Manufacturing method of IGBT (Insulated Gate Bipolar Translator) device

Abstract

The invention belongs to the technical field of IGBT (Insulated Gate Bipolar Translator) devices, and particularly discloses a manufacturing method of an IGBT device, which comprises the following steps of: forming a plurality of first grooves in an n-type semiconductor layer; forming an N ion implantation region located on one side of the first groove in the n-type semiconductor layer through inclined ion implantation; forming an n-type charge storage region through vertical ion implantation; forming an n-type source region through inclined ion implantation; forming a first grid electrode and a second groove through a self-alignment process; and forming a second grid electrode in the second groove, and forming p-type body regions located on the two sides of the first groove in the n-type semiconductor layer through vertical ion implantation. According to the invention, the photoetching process times in the manufacturing process of the IGBT device can be reduced, and the manufacturing cost of the IGBT device is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of IGBT devices, and in particular relates to a method for manufacturing an IGBT device. Background Art

[0002] An insulated gate bipolar transistor (IGBT) is a device composed of a MOS transistor and a bipolar transistor. Its input is a MOS transistor and its output is a PNP transistor. It combines the advantages of these two devices, and has the advantages of low driving power and fast switching speed of MOS transistors, as well as low saturation voltage drop and large capacity of bipolar transistors. It has been increasingly widely used in modern power electronics technology, especially in the application of high-frequency and medium-power transistors. In the manufacturing process of IGBT devices in the prior art, a multi-step photolithography process is required, and the high cost of the photolithography process makes it difficult to reduce the manufacturing cost of IGBT devices. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a method for manufacturing an IGBT device to reduce the manufacturing cost of the IGBT device.

[0004] In order to achieve the above-mentioned object of the present invention, the present invention provides a method for manufacturing an IGBT device, comprising:

[0005] forming a first insulating layer on the provided n-type semiconductor layer, etching the first insulating layer and the n-type semiconductor layer, and forming a plurality of first trenches in the n-type semiconductor layer;

[0006] Performing an inclined ion implantation toward one side of the first trench to form an N ion implantation region located at one side of the first trench in the n-type semiconductor layer;

[0007] Performing vertical ion implantation to form an n-type charge storage region located below the first trench in the n-type semiconductor layer;

[0008] Oxidation is performed on the surface of the first trench to form a gate oxide layer, and then a first conductive layer is formed and etched back, wherein the upper surface of the first conductive layer remaining after the etching back is lower than the upper surface of the n-type semiconductor layer;

[0009] Performing inclined ion implantation on both sides of the first trench to form n-type source regions located on both sides of the first trench in the n-type semiconductor layer;

[0010] Forming a second insulating layer and etching back, forming sidewalls on the first conductive layer on both sides of the first trench respectively, etching the first conductive layer using the first insulating layer and the sidewalls as masks, and forming first gates on both sides of the first trench respectively on the remaining first conductive layer after etching;

[0011] Using the first insulating layer and the sidewall as masks, etching the gate oxide layer and the n-type semiconductor layer to form a second trench in the n-type semiconductor layer;

[0012] A third insulating layer is formed to cover the formed structure, and then a second conductive layer is formed and etched back, and the remaining second conductive layer after etching forms a second gate in the second trench;

[0013] Covering the formed structure to form a fourth insulating layer, and then removing the fourth insulating layer and the third insulating layer on the surface of the first insulating layer;

[0014] The first insulating layer is etched away, and then vertical ion implantation is performed to form p-type body regions located on both sides of the first trench in the n-type semiconductor layer.

[0015] Optionally, the bottom of the second trench is lower than the bottom of the n-type charge storage region.

[0016] Optionally, the material of the first insulating layer is silicon nitride.

[0017] Optionally, materials of the second insulating layer, the third insulating layer and the fourth insulating layer are all silicon oxide.

[0018] Optionally, the fourth insulating layer on the surface of the first insulating layer is removed by chemical mechanical polishing.

[0019] Optionally, the method for manufacturing the IGBT device further includes: forming an interlayer insulating layer, a source metal and a gate metal on the surface of the n-type semiconductor layer.

[0020] Optionally, the method for manufacturing the IGBT device further includes: forming an n-type field stop region and a p-type collector region at the bottom of the n-type semiconductor layer.

[0021] Optionally, the method for manufacturing the IGBT device further includes: forming a collector metal on the bottom surface of the n-type semiconductor layer.

[0022] Optionally, the second gate extends upward into the first trench.

[0023] The manufacturing method of the IGBT device provided by the present invention forms the first groove through a single photolithography process, and no photolithography process is required during the manufacturing process of the N ion implantation region, the n-type source region, the first gate, the second groove, the second gate, and the p-type body region, thereby reducing the number of photolithography processes during the manufacturing process of the IGBT device and effectively reducing the manufacturing cost of the IGBT device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution of the exemplary embodiment of the present invention, the following briefly introduces the drawings required for describing the embodiment.

[0025] Figures 1 to 9 It is a schematic cross-sectional structure diagram of the main structures in the manufacturing process of an embodiment of the method for manufacturing an IGBT device provided by the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be described in detail below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. It should be understood that the terms such as "having", "including" and "comprising" used in the present invention do not indicate the existence or addition of one or more other elements or their combinations. At the same time, in order to clearly illustrate the specific implementation methods of the present invention, the schematic diagrams listed in the drawings of the specification magnify the thickness of the layers and regions described in the present invention, and the listed graphic sizes do not represent the actual sizes.

[0027] Figures 1 to 9 It is a schematic cross-sectional structure diagram of the main structures in the manufacturing process of an embodiment of the method for manufacturing an IGBT device provided by the present invention.

[0028] First, if Figure 1 As shown, a first insulating layer 41 is formed on the provided n-type semiconductor layer 20, and the material of the first insulating layer 41 is generally silicon nitride. The position of the first groove is defined by a photolithography process, and then the first insulating layer 41 and the n-type semiconductor layer 20 are etched to form a plurality of first grooves 51 arranged in sequence in the n-type semiconductor layer 20. The material of the n-type semiconductor layer 20 is generally silicon. The number of the first grooves 51 is determined by the specific device design, and only two first grooves 51 are exemplarily shown in the embodiment of the present invention.

[0029] Next, if Figure 2 As shown, N ions (nitrogen ions) are implanted obliquely toward one side of the first trench 51 to form an N ion implantation region 42 with a high doping concentration located at one side of the first trench 51 in the n-type semiconductor layer 20 .

[0030] Next, if Figure 3As shown, vertical ion implantation is performed to form an n-type charge storage region 22 located below the first trench 51 in the n-type semiconductor layer 20. Optionally, according to the actual manufacturing process, after the n-type charge storage region 22 is diffused, the n-type charge storage regions 22 located below the adjacent first trenches 51 can be connected together, and this structure is no longer shown in the embodiment of the present invention.

[0031] Next, if Figure 4 As shown, a gate oxide layer 23 is formed on the surface of the first trench by thermal oxidation, and then a first conductive layer 24 is formed and etched back. After the etching back, the upper surface of the remaining first conductive layer 24 is lower than the upper surface of the n-type semiconductor layer 20, which can make the subsequent n-type source region easier to form.

[0032] When a gate oxide layer is formed by a thermal oxidation method, N ion doping with a high doping concentration can inhibit the growth of the gate oxide layer on the surface of the n-type semiconductor layer, so that the thickness of the gate oxide layer (23a) at the position where the N ion implantation area is formed is thinner, while the thickness of the gate oxide layer at the position where the N ion implantation area is not formed is thicker, which can make the turn-on voltages of the current channels on both sides of the first groove unequal, that is, the IGBT device has different threshold voltages Vth, thereby reducing the turn-off loss of the IGBT device.

[0033] Next, if Figure 5 As shown, ion implantation is performed obliquely on both sides of the first trench to form n-type source regions 25 located on both sides of the first trench in the n-type semiconductor layer 20. Therefore, the formation of the n-type source region 25 does not require a separate photolithography process.

[0034] Next, if Figure 6 As shown, a second insulating layer is formed and etched back, and sidewalls 26 located on the first conductive layer are formed on both sides of the first trench, and then the first conductive layer is etched using the first insulating layer 41 and the sidewalls 26 as masks, and the remaining first conductive layer after etching forms first gates 27 on both sides of the first trench. The first gate 27 is formed by a self-alignment process, and a separate photolithography process is not required. The material of the second insulating layer is silicon oxide.

[0035] Next, if Figure 7 As shown, the gate oxide layer and the n-type semiconductor layer 20 are etched using the first insulating layer 41 and the sidewall 26 as masks to form a second trench 52 in the n-type semiconductor layer 20. The bottom of the optional second trench 52 can be lower than the bottom of the n-type charge storage region 22, so that the n-type charge storage region 22 is located between adjacent second trenches 52.

[0036] Next, if Figure 8As shown, a third insulating layer 28 is formed to cover the formed structure, and then a second conductive layer is formed and etched back. The remaining second conductive layer after etching forms a second gate 29 in the second trench. Optionally, the second gate 29 extends upward into the first trench. The material of the third insulating layer 28 is silicon oxide.

[0037] Next, if Fig. 9 As shown, the structure formed is covered to form a fourth insulating layer 42, and then the fourth insulating layer and the third insulating layer on the surface of the first insulating layer are removed by chemical mechanical polishing (CMP). Then the first insulating layer is etched away, and then vertical ion implantation is performed to form a p-type body region 21 located on both sides of the first trench in the n-type semiconductor layer 20. The material of the first insulating layer is silicon nitride, and the materials of the second insulating layer, the third insulating layer, and the fourth insulating layer are silicon oxide, so that after the first insulating layer is exposed by the CMP process, the first insulating layer can be directly etched away without the need for an additional photolithography process.

[0038] Finally, an IGBT device can be formed through conventional processes, including, for example: forming an interlayer insulating layer, a source metal, and a gate metal on the surface of the n-type semiconductor layer; forming an n-type field stop region and a p-type collector region at the bottom of the n-type semiconductor layer; and forming a collector metal on the bottom surface of the n-type semiconductor layer. These processes are conventional manufacturing processes in the industry and will not be described in detail in the embodiments of the present invention.

[0039] The above specific implementation methods and examples are specific supports for the technical ideas of the present invention, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or equivalent modifications made on the basis of this technical solution in accordance with the technical ideas proposed by the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for manufacturing an IGBT device, characterized in that: include: forming a first insulating layer on the provided n-type semiconductor layer, etching the first insulating layer and the n-type semiconductor layer, and forming a plurality of first trenches in the n-type semiconductor layer; Performing an inclined ion implantation toward one side of the first trench to form an N ion implantation region located at one side of the first trench in the n-type semiconductor layer; Performing vertical ion implantation to form an n-type charge storage region located below the first trench in the n-type semiconductor layer; Oxidation is performed on the surface of the first trench to form a gate oxide layer, and then a first conductive layer is formed and etched back, wherein the upper surface of the first conductive layer remaining after the etching back is lower than the upper surface of the n-type semiconductor layer; Performing inclined ion implantation on both sides of the first trench to form n-type source regions located on both sides of the first trench in the n-type semiconductor layer; Forming a second insulating layer and etching back, forming sidewalls on the first conductive layer on both sides of the first trench respectively, etching the first conductive layer using the first insulating layer and the sidewalls as masks, and forming first gates on both sides of the first trench respectively on the remaining first conductive layer after etching; Using the first insulating layer and the sidewall as masks, etching the gate oxide layer and the n-type semiconductor layer to form a second trench in the n-type semiconductor layer; A third insulating layer is formed to cover the formed structure, and then a second conductive layer is formed and etched back, and the remaining second conductive layer after etching forms a second gate in the second trench; Covering the formed structure to form a fourth insulating layer, and then removing the fourth insulating layer and the third insulating layer on the surface of the first insulating layer; The first insulating layer is etched away, and then vertical ion implantation is performed to form p-type body regions located on both sides of the first trench in the n-type semiconductor layer.

2. The method for manufacturing an IGBT device according to claim 1, wherein: The bottom of the second trench is lower than the bottom of the n-type charge storage region.

3. The method for manufacturing an IGBT device according to claim 1, wherein: The material of the first insulating layer is silicon nitride.

4. The method for manufacturing an IGBT device according to claim 1, wherein: The second insulating layer, the third insulating layer and the fourth insulating layer are all made of silicon oxide.

5. The method for manufacturing an IGBT device according to claim 1, wherein: The fourth insulating layer on the surface of the first insulating layer is removed by chemical mechanical polishing.

6. The method for manufacturing an IGBT device according to claim 1, wherein: Also includes: An interlayer insulating layer, a source metal and a gate metal are formed on the surface of the n-type semiconductor layer.

7. The method for manufacturing an IGBT device according to claim 1, wherein: Also includes: An n-type field stop region and a p-type collector region are formed at the bottom of the n-type semiconductor layer.

8. The method for manufacturing an IGBT device according to claim 7, wherein: Also includes: A collector metal is formed on the bottom surface of the n-type semiconductor layer.

9. The method for manufacturing an IGBT device according to claim 1, wherein: The second gate extends upward into the first trench.

Images