Reverse blocking type gate commutated thyristor RB-GCT device wavy terminal structure

Abstract

The utility model provides a reverse blocking type gate commutated thyristor RB-GCT device wavy terminal structure which comprises a cathode aluminum layer, a gate aluminum layer, a cathode N + region, a cathode P region, a cathode P-region, an N-base region, an anode P-region, an anode P + region and an anode aluminum layer which are sequentially arranged in an active region from top to bottom. In the terminal region, the anode and the cathode are provided with passivation layers, shallow trenches, a terminal P-region and an N-base region. And an N-type cut-off ring is arranged at the edge of the terminal. According to the wave-shaped P region terminal structure, the terminal voltage efficiency of forward blocking and reverse blocking is 6.47% and 5.26% higher than that of a conventional negative oblique angle terminal, the anode terminal, the cathode terminal and the active region are formed at the same time, the technology is simple, the manufacturing cost is low, and the wave-shaped P region terminal structure is widely applied to deep junction type power semiconductor devices.

Description

Technical Field

[0001] The utility model belongs to the technical field of power semiconductor device manufacturing, and in particular relates to a wavy terminal structure of a reverse resistance gate commutated thyristor RB-GCT device. Background Art

[0002] At present, most of the UHV DC transmission projects built in my country use conventional DC transmission technology, relying on the effect of grid voltage for natural commutation (LCC). It has the advantages of long distance, large capacity, and low construction and operation costs. It is the most mature and widely distributed form of DC transmission in my country.

[0003] The LCC converter uses a semi-controlled thyristor device, which cannot actively shut down the current. When the AC power grid or DC line voltage is disturbed or the AC / DC system fails, there is a risk of commutation failure, resulting in interruption of DC power transmission and overvoltage at the sending end, seriously affecting the safety and stability of the power grid.

[0004] By replacing thyristors with RB-IGCT, the semi-controlled current source converter of LCC can be upgraded to a fully controlled current source converter (HCC commutation). The commutation process under normal conditions is the same as that of LCC. When there is a hidden danger of commutation failure, the RB-IGCT actively shuts off the current and forces commutation. Compared with the traditional LCC, a control method is added to effectively suppress the commutation failure phenomenon, which can greatly improve the safe and stable operation of the DC system and is a new direction for the development of DC power transmission.

[0005] In order to meet the use of UHV DC transmission projects, the supporting HCC equipment and system transmission capacity must be consistent with the existing UHV DC projects, that is, when not in parallel, the voltage level of a single RB-GCT device reaches 8.0kV and the current capacity reaches 5.0kA. The withstand voltage depends on the thickness of the N-base region and the terminal design. The existing 6-inch RB-GCT adopts the same double negative bevel structure as the thyristor. Although the maximum voltage of the manufactured device can reach 8.0kV and the current level reaches 3.0kA, it is affected by the resistivity of the original single crystal and the process. The voltage yield is low, usually about 70%-80%. It is very difficult to further improve the voltage yield and current level without increasing the device area. In order to solve the above problems, there is an urgent need for a terminal structure suitable for bidirectional blocking devices to further improve the current capacity while increasing the blocking voltage. Utility Model Content

[0006] The utility model aims to provide a wavy terminal structure of a reverse resistance gate commutated thyristor RB-GCT device.

[0007] The technical solution adopted by the utility model is a wavy terminal structure of a reverse blocking gate commutation thyristor RB-GCT device, wherein in the active area, a cathode aluminum layer (11) and a gate aluminum layer (10), a cathode N+ region (20), a cathode P region (21), a cathode P- region (22), an N-base region (30), an anode P- region (40), an anode P+ region (41) and an anode aluminum layer (12) are sequentially arranged from top to bottom. In the terminal area, the anode and the cathode are provided with a passivation layer (51), a shallow groove (52), a terminal P- region (50) and an N-base region (30). An N-type cutoff ring (60) is arranged at the edge of the terminal.

[0008] The wavy terminal structure has shallow grooves on the anode and cathode surfaces, and the groove surfaces are covered with a passivation layer. From the active area to the terminal area, the width and spacing of the shallow grooves gradually decrease, and the junction depth of the wavy area gradually decreases.

[0009] The doping concentration of the wavy terminal region is a gradual doping. From the active region to the edge of the terminal region, the doping concentration increases from 1.0×10 15 cm -3 ~1.0×10 14 cm -3 Gradually decreases, the width of the shallow groove gradually decreases from 160μm to 80μm, the spacing between the shallow grooves gradually decreases from 200μm to 70μm, and the junction depth of the wavy area gradually decreases from 150μm to 70μm.

[0010] The wavy terminal shallow groove is formed by selective etching after aluminum pre-deposition, and the etching depth is 1-5μm. The width of the shallow groove determines the corrugation height H(53) of the wavy P region, and the spacing between the shallow grooves determines the longitudinal junction depth of the wavy P region.

[0011] The utility model has the following beneficial effects:

[0012] The wavy P-region terminal structure has a withstand voltage efficiency of about 90% and a terminal size reduction of more than 10% compared to the conventional negative bevel structure. This terminal structure can not only significantly increase the blocking voltage, but also increase the active area, which can further reduce the on-state voltage drop of the device. In addition, the terminal manufacturing process is compatible with the active area, and no additional grinding of the negative bevel is required. The process is simpler, the cost is lower, and it is suitable for large-scale production. It is applicable to power semiconductor devices with deep junctions. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the terminal structure of a double negative bevel device in the prior art.

[0014] Figure 2 It is a schematic diagram of the terminal structure of the wavy P zone of the utility model.

[0015] Figure 3 It is the lateral doping concentration distribution at the terminal surface of the wavy P region of the utility model.

[0016] Figure 4 It is the 3D electric field intensity distribution of the wavy P-region terminal structure of the utility model under forward blocking.

[0017] Figure 5 It is the forward breakdown characteristic curve of the wavy P-region terminal simulation of the utility model.

[0018] Figure 6 It is the reverse breakdown characteristic curve of the wavy P region terminal simulation of the utility model.

[0019] Description of reference numerals:

[0020] Reference Figure 1 and Figure 2 , 10-gate aluminum layer; 11-cathode aluminum layer; 20-cathode N+ region; 21-cathode side P region; 22-cathode side P- region; 30-N-base region; 40-anode P- region; 41-anode P+ region; 12-anode aluminum layer; 50-terminal P- region; 51-terminal passivation layer; 52-terminal shallow trench; 53-terminal wavy P region ripple height. DETAILED DESCRIPTION

[0021] The utility model is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0022] Reference Figure 2 The utility model provides a wavy terminal structure of a reverse-blocking gate-commutated thyristor (RB-GCT) device. In the active region, a cathode aluminum layer (11) and a gate aluminum layer (10), a cathode N+ region (20), a cathode P region (21), a cathode P- region (22), an N-base region (30), an anode P- region (40), an anode P+ region (41) and an anode aluminum layer (12) are sequentially arranged from top to bottom. In the terminal region, the anode and cathode are provided with a passivation layer (51), a shallow trench (52), a terminal P- region (50) and an N-base region (30). An N-type cutoff ring (60) is arranged at the edge of the terminal.

[0023] The doping concentration of the wavy terminal region is a gradual doping. From the active region to the edge of the terminal region, the doping concentration increases from 1.0×10 15 cm -3 ~1.0×10 14 cm -3 Gradually decreases, the groove width gradually decreases from 160μm to 80μm, the spacing between the grooves gradually decreases from 200μm to 70μm, and the junction depth of the wavy area gradually decreases from 150μm to 70μm.

[0024] Combination Figure 1 and Figure 2 The structure of the utility model has the following characteristics:

[0025] Aluminum impurities cannot be masked and diffused by ordinary silicon dioxide (SiO2). If silicon nitride (Si3N4) is used for masking, it is necessary to grow SiO2-Si3N4-SiO2 multilayer films to avoid the problem of excessive stress between Si3N4 and Si surface, which leads to high manufacturing costs. The method of pre-depositing aluminum first and then selectively corroding aluminum is adopted. The aluminum impurity source after silicon corrosion is further selectively diffused under long-term high temperature to form a deep junction. By carefully designing the layout size, shallow grooves with gradually decreasing width (D1, D2...) and spacing (L1, L2...) (D1>D2>..., L1>L2>...) are obtained in the terminal area. Such a clever design can obtain a P-type area with a corrugated terminal at one time, and the P-type area is gradually doped and has a gradually changing junction depth.

[0026] Reference Figure 3 The utility model provides a lateral doping concentration distribution on the surface of the wavy P-region terminal structure. In the terminal region, the doping concentration is distributed from high to low. From the active region to the edge of the terminal region, due to the design of the gradual shallow etching groove spacing, the doping concentration is 1.0×10 15 cm -3 ~1.0×10 14 cm -3 The size of the wavy P-region terminal of the utility model is about 2600 μm, which is about 18.8% smaller than the conventional negative bevel terminal of 3200 μm, which means that the flow area of ​​a 6-inch device will increase by 1.75%.

[0027] Reference Figure 4 The utility model provides a 3D electric field intensity distribution under forward blocking of a wavy P-type terminal structure. Due to the existence of the wavy P-type region, there are multiple peak electric fields in the terminal region, which reduces the peak electric field intensity on the terminal surface, so that multiple P-type wavy regions share the blocking voltage, thereby increasing the blocking voltage.

[0028] Reference Figure 5 The utility model provides a forward breakdown characteristic curve of the wavy P-region terminal simulation. The active region voltage reaches 9600V. The terminal withstand voltage of the ordinary negative bevel structure is 8100V, and the terminal efficiency is 84.38%; the utility model structure achieves a terminal withstand voltage of 8720V and a terminal efficiency of 90.85%, which is 6.47% higher than the ordinary structure.

[0029] Reference Figure 6The utility model provides a reverse breakdown characteristic curve of the wavy P-region terminal simulation. The active region voltage reaches 9300V, the terminal withstand voltage of the ordinary negative bevel structure is 7820V, and the terminal efficiency is 84.09%; the utility model structure achieves a terminal withstand voltage of 8310V and a terminal efficiency of 89.35%, which is 5.26% higher than the ordinary structure.

[0030] The device structure and manufacturing method of the utility model are applicable to all deep junction (typical depth ≥ 80μm) power semiconductor device structures, including unidirectional blocking devices. Any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the utility model without departing from the content of the technical solution of the utility model shall still fall within the scope of protection of the technical solution of the utility model.

Claims

1. A reverse blocking gate commutated thyristor (RB-GCT) device with a wavy terminal structure, comprising an active region and a terminal region, wherein both the active region and the terminal region include an N-base region (30), characterized in that: Shallow grooves (52) are arranged on the surfaces of the anode and cathode of the terminal region, the surface of the shallow grooves (52) is covered with a passivation layer (51), and an N-type cut-off ring (60) is arranged at the edge of the terminal region.

2. The wavy terminal structure of a reverse blocking gate commutated thyristor (RB-GCT) device according to claim 1, characterized in that: The width and spacing of the shallow trenches (52) gradually decrease along the direction from the active area to the terminal area.

3. The wavy terminal structure of a reverse blocking gate commutated thyristor (RB-GCT) device according to claim 2, characterized in that: The width of the shallow grooves (52) gradually decreases from 160 μm to 80 μm, and the spacing between the shallow grooves (52) gradually decreases from 200 μm to 70 μm.

4. The wavy terminal structure of a reverse blocking gate commutated thyristor (RB-GCT) device according to claim 1, characterized in that: It also includes a corrugated region, wherein the junction depth of the corrugated region gradually decreases along the direction from the active region to the terminal region, and the doping concentration of the corrugated region is a graded doping.

5. The wavy terminal structure of a reverse blocking gate commutated thyristor (RB-GCT) device according to claim 4, characterized in that: The doping concentration of the wavy region is 1.0×10 15 cm -3 ~1.0×10 14 cm -3 Gradually decrease.

6. The wavy terminal structure of a reverse blocking gate commutated thyristor (RB-GCT) device according to claim 4, characterized in that: The junction depth of the wavy area gradually decreases from 150 μm to 70 μm.

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