Semiconductor Device

• US 20100176443A1
• Filed: 06/13/2008
• Published: 07/15/2010
• Est. Priority Date: 06/15/2007
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Takaishi, Masaru
• Granted Patent: US 8,217,419 B2
• Time in Patent Office: Days
• US Class Current: 257/328
• CPC Class Codes: H01L 27/0255 using diodes as protective elements
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• 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 29/41766 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 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H01L 29/7808 the other device being a breakdown diode, e.g. Zener 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 29/7828 without inversion channel, e.g. vertical ACCUFETs, normally-on vertical MISFETs
• CPC Class Codes: H01L 29/7839 with Schottky drain or source contact
• CPC Class Codes: H01L 29/866 Zener diodes
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

Provided is a semiconductor device in which on-resistance is largely reduced. In a region (2a) of an N type epitaxial layer (2) of the semiconductor device 20, each region between neighboring trenches (3) is blocked with a depletion layer (14) formed around a trench (3) so that a current passage (12) is interrupted, while a part of the depletion layer (14) formed around the trench (3) is deleted so that the current passage (12) is opened. In a region (2b), a junction portion (8) between the N type epitaxial layer (2) and a P⁺ type diffusion region (7) makes a Zener diode (8).

Claims

1. A semiconductor device comprising:

a semiconductor layer of one conductivity type including an inside region and an outside region disposed outside the inside region;

a plurality of trenches formed in the inside region of the semiconductor layer so as to be arranged with predetermined spaces, an opening end of each of the trenches being positioned on an upper surface side of the semiconductor layer;

a plurality of diffusion regions of an inverse conductivity type formed in the outside region of the semiconductor layer so as to be arranged with predetermined spaces, an upper surface of each of the diffusion regions being exposed to the upper surface side of the semiconductor layer;

a plurality of embedded electrodes filled in the plurality of trenches; and

an electrode layer formed on the upper surface of the semiconductor layer so as to cover the inside region and the outside region of the semiconductor layer, wherein

the inside region of the semiconductor layer has a structure in which each region between the neighboring trenches in the semiconductor layer becomes a current passage, and each region between the neighboring trenches in the semiconductor layer is blocked with a depletion layer formed around the trench so that the current passage is interrupted, while at least a part of the depletion layer formed around the trench is deleted so that the current passage is opened, and

a junction portion between the semiconductor layer and the diffusion region makes a Zener diode in the outside region of the semiconductor layer.

2. The semiconductor device according to claim 1, wherein a junction portion between each region between the neighboring diffusion regions of the semiconductor layer and the electrode layer makes a Schottky barrier diode in the outside region of the semiconductor layer.

3. The semiconductor device according to claim 2, wherein when a reverse bias is applied to the junction portion between each region between the neighboring diffusion regions of the semiconductor layer and the electrode layer in the outside region of the semiconductor layer, each region between the neighboring diffusion regions of the semiconductor layer is blocked with a depletion layer formed around the diffusion region.

4. The semiconductor device according to claim 3, wherein when a reverse bias is applied to the junction portion between each region between the neighboring diffusion regions of the semiconductor layer and the electrode layer in the outside region of the semiconductor layer, the depletion layers formed around the neighboring diffusion region are connected to each other.

5. The semiconductor device according to claim 3, wherein a distance between the neighboring diffusion regions is set so that the depletion layers formed around the neighboring diffusion regions are overlapped with each other in the outside region of the semiconductor layer.

6. The semiconductor device according to claim 1, wherein each region between the neighboring trenches is blocked with every depletion layer formed around each of the plurality of trenches so that the current passage is interrupted, while every depletion layer formed around each of the plurality of trenches is deleted so that the current passage is opened.

7. The semiconductor device according to claim 1, wherein

the plurality of embedded electrodes include two types that are first embedded electrodes and second embedded electrodes to which voltages are applied separately, and

each region between the neighboring trenches is blocked with the depletion layer formed around every trench among the plurality of trenches so that the current passage is interrupted, while the depletion layer formed around the trench filled with the first embedded electrode among the plurality of trenches is deleted so that the current passage is opened.

8. The semiconductor device according to claim 7, wherein the second embedded electrode has a Schottky contact with the semiconductor layer inside the trench.

9. The semiconductor device according to claim 1, further comprising a current passage interrupting diffusion region of an inverse conductivity type formed in each region between the neighboring trenches of the semiconductor layer so as to be disposed with a predetermined space to the trench, wherein

each region between the neighboring trenches is blocked with depletion layers formed around the trench and around the current passage interrupting diffusion region so that the current passage is interrupted, while the depletion layer formed around the trench is deleted so that the current passage is opened.

10. A semiconductor device comprising:

a semiconductor layer including first region of one conductivity type, and a second region of one conductivity type as well as a third region of an inverse conductivity type formed on the first region;

a plurality of trenches formed in at least the second region of the semiconductor layer so as to be arranged with predetermined spaces, an opening end of each of the trenches being positioned on an upper surface side of the semiconductor layer; and

a plurality of embedded electrodes filled in the plurality of trenches, wherein

each region between the neighboring trenches in the second region becomes a current passage, and each region between the neighboring trenches in the second region is blocked with a depletion layer formed around the trench so that the current passage is interrupted, while the at least a part of the depletion layer formed around the trench is deleted so that the current passage is opened, and

a bidirectional Zener diode constituted of the plurality of diffusion regions is formed in the third region of the semiconductor layer.

11. The semiconductor device according to claim 10, further comprising an electrode layer formed on at least the second region of the semiconductor layer, wherein

the second region of the semiconductor layer and a first part of the plurality of diffusion regions constituting the bidirectional Zener diode are electrically connected via the electrode layer.

12. The semiconductor device according to claim 11, further comprising a fourth region of one conductivity type formed on the first region, wherein

a second part of the plurality of diffusion regions constituting the bidirectional Zener diode is electrically connected to the first region via the fourth region.

13. The semiconductor device according to claim 11, wherein a third part of the plurality of diffusion regions constituting the bidirectional Zener diode is electrically connected a predetermined embedded electrode among the plurality of embedded electrodes.

14. The semiconductor device according to claim 10, wherein

the plurality of diffusion regions constituting the bidirectional Zener diode include first diffusion regions of one conductivity type and second diffusion regions of an inverse conductivity type,

the first diffusion regions are arranged with predetermined spaces, and

the second diffusion region is arranged between the neighboring first diffusion regions so as to contact with the first diffusion regions in a plan view.

15. The semiconductor device according to claim 12, wherein

the third region is formed in a region outside the second region so as to enclose the second region in a plan view, and

the fourth region is formed in a region outside the third region so as to enclose the third region in a plan view.

16. The semiconductor device according to claim 10, wherein each region between the neighboring trenches is blocked with every depletion layer formed around each of the plurality of trenches so that the current passage is interrupted, while every depletion layer formed around each of the plurality of trenches is deleted so that the current passage is opened.

17. The semiconductor device according to claim 10, wherein

the plurality of embedded electrodes include two types that are first embedded electrodes and second embedded electrodes to which voltages are applied separately, and

each region between the neighboring trenches is blocked with the depletion layer formed around every trench among the plurality of trenches so that the current passage is interrupted, while the depletion layer formed around the trench filled with the first embedded electrode among the plurality of trenches is deleted so that the current passage is opened.

18. The semiconductor device according to claim 17, wherein the second embedded electrode has a Schottky contact with the semiconductor layer inside the trench.

19. The semiconductor device according to claim 10, further comprising a current passage interrupting diffusion region of an inverse conductivity type formed in each region between the neighboring trenches of the semiconductor layer so as to be disposed with a predetermined space to the trench, wherein

each region between the neighboring trenches is blocked with depletion layers formed around the trench and around the current passage interrupting diffusion region so that the current passage is interrupted, while the depletion layer formed around the trench is deleted so that the current passage is opened.

20. A semiconductor device comprising:

a semiconductor layer including first region of one conductivity type, a second region of one conductivity type formed on the first region and a third region of an inverse conductivity type;

a plurality of trenches formed in at least the second region of the semiconductor layer so as to be arranged with predetermined spaces; and

a plurality of embedded electrodes filled in the plurality of trenches, wherein

each region between the neighboring trenches in the semiconductor layer becomes a current passage, and each region between the neighboring trenches is blocked with a depletion layer formed around the trench so that the current passage is interrupted, while at least a part of the depletion layer formed around the trench is deleted so that the current passage is opened, and

a junction portion between the first region and the third region makes a Zener diode.

21. The semiconductor device according to claim 20, further comprising an electrode layer formed on the upper surface of the semiconductor layer, wherein

the second region and the third region are electrically connected to each other via the electrode layer.

22. The semiconductor device according to claim 20, wherein

the semiconductor layer further includes a Zener diode diffusion region of one conductivity type disposed in the third region of an inverse conductivity type in addition to the first region of one conductivity type, the second region of one conductivity type and the third region of an inverse conductivity type, and

the junction portion between the third region and the Zener diode diffusion region makes a Zener diode.

23. The semiconductor device according to claim 22, wherein the Zener diode diffusion region is electrically connected to a predetermined embedded electrode among the plurality of embedded electrodes.

24. The semiconductor device according to claim 20, wherein each region between the neighboring trenches is blocked with every depletion layer formed around each of the plurality of trenches so that the current passage is interrupted, while every depletion layer formed around each of the plurality of trenches is deleted so that the current passage is opened.

25. The semiconductor device according to claim 20, wherein

the plurality of embedded electrodes include two types that are first embedded electrodes and second embedded electrodes to which voltages are applied separately, and

each region between the neighboring trenches is blocked with the depletion layer formed around every trench among the plurality of trenches so that the current passage is interrupted, while the depletion layer formed around the trench filled with the first embedded electrode among the plurality of trenches is deleted so that the current passage is opened.

26. The semiconductor device according to claim 25, wherein the second embedded electrode has a Schottky contact with the semiconductor layer inside the trench.

27. The semiconductor device according to claim 20, further comprising a current passage interrupting diffusion region of an inverse conductivity type formed in each region between the neighboring trenches of the semiconductor layer so as to be disposed with a predetermined space to the trench, wherein

each region between the neighboring trenches is blocked with depletion layers formed around the trench and around the current passage interrupting diffusion region so that the current passage is interrupted, while the depletion layer formed around the trench is deleted so that the current passage is opened.