approximately 2.5 micrometers and a resistivity of 0.08 Ohm-cm.
6. The semiconductor device as set forth in claim 1 , wherein the trench is substantially filled with polysilicon.
7. The semiconductor device as set forth in claim 6 , wherein the polysilicon is doped with boron.
8. The semiconductor device as set forth in claim 7 , wherein the trench is approximately between 4 micrometers and 5 micrometers deep, and approximately 1 micrometer wide.
9. The semiconductor device as set forth in claim 1 , wherein the first region includes an oxide.
10. The semiconductor device as set forth in claim 1 , wherein the second region includes a p+-type material.