阅读说明：本技术 绝缘栅双极型晶体管 (Insulated gate bipolar transistor ) 是由 张龙 马杰 顾炎 张森 祝靖 龚金丽 孙伟锋 时龙兴 于 2019-11-04 设计创作，主要内容包括：本发明涉及一种绝缘栅双极型晶体管,包括设于所述漂移区上的阳极第一导电类型区,所述阳极第一导电类型区包括第一区和第二区,所述阳极第二导电类型区包括第三区和第四区,所述第一区的掺杂浓度小于所述第二区,所述第三区的掺杂浓度小于所述第四区,所述第三区设于所述第四区和所述体区之间,所述第一区设于所述第四区下方,所述第二区设于所述第三区下方、且位于所述第一区和所述体区之间。本发明能够在线性电流区域提高注入效率,获得更低的导通压降；并且在饱和电流区域降低饱和电流,获得更大的安全工作区。(The invention relates to an insulated gate bipolar transistor which comprises an anode first conduction type region arranged on a drift region, wherein the anode first conduction type region comprises a first region and a second region, the anode second conduction type region comprises a third region and a fourth region, the doping concentration of the first region is smaller than that of the second region, the doping concentration of the third region is smaller than that of the fourth region, the third region is arranged between the fourth region and a body region, the first region is arranged below the fourth region, and the second region is arranged below the third region and between the first region and the body region. The invention can improve the injection efficiency in the linear current region and obtain lower conduction voltage drop; and the saturation current is reduced in a saturation current area, so that a larger safe working area is obtained.)

1. An insulated gate bipolar transistor comprises a drift region of a first conduction type, a body region of a second conduction type on the drift region, a cathode first conduction type region and a cathode second conduction type region in the body region, an anode second conduction type region on the drift region, wherein the first conduction type and the second conduction type are opposite conduction types; the drift region is characterized by further comprising an anode first conduction type region arranged on the drift region, wherein the anode first conduction type region comprises a first region and a second region, the anode second conduction type region comprises a third region and a fourth region, the doping concentration of the first region is smaller than that of the second region, the doping concentration of the third region is smaller than that of the fourth region, the third region is arranged between the fourth region and the body region, the first region is arranged below the fourth region, and the second region is arranged below the third region and between the first region and the body region.

2. The igbt of claim 1 further comprising a substrate of the second conductivity type and a buried oxide layer on the substrate, the drift region being disposed on the buried oxide layer.

3. The igbt of claim 1 further comprising a field oxide layer disposed between the body region and the anodic second conductivity type region.

4. The igbt of claim 1 wherein the third region is a smaller distance from the body region than the fourth region.

5. The igbt of claim 1 wherein the second region is a smaller distance from the body region than the first region.

6. The igbt of claim 1 wherein the body region has a doping concentration that is an order of magnitude lower than the doping concentration of the cathode second conductivity type region.

7. The insulated gate bipolar transistor according to any of claims 1 to 6, wherein said first conductivity type is N-type and said second conductivity type is P-type.

8. The igbt of claim 7 further comprising a buffer layer of the first conductivity type, the anodic first conductivity type region and the anodic second conductivity type region being disposed within the buffer layer.

9. The igbt of claim 8, wherein the buffer layer has a doping concentration that is an order of magnitude lower than the doping concentration of the second region and an order of magnitude higher than the doping concentration of the first region.

10. The igbt of claim 8 or 9, wherein the igbt is equivalent to having a first transistor and a second transistor;

the collector of the first triode comprises the body region, the base comprises the drift region, the buffer layer and the first region, and the emitter comprises the fourth region;

the collector of the second triode comprises the body region, the base comprises the drift region, the buffer layer and the second region, and the emitter comprises the third region.

Technical Field

The invention relates to the field of semiconductor manufacturing, in particular to an insulated gate bipolar transistor.

Background

For a conventional Insulated Gate Bipolar Transistor (IGBT), if the device wants to obtain a lower on-state voltage drop Von, the injection efficiency of carriers needs to be enhanced, but this reduces the Safe Operating Area (SOA), and at the same time, the increase of carrier concentration causes the switching speed of the device switch to be reduced, and a tail current is generated, which further increases the turn-off loss.

Disclosure of Invention

In view of the above, there is a need to provide an insulated gate bipolar transistor with a low turn-on voltage drop and a large safe operating area.

An insulated gate bipolar transistor comprises a drift region of a first conduction type, a body region of a second conduction type on the drift region, a cathode first conduction type region and a cathode second conduction type region in the body region, an anode second conduction type region on the drift region, wherein the first conduction type and the second conduction type are opposite conduction types; still including locating the first conductivity type area of positive pole on the drift region, the first conductivity type area of positive pole includes first district and second area, positive pole second conductivity type area includes third district and fourth district, the doping concentration in first district is less than the second district, the doping concentration in third district is less than the fourth district, the third district is located the fourth district with between the somatic region, the first district is located the fourth district below, the second district is located the third district below, and be located the first district with between the somatic region.

In one embodiment, the semiconductor device further comprises a substrate of the second conduction type and a buried oxide layer on the substrate, wherein the drift region is arranged on the buried oxide layer.

In one embodiment, the field oxide layer is disposed between the body region and the anode second conductivity type region.

In one embodiment, the third region is a smaller distance from the body region than the fourth region.

In one embodiment, the second region is located at a distance from the body region smaller than the first region.

In one embodiment, the doping concentration of the body region is an order of magnitude lower than the doping concentration of the cathode second conductivity type region.

In one embodiment, the first conductivity type is N-type and the second conductivity type is P-type.

In one embodiment, the device further comprises a buffer layer of the first conductivity type, and the anode first conductivity type region and the anode second conductivity type region are arranged in the buffer layer.

In one embodiment, the doping concentration of the buffer layer is one order of magnitude lower than the doping concentration of the second region and one order of magnitude higher than the doping concentration of the first region.

In one embodiment, the insulated gate bipolar transistor is equivalent to having a first transistor and a second transistor; the collector of the first triode comprises the body region, the base comprises the drift region, the buffer layer and the first region, and the emitter comprises the fourth region; the collector of the second triode comprises the body region, the base comprises the drift region, the buffer layer and the second region, and the emitter comprises the third region.

In the insulated gate bipolar transistor, the anode second conductive type region is divided into a lightly doped third region and a heavily doped fourth region, and the anode first conductive type region is arranged below the anode second conductive type region and comprises the lightly doped first region below the fourth region and the heavily doped second region below the third region. Due to the addition of the additional first region, when the anode injects the second conductive type carriers from the fourth region, in order to achieve charge balance, the second conductive type carrier injection efficiency of the fourth region is increased; since the additional second region is newly added and the third region is provided, since the doping concentration of the second region is higher than that of the first region, the second conductive type carrier injection efficiency of the third region will be lower than that of the fourth region. The above-mentioned insulated gate bipolar transistor is equivalent to having two triodes: the fourth region, the first region/drift region and the body region form a first triode, and the third region, the second region/drift region and the body region form a second triode. (1) When the anode voltage is small (the device operates in the linear current region), the first conductivity type carrier current acts as the base driving current of the two triodes, causing the second conductivity type carriers to be injected from the third and fourth regions of the anode into the first and second regions, the injected second conductivity type carriers thereby forming the emitter currents of the two triodes, and since the first region is of the lightly doped first conductivity type, the emitter region is required to contribute more carriers of the first conductivity type. When the first conductivity type carrier current flows to the collector, the collector region attracts more of the second conductivity type carrier injection. Since the second conductive type carrier injection efficiency of the second transistor is lower than that of the first transistor, the anode current mainly flows through the first transistor. The second conduction type carrier concentration of the first region is lower, and the second conduction type carrier injection efficiency of the fourth region is higher than that of the traditional structure, so that the conduction voltage of the structure is lower. (2) With the increase of the anode current voltage (the device works in a saturation current area), the hole injection efficiency of the first triode is reduced, more current flows through the second triode, and the second conduction type carrier injection efficiency of the second triode is lower, so that the saturation current of the device is suppressed. In summary, the insulated gate bipolar transistor can improve the second conductivity type carrier injection efficiency in the linear current region, and obtain a lower conduction voltage drop; and the saturation current is reduced in a saturation current area, so that a larger safe working area is obtained.

Drawings

For a better understanding of the description and/or illustration of embodiments and/or examples of those inventions disclosed herein, reference may be made to one or more of the drawings. The additional details or examples used to describe the figures should not be considered as limiting the scope of any of the disclosed inventions, the presently described embodiments and/or examples, and the presently understood best modes of these inventions.

FIG. 1 is a schematic cross-sectional view of an IGBT according to an embodiment;

fig. 2 is an equivalent circuit diagram of the IGBT shown in fig. 1;

FIG. 3 shows the structure of the present invention and the conventional structure I_CE-V_CE(collector-emitter current-collector-emitter voltage) comparison plot.

Detailed Description

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it can be directly on, adjacent to, connected or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used 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 only 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 invention.

Spatial relational terms such as "under," "below," "under," "above," "over," and the like may be used herein for convenience in describing the relationship of one element or feature to another element or feature 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 the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "under" and "under" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. 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 the associated listed items.

Embodiments of the invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region shown as a rectangle will typically have rounded or curved features and/or implant concentration gradients at its edges rather than a binary change from implanted to non-implanted region. Also, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation is performed. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention.

As used herein, the term semiconductor is used in the art to distinguish between P-type and N-type impurities, and for example, P + type represents P-type with heavy doping concentration, P-type represents P-type with medium doping concentration, P-type represents P-type with light doping concentration, N + type represents N-type with heavy doping concentration, N-type represents N-type with medium doping concentration, and N-type represents N-type with light doping concentration.

To achieve low turn-on voltage drop and large safe operating area for IGBTs, the anodic injection of minority carriers needs to be enhanced in the on-state, reduced or ideally eliminated at turn-off or short-circuit switching. This has been achieved in DB-IGBTs (Dynamic N-Buffer Insulated Gate Bipolar Transistor) and DT-IGBTs (Double Trench Insulated Gate Bipolar Transistor). However, both of these devices require two gates, and the time phases of the switching signals of the two gates need to be precisely controlled during the turn-off process and the short-circuit switching process to obtain desired performance, which complicates the driving circuit.

Fig. 1 is a schematic cross-sectional structure diagram of an igbt according to an embodiment, including a drift region 3, a body region 4, a cathode first conductive type region 6, a cathode second conductive type region 5, an anode first conductive type region (including a first region 17 and a second region 16), and an anode second conductive type region (including a third region 15 and a fourth region 8).

A body region 4 of the second conductivity type is provided on the drift region 3 of the first conductivity type, a cathode first conductivity type region 6 and a cathode second conductivity type region 5 are provided in the body region 4, and an anode first conductivity type region and an anode second conductivity type region are provided on the drift region 3. In the embodiment shown in fig. 1, the first conductivity type is N-type and the second conductivity type is P-type; in another embodiment, the first conductivity type may be P-type and the second conductivity type may be N-type.

The doping concentration of the first region 17 is less than that of the second region 16, the doping concentration of the third region 15 is less than that of the fourth region 8, the third region 15 is arranged between the fourth region 8 and the body region 4, the first region 17 is arranged below the fourth region 8, and the second region 16 is arranged below the third region 15 and is positioned between the first region 17 and the body region 4. In the embodiment shown in fig. 1, the third region 15 is at a smaller distance from the body region 4 than the fourth region 8 is from the body region 4, and the second region 16 is at a smaller distance from the body region than the first region 17 is from the body region 4.

In the embodiment shown in fig. 1, the IGBT further comprises a buffer layer 7 of the first conductivity type, with an anode first conductivity type region and an anode second conductivity type region being provided within the buffer layer 7. In one embodiment, the doping concentration of the buffer layer 7 is less than the doping concentration of the second region 16 and greater than the doping concentration of the first region 17; further, the doping concentration of the buffer layer 7 is an order of magnitude lower than the doping concentration of the second region 16 and an order of magnitude higher than the doping concentration of the first region 17. In the embodiment shown in fig. 1, the buffer layer 7 is an N-type buffer layer.

In the embodiment shown in fig. 1, the doping concentration of the body region 4 is lower than the doping concentration of the cathode second conductivity type region 5; further, the doping concentration of the body region 4 is an order of magnitude lower than the doping concentration of the cathode second conductivity type region 5.

In the embodiment shown in fig. 1, the first region 17 is an N-region, the second region 16 is an N + region, the third region 15 is a P-region, the fourth region 8 is a P + region, the body region 4 is a P-type body region, the cathode first conductivity type region 6 is an N + region, and the cathode second conductivity type region 5 is a P + region.

Fig. 2 is an equivalent circuit diagram of the IGBT shown in fig. 1. An insulated gate bipolar transistor is equivalent to having a first transistor PNP1 and a second transistor PNP 2. The collector of the first transistor PNP1 includes a body region 4, the base includes a drift region 3, a buffer layer 7, and a first region 17, and the emitter includes a fourth region 8. The collector of the second triode PNP2 includes a body region 4, the base includes a drift region 3, a buffer layer 7, and a second region 16, and the emitter includes a third region 15.

In the insulated gate bipolar transistor, the anode second conductive type region is divided into the lightly doped third region 15 and the heavily doped fourth region 8, and the anode first conductive type region is arranged below the anode second conductive type region and comprises the lightly doped first region 17 below the fourth region 8 and the heavily doped second region 16 below the third region 15. Due to the addition of the additional first region 17, when holes are injected from the fourth region 8 by the anode, the hole injection efficiency of the fourth region 8 is increased in order to achieve charge balance; since an additional second region 16 is added and the third region 15 is provided, and the doping concentration of the second region 16 is higher than that of the first region 17, the hole injection efficiency of the third region 15 will be lower than that of the fourth region 8. The above-mentioned insulated gate bipolar transistor is equivalent to having two triodes: the fourth region 8, the first region 17/the buffer layer 7/the drift region 3, and the body region 4 form a first transistor PNP1, and the third region 15, the second region 16/the buffer layer 7/the drift region 3, and the body region 4 form a second transistor PNP 2. (1) When the anode voltage is low (the device operates in the linear current region), the electron current acts as the base drive current for the two transistors, causing holes to be injected from the third 15 and fourth 8 regions of the anode into the first 17 and second 16 regions, the injected holes thereby forming the emitter currents for the two transistors. Since the first region 17 is an N-region, the emitter region needs to contribute more electrons. When the electron current flows to the collector, the collector region attracts more hole injection. Since the injection efficiency of the second transistor PNP2 is lower than that of the first transistor PNP1, the anode current mainly flows through the first transistor PNP 1. Since the hole concentration of the first region 17 is low and the hole injection efficiency of the fourth region 8 is higher than that of the conventional structure, the on-voltage of the structure of the present invention is low. (2) As the anode current voltage increases (the device operates in the saturation current region), the hole injection efficiency of the first transistor PNP1 decreases, more current flows through the second transistor PNP2, and the hole injection efficiency of the second transistor PNP2 is lower, so the saturation current of the device is suppressed. As shown in fig. 3, the linear current of the structure of the present invention is larger than that of the conventional structure, and the saturation current is smaller than that of the conventional structure. In summary, the insulated gate bipolar transistor can improve the hole injection efficiency in the linear current region, and obtain a lower conduction voltage drop; and the saturation current is reduced in a saturation current area, so that a larger safe working area is obtained.

In the embodiment shown in fig. 1, the igbt further includes a substrate 1 of the second conductivity type and a buried oxide BOX on the substrate 1, and the drift region 3 is provided on the buried oxide BOX. Specifically, the substrate 1 may be a P-type substrate.

In the embodiment shown in fig. 1, the igbt further comprises a field oxide layer 9 disposed between the body region 4 and the anode second conductivity type region. Specifically, one side of the field oxide layer 9 may extend to the edges of the third region 15 and the second region 16 and cover a portion of the buffer layer 7.

In the embodiment shown in fig. 1, the insulated gate bipolar transistor further comprises a first polysilicon 10 and a second polysilicon 11. The second polysilicon 11 is provided on the field oxide layer 9 and the first polysilicon 10 extends from the field oxide layer 9 towards the cathode first conductivity type region 6. In the embodiment shown in fig. 1, the portion of the first polysilicon 10 outside the field oxide layer 9 is further provided with a dielectric layer (not labeled in fig. 1) below, i.e. the region between the field oxide layer 9 and the cathode first conductivity type region 6 is provided with a dielectric layer on the drift region 3 and the body region 4, and the first polysilicon 10 is provided on the dielectric layer.

In the embodiment shown in fig. 1, the surface of the igbt is further provided with a dielectric layer 14. A first electrode 12a and a second electrode 13a are disposed on the dielectric layer 14, and the first electrode 12a is electrically connected to and leads out the cathode first conductive type region 6 and the cathode second conductive type region 5 through a conductive material (e.g., metal or alloy) filled in the first contact hole 12. The second electrode 13a is electrically connected to and leads out the second polysilicon 11 through a contact hole 13, and is electrically connected to and leads out the third region 15 and the fourth region 8 through another contact hole 13.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.