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CN117457729A - High-voltage RC-IGBT structure integrated with fast soft recovery diode - Google Patents

High-voltage RC-IGBT structure integrated with fast soft recovery diode Download PDF

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Publication number
CN117457729A
CN117457729A CN202311642087.8A CN202311642087A CN117457729A CN 117457729 A CN117457729 A CN 117457729A CN 202311642087 A CN202311642087 A CN 202311642087A CN 117457729 A CN117457729 A CN 117457729A
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igbt
integrated
diode
type
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CN202311642087.8A
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伍伟
喻明康
舒玉露
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Yangtze River Delta Research Institute of UESTC Huzhou
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Yangtze River Delta Research Institute of UESTC Huzhou
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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Abstract

The invention belongs to the technical field of RC-IGBT, and discloses a high-voltage RC-IGBT structure of an integrated fast soft recovery diode, which comprises an IGBT part and an integrated diode part; the front surfaces of the two parts are respectively provided with a groove gate structure consisting of a polysilicon gate and a gate oxide layer, and a P-type shielding ring is arranged below the groove gate structure. The IGBT part is placed from bottom to top in sequence: the semiconductor device comprises a P+ collector region, an N-type field stop, an N-drift region, a carrier storage layer, a P-type base region, a P+ emitter region and an N+ emitter region; the integrated diode part is placed in sequence from bottom to top: an N+ collector region, an N-type field stop region, an N-drift region, a carrier storage layer, a P-base region and an N+ contact layer. The RC-IGBT structure has shorter reverse recovery time and greater softness; its withstand voltage is not deteriorated compared with the conventional RC-IGBT structure.

Description

High-voltage RC-IGBT structure integrated with fast soft recovery diode
Technical Field
The invention belongs to the technical field of RC-IGBT, and particularly relates to a high-voltage RC-IGBT structure of an integrated fast soft recovery diode.
Background
IGBTs are often required in modern systems for use with freewheeling diodes (Freewheeling Diode, FWD), a typical example being an inverter. If the IGBT and the diode can be integrated on the same silicon wafer, a large area of the silicon wafer can be saved because the monolithically integrated IGBT and FWD share the same junction termination. Particularly, in the case of a high-voltage device with a small area of a single chip, the junction terminal area is large, and the proportion of the area occupied by the active region is relatively small, so that the advantage is obvious. In addition, because the two chips are combined into one die, the packaging processes such as bonding sheets, lead sputtering and the like are reduced, and the required packaging cost is reduced. Such an IGBT having a FWD integrated therein with reverse on-current capability is called a reverse-conducting IGBT (RC-IGBT).
The RC-IGBT integrates the freewheeling diode in the device, but the electric characteristic of the freewheeling diode is limited by the IGBT structure due to the fact that the freewheeling diode and the IGBT share one substrate, the reverse recovery speed of the integrated diode is difficult to be improved, and the application of the RC-IGBT device in the hard switching field is limited. Therefore, how to optimize the reverse recovery characteristics of the integrated diode without deteriorating the forward characteristics of the RC-IGBT is the center of study of each expert learner.
Matsuoka.Y.et al, in 2016, proposed an RC-IGBT structure incorporating a Schottky diode, as shown in FIG. 1, which is characterized in that the Schottky diode is incorporated because the metal anode of the Schottky diode cannot inject holes into the semiconductor material and the doping concentrations of the P-type and N-type regions of the integrated diode are lower than those of conventional RC-IGBT devices, thereby reducing the injection efficiency of the anode and cathode of the integrated diode of the device and reducing the reverse recovery loss of the integrated diode.
The novel structure of the RC-IGBT proposed by Shinya et al in 2020 reduces the reverse recovery loss of the RC-IGBT integrated diode by adopting a life control technology to reduce the service life of the carrier, and as shown in fig. 2, he ions are injected into the drift region by adopting an ion irradiation mode to reduce the service life of the carrier, but the reduction of the service life of the carrier also affects the performances such as conduction voltage drop and the like of the IGBT of the device.
Kenji et Al proposed in 2021 to improve the reverse recovery loss of an integrated diode of an RC-IGBT device by using a new gate electrode structure, and as shown in FIG. 3, the biggest feature of the structure is that the gate oxide of the integrated diode in contact with the P-type emitter is replaced by an Al electrode, and the P+ type emitter is shorted to reduce the carrier injection efficiency, thereby effectively reducing the reverse recovery loss of the integrated diode of the RC-IGBT device.
Through the above analysis, the problems and defects existing in the prior art are as follows: RC-IGBT has strong electrical property relevance due to the fact that the IGBT and the diode are integrated on a substrate, and the performance of the IGBT and the diode have a trade-off relationship, and the prior art is mainly focused on optimizing the performance of the IGBT, so that the reverse recovery characteristic of the integrated diode is poor, and the integrated diode is difficult to apply to a hard switching environment.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a high-voltage RC-IGBT structure of an integrated fast soft recovery diode.
The invention is realized in such a way that the high-voltage RC-IGBT structure of the integrated fast soft recovery diode is divided into an IGBT part and an integrated diode part according to a back P+ collector region and an N+ collector region;
the IGBT part is placed from bottom to top in sequence: the P+ collector region, the N-type field stop, the N-drift region, the carrier storage layer, the P-type base region, the P+ emitter region and the N+ emitter region are arranged on the front surface of the semiconductor device, a groove gate structure consisting of a polysilicon gate and a gate oxide layer is arranged on the front surface of the semiconductor device, and a P-type shielding ring is arranged below the groove gate structure.
Further, the integrated diode portion is placed in order from bottom to top: the N+ collector region, the N-type field stop, the N-drift region, the carrier storage layer, the P-base region and the N+ contact layer are arranged on the front surface of the semiconductor device, a trench gate structure consisting of a polysilicon gate and a gate oxide layer is arranged on the front surface of the semiconductor device, and a P-type shielding ring is arranged below the trench gate structure.
Further, the P-type shielding rings are not contacted every two, but the distance between every two P-type shielding rings is very narrow, so that a current path is formed.
Further, when the device is subjected to forward withstand voltage, the current path is pinched off by a depletion region formed by the P-type shielding ring and the N-drift region, and a blocking layer is formed at the bottom of the gate.
Further, the peak doping concentration of the P-base region is 1×10 15 cm -3 Up to 5X 10 16 cm -3
Further, the P-base region is depleted when the integrated diode is turned on, and the number of carriers in the N-drift region is reduced; when the integrated diode is turned off, the p+ collector region injects holes into the N-drift region.
Another object of the present invention is to provide an application of a high voltage RC-IGBT structure of an integrated fast soft-recovery diode in an integrated fast soft-recovery diode.
In combination with the technical scheme and the technical problems to be solved, the technical scheme to be protected has the following advantages and positive effects:
first, aiming at the technical problems in the prior art and the difficulty of solving the problems, the technical problems solved by the technical proposal of the invention are analyzed in detail and deeply by tightly combining the technical proposal to be protected, the results and data in the research and development process, and the like, and some technical effects brought after the problems are solved have creative technical effects. The specific description is as follows:
according to the RC-IGBT structure of the integrated fast soft recovery diode, provided by the invention, on the premise of ensuring high voltage-withstanding characteristic, the time of the reverse recovery process of the integrated diode is reduced, and the softness of the reverse recovery of the integrated diode is improved.
Compared with the traditional RC-IGBT structure, the integrated diode of the novel RC-IGBT structure provided by the invention has faster reverse recovery time and greater softness, and the withstand voltage of the novel RC-IGBT structure is the same as that of the traditional RC-IGBT structure, so that the problem of deterioration in the withstand voltage is avoided.
The expected benefits and commercial values after the technical scheme of the invention is converted are as follows: the novel RC-IGBT structure provided by the invention has the advantages of short reverse recovery time and soft recovery characteristic of the integrated diode, and expands the application of the IGBT in the field of hard switches.
Second, the high voltage RC-IGBT structure of the integrated fast soft recovery diode of the invention has the following significant technical advances:
1) Integrating diode and IGBT structure: by integrating the IGBT and the fast soft recovery diode in the same structure, not only is space saved, but also the power density and efficiency of the device are improved. Such an integrated design is particularly beneficial for applications requiring high density power conversion, such as electric vehicles, renewable energy systems, and the like.
2) P-type shielding ring design: the design of the P-type shielding ring helps to improve the blocking capability of the device in the forward voltage withstanding, and the blocking layer formed at the bottom of the gate is used for pinching off the current path. This design helps to optimize the switching characteristics of the device while improving the device's voltage withstand characteristics.
3) Adjustment of carrier storage layer and doping concentration: the soft recovery characteristic of the device is further optimized by adjusting the peak doping concentration of the P-base region and the regulation and control of the number of carriers in the N-drift region when the integrated diode is turned on and off. These measures help to reduce the tail current when the diode is turned off, thereby reducing switching losses.
4) Carrier injection mechanism: when the integrated diode is turned off, a mechanism of injecting holes into the N-drift region through the P+ collector region prolongs the tail current and achieves soft recovery characteristics.
In summary, the high-voltage RC-IGBT structure of the invention not only improves the electrical performance of the device (especially in the aspects of switching characteristics and reverse recovery speed), but also optimizes the structural design of the device, so that the high-voltage RC-IGBT structure is more suitable for high-efficiency and high-frequency power electronic application scenes.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of an RC-IGBT structure incorporating a schottky diode provided in the prior art;
FIG. 2 is a schematic diagram of an RC-IGBT structure incorporating life control techniques as provided by the prior art;
FIG. 3 is a schematic diagram of a new gate electrode structure provided by the prior art;
FIG. 4 is a schematic diagram of an RC-IGBT structure of an integrated fast soft recovery diode according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a conventional RC-IGBT structure provided by an embodiment of the present invention;
in the figure: 1. an n+ collector region; 2. a p+ collector region; 3. the N-type field is cut off; 4. an N-drift region; 5. a carrier storage layer; 6. a P-type base region; 7. a P+ emitter region; 8. an n+ emitter region; 9. a polysilicon gate; 10. a gate oxide layer; 11. a P-type shielding ring; 12. an n+ blocking layer; 13. and a P-base region.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Aiming at the problems existing in the prior art, the invention provides a high-voltage RC-IGBT structure of an integrated fast soft recovery diode.
As shown in fig. 1, in the high-voltage RC-IGBT structure of the integrated fast soft-recovery diode provided by the embodiment of the invention, the high-voltage RC-IGBT structure of the integrated fast soft-recovery diode is divided into an IGBT part and an integrated diode part according to the back p+ collector region 2 and the n+ collector region 1;
the IGBT part is placed from bottom to top in sequence: the p+ collector region 2, the N-type field stop 3, the N-drift region 4, the carrier storage layer 5, the P-type base region 6, the p+ emitter region 7 and the N+ emitter region 8 are arranged on the front surface, a trench gate structure consisting of a polysilicon gate 9 and a gate oxide layer 10 is arranged on the front surface, and a P-type shielding ring 11 is arranged below the trench gate structure;
the integrated diode part is placed in sequence from bottom to top: the N+ collector region 1, the N-type field stop 3, the N-drift region 4, the carrier storage layer 5, the P-base region 13 and the N+ contact layer 12 are arranged on the front surface, a trench gate structure consisting of a polysilicon gate 9 and a gate oxide layer 10 is arranged on the front surface, and a P-type shielding ring 11 is arranged below the trench gate structure.
The peak doping concentration of the P-base region 13 of the RC-IGBT structure of the integrated fast soft recovery diode provided by the embodiment of the invention is 1 multiplied by 10 15 cm -3 Up to 5X 10 16 cm -3 This region is depleted when the integrated diode is turned on, forming an electron extraction channel, thereby reducing the number of carriers in the N-drift region 4, allowing a rise time t of the reverse recovery process s Shorter, reverse recovery process is faster. Meanwhile, when the integrated diode is turned off, the P+ collector region 2 injects holes into the N-drift region 4, thereby prolonging t f According to the formula s=t f /t s It can be seen that softness is increased, where S is the softness factor of diode reverse recovery, t f To the fall time of the reverse recovery process, t s Is the rise time of the reverse recovery process.
The P-type shielding rings 11 of the RC-IGBT structure of the integrated fast soft recovery diode provided by the embodiment of the invention are not contacted with each other, but the distance between every two P-type shielding rings 11 is very narrow, a current path is formed, when the device bears forward voltage resistance, the current path is clamped off by a depletion region formed by the P-type shielding rings 11 and the N-drift region 4, so that a layer of blocking layer is formed at the bottom of the grid, the depletion region is prevented from being penetrated, and the device is prevented from being broken down in advance.
As shown in fig. 2, the conventional RC-IGBT structure is different from the RC-IGBT structure of the integrated fast soft-recovery diode in that: the trench gate bottom of the traditional RC-IGBT structure is free of a P-type shielding ring 11, and the peak doping concentration of a P base region of a diode region is 5 multiplied by 10 17 And the diode region has no N + contact layer 13 and only the elongated P + emitter region 7.
The RC-IGBT structure with the integrated rapid soft recovery diode is compared with a control sample, and the novel RC-IGBT structure has shorter reverse recovery time and greater softness S; its withstand voltage is not deteriorated compared with the conventional RC-IGBT structure.
In order to prove the inventive and technical value of the technical solution of the present invention, this section is an application example on specific products or related technologies of the claim technical solution.
Firstly, growing an oxide layer on the front surface of an N-type semiconductor substrate, depositing silicon nitride, then masking and windowing to inject N-type impurities and pushing the junction to form a carrier storage layer 5.
And secondly, removing the oxide layer and the silicon nitride, and epitaxially growing a layer of P-type substrate on the front surface of the semiconductor substrate to form a P-base region 13.
And thirdly, injecting N-type impurities into the back surface of the semiconductor substrate and pushing the junction to form an N-type field stop 3.
And fourthly, growing an oxide layer on the front surface of the semiconductor substrate, depositing silicon nitride, and then injecting P-type impurities through mask windowing and pushing the junction to form the P-type base region 6.
And fifthly, removing the oxide layer and the silicon nitride, regrowing an oxide layer, depositing the silicon nitride, opening a window by a mask, and etching a groove by a dry method.
And step six, after growing an oxide layer, injecting P-type impurities and pushing the P-type impurities to form the P-type shielding ring 11.
And sixthly, removing the oxide layer and the silicon nitride, growing a compact gate oxide layer 10 by dry oxygen, depositing polysilicon and etching the polysilicon by a mask to form a polysilicon gate 9.
And seventh, growing a thin oxide layer on the front surface, windowing by a mask, injecting N-type impurities, replacing the mask, injecting P-type impurities, and rapidly annealing to form an N+ emitter region 8, a P+ emitter region 7 and an N+ contact layer 12.
Eighth, depositing oxide layer on front surface, masking and windowing, and finally depositing metal leading out collector electrode and grid electrode.
And a thin oxide layer grows on the back, N-type impurities are injected into the mask through windowing, then P-type impurities are injected into the mask through replacement, and finally rapid annealing is performed simultaneously to form an N+ collector region 1 and a P+ collector region 2.
And tenth, metal is deposited on the back to lead out a collector electrode.
The embodiment of the invention has a great advantage in the research and development or use process, and has the following description in combination with data, charts and the like of the test process.
In the embodiment of the invention, as the doping concentration of the P-base region 13 is very low, the region is exhausted during reverse conduction to form an electron extraction channel, thereby reducing the number of carriers in the N-drift region 4 and leading the rising time t of the reverse recovery process s T compared with the traditional RC-IGBT structure s Smaller, and at the same time, when the integrated diode is turned off, the p+ collector region 2 injects holes into the N-drift region 4, so the fall time t of the embodiment of the present invention f T is greater than that of the traditional RC-IGBT structure f Larger, by the formula s=t f /t s The softness of the embodiment of the invention is larger than that of the traditional RC-IGBT structure. And embodiment t of the invention s The reduction value ratio t of (2) f The increase in (2) is greater and thus the reverse recovery process of embodiments of the present invention is faster.
According to the embodiment of the invention, the P-type shielding ring 11 with narrow space enables the depletion region formed by the P-type shielding ring 11 and the N-drift region 4 to form a layer of blocking layer at the bottom of the grid when the device bears forward voltage resistance, so that the depletion region is prevented from being penetrated, the device is prevented from being broken down in advance, and meanwhile, the electric field concentration effect at the bottom of the grid is relieved, so that the breakdown voltage of the device is higher.
The foregoing is merely illustrative of specific embodiments of the present invention, and the scope of the invention is not limited thereto, but any modifications, equivalents, improvements and alternatives falling within the spirit and principles of the present invention will be apparent to those skilled in the art within the scope of the present invention.

Claims (7)

1. The high-voltage RC-IGBT structure of the integrated fast soft recovery diode is characterized in that the high-voltage RC-IGBT structure of the integrated fast soft recovery diode is divided into an IGBT part and an integrated diode part according to a back P+ collector region and an N+ collector region;
the IGBT part is placed from bottom to top in sequence: the P+ collector region, the N-type field stop, the N-drift region, the carrier storage layer, the P-type base region, the P+ emitter region and the N+ emitter region are arranged on the front surface of the semiconductor device, a groove gate structure consisting of a polysilicon gate and a gate oxide layer is arranged on the front surface of the semiconductor device, and a P-type shielding ring is arranged below the groove gate structure.
2. The high voltage RC-IGBT structure of integrated fast soft recovery diodes according to claim 1, wherein the integrated diode sections are placed in sequence from bottom to top: the N+ collector region, the N-type field stop, the N-drift region, the carrier storage layer, the P-base region and the N+ contact layer are arranged on the front surface of the semiconductor device, a trench gate structure consisting of a polysilicon gate and a gate oxide layer is arranged on the front surface of the semiconductor device, and a P-type shielding ring is arranged below the trench gate structure.
3. The high voltage RC-IGBT structure of integrated fast soft recovery diodes according to claim 1, wherein the P-type shield rings are not in contact with each other but the distance between each two P-type shield rings is very narrow, forming a current path.
4. The high voltage RC-IGBT structure of the integrated fast soft-recovery diode of claim 1 wherein the depletion region formed by the P-type shield ring and the N-drift region pinches off the current path when the device is subjected to forward withstand voltage, forming a blocking layer at the gate bottom.
5. The high voltage RC-IGBT structure of claim 2 wherein the P-base region has a peak doping concentration of 1 x 10 15 cm -3 Up to 5X 10 16 cm -3
6. The high voltage RC-IGBT structure of an integrated fast soft-recovery diode of claim 1 wherein the P-base region is depleted and the number of carriers in the N-drift region is reduced when the integrated diode is on; when the integrated diode is turned off, the p+ collector region injects holes into the N-drift region.
7. Use of a high voltage RC-IGBT structure of an integrated fast soft recovery diode according to any of claims 1 to 6 in an integrated fast soft recovery diode.
CN202311642087.8A 2023-12-01 2023-12-01 High-voltage RC-IGBT structure integrated with fast soft recovery diode Pending CN117457729A (en)

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CN202311642087.8A CN117457729A (en) 2023-12-01 2023-12-01 High-voltage RC-IGBT structure integrated with fast soft recovery diode

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118472021A (en) * 2024-05-30 2024-08-09 瑶芯微电子科技(上海)有限公司 Dual-gate controlled RC-IGBT device and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118472021A (en) * 2024-05-30 2024-08-09 瑶芯微电子科技(上海)有限公司 Dual-gate controlled RC-IGBT device and preparation method thereof
CN118472021B (en) * 2024-05-30 2025-03-21 瑶芯微(上海)电子科技股份有限公司 Dual-gate controlled RC-IGBT device and preparation method thereof

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