Semiconductor device having a trench MOS barrier schottky diode

• US 20160268255A1
• Filed: 03/07/2016
• Published: 09/15/2016
• Est. Priority Date: 03/09/2015
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: QU, Ning, Goerlach, Alfred
• Granted Patent: US 9,941,381 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• CPC Class Codes: H01L 29/0623 Buried supplementary region, e.g. buried guard ring multi-RESURF H01L29/0634
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/20 including, apart from doping materials or other impurities, only AIIIBV compounds
• CPC Class Codes: H01L 29/66143 Schottky diodes
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

A semiconductor device having a trench MOS barrier Schottky diode includes a semiconductor volume of a first conductivity type, the semiconductor volume (i) having a first side which is covered with a metal layer, and (ii) including at least one trench which extends in the first side and is at least partially filled with metal and/or with a semiconductor material of a second conductivity type. The trench has at least one wall section which includes an oxide layer, at least in areas. At least one area, situated next to the trench, of the first side covered with the metal layer has a layer, situated between the metal layer and the semiconductor volume, made of a first semiconductor material of the second conductivity type.

Claims

1. A semiconductor device having a trench MOS barrier Schottky diode, comprising:

a semiconductor volume of a first conductivity type, the semiconductor volume (i) having a first side which is covered with a metal layer, and (ii) including at least one trench which extends in the first side and is at least partially filled with at least one of metal and a semiconductor material of a second conductivity type, the trench having at least one wall section which includes an oxide layer, at least in areas;

wherein at least one area, situated next to the trench, of the first side covered with the metal layer has a layer, situated between the metal layer and the semiconductor volume, made of a first semiconductor material of the second conductivity type.

2. The semiconductor device as recited in claim 1, wherein the semiconductor volume includes at least two trenches.

3. The semiconductor device as recited in claim 1, wherein at least one area of a base of the at least one trench is filled with a second semiconductor material which is a semiconductor material of the second conductivity type.

4. The semiconductor device as recited in claim 1, wherein at least one area of a base of the at least one trench is converted into a second semiconductor material of the second conductivity type with the aid of ion implantation.

5. The semiconductor device as recited in claim 1, wherein a second side of the semiconductor volume, facing away from the first side covered with the metal layer, is covered with an electrically conductive contact material, and a partial volume of the semiconductor volume bordering the contact material is more strongly doped than the remaining semiconductor volume of the first conductivity type.

6. The semiconductor device as recited in claim 3, wherein the metal layer is separated in sections from the semiconductor volume of the first conductivity type, by one of (i) the oxide layer, (ii) the layer made of the first semiconductor material of the second conductivity type, or (iii) the second semiconductor material of the second conductivity type.

7. The semiconductor device as recited claim 3, wherein the first semiconductor material of the second conductivity type has a layer thickness of approximately 10 nanometers (nm) to approximately 500 nm.

8. The semiconductor device as recited in claim 3, wherein a doping concentration of the first semiconductor material of the second conductivity type is approximately 10¹⁶ atoms per cubic centimeter volume to approximately 10¹⁷ atoms per cubic centimeter volume.

9. The semiconductor device as recited in claim 3, wherein a depth of the at least one trench is 1 micron (μ

m) to 4 μ

m, preferably approximately 2 μ

m.

10. The semiconductor device as recited in claim 2, wherein a ratio of a depth of one of the two trenches to a clearance between the two trenches is at least equal to 2.

11. The semiconductor device as recited in claim 3, wherein one of (i) the first conductivity type corresponds to an n-doped semiconductor material and the second conductivity type corresponds to a p-doped semiconductor material, or (ii) the first conductivity type corresponds to a p-doped semiconductor material and the second conductivity type corresponds to an n-doped semiconductor material.

12. A method for manufacturing a semiconductor device having a trench MOS barrier Schottky diode, the method comprising:

creating a first semiconductor volume of a first conductivity type, a partial volume of the first semiconductor volume being comparatively strongly doped;

etching at least one trench into the first semiconductor volume;

creating an oxide layer on at least one wall section of the at least one trench;

removing at least one section of the oxide layer in an area of a base of the trench;

creating a semiconductor volume of a second conductivity type in the area of the base by doping the first semiconductor volume with a dopant which increases the conductivity of the second conductivity type;

filling at least a portion of a remaining volume of the at least one trench with one of a metal or a polycrystalline semiconductor material of the second conductivity type;

creating a layer made of a semiconductor material of a second conductivity type on the first semiconductor volume of the first conductivity type on a side of the first semiconductor volume facing away from the electrically conductive contact material;

providing a metal layer on the layer made of the semiconductor material of the second conductivity type and on the metal or polycrystalline semiconductor material, which fills at least a portion of the remaining volume of the trench; and

providing an electrically conductive contact material on the partial volume of the first semiconductor volume.