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; and
a source metal layer on and in contact with the source ohmic contacts and on and in contact with the one or more n-type Schottky regions, the source metal layer forming a Schottky contact with the one or more n-type Schottky regions;
wherein each of the one or more n-type Schottky regions is adjacent and between the p-type body contact regions of adjacent cells; and
wherein the gate layer extends over the JFET region and the adjacent channel regions in the plane of the device.
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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.
57 Citations
16 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; and a source metal layer on and in contact with the source ohmic contacts and on and in contact with the one or more n-type Schottky regions, the source metal layer forming a Schottky contact with the one or more n-type Schottky regions; wherein each of the one or more n-type Schottky regions is adjacent and between the p-type body contact regions of adjacent cells; and wherein the gate layer extends over the JFET region and the adjacent channel regions in the plane of the device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16)
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14. A method of making a multi-cell MOSFET device, the method comprising:
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forming first and second p-type well regions in an n-type drift layer, wherein the n-type drift layer is on an n-type substrate and wherein the first and second p-type well regions are spaced apart forming an n-type Schottky region therebetween and wherein an n-type region of the drift layer adjacent the first and second well regions and opposite the n-type Schottky region forms first and second JFET regions; forming first and second n-type source regions in each of the first and second p-type well regions respectively, wherein the n-type source regions are spaced from the first and second JFET regions leaving a p-type channel region between the n-type source regions and the JFET regions; forming first and second p-type body contact regions adjacent and between the Schottky region and the first and second n-type source regions, respectively; depositing a gate oxide layer on the first and second JFET regions and on adjacent channel regions; depositing a gate layer on the gate oxide layer; depositing an interlayer dielectric material on the gate layer; forming source ohmic contacts on the first and second n-type source regions and on the adjacent first and second p-type body contact regions; depositing a source metal layer on the source ohmic contacts and on the n-type Schottky region, wherein the source metal layer forms a Schottky contact with the n-type Schottky region; and depositing final metal on the source metal layer. - View Dependent Claims (15)
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Specification