JFET and method of manufacturing thereof

• US 9,711,660 B2
• Filed: 03/13/2014
• Issued: 07/18/2017
• Est. Priority Date: 03/13/2014
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Ouvrard, Cedric, Konrath, Jens Peter, Schulze, Hans-Joachim, Siemieniec, Ralf
• Primary Examiner(s): Prenty, Mark
• Application Number:
  US14/207,733
• Publication Number:
  US 20150263178A1
• Time in Patent Office: 1,223 Days
• Field of Search: 257263
• CPC Class Codes: H01L 21/266 using masks H01L21/26586 takes precedence
• CPC Class Codes: H01L 29/1066 Gate region of field-effect devices with PN junction gate
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/36 characterised by the concentration or distribution of impurities in the bulk material within semiconductor regions H01L29/06
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/66909 Vertical transistors, e.g. tecnetrons
• CPC Class Codes: H01L 29/8083 Vertical transistors SIT H01L29/7722

Abstract

A JFET has a semiconductor body with a first surface and second surface substantially parallel to the first surface. A source metallization and gate metallization are arranged on the first surface. A drain metallization is arranged on the second surface. In a sectional plane substantially perpendicular to the first surface, the semiconductor body includes: a first semiconductor region in ohmic contact with the source and drain metallizations, at least two second semiconductor regions in ohmic contact with the gate metallization, spaced apart from one another, and forming respective first pn-junctions with the first semiconductor region, and at least one body region forming a second pn-junction with the first semiconductor region. The at least one body region is in ohmic contact with the source metallization. At least a portion of the at least one body region is, in a projection onto the first surface, arranged between the two second semiconductor regions.

Claims

1. A vertical JFET, comprising:

a semiconductor body having a first surface and a second surface that runs substantially parallel to the first surface;

a source metallization arranged on the first surface;

a drain metallization arranged on the second surface; and

a gate metallization arranged on the first surface, wherein, in a sectional plane substantially perpendicular to the first surface, the semiconductor body comprises;

an n-doped first semiconductor region in ohmic contact with the drain metallization and the source metallization;

a plurality of p-doped second semiconductor regions in ohmic contact with the gate metallization, substantially extending to the first surface, spaced apart from one another and forming respective first pn-junctions with the first semiconductor region; and

a plurality of p-doped body regions in ohmic contact with the source metallization, spaced apart from one another, from the p-doped second semiconductor regions, from the first surface and from the second surface, and forming respective second pn-junctions with the first semiconductor region,

wherein the semiconductor body further comprises at least one conductive plug extending from the source metallization to one of the body regions.

2. The vertical JFET of claim 1, wherein at least one current path runs in the semiconductor body from the drain metallization to the source metallization only through n-doped semiconductor regions.

3. The vertical JFET of claim 1, wherein a space charge region extends at least between at least one of the body regions and an adjacent second semiconductor region, and/or at least between at least two of the body regions, and/or at least between at least two of the second semiconductor regions when a voltage difference higher than a pinch-off voltage is applied between the source metallization and the gate metallization;

or wherein a space charge region extends at least between at least one of the body regions and an adjacent second semiconductor region, and/or at least between at least two of the body regions, and/or at least between at least two of the second semiconductor regions when the gate metallization and the source metallization are substantially on the same potential.

4. The vertical JFET of claim 1, wherein a lower space charge region and an upper space charge region spaced apart from the lower space charge region are formed when the gate metallization and the source metallization are substantially on the same potential, so that the lower space charge region includes at least two of the second pn-junctions and that the upper space charge region includes at least two of the first pn-junctions.

5. The vertical JFET of claim 1, wherein at least one of the p-doped body regions partly overlaps with two of the second semiconductor regions when seen from above.

6. The vertical JFET of claim 1, wherein the at least one conductive plug is arranged in a trench extending from the first surface to one of the body regions.

7. The vertical JFET of claim 6, further comprising a dielectric region arranged on a sidewall of the trench.

8. The vertical JFET of claim 1, wherein the at least one conductive plug comprises a p-doped semiconductor material.

9. The vertical JFET of claim 1, wherein the semiconductor body is comprised of a semiconductor material that has a band-gap higher than about two electron volts.

10. The vertical JFET of claim 1, wherein the n-doped first semiconductor region comprises at least one of:

an n-doped current-spread portion forming at least a part of the first pn-junctions and forming at least a part of the second pn-junctions;

an n-doped drift portion having a lower maximum doping concentration than the current-spread portion, and arranged between the current-spread portion and the drain metallization;

an n-doped first contact portion having a higher maximum doping concentration than the current-spread portion, arranged between a pair of adjacent p-doped second semiconductor regions, and arranged between the current-spread portion and the source metallization;

an n-doped embedded portion completely embedded in the current-spread portion, and having a higher maximum doping concentration than the current-spread portion; and

an n-doped second contact portion having a higher maximum doping concentration than the drift portion and arranged between the drain metallization and at least one of the drift portion and the current-spread portion.

11. A JFET, comprising:

a semiconductor body comprising a semiconductor material that has a band-gap higher than about two electron volts and extends between a first surface and a second surface which runs substantially parallel to the first surface;

a source metallization arranged on the first surface;

a gate metallization arranged on the first surface; and

a drain metallization arranged on the second surface, wherein, in a sectional plane substantially perpendicular to the first surface, the semiconductor body comprises;

a first semiconductor region in ohmic contact with the source metallization and the drain metallization;

at least two second semiconductor regions in ohmic contact with the gate metallization, spaced apart from one another, and forming respective first pn-junctions with the first semiconductor region; and

at least one body region completely embedded in the first semiconductor region and forming a second pn-junction with the first semiconductor region,

wherein the at least one body region is spaced apart from the first surface and from the source metallization,

wherein at least a portion of the at least one body region is, in a projection onto the first surface, arranged between the two second semiconductor regions, and

wherein the semiconductor body further comprises in the sectional plane a plurality of second semiconductor regions forming a first lattice and a plurality of body regions forming a second lattice.

12. The JFET of claim 11, further comprising at least one of a conductive region forming at least a portion of an ohmic current path between the source metallization and the at least one body region, and a dielectric region separating the conductive region from the first semiconductor region.

13. The JFET of claim 11, wherein the second semiconductor regions substantially extend to the first surface.

14. The JFET of claim 11, wherein at least one ohmic current path runs in the semiconductor body from the source metallization to the drain metallization.