MOS junction barrier Schottky diode

Abstract

MOS junction barrier Schottky diode relates to the technical field of power semiconductor device. N-type substrate, N-type epitaxial layer, deep P region, slot gate, slot gate oxide layer, conductive enhancement region and isolation oxide layer are arranged between cathode metal and anode metal, the lower surface of the N-type substrate is in contact with the cathode metal, the upper surface is in contact with the lower surface of the N-type epitaxial layer, the upper surface of the N-type epitaxial layer is in contact with the P region, the conductive enhancement region is arranged on the outer surface of the slot gate oxide layer and is in contact with the N-type epitaxial layer, part of the slot gate oxide layer, the conductive enhancement region, the isolation oxide layer and part of the deep P region are respectively in contact with part of the anode metal. The MOS junction barrier Schottky diode structure of the application improves the carrier density at the channel, reduces the channel resistance, and further improves the reverse leakage current characteristics and the forward voltage drop by inserting a slot gate MOS structure in the adjacent P region of the traditional junction barrier Schottky (JBS) diode.

Description

Technical Field

[0001] This invention relates to the field of power semiconductor device technology, and more specifically to a MOS junction barrier Schottky diode structure. Background Technology

[0002] Traditional Schottky barrier diodes allow forward current to flow through the Schottky barrier, and their reverse blocking capability also relies on the height of the Schottky barrier. This means there is a severe coupling problem between the forward voltage drop and the reverse leakage current. Junction barrier Schottky (JBS) diodes insert deep P-regions on both sides of the Schottky contact, utilizing the shielding effect of the PN junction barrier on the Schottky contact to reduce the coupling. However, the conductivity of the drift region of the JBS diode is limited by the doping concentration, preventing a further reduction in its forward voltage drop, and the coupling with the reverse leakage current is not fully resolved.

[0003] Therefore, existing technologies have shortcomings and need to be improved. Summary of the Invention

[0004] To overcome the above-mentioned technical problems, the present invention provides a MOS junction barrier Schottky (MJBS) diode structure.

[0005] The present invention provides a MOS junction barrier Schottky diode structure, comprising a cathode metal, an anode metal, an N-type substrate, an N-type epitaxial layer, a deep P-region, a trench gate, a trench gate oxide layer, an isolation oxide layer, a conductivity enhancement region, a Schottky contact, and an ohmic contact. The N-type substrate, the N-type epitaxial layer, the deep P-region, the trench gate, the trench gate oxide layer, and the isolation oxide layer are disposed between the cathode metal and the anode metal. The lower surface of the N-type substrate is in contact with the cathode metal, and the upper surface is in contact with the lower surface of the N-type epitaxial layer. A portion of the upper surface of the N-type epitaxial layer is in contact with the deep P-region. The conductivity enhancement region is disposed on the outer surface of the trench gate oxide layer and is in contact with the N-type epitaxial layer. A portion of the trench gate oxide layer, the conductivity enhancement region, the isolation oxide layer, and a portion of the deep P-region are in contact with a portion of the anode metal.

[0006] Preferably, the grid oxide layer has an enclosed structure, with its outer surface in contact with the conductive enhancement region and its inner surface in contact with the grid. The grid oxide layer is also in contact with the anode metal.

[0007] Preferably, the MOS junction barrier Schottky diode structure is a wide bandgap material diode.

[0008] Preferably, the portion of the anode metal that contacts the N-type epitaxial layer is a Schottky contact with a length of 0.1–1 μm.

[0009] Preferably, the portion of the anode metal that contacts the deep P region is an ohmic contact with a length of 0.1–3 μm.

[0010] Preferably, the thickness of the N-type epitaxial layer is 1–40 μm, and its doping concentration is 1 × 10⁻⁶. 14 cm -3 ~1×10 17 cm -3 .

[0011] Preferably, the thickness of the conductive enhancement region is 0.1–0.2 μm, and its doping concentration is 1 × 10⁻⁶. 14 cm -3 ~1×10 17 cm -3 Furthermore, the doping concentration of the conductive enhancement region is not lower than the doping concentration of the N-type epitaxial layer.

[0012] Preferably, the depth of the trench gate is 0.5-3 μm, and the thickness of the trench gate oxide layer is 40-100 nm.

[0013] Preferably, the depth of the deep P-region is 1-4 μm and greater than the depth of the trench gate, and its doping concentration is 1×10⁻⁶. 17 cm -3 ~1×10 20 cm -3 .

[0014] Compared with the prior art, the MOS junction barrier Schottky diode structure of the present invention has the following advantages:

[0015] The MOS junction barrier Schottky diode structure of this invention inserts a MOS structure into the adjacent deep P-region of a conventional JBS diode. That is, a MOS barrier is introduced outside the PN junction barrier of the JBS diode, and the two work together to form a channel barrier. When the device is forward biased, the gate of the MOS structure and the Schottky anode simultaneously receive a positive voltage, attracting electrons from the N-type epitaxial layer (drift region) to accumulate in the conductivity enhancement region, forming an electron accumulation layer, such as... Figure 2 As shown, when the MJBS is forward-biased, most of the current flows through the electron accumulation layer, causing the diode current to be mainly conducted along the channel of the accumulation layer with a high electron concentration, which helps to reduce the forward voltage drop. When reverse-biased, the gate receives a negative voltage, which repels electrons in the N-type epitaxial layer, forming an electron depletion layer near the gate. This layer connects with the depletion region of the adjacent PN junction formed by the deep P-region and the N-type epitaxial layer, thus shielding the Schottky contact and ensuring a low order of magnitude leakage current. Therefore, the MOS junction barrier Schottky diode structure of this invention can reduce the coupling between the forward voltage drop and the reverse leakage current to a greater extent. Attached Figure Description

[0016] Figure 1 This is a simplified structural diagram of the MOS junction barrier Schottky diode structure of the present invention.

[0017] Figure 2 This is a diagram showing the forward current distribution of the MOS junction barrier Schottky diode structure of this invention.

[0018] Figure 3 This is a simplified structural diagram of a modified embodiment of the MOS junction barrier Schottky diode structure of the present invention.

[0019] Explanation of reference numerals in the attached figures:

[0020] 1. Cathode metal; 2. N-type substrate; 3. N-type epitaxial layer; 4. Deep P-region; 5. Trench gate; 6. Trench gate oxide layer; 7. Conductivity enhancement region; 8. Isolation oxide layer; 9. Schottky contact; 10. Ohmic contact; 11. Anode metal. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0022] Example 1

[0023] Please see Figure 1 This invention provides a MOS junction barrier Schottky diode structure, including a cathode metal 1, an N-type substrate 2, an N-type epitaxial layer 3, a deep P-region 4, a trench gate 5, a trench gate oxide layer 6, a conductivity enhancement region 7, an isolation oxide layer 8, a Schottky contact 9, an ohmic contact 10, and an anode metal 11. The N-type substrate 2, N-type epitaxial layer 3, deep P-region 4, trench gate 5, trench gate oxide layer 6, conductivity enhancement region 7, and isolation oxide layer 8 are disposed between the cathode metal 1 and the anode metal 11, wherein the deep P-region 4 is configured as two... The lower surface of the N-type substrate 2 is in contact with the cathode metal 1, and the upper surface is in contact with the lower surface of the N-type epitaxial layer 3. The upper surface of the N-type epitaxial layer 3 is partially in contact with the deep P-region 4. The two deep P-regions 4 are disposed on both sides of the trench gate oxide layer 6 and extend from the upper surface of the N-type epitaxial layer 3 into the bulk. The conductivity enhancement region 7 is disposed on the outer surface of the trench gate oxide layer 6 and is in contact with the N-type epitaxial layer 3. Parts of the trench gate oxide layer 6, the conductivity enhancement region 7, the isolation oxide layer 8, and part of the deep P-region 4 are in contact with parts of the anode metal 11.

[0024] Preferably, the MOS junction barrier Schottky diode structure of the present invention is a wide bandgap material diode, specifically a silicon carbide diode or a gallium nitride diode, including but not limited to these. It can also be other specific types of wide bandgap material diodes, which can be selected in practice.

[0025] Furthermore, the thickness of the N-type epitaxial layer 3 is 1–40 μm, and its doping concentration is 1 × 10⁻⁶. 14 cm -3 ~1×10 17cm -3 The thickness of the conductivity enhancement region 7 is 0.1–0.2 μm, and its doping concentration is 1 × 10⁻⁶. 15 cm -3 ~1×10 17 cm -3 In this invention, it is preferable that the doping concentration of the conductivity enhancement region 7 is not lower than the doping concentration of the N-type epitaxial layer 3.

[0026] Furthermore, the trench grid oxide layer 6 has an enclosed structure, with the outer surface of the trench grid oxide layer 6 in contact with the conductive enhancement region 7, the inner surface of the trench grid oxide layer 6 in contact with the trench grid 5 and the isolation oxide layer 8, and the trench grid oxide layer 6 also in contact with the anode metal 11.

[0027] Preferably, the depth of the trench gate 5 is 0.5-3 μm, and the thickness of the trench gate oxide layer 6 is 40-100 nm; the depth of the deep P-region 4 is 1-4 μm and greater than the depth of the trench gate 5, wherein the doping concentration of the deep P-region 4 is 1×10⁻⁶. 17 cm -3 ~1×10 20 cm -3 .

[0028] The MOS junction barrier Schottky diode structure of the present invention is basically the same as that of the JBS diode in terms of turn-on voltage, but its forward voltage drop is 0.1-0.2V lower than that of the JBS diode, and its reverse leakage current is two orders of magnitude lower.

[0029] Preferably, the anode metal 11 of the present invention has a flat plate structure.

[0030] Example 2

[0031] Please see Figure 3 As a modified embodiment of the MOS junction barrier Schottky diode structure of the present invention, this modified embodiment includes a cathode metal 1, an N-type substrate 2, an N-type epitaxial layer 3, a deep P-region 4, a trench gate 5, a trench gate oxide layer 6, a conductivity enhancement region 7, an isolation oxide layer 8, a Schottky contact 9, an ohmic contact 10, and an anode metal 11. The connection relationships, dimensions, and doping concentrations among the cathode metal 1, N-type substrate 2, N-type epitaxial layer 3, trench gate 5, trench gate oxide layer 6, conductivity enhancement region 7, isolation oxide layer 8, and Schottky contact 9 are consistent with the first embodiment. The difference lies in that the deep P-region 4 in this modified embodiment is composed of a P-type doped region surrounding a deep trench opening on the upper surface of the N-type epitaxial layer 3. The portion of the anode metal 11 that contacts the deep P-region 4 constitutes the ohmic contact 10, with a length of 0.1–3 μm.

[0032] Compared with the prior art, the MOS junction barrier Schottky diode structure of the present invention has the following advantages:

[0033] The MOS junction barrier Schottky diode structure of this invention inserts a MOS structure into the adjacent deep P-region of a conventional JBS diode. That is, a MOS barrier is introduced outside the PN junction barrier of the JBS diode, and the two work together to form a channel barrier. When the device is forward biased, the gate of the MOS structure and the Schottky anode simultaneously receive a positive voltage, attracting electrons from the N-type epitaxial layer (drift region) to accumulate in the conductivity enhancement region, forming an electron accumulation layer, such as... Figure 2 As shown, when the MJBS is forward-biased, most of the current flows through the electron accumulation layer, causing the diode current to be mainly conducted along the channel of the accumulation layer with a high electron concentration, which helps to reduce the forward voltage drop. When reverse-biased, the gate receives a negative voltage, which repels electrons in the N-type epitaxial layer, forming an electron depletion layer near the gate. This layer connects with the depletion region of the adjacent PN junction formed by the deep P-region and the N-type epitaxial layer, thus shielding the Schottky contact and ensuring a low order of magnitude leakage current. Therefore, the MOS junction barrier Schottky diode structure of this invention can reduce the coupling between the forward voltage drop and the reverse leakage current to a greater extent.

[0034] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications, equivalent substitutions and improvements made within the concept of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A MOS junction barrier Schottky diode, characterized by: The MOS junction barrier Schottky diode structure comprises a cathode metal (1), an anode metal (11), an N-type substrate (2), an N-type epitaxial layer (3), a deep P region (4), a slot gate (5), a slot gate oxide layer (6), a conductive enhancement region (7), an isolation oxide layer (8), a Schottky contact (9) and an Ohmic contact (10), the N-type substrate (2), the N-type epitaxial layer (3), the deep P region (4), the slot gate (5), the slot gate oxide layer (6), the conductive enhancement region (7) and the isolation oxide layer (8) are arranged between the cathode metal (1) and the anode metal (11), the lower surface of the N-type substrate (2) is in contact with the cathode metal (1), the upper surface is in contact with the lower surface of the N-type epitaxial layer (3), the upper surface of the N-type epitaxial layer (3) is partially in contact with the deep P region (4), the conductive enhancement region (7) is arranged on the outer surface of the slot gate oxide layer (6) and is in contact with the N-type epitaxial layer (3), the slot gate oxide layer (6) is in a surrounding structure, the inner surface is in contact with the slot gate (5), the isolation oxide layer (8) is arranged on the upper surface of the slot gate (5), part of the slot gate oxide layer (6), the conductive enhancement region (7), the isolation oxide layer (8) and part of the deep P region (4) are respectively in contact with part of the anode metal (11).

2. The MOS junction barrier Schottky diode structure of claim 1, wherein The MOS junction barrier Schottky diode structure is a wide band gap material diode.

3. The MOS junction barrier Schottky diode structure of claim 1, wherein the gate oxide layer is formed of silicon dioxide. The part of the anode metal (11) in contact with the N-type epitaxial layer (3) is a Schottky contact (9), and the length of the Schottky contact (9) is 0.1-1 μm.

4. The MOS junction barrier Schottky diode structure of claim 1, wherein the gate oxide layer is formed of silicon dioxide. The part of the anode metal (11) in contact with the deep P region (4) is an Ohmic contact (10), and the length of the Ohmic contact (10) is 0.1-3 μm.

5. The MOS junction barrier Schottky diode structure of claim 1, wherein the gate oxide layer is formed of silicon dioxide. : The thickness of the N-type epitaxial layer (3) is 1-40 μm, and the doping concentration is 1 x 10 14 cm -3 ~ 1 x 10 17 cm -3 .

6. The MOS junction barrier Schottky diode structure of claim 1, wherein the gate oxide layer is formed of silicon dioxide. The thickness of the conductive enhancement region (7) is 0.1-0.2 μm, the doping concentration is 1 x 10 14 cm -3 -1 x 10 17 cm -3 , and the doping concentration of the conductive enhancement region (7) is not lower than the doping concentration of the N-type epitaxial layer (3).

7. The MOS junction barrier Schottky diode structure of claim 1, wherein the gate oxide layer is formed of silicon dioxide. The depth of the slot gate (5) is 0.5-3 μm, the thickness of the slot gate oxide layer (6) is 40-100 nm, and the thickness of the isolation oxide layer (8) is 0.5-1.5 μm.

8. The MOS junction barrier Schottky diode structure of claim 1, wherein the gate oxide layer is formed of silicon dioxide. The deep P region (4) has a depth of 1-4 μm and is greater than the depth of the trench gate (5), and has a doping concentration of 1 x 1018-1 x 1020 cm-3. 17 cm -3 -1 x 1020 cm-3. 20 cm -3 .

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