RC-IGBT structure, manufacturing method thereof and semiconductor device

Abstract

The invention discloses an RC-IGBT structure and a manufacturing method thereof, and a semiconductor device, and the RC-IGBT structure comprises a substrate, a drift region of a first conduction type, a trench gate, a body region of a second conduction type, an emitter region of the first conduction type, a first contact region of the second conduction type, and an isolation region of the second conduction type. The substrate is provided with a first surface and a second surface which are deviated from each other in a first direction, the substrate comprises an IGBT region, a transition region and an FRD region which are sequentially arranged along a second direction, the trench gate comprises an active gate and a virtual gate which are arranged at an interval along the second direction, the isolation region is arranged in the transition region and is arranged between the adjacent virtual gates, and the isolation region is arranged between the active gate and the virtual gate. The isolation region is arranged on one side, facing the second surface, of the drift region, and the doping concentration of the isolation region is larger than that of the body region. According to the RC-IGBT structure, the manufacturing method of the RC-IGBT structure and the semiconductor device, the performance of the IGBT region and the performance of the FRD region can be better and separately regulated and controlled.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductors, and in particular to an RC-IGBT structure and a manufacturing method thereof, and a semiconductor device. Background Art

[0002] At present, IGBT (Insulated Gate Bipolar Transistor) is a MOS-bipolar composite transistor developed on the basis of Metal Oxide Semiconductor Field Effect Transistor (MOSFET). It has the common advantages of power bipolar transistors and power MOSFETs, and has different advantages in on-state voltage drop and switching, thus becoming a core device in power supply, drive, and control circuits. Among them, RC-IGBT (Reverse Conducting IGBT) is a power device that integrates FRD (Fast Recovery Diode) and IGBT.

[0003] In the related art, it is difficult to separately regulate the performance of the IGBT region and the FRD region in the RC-IGBT, resulting in limited performance of the RC-IGBT.

[0004] Improvements are therefore needed to at least partially address the above-mentioned problems. Summary of the invention

[0005] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further described in detail in the Detailed Description of the Invention section. The Summary of the Invention section of this application does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0006] In order to at least partially solve the above problems, according to a first aspect of the present application, a RC-IGBT structure is provided, comprising:

[0007] A substrate, the substrate having a first surface and a second surface that are separated from each other in a first direction, and the substrate comprising an IGBT region, a transition region, and an FRD region arranged in sequence along a second direction, wherein the second direction is perpendicular to the first direction;

[0008] A drift region of a first conductivity type, disposed between the first surface and the second surface;

[0009] A trench gate extending from the second surface to the drift region, comprising an active gate and a dummy gate, wherein the active gate is arranged in the IGBT region and the dummy gate and the active gate are spaced apart from each other along the second direction;

[0010] A body region of a second conductivity type, disposed in the IGBT region and the FRD region, the body region being disposed on a side of the drift region facing the second surface and between adjacent trench gates;

[0011] An emitter region of a first conductivity type and a first contact region of a second conductivity type are arranged outside the active gate and on a side of the body region facing the second surface, and a side of the emitter region and the first contact region away from the body region constitute part of the second surface;

[0012] An isolation region of the second conductivity type is arranged in the transition region and between adjacent virtual gates, and the isolation region is arranged on a side of the drift region facing the second surface, and the doping concentration of the isolation region is greater than the doping concentration of the body region.

[0013] The above technical solution has the following advantages and beneficial effects: According to the RC-IGBT structure of the present application, an isolation region of the second conductive type is arranged in the transition region and between adjacent virtual gates, and the isolation region is arranged on the side of the drift region facing the second surface, and the doping concentration of the isolation region is greater than the doping concentration of the body region. The isolation region plays a role of electric field cutoff, which can reduce the impact between the IGBT region and the FRD region processes, and thus can better separately regulate the performance of the IGBT region and the FRD region.

[0014] Optionally, a side of the isolation region away from the drift region constitutes part of the second surface; or,

[0015] The body region is further disposed on a side of the isolation region facing the second surface, and a side of the body region away from the isolation region constitutes a portion of the second surface.

[0016] The above technical solution has the following advantages and beneficial effects: through such a setting, the influence between the processes of the IGBT region and the FRD region can be reduced, thereby better separately regulating the performance of the IGBT region and the FRD region.

[0017] Optionally, it also includes a second contact region of the second conductivity type and a third contact region of the first conductivity type, the second contact region and the third contact region are arranged in the FRD region and between adjacent virtual gates, and the second contact region and the third contact region are arranged on the side of the body region facing the second surface, and the side of the second contact region and the third contact region away from the body region constitute part of the second surface, wherein the doping concentration of the second contact region is greater than the doping concentration of the body region, and the doping concentration of the third contact region is less than the doping concentration of the emitter region.

[0018] The above technical solution has the following advantages and beneficial effects: the third contact region of the first conductivity type can reduce the amount of carriers injected from the second contact region into the drift region of the FRD region, thereby reducing the reverse recovery current of the FRD region and further reducing the switching loss of the RC-IGBT.

[0019] Optionally, the number of the third contact regions between adjacent virtual gates is at least two, and at least two of the third contact regions are arranged at intervals along a third direction, and the third direction is perpendicular to the first direction and the second direction.

[0020] The above technical solution has the following advantages and beneficial effects: through such a setting, the amount of carriers injected from the second contact region into the drift region of the FRD region can be reduced, thereby reducing the reverse recovery current of the FRD region, and further reducing the switching loss of the RC-IGBT.

[0021] Optionally, the third contact region is a lightly doped region.

[0022] The above technical solution has the following advantages and beneficial effects: through such a setting, the amount of carriers injected from the second contact region into the drift region of the FRD region can be reduced, thereby reducing the reverse recovery current of the FRD region, and further reducing the switching loss of the RC-IGBT.

[0023] Optionally, the active gate is disposed in a first gate trench, the first gate trench extends from the second surface to the drift region, and the active gate comprises a first gate dielectric layer located on an inner surface of the first gate trench and a first polysilicon gate filling the first gate trench;

[0024] The virtual gate is arranged in a second gate trench, the second gate trench extends from the second surface to the drift region, and the virtual gate includes a second gate dielectric layer located on the inner surface of the second gate trench and a second polysilicon gate filling the second gate trench.

[0025] The above technical solution has the following advantages and beneficial effects: the active gate plays a controlling role in the RC-IGBT. When the gate voltage is applied to the active gate, a conductive channel can be formed around the active gate, so that electrons and holes can move in the channel, thereby controlling the on and off of the RC-IGBT; the virtual gate can reduce the feedback capacitance of the RC-IGBT.

[0026] Optionally, it also includes:

[0027] A collector region of a second conductivity type is arranged in the IGBT region and the transition region and on a side of the drift region facing the first surface, and a side of the collector region away from the drift region constitutes a part of the first surface;

[0028] An injection region of a first conductivity type is disposed in the FRD region and is arranged in parallel with the collector region on a side of the drift region facing the first surface, and a side of the injection region away from the drift region constitutes a part of the first surface;

[0029] A field stop region of a first conductivity type is disposed between the collector region and the drift region, and between the injection region and the drift region.

[0030] The above technical solution has the following advantages and beneficial effects: the main function of the field stop region is to terminate the electric field when the RC-IGBT is in the off state, preventing the electric field from penetrating into the collector region, thereby improving the withstand voltage performance of the device.

[0031] According to a second aspect of the present application, a method for manufacturing an RC-IGBT structure is provided, comprising:

[0032] Providing a substrate, the substrate having a first surface and a second surface which are separated from each other in a first direction, a drift region of a first conductivity type being formed between the first surface and the second surface of the substrate, and the substrate comprising an IGBT region, a transition region and an FRD region which are sequentially arranged along a second direction, the second direction being perpendicular to the first direction;

[0033] forming a trench gate extending from the second surface to the drift region, the trench gate comprising an active gate and a dummy gate, the active gate being arranged in the IGBT region and the dummy gate being spaced apart from the active gate along the second direction;

[0034] forming a body region of a second conductivity type in the IGBT region and the FRD region, wherein the body region is disposed on a side of the drift region facing the second surface and between adjacent trench gates;

[0035] forming an isolation region of a second conductivity type, wherein the isolation region is disposed in the transition region and between adjacent virtual gates, and the isolation region is disposed on a side of the drift region facing the second surface, and the doping concentration of the isolation region is greater than the doping concentration of the body region;

[0036] An emitter region of a first conductivity type and a first contact region of a second conductivity type are formed, wherein the emitter region and the first contact region are arranged outside the active gate and on a side of the body region facing the second surface, and a side of the emitter region and the first contact region away from the body region constitute part of the second surface.

[0037] The above technical solution has the following advantages and beneficial effects: According to the manufacturing method of the RC-IGBT structure of the present application, an isolation region of the second conductive type is arranged in the transition region and between adjacent virtual gates, and the isolation region is arranged on the side of the drift region facing the second surface, and the doping concentration of the isolation region is greater than the doping concentration of the body region. The isolation region plays a role of electric field cutoff, which can reduce the impact between the IGBT region and the FRD region processes, and thus can better separately regulate the performance of the IGBT region and the FRD region.

[0038] Optionally, after forming the emitter region and the first contact region, the step of forming a second contact region of the second conductivity type and a third contact region of the first conductivity type is also included, the second contact region and the third contact region are arranged in the FRD region and between adjacent virtual gates, and the second contact region and the third contact region are arranged on the side of the body region facing the second surface, and the side of the second contact region and the third contact region away from the body region constitute part of the second surface, wherein the doping concentration of the second contact region is greater than the doping concentration of the body region, and the doping concentration of the third contact region is less than the doping concentration of the emitter region.

[0039] The above technical solution has the following advantages and beneficial effects: the third contact region of the first conductivity type can reduce the amount of carriers injected into the drift region of the FRD region by the second contact region of the second conductivity type, thereby reducing the reverse recovery current of the FRD region and further reducing the switching loss of the RC-IGBT.

[0040] The semiconductor device according to the embodiment of the present application includes the above-mentioned RC-IGBT structure.

[0041] The above technical solution has the following advantages and beneficial effects: Since the semiconductor device in the present application includes the above RC-IGBT structure, it also has the advantages and beneficial effects of the above RC-IGBT structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0043] Figure 1A-1I A cross-sectional view of the RC-IGBT structure obtained by sequentially implementing the manufacturing method of the RC-IGBT structure in the embodiment of the present application is shown.

[0044] Figure 2 A cross-sectional view of an RC-IGBT structure in another embodiment of the present application is shown.

[0045] Figure 3 A flow chart showing a method for manufacturing an RC-IGBT structure in an embodiment of the present application is shown.

[0046] Reference numerals:

[0047] 100. substrate; 101. first surface; 102. second surface; 110. drift region; 121. active gate; 122. virtual gate; 130. body region; 140. isolation region; 150. emitter region; 161. first contact region; 162. second contact region; 163. third contact region; 170. field stop region; 180. collector region; 190. injection region. DETAILED DESCRIPTION

[0048] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described.

[0049] It should be understood that the present application can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0050] It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part.

[0051] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used herein for convenience of description to describe the relationship of one element or feature to other elements or features shown in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation shown in the figures.

[0052] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0053] Embodiments of the application are described herein with reference to cross-sectional views as schematic diagrams of ideal embodiments (and intermediate structures) of the application. In this way, variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the application should not be limited to the specific shapes shown herein, but include shape deviations due to, for example, manufacturing. Therefore, what is shown in the figures is schematic in nature, and their shapes are not intended to display the actual shapes of the devices and are not intended to limit the scope of the application.

[0054] In the RC-IGBT structure in the related art, the IGBT region and the FRD region are in direct contact with each other. When the performance of the IGBT region and the FRD region are adjusted through the process, the processes of the IGBT region and the FRD region will affect each other, making it difficult to separately regulate the performance of the IGBT region and the FRD region.

[0055] like Fig. 1I and Figure 2As shown, in order to solve the above problems, an embodiment of the present application provides an RC-IGBT structure, which mainly includes: a substrate 100, a drift region 110 of a first conductive type, a trench gate, a body region 130 of a second conductive type, an emitter region 150 of a first conductive type, a first contact region 161 of a second conductive type, and an isolation region 140 of a second conductive type.

[0056] First, it should be noted that, in this article, N and P represent the conductivity type of the semiconductor. In the following, the first conductivity type is set to N type and the second conductivity type is set to P type for description.

[0057] The substrate 100 has a first direction ( Fig. 1I and Figure 2 The first surface 101 and the second surface 102 are separated from each other in the up-down direction (in the vertical direction), and the first surface 101 and the second surface 102 are spaced apart along the first direction.

[0058] The substrate 100 includes a Fig. 1I and Figure 2 The IGBT region, transition region and FRD region are arranged in sequence in the left and right directions (in the second direction), and the second direction is perpendicular to the first direction. Among them, the IGBT region is the main region responsible for current conduction in the RC-IGBT, and the channel is formed in the IGBT region; the FRD region is the region in the RC-IGBT that plays the role of freewheeling reverse current.

[0059] Exemplarily, the substrate 100 may be any suitable semiconductor substrate, such as a silicon substrate, and may also be at least one of the following materials: Si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP or other III / V compound semiconductors, including a multilayer structure composed of these semiconductor materials, or silicon on insulator (SOI), stacked silicon on insulator (SSOI), stacked silicon germanium on insulator (S-SiGeOI), silicon germanium on insulator (SiGeOI) and germanium on insulator (GeOI).

[0060] The drift region 110 is disposed between the first surface 101 and the second surface 102. The drift region 110 determines the saturation voltage drop and voltage level of the RC-IGBT and is the main region that affects the switching speed of the RC-IGBT. The conductivity type of the drift region 110 is the first conductivity type.

[0061] The trench gate extends from the second surface to the drift region 110, and the trench gate includes an active gate 121 and a dummy gate 122. The active gate 121 is disposed in the IGBT region, and the dummy gate 122 is spaced from the active gate 121 along the second direction. Exemplarily, Fig. 1I and Figure 2The RC-IGBT shown is provided with an active gate 121 and multiple virtual gates 122, but this does not mean that the number of active gates 121 can only be 1. In other embodiments, multiple active gates 121 can also be provided. When multiple active gates 121 are provided, the arrangement of the active gates 121 and the virtual gates 122 can be reasonably set as needed, and the present application does not impose any restrictions on this.

[0062] The active gate 121 plays a control role in the RC-IGBT. When a gate voltage is applied to the active gate 121, a conductive channel can be formed around the active gate 121, so that electrons and holes can move in the channel, thereby controlling the on and off of the RC-IGBT.

[0063] The virtual gate 122 is a gate structure that exists in the RC-IGBT structure but does not directly participate in the conduction, and it is usually unable to form a conductive channel. The virtual gate 122 is in contact with the emitter metal (not shown), that is, the virtual gate 122 is short-circuited with the emitter region 150 (the emitter metal is in contact with the emitter region 150 to lead out the emitter region 150). By short-circuiting the virtual gate 122 with the emitter region, the virtual gate 122 can be made to have the same properties as the emitter region 150 and be negatively charged. Some holes can be attracted to transfer to the virtual gate 122, thereby reducing the number of holes flowing under the emitter region 150, that is, reducing the number of holes flowing in the channel, reducing the risk of latch-up effect under high current conditions, and can also reduce the feedback capacitance of the RC-IGBT (that is, the gate-collector capacitance), thereby reducing switching losses. Exemplarily, the virtual gate 122 can also be called a virtual cell narrow groove gate (dummy gate).

[0064] The second conductive type body region 130 (also referred to as the base region) is disposed in the IGBT region and the FRD region, and the body region 130 is disposed on the side of the drift region 110 facing the second surface 102 and between adjacent trench gates. Exemplarily, the body region 130 is located between the active gate 121 and the dummy gate 122, and between adjacent dummy gates 122.

[0065] The emitter region 150 of the first conductivity type is disposed outside the active gate 121 (on both sides of the active gate 121 along the second direction) and on the side of the body region 130 facing the second surface 102, and the side of the emitter region 150 away from the body region 130 constitutes a portion of the second surface 102. The doping concentration of the emitter region 150 of the first conductivity type is higher than the doping concentration of the drift region 110.

[0066] The first contact region 161 of the second conductivity type is arranged outside the active gate 121 and on the side of the body region 130 facing the second surface 102, and the side of the emitter region 150 away from the body region 130 constitutes part of the second surface 102. The doping concentration of the first contact region 161 is higher than the doping concentration of the body region 130. By simultaneously arranging the emitter region 150 of the first conductivity type and the first contact region 161 of the second conductivity type, the current output capacity of the RC-IGBT is effectively improved. Exemplarily, the number of the first contact regions 161 located on one side of the active gate 121 is at least two, and the at least two first contact regions 161 are arranged at intervals along the third direction, and the third direction is perpendicular to the first direction and the second direction. Exemplarily, the emitter region 150 and the first contact region 161 are both heavily doped regions.

[0067] The isolation region 140 of the second conductivity type is arranged in the transition region and between adjacent virtual gates 122, and the isolation region 140 is arranged on the side of the drift region 110 facing the second surface 102, and the doping concentration of the isolation region 140 is greater than the doping concentration of the body region. The transition region is arranged between the IGBT region and the FRD region, and the isolation region 140 arranged in the transition region plays the role of electric field cutoff, which can reduce the influence between the processes of the IGBT region and the FRD region, and thus can better separately regulate the performance of the IGBT region and the FRD region. For example, when an ion implantation process of changing the doping concentration is performed in the IGBT region (for example, forming a first contact region 161 with a doping concentration greater than that of the body region 130 in the IGBT region), the isolation region 140 plays the role of electric field cutoff, so that the ion implantation dose has almost no effect on the FRD region. Similarly, when an ion implantation process of changing the doping concentration is performed in the FRD region, it has almost no effect on the IGBT region, so that the doping concentration in the IGBT region and the FRD region can be separately regulated, and the doping concentration will affect the conduction loss and switching loss, thereby better separately regulating the conduction loss and switching loss of the IGBT region and the FRD region. Exemplarily, the isolation region 140 is a heavily doped region. Taking the second conductivity type as P type as an example, the isolation region 140 is a P+ doped region.

[0068] like Figure 2 As shown, the side of the isolation region 140 away from the drift region 110 constitutes a portion of the second surface 102; or Fig. 1I As shown, a body region 130 is further disposed on the side of the isolation region 140 facing the second surface 102 , and a side of the body region 130 away from the isolation region 140 constitutes a portion of the second surface. The isolation region 140 is disposed between the body region 130 and the drift region 110 .

[0069] Furthermore, if Fig. 1I and Figure 2As shown, the RC-IGBT structure further includes a second contact region 162 of the second conductivity type and a third contact region 163 of the first conductivity type, the second contact region 162 and the third contact region 163 are arranged in the FRD region and between adjacent virtual gates 122, and the second contact region 162 and the third contact region 163 are arranged on the side of the body region 130 facing the second surface 102, and the side of the second contact region 162 and the third contact region 163 away from the body region 130 constitutes part of the second surface 102, wherein the doping concentration of the second contact region 162 is greater than the doping concentration of the body region 130, and the doping concentration of the third contact region 163 is less than the doping concentration of the emitter region 150. The second contact region 162 can enhance the current output capability. Exemplarily, the second contact region 162 is a heavily doped region.

[0070] When the FRD region in the RC-IGBT is forward-conducted, the second contact region 162 will inject holes into the drift region 110 of the FRD region; when the RC-IGBT is turned on (IGBT region is forward-conducted), the FRD region will perform reverse recovery. At this time, since the holes in the drift region 110 need to be extracted, a large reverse recovery current is generated, thereby increasing the switching loss. The third contact region 163 provided in the present application will not inject holes into the drift region 110 when the FRD region is forward-conducted, and the third contact region 163 can provide free electrons to recombine the holes in the second contact region 162, so as to reduce the amount of holes injected into the drift region 110 by the second contact region 162 when the FRD region is forward-conducted, thereby reducing the amount of holes that the FRD region needs to extract during reverse recovery, thereby reducing the switching loss. Exemplarily, the third contact region 163 is a lightly doped region. Exemplarily, by adjusting the proportion of the third contact region 163 , the balance between the forward conduction voltage and the reverse recovery current of the FRD region can be optimized, thereby adjusting the conduction loss and switching loss of the RC-IGBT.

[0071] The number of the third contact regions 163 between adjacent dummy gates 122 is at least two, and the at least two third contact regions 163 are arranged at intervals along the third direction.

[0072] In some embodiments, a first gate trench extending from the second surface 102 to the drift region 110 is formed in the substrate, and an active gate 121 is disposed in the first gate trench. The active gate 121 includes a first gate dielectric layer located on the inner surface of the first gate trench and a first polysilicon gate filling the first gate trench. Exemplarily, the first gate dielectric layer may be a silicon dioxide layer.

[0073] In some embodiments, a second gate trench extending from the second surface 102 to the drift region 110 is formed in the substrate, and a dummy gate 122 is disposed in the second gate trench, and the dummy gate 122 includes a second gate dielectric layer located on the inner surface of the second gate trench and a second polysilicon gate filling the second gate trench. Exemplarily, the second gate dielectric layer may be a silicon dioxide layer.

[0074] In some embodiments, the second polysilicon gate in the virtual gate 122 may be a floating gate, that is, the second polysilicon gate is a gate that is not directly electrically connected to an external circuit. It is surrounded by an insulating layer and is in a "floating" state, and is not directly connected to a fixed potential point such as a power supply or ground.

[0075] Furthermore, if Fig. 1I and Figure 2 As shown, the RC-IGBT structure further includes a collector region 180 of the second conductivity type, which is arranged in the IGBT region and the transition region and on the side of the drift region 110 facing the first surface 101 , and the side of the collector region 180 away from the drift region 110 constitutes a portion of the first surface 101 .

[0076] Furthermore, if Fig. 1I and Figure 2 As shown, the RC-IGBT structure also includes an injection region 190 of the first conductivity type, which is arranged in the FRD region and parallel to the collector region 180 on the side of the drift region 110 facing the first surface 101, and the side of the injection region 190 away from the drift region 110 constitutes a portion of the first surface 101.

[0077] Furthermore, if Fig. 1I and Figure 2 As shown, the RC-IGBT structure also includes a field stop region 170 of the first conductivity type, and the field stop region 170 is arranged between the collector region 180 and the drift region 110, and between the injection region 190 and the drift region 110. The doping concentration of the field stop region 170 is higher than the doping concentration of the drift region 110. The main function of the field stop region 170 is to terminate the electric field when the RC-IGBT is turned off, to prevent the electric field from penetrating into the collector region 180, thereby improving the withstand voltage capability of the device. When a high voltage is applied, the field stop region 170 can withstand a part of the electric field, so that the electric field gradually weakens before reaching the collector region 180, avoiding the breakdown of the collector region 180. The field stop region 170 can also reduce the duration and amplitude of the tail current by adjusting the carrier distribution and extraction speed. The reduction of the tail current helps to reduce the turn-off loss.

[0078] In the RC-IGBT structure of the embodiment of the present application, the isolation region of the second conductivity type plays the role of electric field cutoff, which can reduce the influence between the processes of the IGBT region and the FRD region, thereby being able to better separately regulate the performance of the IGBT region and the FRD region. Exemplarily, it also includes a third contact region of the first conductivity type, which can reduce the amount of holes injected into the drift region by the second contact region when the FRD region is forward-conducted, thereby reducing the reverse recovery current and thus reducing the switching loss.

[0079] The present application also provides a method for manufacturing an RC-IGBT structure. The method is used to manufacture the RC-IGBT structure described above. Figure 1A-1I , Figure 2 as well as Figure 3 A method for manufacturing an RC-IGBT structure according to an embodiment of the present application is exemplified.

[0080] First, execute step S1, such as Figure 1A As shown, a substrate 100 is provided, the substrate 100 has a first surface 101 and a second surface 102 which are opposite to each other in a first direction, a drift region 110 of a first conductivity type is formed between the first surface 101 and the second surface 102 of the substrate 100, and the substrate 100 includes an IGBT region, a transition region and an FRD region which are arranged in sequence along a second direction, and the second direction is perpendicular to the first direction.

[0081] Next, execute step S2, such as Figure 1A As shown, a trench gate is formed extending from the second surface 102 to the drift region 110 , the trench gate includes an active gate 121 and a dummy gate 122 , the active gate 121 is disposed in the IGBT region and the dummy gate 122 is spaced apart from the active gate 121 along the second direction.

[0082] Next, execute step S3, such as Figure 1B As shown, a body region 130 of the second conductivity type is formed in the IGBT region and the FRD region, and the body region 130 is disposed on the side of the drift region 110 facing the second surface 102 and between adjacent trench gates. Exemplarily, the body region 130 is formed by an ion implantation process.

[0083] Next, execute step S4, such as Figure 1C , forming an isolation region 140 of the second conductivity type, the isolation region 140 is arranged in the transition region and between adjacent dummy gates 122, and the isolation region 140 is arranged on the side of the drift region 110 facing the second surface 102, and the doping concentration of the isolation region 140 is greater than the doping concentration of the body region. Exemplarily, the isolation region 140 is formed by an ion implantation process.

[0084] The transition region is arranged between the IGBT region and the FRD region, and the isolation region 140 arranged in the transition region plays the role of electric field cutoff, which can reduce the influence between the processes of the IGBT region and the FRD region, and thus can better separately regulate the performance of the IGBT region and the FRD region. For example, when an ion implantation process of changing the doping concentration is performed in the IGBT region (for example, forming a first contact region 161 with a doping concentration greater than the doping concentration of the body region 130 in the IGBT region), the isolation region 140 plays the role of electric field cutoff, so that the ion implantation dose has almost no influence on the FRD region. Similarly, when an ion implantation process of changing the doping concentration is performed in the FRD region, it has almost no influence on the IGBT region, so that the doping concentration in the IGBT region and the FRD region can be separately regulated, and the doping concentration will affect the conduction loss and the switching loss, thereby better separately regulating the conduction loss and the switching loss of the IGBT region and the FRD region.

[0085] In one example, if Figure 2 As shown, the side of the isolation region 140 away from the drift region 110 constitutes a portion of the second surface 102; or Figure 1B and 1C As shown, a body region 130 of the second conductivity type is formed in the IGBT region and the FRD region, and a body region 130 is also formed in the transition region. An isolation region 140 is disposed between the body region 130 and the drift region 110 .

[0086] Then, execute step S5, such as Figure 1D and Figure 1E As shown, an emitter region 150 of a first conductivity type and a first contact region 161 of a second conductivity type are formed, the emitter region 150 and the first contact region 161 are arranged outside the active gate 121 and on the side of the body region 130 facing the second surface 102, and the side of the emitter region 150 and the first contact region 161 away from the body region 130 constitutes a part of the second surface 102. Specifically, as Figure 1D As shown, an emitter region 150 of the first conductivity type is first formed; Figure 1E As shown, a first contact region 161 of the second conductivity type is formed. Exemplarily, the emitter region 150 and the first contact region 161 are formed by an ion implantation process.

[0087] Furthermore, if Figure 1F and Figure 1GAs shown, after forming the emitter region 150 and the first contact region 161, the step of forming a second contact region 162 of the second conductivity type and a third contact region 163 of the first conductivity type is also included, the second contact region 162 and the third contact region 163 are arranged in the FRD region and between adjacent virtual gates 122, and the second contact region 162 and the third contact region 163 are arranged on the side of the body region 130 facing the second surface 102, and the side of the second contact region 162 and the third contact region 163 away from the body region 130 constitutes a part of the second surface 102, wherein the doping concentration of the second contact region 162 is greater than the doping concentration of the body region 130, and the doping concentration of the third contact region 163 is less than the doping concentration of the emitter region 150. Specifically, as Figure 1F As shown in FIG. 1A , the third contact region 163 is first formed; and then, as shown in FIG. 1G , the second contact region 162 of the second conductivity type is formed. Exemplarily, the second contact region 162 and the third contact region 163 are formed by an ion implantation process.

[0088] When the FRD region in the RC-IGBT is forward-conducted, the second contact region 162 will inject holes into the drift region 110 of the FRD region; when the RC-IGBT is turned on (IGBT region is forward-conducted), the FRD region will perform reverse recovery. At this time, since the holes in the drift region 110 need to be extracted, a large reverse recovery current is generated, thereby increasing the switching loss. The third contact region 163 provided in the present application will not inject holes into the drift region 110 when the FRD region is forward-conducted, and the third contact region 163 can provide free electrons to recombine the holes in the second contact region 162, so as to reduce the amount of holes injected into the drift region 110 by the second contact region 162 when the FRD region is forward-conducted, thereby reducing the amount of holes that the FRD region needs to extract during reverse recovery, thereby reducing the switching loss. Exemplarily, the third contact region 163 is a lightly doped region. Exemplarily, by adjusting the proportion of the third contact region 163 , the balance between the forward conduction voltage and the reverse recovery current of the FRD region can be optimized, thereby adjusting the conduction loss and switching loss of the RC-IGBT.

[0089] Furthermore, if Figure 1H and Fig. 1IAs shown, it also includes the steps of forming a field stop region 170 of the first conductivity type, a collector region 180 of the second conductivity type, and an injection region 190 of the first conductivity type. The collector region 180 is arranged in the IGBT region and the transition region and is arranged on the side of the drift region 110 facing the first surface 101, and the side of the collector region 180 away from the drift region 110 constitutes a part of the first surface 101; the injection region 190 is arranged in the FRD region and is arranged in parallel with the collector region 180 on the side of the drift region 110 facing the first surface 101, and the side of the injection region 190 away from the drift region 110 constitutes a part of the first surface 101; the field stop region 170 is arranged between the collector region 180 and the drift region 110, and between the injection region 190 and the drift region 110. Specifically, first Figure 1H As shown, a field stop region 170 of the first conductivity type is formed; Fig. 1I As shown, a collector region 180 of the second conductivity type and an implantation region 190 of the first conductivity type are formed. Exemplarily, the field stop region 170, the collector region 180 and the implantation region 190 are formed by an ion implantation process.

[0090] In the manufacturing method of the RC-IGBT structure of the embodiment of the present application, the isolation region of the second conductivity type plays the role of electric field cutoff, which can reduce the influence between the processes of the IGBT region and the FRD region, and thus can better separate and regulate the performance of the IGBT region and the FRD region. Exemplarily, a third contact region of the first conductivity type is also formed, and the third contact region can reduce the amount of holes injected into the drift region by the second contact region when the FRD region is forward-conducted, thereby reducing the reverse recovery current and thus reducing the switching loss.

[0091] The present application also provides a semiconductor device in an embodiment, which includes the RC-IGBT structure as described above, wherein the semiconductor device may be a power semiconductor device.

[0092] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0093] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0094] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0095] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0096] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0097] The above is only a specific implementation method or description of a specific implementation method of the present application, and the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An RC-IGBT structure, characterized in that: include: A substrate, the substrate having a first surface and a second surface that are separated from each other in a first direction, and the substrate comprising an IGBT region, a transition region, and an FRD region arranged in sequence along a second direction, wherein the second direction is perpendicular to the first direction; A drift region of a first conductivity type, disposed between the first surface and the second surface; A trench gate extending from the second surface to the drift region, comprising an active gate and a dummy gate, wherein the active gate is arranged in the IGBT region and the dummy gate and the active gate are spaced apart from each other along the second direction; A body region of a second conductivity type, disposed in the IGBT region and the FRD region, the body region being disposed on a side of the drift region facing the second surface and between adjacent trench gates; An emitter region of a first conductivity type and a first contact region of a second conductivity type are arranged outside the active gate and on a side of the body region facing the second surface, and a side of the emitter region and the first contact region away from the body region constitute part of the second surface; An isolation region of the second conductivity type is arranged in the transition region and between adjacent virtual gates, and the isolation region is arranged on a side of the drift region facing the second surface, and the doping concentration of the isolation region is greater than the doping concentration of the body region.

2. The RC-IGBT structure according to claim 1, characterized in that: A side of the isolation region away from the drift region constitutes part of the second surface; or, The body region is further disposed on a side of the isolation region facing the second surface, and a side of the body region away from the isolation region constitutes a portion of the second surface.

3. The RC-IGBT structure according to claim 1 or 2, characterized in that: It also includes a second contact region of the second conductivity type and a third contact region of the first conductivity type, wherein the second contact region and the third contact region are arranged in the FRD region and between adjacent virtual gates, and the second contact region and the third contact region are arranged on the side of the body region facing the second surface, and the side of the second contact region and the third contact region away from the body region constitute part of the second surface, wherein the doping concentration of the second contact region is greater than the doping concentration of the body region, and the doping concentration of the third contact region is less than the doping concentration of the emitter region.

4. The RC-IGBT structure according to claim 3, characterized in that: The number of the third contact regions between adjacent dummy gates is at least two, and at least two third contact regions are arranged at intervals along a third direction, and the third direction is perpendicular to the first direction and the second direction.

5. The RC-IGBT structure according to claim 3 or 4, characterized in that: The third contact region is a lightly doped region.

6. The RC-IGBT structure according to any one of claims 1 to 5, characterized in that: The active gate is disposed in a first gate trench, the first gate trench extends from the second surface to the drift region, and the active gate comprises a first gate dielectric layer located on an inner surface of the first gate trench and a first polysilicon gate filling the first gate trench; The virtual gate is arranged in a second gate trench, the second gate trench extends from the second surface to the drift region, and the virtual gate includes a second gate dielectric layer located on the inner surface of the second gate trench and a second polysilicon gate filling the second gate trench.

7. The RC-IGBT structure according to any one of claims 1 to 6, characterized in that: Also includes: A collector region of a second conductivity type is arranged in the IGBT region and the transition region and on a side of the drift region facing the first surface, and a side of the collector region away from the drift region constitutes a part of the first surface; An injection region of a first conductivity type is disposed in the FRD region and is arranged in parallel with the collector region on a side of the drift region facing the first surface, and a side of the injection region away from the drift region constitutes a part of the first surface; A field stop region of a first conductivity type is disposed between the collector region and the drift region, and between the injection region and the drift region.

8. A method for manufacturing an RC-IGBT structure, characterized in that: include: Providing a substrate, the substrate having a first surface and a second surface which are separated from each other in a first direction, a drift region of a first conductivity type being formed between the first surface and the second surface of the substrate, and the substrate comprising an IGBT region, a transition region and an FRD region which are sequentially arranged along a second direction, the second direction being perpendicular to the first direction; forming a trench gate extending from the second surface to the drift region, the trench gate comprising an active gate and a dummy gate, the active gate being arranged in the IGBT region and the dummy gate being spaced apart from the active gate along the second direction; forming a body region of a second conductivity type in the IGBT region and the FRD region, wherein the body region is disposed on a side of the drift region facing the second surface and between adjacent trench gates; forming an isolation region of a second conductivity type, wherein the isolation region is disposed in the transition region and between adjacent virtual gates, and the isolation region is disposed on a side of the drift region facing the second surface, and the doping concentration of the isolation region is greater than the doping concentration of the body region; An emitter region of a first conductivity type and a first contact region of a second conductivity type are formed, wherein the emitter region and the first contact region are arranged outside the active gate and on a side of the body region facing the second surface, and a side of the emitter region and the first contact region away from the body region constitute part of the second surface.

9. The manufacturing method according to claim 8, characterized in that: After forming the emitter region and the first contact region, the step of forming a second contact region of the second conductivity type and a third contact region of the first conductivity type is also included, the second contact region and the third contact region are arranged in the FRD region and between adjacent virtual gates, and the second contact region and the third contact region are arranged on the side of the body region facing the second surface, and the side of the second contact region and the third contact region away from the body region constitute part of the second surface, wherein the doping concentration of the second contact region is greater than the doping concentration of the body region, and the doping concentration of the third contact region is less than the doping concentration of the emitter region.

10. A semiconductor device, characterized in that: The invention comprises the RC-IGBT structure according to any one of claims 1 to 7.

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