SEMICONDUCTOR DEVICE HAVING SWITCHING ELEMENT AND FREE WHEEL DIODE AND METHOD FOR CONTROLLING THE SAME

• US 20150041850A1
• Filed: 10/14/2014
• Published: 02/12/2015
• Est. Priority Date: 07/27/2010
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: YAMAMOTO, Tsuyoshi, MIZUNO, Shoji, SUMITOMO, Masakiyo, FUJII, Tetsuo, YAMAGUCHI, Hitoshi, SAIKAKU, Hirotaka, SAKAKIBARA, Jun, HATTORI, Yoshiyuki, TAGUCHI, Rie, KUWAHARA, Makoto
• Granted Patent: US 9,515,067 B2
• Time in Patent Office: Days
• US Class Current: 257/140
• CPC Class Codes: H01L 27/0629 in combination with diodes, or resistors, or capacitors
• CPC Class Codes: H01L 27/0635 in combination with bipolar transistors and diodes, or resistors, or capacitors
• CPC Class Codes: H01L 29/0634 Multiple reduced surface field (multi-RESURF) structures, e.g. double RESURF, charge compensation, cool, superjunction (SJ), 3D-RESURF, composite buffer (CB) structures
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• 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 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/42368 the thickness being non-uniform
• CPC Class Codes: H01L 29/4238 characterised by the surface lay-out
• CPC Class Codes: H01L 29/4983 with a lateral structure, e.g. a Polysilicon gate with a lateral doping variation or with a lateral composition variation or characterised by the sidewalls being composed of conductive, resistive or dielectric material
• 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 29/7391 Gated diode structures
• CPC Class Codes: H01L 29/7393 Insulated gate bipolar mode transistors, i.e. IGBT; IGT; COMFET
• 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 29/7398 with both emitter and collector contacts in the same substrate side
• 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
• CPC Class Codes: H01L 29/7819 in antiparallel, e.g. freewheel diode
• CPC Class Codes: H01L 29/7825 with trench gate electrode trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 29/7831 : with multiple gate structure FinFETs or MuGFETs H01L29/7855, thin film transistors H01L29/78645
• CPC Class Codes: H01L 29/861 : Diodes
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H02M 7/003 : Constructional details, e.g. physical layout, assembly, wiring or busbar connections

Abstract

A semiconductor device includes a switching element having: a drift layer; a base region; an element-side first impurity region in the base region; an element-side gate electrode sandwiched between the first impurity region and the drift layer; a second impurity region contacting the drift layer; an element-side first electrode coupled with the element-side first impurity region and the base region; and an element-side second electrode coupled with the second impurity region, and a FWD having: a first conductive layer; a second conductive layer; a diode-side first electrode coupled to the second conductive layer; a diode-side second electrode coupled to the first conductive layer; a diode-side first impurity region in the second conductive layer; and a diode-side gate electrode in the second conductive layer sandwiched between first impurity region and the first conductive layer and having a first gate electrode as an excess carrier injection suppression gate.

Claims

1. A semiconductor device comprising:

a semiconductor switching element with an insulated gate structure; and

a free wheel diode,

wherein the semiconductor switching element includes;

a drift layer having a first conductivity type;

a base region having a second conductivity type and arranged on the drift layer;

an element-side first impurity region having the first conductivity type, arranged in a surface part of the base region, separated from the drift layer by the base region therebetween, and having an impurity concentration higher than the drift layer;

an element-side gate electrode disposed in the base region sandwiched between the first impurity region and the drift layer through a gate insulating film;

a second impurity region having the first or second conductivity type, contacting the drift layer, having an impurity concentration higher than the drift layer, and separated from the base region;

an element-side first electrode electrically coupled with the element-side first impurity region and the base region; and

an element-side second electrode electrically coupled with the second impurity region,

wherein the semiconductor switching element provides an inversion channel in a portion of the base region opposite to the element-side gate electrode via the gate insulating film therebetween,

wherein the semiconductor switching element provides a current flowing between the element-side first electrode and the element-side second electrode through the channel,

wherein the free wheel diode includes;

a first conductivity type layer;

a second conductivity type layer arranged on the first conductivity type layer;

a diode-side first electrode coupled to the second conductivity type layer; and

a diode-side second electrode coupled to the first conductivity type layer,

wherein the free wheel diode provides a p-n junction including the first conductivity type layer and the second conductivity type layer,

wherein the free wheel diode provides a current flowing between the diode-side first electrode and the diode-side second electrode,

wherein the semiconductor switching element and the free wheel diode are coupled in parallel with each other,

wherein the free wheel diode further includes;

a diode-side first impurity region having the first conductivity type, arranged in a surface part of the second conductivity type layer, and having an impurity concentration higher than the first conductivity type layer; and

a diode-side gate electrode arranged in the second conductivity type layer sandwiched between the first impurity region and the first conductivity type layer through a gate insulating film,

wherein the diode-side gate electrode includes a first gate electrode,

wherein the first gate electrode provides an excess carrier injection suppression gate,

wherein, when a gate voltage is applied to the diode-side gate electrode, the first gate electrode provides the channel in a part of the second conductivity type layer, and

wherein the part of the second conductivity type layer is arranged between the diode-side first impurity region and a predetermined position, which is disposed between the diode-side first impurity region and the first conductivity type layer.

2. The semiconductor device of claim 1,

wherein the semiconductor switching element and the free wheel diode are arranged in one chip,

wherein the drift layer is the first conductivity type layer,

wherein the base region is the second conductivity type layer,

wherein the element-side first electrode is the diode-side first electrode,

wherein the element-side second electrode is the diode-side second electrode,

wherein the element-side first impurity region is the diode-side first impurity region, and

wherein the element-side gate electrode is the diode-side gate electrode.

3. The semiconductor device of claim 2,

wherein the first gate electrode is arranged between the element-side first impurity region via the gate insulating film and a predetermined position of the base region.

4. The semiconductor device of claim 3,

wherein the element-side gate electrode includes a second gate electrode,

wherein the second gate electrode is arranged between the predetermined position of the base region via the gate insulating film and the drift layer,

wherein, when the gate voltage is applied to the element-side gate electrode, the first gate electrode and the second gate electrode function as a semiconductor switching element driving gate, and

wherein the semiconductor switching element driving gate provides the channel connecting between the element-side first impurity region and the drift layer together in the base region.

5. The semiconductor device of claim 4, further comprising:

a trench penetrating the element-side first impurity region and the base region and reaching the drift layer,

wherein the first gate electrode and the second gate electrode are arranged in the trench with an insulating film therebetween so that a double gate-type trench gate structure is provided, and

wherein the semiconductor switching element has a trench gate structure.

6. The semiconductor device of claim 5,

wherein the second impurity region is a semiconductor substrate having the first conductivity type,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the trench, and

wherein the semiconductor switching element is a vertical MOSFET for flowing a current in a direction perpendicular to the semiconductor substrate.

7. The semiconductor device of claim 5,

wherein the second impurity region is a semiconductor substrate further including a second conductivity type portion,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the trench, and

wherein the semiconductor switching element is a vertical IGBT for flowing a current in a direction perpendicular to the semiconductor substrate.

8. The semiconductor device of claim 5, wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region has the first conductivity type,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the trench extends in a direction parallel to a surface of the drift layer,

wherein the trench penetrates the first impurity region and the base region and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the trench, and

wherein the semiconductor switching element is a horizontal MOSFET for flowing a current in a horizontal direction parallel to the surface of the drift layer.

9. The semiconductor device of claim 5,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region further includes a second conductivity type portion,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the trench extends in a direction parallel to a surface of the drift layer,

wherein the trench penetrates the first impurity region and the base region and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the trench, and

wherein the semiconductor switching element is a horizontal IGBT for flowing a current in a horizontal direction parallel to the surface of the drift layer.

10. The semiconductor device of claim 4,

wherein the second impurity region is a semiconductor substrate having the first conductivity type,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the first gate electrode and the second gate electrode are arranged on a surface portion of the base region located between the element-side first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in the surface portion of the base region in a horizontal direction parallel to the semiconductor substrate, and

wherein the semiconductor switching element is a planar vertical MOSFET for flowing a current in a direction perpendicular to the semiconductor substrate.

11. The semiconductor device of claim 4,

wherein the second impurity region is a semiconductor substrate further including a second conductivity type portion,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the first gate electrode and the second gate electrode are arranged on a surface portion of the base region located between the first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in a surface of the base region in a horizontal direction parallel to the semiconductor substrate, and

wherein the semiconductor switching element is a planar vertical IGBT for flowing a current in a direction perpendicular to the semiconductor substrate.

12. The semiconductor device of claim 4,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region has the first conductivity type,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the first gate electrode and the second gate electrode are arranged on a surface portion of the base region located between the first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in the surface portion of the base region opposed to the first gate electrode and the second gate electrode in a horizontal direction parallel to a surface of the drift layer, and

wherein the semiconductor switching element is a planar horizontal MOSFET for flowing a current in a direction parallel to the surface of the drift layer.

13. The semiconductor device of claim 4,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region includes a second conductivity type region,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the first gate electrode and the second gate electrode are arranged on a surface portion of the base region located between the first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in a surface part of the base region opposed to the first gate electrode and the second gate electrode in a horizontal direction parallel to a surface of the drift layer, and

wherein the semiconductor switching element is a planar horizontal IGBT for flowing a current in a direction parallel to the surface of the drift layer.

14. The semiconductor device of claim 3,

wherein the element-side gate electrode includes a second gate electrode,

wherein the first gate electrode is spaced apart from the second gate electrode,

wherein the second gate electrode is arranged between the first impurity region via the gate insulating film and the drift layer,

wherein, when the gate voltage is applied to the element-side gate electrode, the second gate electrode functions as a semiconductor switching element driving gate, and

wherein the semiconductor switching element driving gate provides the channel in the base region connecting between the first impurity region and the drift layer.

15. The semiconductor device of claim 14, further comprising:

a first trench extending from the element-side first impurity region to the base region; and

a second trench penetrating the element-side first impurity region and the base region and reaching the drift layer,

wherein the first gate electrode is arranged in the first trench, and the second gate electrode is arranged in the second trench different from the first trench so that a trench gate structure is provided, and

wherein the semiconductor switching element has a trench gate structure.

16. The semiconductor device of claim 15,

wherein the second impurity region is a semiconductor substrate having the first conductivity type,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the first trench extends from the first impurity region to a predetermined position of the base region,

wherein the second trench penetrates the first impurity region and the base region and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the second trench, and

wherein the semiconductor switching element is a vertical MOSFET for flowing a current in a direction perpendicular to the semiconductor substrate.

17. The semiconductor device of claim 15,

wherein the second impurity region is a semiconductor substrate including a second conductivity type portion,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the first trench is arranged between the first impurity region and a predetermined position of the base region,

wherein the second trench penetrates the first impurity region and the base region and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the second trench, and

wherein the semiconductor switching element is a vertical IGBT for flowing a current in a direction perpendicular to the semiconductor substrate.

18. The semiconductor device of claim 15,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region has the first conductivity type,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the first trench extends in a direction parallel to a surface of the drift layer,

wherein the first trench is arranged between the first impurity region and a predetermined position of the base region,

wherein the second trench extends in the direction parallel to the surface of the drift layer,

wherein the second trench penetrates the first impurity region and the base region and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the second trench, and

wherein the semiconductor switching element is a horizontal MOSFET for flowing a current in a horizontal direction parallel to the surface of the drift layer.

19. The semiconductor device of claim 15,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region includes a second conductivity type region,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the first trench extends in a direction parallel to a surface of the drift layer,

wherein the first trench is arranged between the first impurity region and a predetermined position of the base region,

wherein the second trench extends in the direction parallel to the surface of the drift layer,

wherein the second trench penetrates the first impurity region and the base region and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the second trench, and

wherein the semiconductor switching element is a horizontal IGBT for flowing a current in a horizontal direction parallel to the surface of the drift layer.

20. The semiconductor device of claim 14,

wherein the second impurity region is a semiconductor substrate having the first conductivity type,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the first gate electrode and the second gate electrode are arranged on a surface portion of the base region located between the element-side first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in a surface part of the base region opposed to the second gate electrode in a horizontal direction parallel to the semiconductor substrate, and

wherein the semiconductor switching element is a planar vertical MOSFET for flowing a current in a direction perpendicular to the semiconductor substrate.

21. The semiconductor device of claim 14,

wherein the second impurity region is a semiconductor substrate including a second conductivity type portion,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the first gate electrode and the second gate electrode are arranged on a surface portion of the base region located between the first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in the surface portion of the base region opposed to the second gate electrode in a horizontal direction parallel to the semiconductor substrate, and

wherein the semiconductor switching element is a planar vertical IGBT for flowing a current in a direction perpendicular to the semiconductor substrate.

22. The semiconductor device of claim 14,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region has the first conductivity type,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the first gate electrode and the second gate electrode are arranged on different surface portions of the base region located between the first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in the surface portion of the base region opposed to the second gate electrode in a horizontal direction parallel to the surface of the drift layer, and

wherein the semiconductor switching element is a planar horizontal MOSFET for flowing a current in a horizontal direction parallel to the surface of the drift layer.

23. The semiconductor device of claim 14,

wherein the base region is arranged in a surface part of the drift layer,

wherein the first impurity region is arranged in a surface part of the base

wherein the second impurity region includes a second conductivity type

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the first gate electrode and the second gate electrode are arranged in different surface portions of the base region located between the first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in a surface portion of the base region opposed to the second gate electrode in a horizontal direction parallel to the surface of the drift layer, and

wherein the semiconductor switching element is a planar horizontal IGBT for flowing a current in a horizontal direction parallel to the surface of the drift layer.

24. The semiconductor device of claim 2, further comprising:

a first trench and a second trench having a same depth,

wherein the second impurity region is a semiconductor substrate having the first conductivity type,

wherein the drift layer is arranged on the semiconductor substrate,

wherein each of the first trench and the second trench penetrates the element-side first impurity region and the base region and reaches the drift layer,

wherein the element-side gate electrode includes a second gate electrode,

wherein the first gate electrode is arranged in the first trench and the second gate electrode is arranged in the second trench, which is different from the first trench,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the second trench,

wherein the semiconductor switching element is a vertical MOSFET for flowing a current in a direction perpendicular to the semiconductor substrate,

wherein the gate insulating film arranged in the first trench has a first portion deeper than a predetermined intermediate position and a second portion shallower than the predetermined intermediate position,

wherein the intermediate position is deeper than a top of the base region and shallower than a top of the drift layer, and

wherein the first portion is thicker than the second portion.

25. The semiconductor device of claim 2, further comprising:

a first trench and a second trench having a same depth,

wherein the second impurity region is a semiconductor substrate having the first conductivity type,

wherein the drift layer is arranged on the semiconductor substrate,

wherein each of the first trench and the second trench penetrates the element-side first impurity region and the base region and reaches the drift layer,

wherein the element-side gate electrode includes a second gate electrode,

wherein the first gate electrode is arranged in the first trench and the second gate electrode is arranged in the second trench, which is different from the first trench,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the second trench,

wherein the semiconductor switching element is a vertical MOSFET for flowing a current in a direction perpendicular to the semiconductor substrate,

wherein the base region located on a side of the first trench includes a first region shallower than a predetermined intermediate position and a second region deeper than the predetermined intermediate position,

wherein the intermediate position is deeper than an upper part of the base region and shallower than an upper part of the drift layer, and

wherein the second region is higher in impurity concentration than the first region.

26. The semiconductor device of claim 1,

wherein the free wheel diode is arranged in a first chip and the semiconductor switching element is arranged in a second chip, which is different from the first chip.

27. The semiconductor device of claim 26,

wherein the first gate electrode is arranged between the diode-side first impurity region via the gate insulating film and a predetermined position of the second conductivity type region.

28. The semiconductor device of claim 27,

wherein the element-side gate electrode includes a second gate electrode and a third gate electrode,

wherein the second gate electrode is arranged between the element-side first impurity region via the gate insulating film and a predetermined position of the base region,

wherein the third gate electrode is arranged between the element-side first impurity region via the gate insulating film and a predetermined position of the drift layer,

wherein, when the gate voltage is applied to the element-side gate electrode, the third gate electrode functions as a semiconductor switching element driving gate, and

wherein the semiconductor switching element driving gate provides the channel in the base region connecting between the first impurity region and the drift layer.

29. The semiconductor device of claim 28,

wherein the first chip further includes a first trench,

wherein the first trench extends from the diode-side first impurity region to the second conductivity type layer,

wherein the first gate electrode is arranged in the first trench,

wherein the second chip further includes a second trench and a third trench,

wherein the second trench extends from the element-side first impurity region to the base region,

wherein the third trench penetrates the element-side first impurity region and the base region and reaches the drift layer,

wherein the second gate electrode is arranged in the second trench, and the third gate electrode is arranged in the third trench so that a trench gate structure is provided, and

wherein the semiconductor switching element has a trench gate structure.

30. The semiconductor device of claim 29,

wherein the second impurity region is a semiconductor substrate having the first conductivity type,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the first trench is arranged between the diode-side first impurity region and a predetermined position of the second conductivity type layer,

wherein the second trench is arranged between the element-side first impurity region and a predetermined position of the base region,

wherein the third trench penetrates the first impurity region and the base region and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the third trench, and

wherein the semiconductor switching element is a vertical MOSFET for flowing a current in a direction perpendicular to the semiconductor substrate.

31. The semiconductor device of claim 29,

wherein the second impurity region is a semiconductor substrate including a second conductivity type portion,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the second trench is arranged between the element-side first impurity region and a predetermined position of the base region,

wherein the third trench penetrates the element-side first impurity region and the base region and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the third trench, and

wherein the semiconductor switching element is a vertical IGBT for flowing a current in a direction perpendicular to the semiconductor substrate.

32. The semiconductor device of claim 29,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region has the first conductivity type,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the second trench extends in a direction parallel to the surface of the drift layer and extends from the element-side first impurity region to a predetermined position of the base region,

wherein the third trench extends in the direction parallel to the surface of the drift layer and penetrates the element-side first impurity region and the base region and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the third trench, and

wherein the semiconductor switching element is a horizontal MOSFET for flowing a current in a horizontal direction parallel to the surface of the drift layer.

33. The semiconductor device of claim 29,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region includes a second conductivity type portion,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the second trench extends in a direction parallel to the surface of the drift layer and extends from the element-side first impurity region to a predetermined position of the base region,

wherein the third trench extends in the direction parallel to the surface of the drift layer, penetrates the element-side first impurity region and the base region, and reaches the drift layer,

wherein the semiconductor switching element provides the channel in a portion of the base region located on a side of the third trench, and

wherein the semiconductor switching element is a horizontal IGBT for flowing a current in a horizontal direction parallel to the surface of the drift layer.

34. The semiconductor device of claim 28,

wherein the second impurity region is a semiconductor substrate having the first conductivity type,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the second gate electrode and the third gate electrode are arranged on a surface portion of the base region located between the element-side first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in a surface of the base region opposed to the third gate electrode in a horizontal direction parallel to the semiconductor substrate, and

wherein the semiconductor switching element is a planar vertical MOSFET for flowing a current in a direction perpendicular to the semiconductor substrate.

35. The semiconductor device of claim 28,

wherein the second impurity region is a semiconductor substrate including a second conductivity type portion,

wherein the drift layer is arranged on the semiconductor substrate,

wherein the second gate electrode and the third gate electrode are arranged on a surface portion of the base region located between the element-side first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in a surface of the base region opposed to the third gate electrode in a horizontal direction parallel to the semiconductor substrate, and

wherein the semiconductor switching element is a planar vertical IGBT for flowing a current in a direction perpendicular to the semiconductor substrate.

36. The semiconductor device of claim 28,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region has the first conductivity type,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the second gate electrode and the third gate electrode are arranged in different surface portions of the base region located between the element-side first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in a surface of the base region opposed to the third gate electrode in a horizontal direction parallel to the surface of the drift layer, and

wherein the semiconductor switching element is a planar horizontal MOSFET for flowing a current in the horizontal direction parallel to the surface of the drift layer.

37. The semiconductor device of claim 28,

wherein the base region is arranged in a surface part of the drift layer,

wherein the element-side first impurity region is arranged in a surface part of the base region,

wherein the second impurity region includes a second conductivity type region,

wherein the second impurity region is arranged in another surface part of the drift layer and separated from the base region,

wherein the second gate electrode and the third gate electrode are arranged in different surface portions of the base region located between the element-side first impurity region and the drift layer via the gate insulating film,

wherein the semiconductor switching element provides the channel in a surface of the base region opposed to the third gate electrode in a horizontal direction parallel to the surface of the drift layer, and

wherein the semiconductor switching element is a planar horizontal IGBT for flowing a current in the horizontal direction parallel to the surface of the drift layer.

38. The semiconductor device of claim 26,

wherein the first chip further includes a first trench,

wherein the first trench penetrates the diode-side first impurity region and the second conductivity type layer and reaches the first conductivity type layer,

wherein the first gate electrode is arranged in the first trench,

wherein the gate insulating film arranged in the first trench has a first portion deeper than a predetermined intermediate position and a second portion shallower than the predetermined intermediate position,

wherein the intermediate position is deeper than an upper part of the second conductivity type layer and shallower than an upper part of the first conductivity type layer, and

wherein the first portion is thicker than the second portion.

39. The semiconductor device of claim 26,

wherein the first chip further includes a first trench,

wherein the first trench penetrates the diode-side first impurity region and the second conductivity type layer and reaches the first conductivity type layer,

wherein the first gate electrode is arranged in the first trench,

wherein the second conductivity type layer located on a side of the first trench has a first region shallower than a predetermined intermediate position and a second region deeper than the predetermined intermediate position,

wherein the intermediate position is deeper than an upper part of the second conductivity type layer and shallower than an upper part of the first conductivity type layer, and

wherein the second region is higher in impurity concentration than the first region.

40. A control method for the semiconductor device of claim 1, comprising:

switching from a diode operation state of the free wheel diode to an on-state of the semiconductor switching element; and

before the semiconductor switching element turns on in the switching, applying a gate voltage to the first gate electrode in order to generate an inversion layer in a portion of the second conductivity type layer opposed to the first gate electrode via the gate insulating film.

41. The semiconductor device of claim 3,

wherein the element-side gate electrode includes a second gate electrode,

wherein the second gate electrode is arranged between a predetermined position of the base region via the gate insulating film and the drift layer,

wherein the first gate electrode and the second gate electrode are made of materials having different work functions, respectively, and

wherein, based on a difference of work functions, the gate voltage applied to the first electrode is also applied to the second gate electrode.

42-49. -49. (canceled)