Semiconductor field effect power switching device

• US 8,541,837 B2
• Filed: 05/01/2012
• Issued: 09/24/2013
• 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:
  US13/461,198
• Publication Number:
  US 20120217540A1
• Time in Patent Office: 511 Days
• Field of Search: 257/331, 257/401, 257/E29.201, 257/E29.26, 257/337, 257/341, 257/E21.418, 257/E21.419
• 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 source metallization;

a first field-effect structure including a source region of a first conductivity type, the source region being electrically connected to the source metallization;

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

a first gate electrode and a first insulating region arranged at least between the first gate electrode and the body region, the first gate electrode, the first insulating region and the body region forming a first capacitance, the first capacitance having a first capacitance per unit area;

a second field-effect structure including a source region of the first conductivity type;

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

an electrode structure and a second insulating region which is, in a first vertical cross-section, arranged at least between the electrode structure and the body region, the source region and the electrode structure being electrically connected to the source metallization;

the electrode structure, the second insulating region and the body region forming a second capacitance, the second capacitance having a second capacitance per unit area;

the second capacitance per unit area being larger than the first capacitance per unit area; and

a body contact region of the second conductivity type which adjoins, in a second vertical cross-section, the electrode structure and the body region of at least one of the first field-effect structure and the second field-effect structure;

wherein the body region to which the body contact region adjoins has a first doping concentration; and

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

2. The semiconductor device of claim 1, further comprising a common drift region of the first conductivity type;

the common drift region forming a pn-junction with the body regions of the first field-effect structure and the second field-effect structure;

wherein the body region of the first field effect structure and the common drift region form a body diode;

wherein the second field effect structure forms a MOS-gated diode (MGD) connected in parallel to at least one of the body diode and the first field-effect structure;

wherein the total current through the semiconductor device in forward biasing of the body diode is dominated by an unipolar current above an average current flow density in the drift region; and

wherein the average current flow density is about 1 mA/mm².

3. The semiconductor device of claim 1, comprising a plurality of first field-effect structures and second field-effect structures, wherein at least a part of the plurality of first field-effect structures and second field-effect structures are arranged in a regular pattern.

4. The semiconductor device of claim 1, wherein the body region of the first field-effect structure includes a first body sub-region adjoining the first insulating region;

wherein the body region of the second field-effect structure includes a second body sub-region adjoining the second insulating region; and

wherein the doping concentration of the second body sub-region is lower than the doping concentration of the first body sub-region.

5. The semiconductor device of claim 1, wherein at least one of the first field-effect structures further includes at least one field plate electrically connected to the source metallization.

6. The semiconductor device of claim 1, wherein the first gate electrode includes a material having a first work function, and wherein the second gate electrode includes a material having a second work function which is smaller than the first work function.

7. A semiconductor device comprising:

a source metallization;

a first field-effect structure including a source region of a first conductivity type, the source region being electrically connected to the source metallization;

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

a first gate electrode and a first insulating region arranged at least between the first gate electrode and the body region, the first gate electrode, the first insulating region and the body region forming a first capacitance, the first capacitance having a first capacitance per unit area;

a second field-effect structure including a source region of the first conductivity type;

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

an electrode structure and a second insulating region which is, in a first vertical cross-section, arranged at least between the electrode structure and the body region, the source region and the electrode structure being electrically connected to the source metallization;

the electrode structure, the second insulating region and the body region forming a second capacitance, the second capacitance having a second capacitance per unit area;

the second capacitance per unit area being larger than the first capacitance per unit area; and

a common drift region of the first conductivity type;

the common drift region forming a pn-junction with the body regions of the first field-effect structure and the second field-effect structure;

wherein the body region of the first field effect structure and the common drift region form a body diode;

wherein the second field effect structure forms a MOS-gated diode (MGD) connected in parallel to at least one of the body diode and the first field-effect structure;

wherein the total current through the semiconductor device in forward biasing of the body diode is dominated by an unipolar current above an average current flow density in the drift region; and

wherein the average current flow density is about 1 mA/mm².

8. The semiconductor device of claim 7, further comprising a body contact region of the second conductivity type which adjoins, in a second vertical cross-section, the electrode structure and the body region of at least one of the first field-effect structure and the second field-effect structure;

wherein the body region to which the body contact region adjoins 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. A semiconductor device comprising:

a source metallization;

a first field-effect structure including a source region of a first conductivity type, the source region being electrically connected to the source metallization;

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

a first gate electrode and a first insulating region arranged at least between the first gate electrode and the body region, the first gate electrode, the first insulating region and the body region forming a first capacitance, the first capacitance having a first capacitance per unit area;

a second field-effect structure including a source region of the first conductivity type;

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

an electrode structure and a second insulating region which is, in a first vertical cross-section, arranged at least between the electrode structure and the body region, the source region and the electrode structure being electrically connected to the source metallization;

the electrode structure, the second insulating region and the body region forming a second capacitance, the second capacitance having a second capacitance per unit area;

the second capacitance per unit area being larger than the first capacitance per unit area; and

wherein the body region of the first field-effect structure includes a first body sub-region adjoining the first insulating region;

wherein the body region of the second field-effect structure includes a second body sub-region adjoining the second insulating region; and

wherein the doping concentration of the second body sub-region is lower than the doping concentration of the first body sub-region.

10. A semiconductor device comprising:

a source metallization;

a first field-effect structure including a source region of a first conductivity type, the source region being electrically connected to the source metallization;

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

a first gate electrode and a first insulating region arranged at least between the first gate electrode and the body region, the first gate electrode, the first insulating region and the body region forming a first capacitance, the first capacitance having a first capacitance per unit area;

a second field-effect structure including a source region of the first conductivity type;

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

an electrode structure and a second insulating region which is, in a first vertical cross-section, arranged at least between the electrode structure and the body region, the source region and the electrode structure being electrically connected to the source metallization;

the electrode structure, the second insulating region and the body region forming a second capacitance, the second capacitance having a second capacitance per unit area;

the second capacitance per unit area being larger than the first capacitance per unit area; and

wherein at least one of the first field-effect structures further includes at least one field plate electrically connected to the source metallization.

11. A semiconductor device comprising:

a source metallization;

a first field-effect structure including a source region of a first conductivity type, the source region being electrically connected to the source metallization;

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

a first gate electrode and a first insulating region arranged at least between the first gate electrode and the body region, the first gate electrode, the first insulating region and the body region forming a first capacitance, the first capacitance having a first capacitance per unit area;

a second field-effect structure including a source region of the first conductivity type;

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

an electrode structure and a second insulating region which is, in a first vertical cross-section, arranged at least between the electrode structure and the body region, the source region and the electrode structure being electrically connected to the source metallization;

the electrode structure, the second insulating region and the body region forming a second capacitance, the second capacitance having a second capacitance per unit area;

the second capacitance per unit area being larger than the first capacitance per unit area; and

wherein the first gate electrode includes a material having a first work function, and wherein the second gate electrode includes a material having a second work function which is smaller than the first work function.