Integrated circuit power devices having junction barrier controlled schottky diodes therein

• US 6,800,897 B2
• Filed: 09/24/2003
• Issued: 10/05/2004
• Est. Priority Date: 04/11/2001
• Status: Expired due to Term

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Silicon Semiconductor Corporation
• Inventors: Baliga, Bantval Jayant
• Primary Examiner(s): Tran, Minhloan
• Assistant Examiner(s): FORDE, REMMON R
• Application Number:
  US10/671,333
• Publication Number:
  US 20040099905A1
• Time in Patent Office: 377 Days
• Field of Search: 257/328, 257/341, 257/139, 257/333, 257/327, 257/329, 257/335, 257/153, 257/472, 257/339, 257/242
• US Class Current: 257/328
• CPC Class Codes: H01L 29/0847 of field-effect transistors with insulated gate H01L29/0653 takes precedence; with a passive supplementary region between source or drain and substrate related to punch-through, capacity or isolation phenomena H01L29/1079; with LDD or DDD structure H01L29/7833; for thin film transistors H01L29/78618
• 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 29/402 Field plates
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/41741 for vertical or pseudo-vertical devices
• 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 29/66727 with a step of recessing the source electrode
• CPC Class Codes: H01L 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• CPC Class Codes: H01L 29/7806 the other device being a Schottky barrier diode
• CPC Class Codes: H01L 29/872 Schottky diodes

Abstract

A power MOSFET includes a semiconductor substrate having a drift region therein and first and second transition regions of first conductivity type that extend between the drift region and a first surface of the semiconductor substrate. Each of the first and second transition regions has a vertically retrograded first conductivity type doping profile therein that peaks at a first depth relative to the first surface. First and second shielding regions of second conductivity type are provided in the drift region and define respective P-N junctions with the first transition region. The shielding regions extending laterally towards each other in a manner that constricts a neck of the first transition region to a minimum width at a second depth relative to the first surface. An anode electrode is provided. The anode electrode that extends on the first surface of the semiconductor substrate and defines a Schottky rectifying junction with the second transition region.

Claims

1. A semiconductor device, comprising:

a semiconductor substrate having a drift region of first conductivity type therein and transition region of first conductivity type that extends between the drift region and a first surface of said semiconductor substrate and has a vertically retrograded first conductivity type doping profile therein that peaks at a first depth relative to the first surface;

first and second shielding regions of second conductivity type that extend in the drift region and define respective P-N junctions with the transition region, said first and second shielding regions extending laterally towards each other in a manner that constricts a neck of the transition region to a minimum width at a second depth relative to the first surface; and

an anode electrode that extends on the first surface of said semiconductor substrate and defines a Schottky rectifying junction with the transition region.

2. The device of claim 1, wherein a product of a peek first conductivity type dopant concentration in the transition region and a width of the transition region at the first depth is in a range between about 1×

10¹² cm<sup>−

2</sup> and about 7×

10¹² cm<sup>−

2</sup>.

3. The wherein a product of claim 1, wherein a product of a peak first conductivity type dopant concentration in the transition region and a width of the transition region at the first depth is in a range between about 3.5×

10¹² cm<sup>−

2</sup> and about 6.5×

10¹² cm<sup>−

2</sup>.

4. A vertical power device, comprising:

a semiconductor substrate having a drift region of first conductivity type therein and a transition region of first conductivity type that extends between the drift region and a first surface of said semiconductor substrate, said transition region having a vertically retrograded first conductivity type doping profile therein that peaks at a first depth relative to the first surface;

first and second base regions of second conductivity type that extend in said semiconductor substrate and define respective P-N junctions with opposing sides of said transition region;

first and second source regions of first conductivity type in said first and second base regions, respectively;

first and second base shielding regions of second conductivity type that are more highly doped than said first and second base regions and extend laterally towards each other in said semiconductor substrate to thereby constrict a neck of said transition region to a minimum width at a second depth relative to the first surface; and

an electrode that extends on the first surface and defines a Schottky rectifying junction with said transition region.

5. The device of claim 4, wherein a product of a peak first conductivity type dopant concentration in said transition region and a width of said transition region at the first depth is In a range between about 1×

10¹² cm<sup>−

2</sup> and about 7×

10¹² cm<sup>−

2</sup>.

6. The device of claim 4, wherein a product of a peak first conductivity type dopant concentration in said transition region and a width of said transition region at the first depth is in a range between about 3.5×

10¹² cm<sup>−

2</sup> and about 6.5×

10¹² cm<sup>−

2</sup>.

7. The device of claim 4, further comprising:

a second transition region that extends between the first surface and the drift region and defines a P-N junction with said first base region; and

an insulated gate electrode of a MOSFET that extends opposite said second transition region.

8. A vertical power device, comprising:

a semiconductor substrate having a drift region of first conductivity type therein and a transition region of first conductivity type that extends between the drift region and a first surface of said semiconductor substrate;

first and second regions of second conductivity type that form respective P-N junctions with opposing sides of said transition region and constrict a neck of said transition region to a minimum width at a first depth that is greater than about 0.25 microns relative to the first surface; and

an anode electrode that extends on the first surface and defines a Schottky rectifying junction with said transition region; and

wherein a product of a first conductivity type dopant concentration in said transition region at the first depth and a width of said transition region at the first depth is in a range between about 1×

10¹² cm<sup>−

2</sup> and about 7×

10¹² cm<sup>−

2</sup>.

9. The device of claim 8, wherein the product is in a range between about 3.5×

10¹² cm<sup>−

2</sup> and about 6.5×

10¹² cm<sup>−

2</sup>.

10. The device of claim 8, further comprising:

a second transition region that extends between the first surface and the drift region and defines a P-N Junction with said first region of second conductivity type; and

an insulated gate electrode of a MOSFET that extends opposite said second transition region.

11. A Schottky diode, comprising:

a semiconductor substrate having a region of first conductivity type therein that extends to a first surface thereof;

first and second shielding regions of second conductivity type that form respective P-N junctions with opposing sides of the region of first conductivity type and constrict a neck of the first region of first conductivity type to first width at a first depth relative to the first surface; and

an electrode that extends on the first surface and defines a Schottky rectifying junction with the region of first conductivity type and an ohmic contact with said first and second shielding regions; and

wherein a product of a first conductivity type dopant concentration in the region of first conductivity type and the first width is in a range between about 1×

10¹² cm<sup>−

2</sup> and about 7×

10¹² cm<sup>−

2</sup>.

12. The Schottky diode of claim 11, wherein the product is in a range between about 3.5×

10¹² cm<sup>−

2</sup> and about 6.5×

10¹² cm<sup>−

2</sup>.

13. The Schottky diode of claim 11, wherein the first depth is greater then about 0.25 microns.