IGBT structure

Abstract

The utility model provides an IGBT structure which comprises a drift region, a CS layer, a P-type base region and a trench gate, the CS layer is located between the P-type base region and the drift region, the trench gate penetrates through the P-type base region, and the bottom of the trench gate is located on the CS layer; the groove gate is made of polycrystalline silicon; an N-type injection region and a P-type injection region are arranged at the bottom and the periphery of the bottom of the trench gate; the concentration of the N-type injection region is equal to that of the P-type injection region, and the N-type injection region is larger than and comprises the P-type injection region; or, the concentration of the N-type injection region is equal to that of the P-type injection region, and the P-type injection region is larger than and contains the N-type injection region. The utility model can reduce the grid oscillation effect.

Description

TECHNICAL FIELD

[0001] The utility model relates to a semiconductor device technical field, concretely relates to a kind of IGBT structure. BACKGROUND

[0002] IGBT (Insulated Gate Bipolar Transistor) as a kind of MOSFET controlled bipolar junction transistor, it has the advantages of high frequency of power MOSFET and low on-voltage of BJT, so it is widely used in low-power, low-frequency market. With the rapid development of electronic industry, higher demand is put forward for IGBT at present, and it is required to have high voltage resistance, low switching loss and high switching reliability while being low on.

[0003] Figure 1 It is the structure diagram of current mainstream CS-IGBT (carrier storage type IGBT), although it greatly reduces the on-voltage of device without increasing the back collector dose, but after adopting CS layer, it will form a potential barrier, which blocks the holes from being emitted and extracted by the collector, and the holes will gather at the bottom of the trench, eventually leading to serious gate oscillation effect of the device in the on state.

[0004] Therefore, how to reduce the gate oscillation effect is a problem to be solved at present. SUMMARY

[0005] The utility model aims at providing a kind of IGBT structure, can reduce the gate oscillation effect.

[0006] To achieve the above object, the utility model provides a kind of IGBT structure, comprising:

[0007] Drift region, CS layer, P-type base region and slot gate, the CS layer is located between the P-type base region and the drift region, the slot gate passes through the P-type base region, and the bottom is located in the CS layer;

[0008] The bottom and the outer periphery of the bottom of the slot gate are provided with N-type injection area and P-type injection area;

[0009] The concentration of the N-type injection area is equal to the concentration of the P-type injection area, and the N-type injection area is greater than and includes the P-type injection area;Or,

[0010] The concentration of the N-type injection area is equal to the concentration of the P-type injection area, and the P-type injection area is greater than and includes the N-type injection area.

[0011] In an optional scheme, the IGBT structure is sequentially from bottom to top: P-type collector region, N-type buffer region, the drift region, the CS layer, the P-type base region.

[0012] In an alternative, the top surface of the N-type injection region and the P-type injection region is higher or lower than the top surface of the CS layer.

[0013] In an alternative, the bottom surface of the N-type injection region and the P-type injection region is higher or lower than the bottom surface of the CS layer.

[0014] In an alternative, the slot gate is arranged periodically and discontinuously in the longitudinal direction.

[0015] In an alternative, N-type high-doped regions are arranged on both sides of the top of the slot gate.

[0016] In an alternative, the P-type injection region circumscribes the collector region.

[0017] In an alternative, the CS layer is a high N-type injection dose layer, and the drift region is N-type.

[0018] The IGBT structure of the present application has the following advantages:

[0019] The N-type injection region and the P-type injection region are formed at the bottom of the slot gate, thereby forming a depletion layer, and the potential at the bottom of the slot gate can be clamped in the off state of the IGBT, and compared with the conventional IGBT, the rate of change of the potential at the bottom of the slot gate is reduced when the IGBT is turned on, and the oscillation effect of the gate switch of the device is weakened. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the different views. The same reference numbers in different drawings represent the same or similar components.

[0021] Figure 1 FIG. 1 is a schematic diagram of the IGBT structure in the prior art.

[0022] Figure 2 FIG. 2 is a schematic diagram of the IGBT structure in an embodiment of the present application.

[0023] Figure 3 FIG. 3 is a schematic diagram of the IGBT structure forming a depletion layer in an embodiment of the present application.

[0024] Figure 4 FIG. 4 is a flow chart of the manufacturing process of the IGBT structure in an embodiment of the present application.

[0025] Figures 5 to 9 FIG. 5 is a schematic diagram of the structure corresponding to the different steps in the manufacturing process of the IGBT structure in an embodiment of the present application.

[0026] Figure 10 FIG. 6 is a schematic diagram of the IGBT structure in another embodiment of the present application.

[0027] Reference numerals:

[0028] 1-collector region; 2-N-type buffer region; 3-drift region; 4-CS layer; 5-P-type base region; 6-N-type injection region; 7-P-type injection region; 8-trench gate; 9-N-type high-doped region; 10-trench; 11-sacrificial oxide layer. DETAILED DESCRIPTION

[0029] The utility model will be explained further in detail below in combination with the drawings and specific embodiments. According to the following description and drawings, the advantages and features of the utility model will be more clear, however, it is stated that the conception of the technical scheme of the utility model can be implemented in multiple different forms, and is not limited to the specific embodiments set forth herein. The drawings all adopt very simplified form and all use non-precise proportion, only to facilitate, clear and assist the purpose of explaining the utility model embodiments.

[0030] It should be understood that when an element or layer is referred to as being "on", "adjacent", "connected to", or "coupled to" another element or layer, it can be directly on, adjacent, connected or coupled to the other element or layer, or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on", "directly adjacent", "directly connected to", or "directly coupled to" another element or layer, then there are no intervening elements or layers present. It will be appreciated with understanding that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are simply used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application.

[0031] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] Embodiment 1

[0034] With reference to Figures 2 to 9 The embodiment provides an IGBT structure, comprising:

[0035] a drift region 3, a CS layer 4, a P-type base region 5, and a slot gate 8, the CS layer 4 is located between the P-type base region 5 and the drift region 3, and the slot gate 8 penetrates through the P-type base region 5 and has a bottom located in the CS layer 4;

[0036] The bottom and the outer periphery of the bottom of the slot gate 8 are provided with an N-type injection region 6 and a P-type injection region 7;

[0037] The concentration of the N-type injection region 6 is equal to the concentration of the P-type injection region 7, and the N-type injection region 6 is greater than and contains the P-type injection region 7.

[0038] In the embodiment, the IGBT structure is sequentially from bottom to top: a P-type collector region 1, an N-type buffer region 2, the drift region 3, the CS layer 4, and the P-type base region 5. The CS layer 4 is a high N-type injection dose layer, and the drift region 3 is N-type. The top of the slot gate 8 is provided with an N-type high-doped region 9 on both sides.

[0039] In the embodiment, the P-type injection region 7 circumscribes the collector region 1.

[0040] In the embodiment, the top surface of the N-type injection region 6 and the P-type injection region 7 is higher or lower than the top surface of the CS layer 4. The bottom surface of the N-type injection region 6 and the P-type injection region 7 is higher or lower than the bottom surface of the CS layer 4.

[0041] In the embodiment, the slot gate 8 is arranged longitudinally and discontinuously in cycles. The longitudinal length of the slot gate 8 is considered in compromise according to the short-circuit capability of the device. The material of the slot gate 8 is polysilicon.

[0042] With reference to Figures 4 to 9 The manufacturing method of the IGBT structure is:

[0043] The CS layer is injected on the drift layer, and then the trench 10 is etched to form the sacrificial oxide layer 11. The universal injection process is used to form the N-type injection region 6 and the P-type injection region 7 at the bottom of the trench 10, wherein Figure 8 The red region at the uppermost layer in the middle refers to the N-type region formed when the N-type injection region and the P-type injection region are formed by the universal injection. After the sacrificial oxide layer is removed, the gate oxide and the polysilicon are formed, the P-type base region 8 is formed by P-type injection, the N-type high-doped region 9 is formed at the outer periphery of the trench gate 8, the IDL is formed, the CT hole etching and the P-type high-doped region are performed, and finally the metal deposition and etching are performed.

[0044] In the embodiment, the high-doped N-type injection region 6 at the bottom of the trench cooperates with the CS layer 4 and the drift region 3 to form a hole potential barrier, so as to block the holes from being extracted, and further reduce the on-state voltage drop.

[0045] The high-doped N-type injection region 6 at the bottom of the trench isolates the holes from gathering at the bottom of the gate, reduces the potential change gradient at the bottom of the trench when the device is turned on, and reduces the switching oscillation effect of the gate of the device.

[0046] The depletion layer formed at the bottom of the trench gate can clamp the potential at the bottom of the trench gate in the off-state of the IGBT. Compared with the conventional IGBT, the potential change rate at the bottom of the trench gate is reduced when the device is turned on, and the switching oscillation effect of the gate of the device is weakened.

[0047] The N-type and P-type injection regions can be used to adjust the size of the depletion layer by adjusting the energy and dose of the N-type and P-type injection regions, so as to control the Cgd (the equivalent capacitance between the gate and the drain of the IGBT and the potential at the bottom of the trench gate when the IGBT is turned off), and finally optimize the switching loss and the waveform.

[0048] The N-type injection region and the P-type injection region are formed by the universal injection after the formation of the sacrificial oxide layer, and do not need the formation of an additional oxide barrier layer and an additional photolithography mask. In addition, the junction of the N-type injection region and the P-type injection region is compatible with the gate oxide and the subsequent heat process, and does not need an additional heat process.

[0049] Although the addition of the N-type injection region causes the reverse voltage of the device to be weakened, the simultaneous addition of the P-type injection region at the bottom of the gate causes the P-type injection regions to be mutually depleted when the device is in the reverse voltage, and further compensates for the reduction of the reverse voltage of the device caused by the N-type region.

[0050] The discontinuous arrangement of the trench gates ensures that the P-type region at the bottom of the trench gate is grounded, while the short-circuit capability of the device is optimized.

[0051] Embodiment 2

[0052] Referring to Figure 10 The embodiment provides an IGBT structure, which comprises:

[0053] The drift region 3, CS layer 4, P-type base region 5 and slot grid 8 are provided. The CS layer 4 is located between the P-type base region 5 and the drift region 3. The slot grid 8 passes through the P-type base region 5 and its bottom is located on the CS layer 4.

[0054] The material of the slot gate 4 is polycrystalline silicon;

[0055] The bottom and outer periphery of the slot 4 are provided with an N-type injection area 6 and a P-type injection area 7;

[0056] The concentration of the N-type injection region 6 is equal to the concentration of the P-type injection region 7, and the P-type injection region 7 is greater than and includes the N-type injection region 6.

[0057] The difference between this embodiment and Embodiment 1 is that the P-type injection region 7 is larger than and includes the N-type injection region 6, while the other structures are the same as in Embodiment 1.

[0058] In this embodiment, a depletion layer is formed at the bottom of the slot gate, which can clamp the potential at the bottom of the slot gate when the IGBT is off. Compared with traditional IGBTs, the rate of change of the potential at the bottom of the slot gate is reduced when the IGBT is on, and the gate switching oscillation effect of the device is weakened.

[0059] Using N-type and P-type injections, the size of the depletion layer can be adjusted by regulating the energy and dosage of the N-type and P-type injections, thereby controlling C. gd And the magnitude of the potential at the bottom of the slot gate when the IGBT is turned off, ultimately optimizing switching losses and waveforms.

[0060] N-type and P-type implanted regions are formed by general implantation after the formation of the sacrificial oxide layer, without the need for additional oxide barrier layers or additional photomasks. Furthermore, the push-in of N-type and P-type implanted regions is compatible with gate oxide and its subsequent thermal processes, requiring no additional thermal processes.

[0061] By employing a P-type injection region containing an N-type injection region, the device's withstand voltage can be significantly improved during reverse breakdown. Therefore, the reverse design window of the device is increased, which can further optimize the injection dose and energy of the carrier storage layer or reduce the thickness of the device's drift region, ultimately reducing the device's on-state voltage drop and optimizing switching losses.

[0062] In existing technologies, such as Figure 1 As shown, the depth of the CS layer does not exceed the bottom of the trench (the trench depth is set). In the above two embodiments, P and N injections are formed at the bottom of the trench, which can make the CS layer deeper and improve the withstand voltage and reliability of the device.

[0063] The above description is only the description of the preferred embodiment of the utility model, and is not any limitation on the range of the utility model. Any change and modification of the above disclosure by the ordinary skilled in the art is within the protection scope of the claims.

Claims

1. An IGBT structure, characterized in that, include: The system comprises a drift region, a CS layer, a P-type base region, and a slot gate, wherein the CS layer is located between the P-type base region and the drift region, and the slot gate passes through the P-type base region and has its bottom located on the CS layer; The bottom and outer periphery of the slot grid are provided with an N-type injection area and a P-type injection area; The concentration of the N-type injection region is equal to the concentration of the P-type injection region, and the N-type injection region is larger than and includes the P-type injection region; or... The concentration of the N-type injection region is equal to the concentration of the P-type injection region, and the P-type injection region is larger than and includes the N-type injection region.

2. The IGBT structure as described in claim 1, characterized in that, The IGBT structure, from bottom to top, consists of: a P-type collector region, an N-type buffer region, the drift region, the CS layer, and the P-type base region.

3. The IGBT structure as described in claim 1, characterized in that, The top surfaces of the N-type injection region and the P-type injection region are either higher or lower than the top surface of the CS layer.

4. The IGBT structure as described in claim 1, characterized in that, The bottom surfaces of the N-type injection region and the P-type injection region are either higher or lower than the bottom surface of the CS layer.

5. The IGBT structure as described in claim 1, characterized in that, The slot grid is arranged in a longitudinally discontinuous periodic pattern.

6. The IGBT structure as described in claim 1, characterized in that, The top two sides of the trench gate are provided with N-type highly doped regions.

7. The IGBT structure as described in claim 2, characterized in that, The P-type injection region is connected to the collector region.

8. The IGBT structure as described in claim 1, characterized in that, The CS layer is a high N-type injection dose layer, and the drift region is N-type.

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