High voltage semiconductor devices and methods of making the devices
First Claim
1. A multi-cell MOSFET device comprising:
- an n-type drift layer on an n-type substrate;
a plurality of MOSFET cells, each of the MOSFET cells comprising;
first and second p-type well regions in spaced relation on the n-type drift layer;
an n-type JFET region on the n-type drift layer between the first and second p-type well regions, wherein each of the first and second p-type well regions has a channel region adjacent the JFET region;
first and second n-type source regions on each of the first and second p-type well regions and adjacent the channel regions opposite the JFET region, wherein the first and second n-type source regions have a higher dopant concentration than the n-type drift layer;
source ohmic contacts on each of the first and second n-type source regions;
a gate dielectric layer on the JFET region and channel regions;
a gate layer on the gate dielectric layer;
an interlayer dielectric layer on the gate layer; and
first and second p-type body contact regions on the n-type drift layer and adjacent the first and second n-type source regions opposite the channel regions, wherein the first and second p-type body contact regions have a higher dopant concentration than the first and second p-type well regions;
one or more n-type Schottky regions on the n-type drift layer adjacent one or more of the MOSFET cells;
a source metal layer on and in contact with the source ohmic contacts; and
a Schottky metal layer on and in contact with the one or more n-type Schottky regions, the Schottky metal layer forming a Schottky contact with the one or more n-type Schottky regions;
whereineach of the one or more n-type Schottky regions is adjacent and between the p-type body contact regions of adjacent MOSFET cells;
the first and second p-type well regions are elongate regions spaced from one another in an x direction and extending in a y direction perpendicular to the x direction;
the n-type JFET region is an elongate region extending in the x direction between the first and second p-type well regions;
the first and second p-type body contact regions are elongate regions extending in the y direction;
a p-type body contact region of a first of the plurality of MOSFET cells is connected to an adjacent p-type body contact regions of a second of the plurality of MOSFET cells by lateral p-type body contact regions spaced in the y-direction and extending in the x direction; and
the Schottky region between the first and second MOSFET cells comprises a plurality of separate Schottky regions between the lateral p-type body contact regions in the y direction and between the p-type body contact regions of the first and second MOSFET cells in the x direction.
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Accused Products
Abstract
A multi-cell MOSFET device including a MOSFET cell with an integrated Schottky diode is provided. The MOSFET includes n-type source regions formed in p-type well regions which are formed in an n-type drift layer. A p-type body contact region is formed on the periphery of the MOSFET. The source metallization of the device forms a Schottky contact with an n-type semiconductor region adjacent the p-type body contact region of the device. Vias can be formed through a dielectric material covering the source ohmic contacts and/or Schottky region of the device and the source metallization can be formed in the vias. The n-type semiconductor region forming the Schottky contact and/or the n-type source regions can be a single continuous region or a plurality of discontinuous regions alternating with discontinuous p-type body contact regions. The device can be a SiC device. Methods of making the device are also provided.
51 Citations
10 Claims
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1. A multi-cell MOSFET device comprising:
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an n-type drift layer on an n-type substrate; a plurality of MOSFET cells, each of the MOSFET cells comprising; first and second p-type well regions in spaced relation on the n-type drift layer; an n-type JFET region on the n-type drift layer between the first and second p-type well regions, wherein each of the first and second p-type well regions has a channel region adjacent the JFET region; first and second n-type source regions on each of the first and second p-type well regions and adjacent the channel regions opposite the JFET region, wherein the first and second n-type source regions have a higher dopant concentration than the n-type drift layer; source ohmic contacts on each of the first and second n-type source regions; a gate dielectric layer on the JFET region and channel regions; a gate layer on the gate dielectric layer; an interlayer dielectric layer on the gate layer; and first and second p-type body contact regions on the n-type drift layer and adjacent the first and second n-type source regions opposite the channel regions, wherein the first and second p-type body contact regions have a higher dopant concentration than the first and second p-type well regions; one or more n-type Schottky regions on the n-type drift layer adjacent one or more of the MOSFET cells; a source metal layer on and in contact with the source ohmic contacts; and a Schottky metal layer on and in contact with the one or more n-type Schottky regions, the Schottky metal layer forming a Schottky contact with the one or more n-type Schottky regions;
whereineach of the one or more n-type Schottky regions is adjacent and between the p-type body contact regions of adjacent MOSFET cells; the first and second p-type well regions are elongate regions spaced from one another in an x direction and extending in a y direction perpendicular to the x direction; the n-type JFET region is an elongate region extending in the x direction between the first and second p-type well regions; the first and second p-type body contact regions are elongate regions extending in the y direction; a p-type body contact region of a first of the plurality of MOSFET cells is connected to an adjacent p-type body contact regions of a second of the plurality of MOSFET cells by lateral p-type body contact regions spaced in the y-direction and extending in the x direction; and the Schottky region between the first and second MOSFET cells comprises a plurality of separate Schottky regions between the lateral p-type body contact regions in the y direction and between the p-type body contact regions of the first and second MOSFET cells in the x direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification