Trench MOSFET semiconductor device and manufacturing method therefor

• US 8,203,181 B2
• Filed: 08/13/2009
• Issued: 06/19/2012
• 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: Hirler, Franz
• Primary Examiner(s): Jackson, Jr., Jerome
• Assistant Examiner(s): BUDD, PAUL A
• Application Number:
  US12/540,860
• Publication Number:
  US 20100301410A1
• Time in Patent Office: 1,041 Days
• Field of Search: 257/331, 257/E29.201, 257/E29.26, 257/401, 438/221, 438/219
• US Class Current: 257/331
• 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 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 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236

Abstract

A semiconductor device having a semiconductor body, a source metallization arranged on a first surface of the semiconductor body and a trench including a first trench portion and a second trench portion and extending from the first surface into the semiconductor body is provided. The semiconductor body further includes a pn-junction formed between a first semiconductor region and a second semiconductor region. The first trench portion includes an insulated gate electrode which is connected to the source metallization, and the second trench portion includes a conductive plug which is connected to the source metallization and to the second semiconductor region.

Claims

1. A semiconductor device comprising:

a semiconductor body comprising a first surface, a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type, the first semiconductor region and the second semiconductor region forming a pn-junction;

a source metallization arranged on the first surface; and

a trench extending from the first surface into the semiconductor body and comprising, in a horizontal plane substantially parallel to the first surface, a first trench portion and a second trench portion; and

the first trench portion comprising a gate electrode connected to the source metallization and an insulating layer arranged between the gate electrode and the second semiconductor region;

the second trench portion comprising a conductive plug which is connected to the source metallization and to the second semiconductor region;

wherein the first semiconductor region forms a source region which is connected to the source metallization and extends to the first surface;

wherein the second semiconductor region forms a body region;

wherein the semiconductor body further comprises a drift region of the first conductivity type adjacent to the body region; and

wherein the first trench portion and the second trench portion extend through the source region and at least partially into the body region; and

wherein the semiconductor body further comprises a body contact region of the second conductivity type which provides an electrical connection between the body region and the conductive plug of the second trench portion;

wherein the body region comprises a first doping concentration; and

wherein the body contact region comprises a second doping concentration which is higher than the first doping concentration.

2. The semiconductor device of claim 1, wherein the first trench portion and the second trench portion form a simply connected trench.

3. The semiconductor device of claim 1, wherein the semiconductor device comprises a plurality of first trench portions and second trench portions which are, in a horizontal direction, arranged in a regular pattern.

4. The semiconductor device of claim 1, wherein the first trench portion comprises a first vertical depth;

and wherein the second trench portion comprises a second vertical depth which is lower than the first vertical depth.

5. The semiconductor device of claim 1, wherein the semiconductor device further comprises at least one additional field effect structure which is selected from a group consisting of a lateral MOSFET, a UMOSFET, a DMOSFET, a Superjunction-MOSFET or an reverse conducting IGBT.

6. The semiconductor device of claim 1, further comprising an additional field effect structure which comprises an additional gate electrode and a first capacitance formed between the additional gate electrode and the body region and comprising a first capacitance per unit area;

and wherein the gate electrode, the insulating layer and the body region form a second capacitance comprising a second capacitance per unit area which is larger than the first capacitance per unit area.

7. The semiconductor device of claim 1, wherein the insulating layer forms a part of a MOS-gated diode.

8. A semiconductor device comprising:

a source metallization;

a field-effect structure comprising a source region of a first conductivity type connected to the source metallization, a body region of a second conductivity type adjacent to the source region, a drift region of the first conductivity type adjacent to the body region and a first insulated gate electrode;

a trench comprising a first trench portion and a second trench portion, the first trench portion comprising a second insulated gate electrode and an insulating layer arranged between the gate electrode and the body region and connected to the source metallization;

the second trench portion comprising a conductive plug electrically connecting the source metallization with the body region; and

a body contact region of the second conductivity type which adjoins the body region and a lower part of the second trench portion;

wherein the body region has a first doping concentration; and

wherein the body contact region has a second doping concentration which is higher than the first doping concentration.

9. The semiconductor device of claim 8, wherein the body contact regions are embedded within the body region.

10. The semiconductor device of claim 8, wherein the body region and the drift region form a body diode of the field-effect structure;

and wherein the second insulated gate electrode forms the gate electrode of a MOS-gated diode connected in parallel to at least one of the body diode and the field-effect structure.

11. A power semiconductor device comprising:

a source metallization;

a field-effect structure comprising a source region of a first conductivity type connected to the source metallization, a body region of a second conductivity type adjacent to the source region, a drift region of the first conductivity type adjacent to the body region and a first trench comprising an insulated gate electrode; and

a second trench comprising a first trench portion and a second trench portion, the first trench portion comprising a second gate electrode connected to the source metallization and an insulating layer arranged between the second gate electrode and the body region;

the second trench portion comprising a conductive plug electrically connecting the source metallization with the body region;

wherein the conductive plug and the second gate electrode are formed by a common conductive structure.

12. The power semiconductor device of claim 11, wherein the body region comprises a first doping concentration;

and wherein the power semiconductor device further comprises a third conductive region of the second conductivity type which adjoins the body region and the conductive plug, the third conductive region Comprising a second doping concentration which is higher than the first doping concentration.

13. The power semiconductor device of claim 11, further comprising a fourth semiconductor region adjoining the drift region, the body region and the insulating layer;

wherein the fourth semiconductor region is selected from a group consisting of a semiconductor region of the first conductivity type and a weakly doped semiconductor region of the second conductivity type.

14. A method for forming a semiconductor device comprising:

providing a semiconductor body comprising a first surface, a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type, the first semiconductor region comprising a first doping concentration, the first semiconductor region and the second semiconductor region forming a pn-junction;

forming a trench such that the trench extends from the first surface into the semiconductor body and comprises, in a horizontal plane substantially parallel to the first surface, a first trench portion and second trench portion;

forming a gate electrode and an insulating layer arranged between the gate electrode and the second semiconductor region in the first trench portion;

forming a conductive plug in the second trench portion such that the conductive plug is connected with the second semiconductor region;

forming a source metallization on the first surface such that the source metallization is connected to the gate electrode and the conductive plug; and

forming a third semiconductor region of the second conductivity type such that the third semiconductor region adjoins the second semiconductor region, is electrically connected to the conductive plug and comprises a doping concentration which is higher than the first doping concentration.

15. A semiconductor device comprising:

a semiconductor body comprising a first surface, a first semiconductor region of a first conductivity type and a second semiconductor region of a second conductivity type, the first semiconductor region and the second semiconductor region forming a pn-junction;

a source metallization arranged on the first surface; and

a trench extending from the first surface into the semiconductor body and comprising, in a horizontal plane substantially parallel to the first surface, a first trench portion and a second trench portion; and

the first trench portion comprising a gate electrode connected to the source metallization and an insulating layer arranged between the gate electrode'"'"'and the second semiconductor region;

the second trench portion comprising a conductive plug which is connected to the source metallization and to the second semiconductor region;

wherein the first trench portion comprises a first vertical depth; and

wherein the second trench portion comprises a second vertical depth which is lower than the first vertical depth.