US-12622039-B2 - Schottky barrier diode

Abstract

A Schottky barrier diode according to the present disclosure includes an n-type semiconductor substrate, one or more p-type guard rings provided on a side of an upper surface of the semiconductor substrate, an anode electrode provided on the upper surface of the semiconductor substrate, a cathode electrode provided on a rear surface of the semiconductor substrate and an insulating film provided on an inner guard ring on an innermost side among the one or more guard rings, wherein the anode electrode rides on the insulating film and has its end portion provided just above the inner guard ring, the anode electrode and the inner guard ring are provided away from each other, and a thickness of the insulating film is 1.0 μm or more.

Inventors

• Seiya Nakano
• Yoshifumi Tomomatsu
• Yasuo ATA

Assignees

• MITSUBISHI ELECTRIC CORPORATION

Dates

Publication Date

20260505

Application Date

20200114

Claims (20)

1. 1 . A Schottky barrier diode comprising: an n-type semiconductor substrate; one or more p-type guard rings provided on a side of an upper surface of the semiconductor substrate; an anode electrode provided on the upper surface of the semiconductor substrate; a cathode electrode provided on a rear surface of the semiconductor substrate; an insulating film provided on an inner guard ring on an innermost side among the one or more guard rings; and a high-resistance layer having a higher resistance than that of the inner guard ring and spacing the inner guard ring and the anode electrode apart from each other, wherein the anode electrode rides on the insulating film and has its end portion provided just above the inner guard ring, the inner guard ring extends further on the innermost side than an edge of the insulating film that is covered by the anode electrode, the anode electrode and the inner guard ring are provided away from each other, the high-resistance layer includes a polysilicon resistor provided further on the innermost side than the insulating film on the upper surface of the semiconductor substrate, and a thickness of the insulating film is 1.0 μm or more.
2. 2 . The Schottky barrier diode according to claim 1 , wherein a width of the inner guard ring is equal to or more than a width of a portion, which rides on the insulating film, of the anode electrode.
3. 3 . The Schottky barrier diode according to claim 1 , wherein an end portion, which is provided on an inner side of the semiconductor substrate, out of end portions of the insulating film has a tapered shape.
4. 4 . The Schottky barrier diode according to claim 1 , wherein the thickness of the insulating film is 1.0 μm or more just above an end portion, which is provided on the inner side of the semiconductor substrate, out of end portions of the inner guard ring.
5. 5 . The Schottky barrier diode according to claim 1 , wherein the cathode electrode has an opening, which exposes the semiconductor substrate, formed therein just below the inner guard ring.
6. 6 . The Schottky barrier diode according to claim 5 , wherein the opening exposes the semiconductor substrate in a predetermined range from just below the inner guard ring.
7. 7 . The Schottky barrier diode according to claim 1 , further comprising a second p-type semiconductor layer provided just below the inner guard ring in the semiconductor substrate.
8. 8 . The Schottky barrier diode according to claim 7 , wherein the second p-type semiconductor layer is provided up to a predetermined range from just below the inner guard ring.
9. 9 . The Schottky barrier diode according to claim 1 , further comprising a crystal defect layer provided just below the inner guard ring in the semiconductor substrate.
10. 10 . The Schottky barrier diode according to claim 1 , wherein the semiconductor substrate is made with a wide band gap semiconductor.
11. 11 . The Schottky barrier diode according to claim 10 , wherein the wide band gap semiconductor is silicon carbide, gallium oxide, gallium-nitride-based material or diamond.
12. 12 . A Schottky barrier diode comprising: an n-type semiconductor substrate; a plurality of p-type guard rings provided on a side of an upper surface of the semiconductor substrate; an anode electrode provided on the upper surface of the semiconductor substrate; a cathode electrode provided on a rear surface of the semiconductor substrate; an insulating film provided on an inner guard ring on an innermost side among the plurality of guard rings; and a high-resistance layer having a higher resistance than that of the inner guard ring and spacing the inner guard ring and the anode electrode apart from each other, wherein the anode electrode rides on the insulating film and has its end portion provided just above the inner guard ring, the inner guard ring extends further on the innermost side than an edge of the insulating film that is covered by the anode electrode, the high-resistance layer includes a polysilicon resistor provided further on the innermost side than the insulating film on the upper surface of the semiconductor substrate, and the anode electrode and the inner guard ring are provided away from each other.
13. 13 . The Schottky barrier diode according to claim 12 , wherein the thickness of the insulating film is 1.0 μm or more.
14. 14 . The Schottky barrier diode according to claim 12 , wherein a width of the inner guard ring is equal to or more than a width of a portion, which rides on the insulating film, of the anode electrode.
15. 15 . The Schottky barrier diode according to claim 12 , wherein an end portion, which is provided on an inner side of the semiconductor substrate, out of end portions of the insulating film has a tapered shape.
16. 16 . The Schottky barrier diode according to claim 12 , wherein the thickness of the insulating film is 1.0 μm or more just above an end portion, which is provided on the inner side of the semiconductor substrate, out of end portions of the inner guard ring.
17. 17 . The Schottky barrier diode according to claim 12 , wherein the cathode electrode has an opening, which exposes the semiconductor substrate, formed therein just below the inner guard ring.
18. 18 . The Schottky barrier diode according to claim 17 , wherein the opening exposes the semiconductor substrate in a predetermined range from just below the inner guard ring.
19. 19 . The Schottky barrier diode according to claim 12 , further comprising a second p-type semiconductor layer provided just below the inner guard ring in the semiconductor substrate.
20. 20 . The Schottky barrier diode according to claim 19 , wherein the second p-type semiconductor layer is provided up to a predetermined range from just below the inner guard ring.

Description

FIELD The present disclosure relates to a Schottky barrier diode. BACKGROUND Patent Literature 1 discloses a Schottky barrier diode in which on a surface of a semiconductor substrate of one conductivity type, a guard ring composed of a semiconductor layer of an opposite conductivity type is formed. CITATION LIST Patent Literature [PTL 1] JP 63-138769 A SUMMARY Technical Problem In the Schottky barrier diode disclosed in Patent Literature 1, if a forward current increases, a forward voltage drop across a pn junction to be formed between the guard ring and the semiconductor substrate may be lower than a forward voltage drop of a Schottky portion. As a result, a termination region may be destroyed due to current concentration. The present disclosure has been made to solve the above-described problem, and is directed to obtaining a Schottky barrier diode capable of suppressing current concentration in a guard ring. Solution to Problem A Schottky barrier diode according to the present disclosure includes an n-type semiconductor substrate, one or more p-type guard rings provided on a side of an upper surface of the semiconductor substrate, an anode electrode provided on the upper surface of the semiconductor substrate, a cathode electrode provided on a rear surface of the semiconductor substrate and an insulating film provided on an inner guard ring on an innermost side among the one or more guard rings, wherein the anode electrode rides on the insulating film and has its end portion provided just above the inner guard ring, the anode electrode and the inner guard ring are provided away from each other, and a thickness of the insulating film is 1.0 μm or more. A Schottky barrier diode according to the present disclosure includes an n-type semiconductor substrate, a plurality of p-type guard rings provided on a side of an upper surface of the semiconductor substrate, an anode electrode provided on the upper surface of the semiconductor substrate, a cathode electrode provided on a rear surface of the semiconductor substrate and an insulating film provided on an inner guard ring on an innermost side among the plurality of guard rings, wherein the anode electrode rides on the insulating film and has its end portion provided just above the inner guard ring, and the anode electrode and the inner guard ring are provided away from each other. A Schottky barrier diode according to the present disclosure includes an n-type semiconductor substrate, one or more p-type guard rings provided on a side of an upper surface of the semiconductor substrate, an insulating film provided on an inner guard ring on an innermost side among the one or more guard rings, an anode electrode provided on the upper surface of the semiconductor substrate and riding on the insulating film, a cathode electrode provided on a rear surface of the semiconductor substrate and a high-resistance layer having a higher resistance than that of the inner guard ring and spacing the inner guard ring and the anode electrode apart from each other. Advantageous Effects of Invention In the Schottky barrier diode according to the present disclosure, the anode electrode and the guard ring are connected to each other via a capacitive component of the insulating film. Therefore, current concentration in the guard ring can be suppressed. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view of a Schottky barrier diode according to the first embodiment. FIG. 2 is a diagram for describing dimensions of the Schottky barrier diode according to the first embodiment. FIG. 3 is a cross-sectional view of a Schottky barrier diode according to the second embodiment. FIG. 4 is a cross-sectional view of a Schottky barrier diode according to the third embodiment. FIG. 5 is a cross-sectional view of a Schottky barrier diode according to the fourth embodiment. FIG. 6 is a cross-sectional view of a Schottky barrier diode according to the fifth embodiment. FIG. 7 is a cross-sectional view of a Schottky barrier diode according to the sixth embodiment. FIG. 8 is a cross-sectional view of a Schottky barrier diode according to the seventh embodiment. DESCRIPTION OF EMBODIMENTS A Schottky barrier diode according to each embodiments of the present disclosure is described with reference to drawings. Identical or corresponding constitutional elements are given the same reference numerals, and the repeated description of such constitutional elements may be omitted. First Embodiment FIG. 1 is a cross-sectional view of a Schottky barrier diode 100 according to the first embodiment. The Schottky barrier diode 100 includes a semiconductor substrate 10. The semiconductor substrate 10 is formed of silicon, for example. The semiconductor substrate 10 includes an n+-type semiconductor layer 12 and an n-type semiconductor layer 14 provided on the n+-type semiconductor layer 12. A plurality of p-type guard rings 16 are provided on the side of an upper surface of the semiconductor substrate 10. Th