Power MOSFET semiconductor

• US 9,202,909 B2
• Filed: 03/28/2013
• Issued: 12/01/2015
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Inventors: Haeberlen, Oliver, Krumrey, Joachim, Hirler, Franz, Rieger, Walter
• Primary Examiner(s): Jackson, Jr., Jerome
• Assistant Examiner(s): BUDD, PAUL A
• Application Number:
  US13/852,127
• Publication Number:
  US 20130228858A1
• Time in Patent Office: 978 Days
• Field of Search: 257/329, 257/401, 257/E29.262
• US Class Current: 1/1
• CPC Class Codes: H01L 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface
• CPC Class Codes: H01L 27/0629 in combination with diodes, or resistors, or capacitors
• CPC Class Codes: H01L 29/0623 Buried supplementary region, e.g. buried guard ring multi-RESURF H01L29/0634
• CPC Class Codes: H01L 29/0834 Anode regions of thyristors or gated bipolar-mode devices, e.g. supplementary regions surrounding anode regions
• CPC Class Codes: H01L 29/086 Impurity concentration or distribution
• CPC Class Codes: H01L 29/0878 Impurity concentration or distribution
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/404 Multiple field plate structures
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41766 with at least part of the source or drain electrode having contact below the semiconductor surface, e.g. the source or drain electrode formed at least partially in a groove or with inclusions of conductor inside the semiconductor H01L29/41733 - H01L29/41758 take precedence
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/495 the conductor material next to the insulator being a simple metal, e.g. W, Mo H01L29/4908, H01L29/4983 take precedence
• CPC Class Codes: H01L 29/4966 the conductor material next to the insulator being a composite material, e.g. organic material, TiN, MoSi2 H01L29/4908, H01L29/4983 take precedence
• CPC Class Codes: H01L 29/66727 with a step of recessing the source electrode
• CPC Class Codes: H01L 29/66734 with a step of recessing the gate electrode, e.g. to form a trench gate electrode
• CPC Class Codes: H01L 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
• CPC Class Codes: H01L 29/7803 structurally associated with at least one other device assemblies H01L25/00; integrated circuits H01L27/00
• CPC Class Codes: H01L 29/7805 in antiparallel, e.g. freewheel diode
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A semiconductor device includes a source metallization, a source region of a first conductivity type in contact with the source metallization, a body region of a second conductivity type which is adjacent to the source region. The semiconductor device further includes a first field-effect structure including a first insulated gate electrode and a second field-effect structure including a second insulated gate electrode which is electrically connected to the source metallization. The capacitance per unit area between the second insulated gate electrode and the body region is larger than the capacitance per unit area between the first insulated gate electrode and the body region.

Claims

1. A semiconductor device, comprising:

a source metallization;

a source region of a first conductivity type, the source region being connected to the source metallization;

a body region of a second conductivity type adjacent to the source region;

a drift region of a first conductivity type adjacent to the body region;

a third conductive region of a second conductivity type buried within the drift region; and

a trench extending from the source region through the body region and at least to the third conductive region;

the trench adjoining the third conductive region and including a conductive plug and an insulating layer, which is arranged between the conductive plug and the body region, the conductive plug forming at least a portion of an Ohmic connection between the source metallization and the third conductive region;

the conductive plug, the insulating layer and the body region forming a field effect structure.

2. The semiconductor device of claim 1, wherein the body region is electrically connected to the source metallization.

3. The semiconductor device of claim 1, further comprising a further field-effect structure having a gate capacitance per unit area.

4. The semiconductor device of claim 3, wherein the field effect structure has a capacitance per unit area higher than the gate capacitance per unit area of the further field effect structure.

5. The semiconductor device of claim 1, the third conductive region and the body region having respective doping concentrations, wherein the doping concentration of the third conductive region is higher than the doping concentration of the body region.

6. The semiconductor device of claim 1, wherein the insulating layer is arranged between the conductive plug and the source region.

7. The semiconductor device of claim 1, wherein the semiconductor device is a power semiconductor device.

11. The semiconductor device of claim 1, where the trench further comprises a conductive contact layer arranged between the conductive plug and the third conductive region and having a higher electric conductivity than the third conductive region.

12. The semiconductor device of claim 11, wherein the conductive contact layer comprises one of a metal, a silicide, and a titanium nitride.

13. The semiconductor device of claim 1, wherein the conductive plug comprises poly-silicon.

14. The semiconductor device of claim 1, further comprising a first doped region of the first conductivity type adjoining the source metallization, the source region, and the insulating layer.

15. The semiconductor device of claim 1, further comprising a second doped region of the first conductivity type having a doping concentration higher than a doping concentration of the drift region, and a third doped region of the first conductivity type having a doping concentration higher than the doping concentration of the drift region, the second doped region adjoining the source metallization, the source region, the body region, the insulating layer, and the third doped region, the third doped region being arranged between the body region and the drift region.

8. A converter circuit, comprising a high-side switch and at least one low-side switch connected to the high-side switch, the at least one low-side switch comprising:

a source metallization;

a source region of a first conductivity type, the source region being connected to the source metallization;

a body region of a second conductivity type adjacent to the source region;

a drift region of a first conductivity type adjacent to the body region;

a third conductive region of a second conductivity type buried within the drift region; and

a trench extending from the source region through the body region and at least partially into the drift region;

the trench adjoining the third conductive region and including a conductive plug and an insulating layer, which is arranged between the conductive plug and the body region, the conductive plug forming an Ohmic connection between the source metallization and the third conductive region.

9. The circuit of claim 8, wherein the conductive plug, the insulating layer and the body region form a field effect structure having a gate capacitance per unit area.

10. The circuit of claim 9, further comprising a further field-effect structure having a gate capacitance per unit area lower than the gate capacitance per unit area of the field effect structure.