Three-dimensional hexagonal cell structure, preparation method and device thereof

Abstract

The application discloses a three-dimensional hexagonal cell structure, which comprises a first conductive type epitaxial region, a second conductive type well region in the first conductive type epitaxial region, a first conductive type source region in the second conductive type well region and a second conductive type body region in the first conductive type source region; wherein the second conductive type body region is in a convex shape; and a plurality of convexes with the same width and height are arranged on the first conductive type epitaxial region, the second conductive type well region and the first conductive type source region in the vertical direction of the six sides of the hexagonal cell structure, so as to form a plurality of convex mesa surfaces in each direction and a hexagonal mesa structure intersecting the second conductive type body region on the hexagonal cell structure. The structure makes the device have two channels parallel to the cell surface and perpendicular to the cell surface, thereby improving the channel density, reducing the on-resistance of the channel and improving the current-carrying capacity of the device.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microelectronics technology, and particularly relates to a three-dimensional hexagonal cell structure, a preparation method and a device thereof. BACKGROUND

[0002] In the development process of the power electronics industry, semiconductor technology has played a decisive role. Among them, MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor, metal-oxide semiconductor field effect transistor, for short, metal-oxide semiconductor field effect transistor) and IGBT (Insulated Gate Bipolar Transistor, Insulated Gate Bipolar Transistor) are two typical semiconductor devices that are widely used.

[0003] MOSFET, as a kind of power semiconductor device, can reduce the conversion loss of the converter, improve the power density, reduce the heat dissipation requirement, reduce the system size and complexity, and obviously improve the system performance. In addition, the characteristics of high temperature, high pressure and low loss make MOSFET suitable for power supply, rail transit, motor control, electric vehicle, aerospace and other systems. IGBT is a composite full-controlled voltage drive power semiconductor device composed of BJT (Bipolar Junction Transistor) and MOS (Insulated Gate Field Effect Tube), which has the advantages of high input impedance of MOSFET and low on-voltage of GTR. It is very suitable for application in variable current system such as alternating current motor, frequency converter, switching power supply, lighting circuit, traction drive and other fields with DC voltage of 600V and above.

[0004] However, the common MOSFET or IGBT cell structure at present is mostly a planar cell structure. Due to the limitation of process, this planar cell structure cannot further improve the channel density and reduce the device channel resistance, thereby affecting the current carrying capacity of the device and limiting the application of the device. SUMMARY

[0005] In order to solve the above problems existing in the prior art, the present application provides a three-dimensional hexagonal cell structure, a preparation method and a device thereof. The technical problem to be solved by the present application is solved by the following technical scheme:

[0006] In the first aspect, the present application provides a three-dimensional hexagonal cell structure, comprising: a first conductive type epitaxial region, a second conductive type well region located in the first conductive type epitaxial region, a first conductive type source region located in the second conductive type well region, and a second conductive type body region located in the first conductive type source region; wherein,

[0007] The second type of conductive body region is convex;

[0008] Furthermore, along the vertical directions of the six sides of the hexagonal cell structure, the first conductive type epitaxial region, the second conductive type well region, and the first conductive type source region are all provided with several protrusions of the same width and height, so as to form several protruding mesa in each direction, and at the same time, a hexagonal mesa structure intersecting with the second conductive type body region is formed on the hexagonal cell structure.

[0009] In one embodiment of the invention, the width of each of the raised platforms does not exceed the inner side length of the second conductivity type well region.

[0010] In one embodiment of the present invention, the width of the raised platform is 1-5 μm and the height is 0.1-1 μm.

[0011] In one embodiment of the present invention, the first conductivity type is N-type and the second conductivity type is P-type.

[0012] Secondly, the present invention also provides another three-dimensional hexagonal cell structure, comprising: a first conductivity type epitaxial region, a second conductivity type well region located within the first conductivity type epitaxial region, a first conductivity type source region located within the second conductivity type well region, and a second conductivity type body region located within the first conductivity type source region; wherein...

[0013] Along the vertical direction of the six sides of the hexagonal cell structure, a plurality of grooves with the same width and depth are symmetrically provided on the first conductive type epitaxial region, the second conductive type well region and the first conductive type source region around the second conductive type body region, so as to form a plurality of grooves in each direction, and at the same time, a hexagonal groove structure intersecting the second conductive type body region is formed on the hexagonal cell structure.

[0014] In one embodiment of the invention, the width of each groove does not exceed the inner side length of the second conductivity type well region.

[0015] In one embodiment of the present invention, the width of the groove is 1-5 μm and the depth is 0.1-1 μm.

[0016] Thirdly, the present invention provides a method for preparing a three-dimensional hexagonal cell structure, comprising:

[0017] Prepare an epitaxial region of the first conductivity type;

[0018] An ion implantation process is used to sequentially form a second conductivity type well region, a first conductivity type source region, and a second conductivity type body region on the first conductivity type epitaxial region.

[0019] The obtained sample is etched to form a hexagonal mesa structure or a hexagonal groove structure on the sample surface.

[0020] Fourthly, the present invention provides a MOSFET device comprising any of the three-dimensional hexagonal cell structures described in the above embodiments.

[0021] Fifthly, the present invention provides an IGBT device comprising any of the three-dimensional hexagonal cell structures described in the above embodiments.

[0022] The beneficial effects of this invention are:

[0023] This invention creates a three-dimensional hexagonal cell structure by adding mesa or groove structures to the surface of the cell structure. This results in the device having not only parallel channels parallel to the cell surface but also vertical channels perpendicular to the cell surface, thereby increasing the channel density, reducing the channel resistance, and ultimately improving the device's current carrying capacity.

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a three-dimensional hexagonal cell structure with a set of raised platforms provided in Embodiment 1 of the present invention;

[0026] Figure 2 This is a top view of a three-dimensional hexagonal cell structure with a set of raised platforms provided in Embodiment 1 of the present invention;

[0027] Figure 3 This is a cross-sectional view of a three-dimensional hexagonal cell structure with a set of raised platforms provided in Embodiment 1 of the present invention;

[0028] Figure 4 This is a schematic diagram of a three-dimensional hexagonal cell structure with two sets of raised platforms provided in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of a three-dimensional hexagonal cell structure with a set of grooves provided in Embodiment 2 of the present invention;

[0030] Figure 6 This is a top view of a three-dimensional hexagonal cell structure with a set of grooves provided in Embodiment 2 of the present invention;

[0031] Figure 7 This is a cross-sectional view of a three-dimensional hexagonal cell structure with a set of grooves provided in Embodiment 2 of the present invention;

[0032] Figure 8 This is a schematic diagram of a three-dimensional hexagonal cell structure with two sets of grooves provided in an embodiment of the present invention;

[0033] Figure 9 This is a schematic diagram of the preparation method of the three-dimensional hexagonal cell structure provided in Embodiment 3 of the present invention. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0035] Example 1

[0036] This embodiment provides a three-dimensional hexagonal cell structure with a raised mesa structure, comprising: a first conductivity type epitaxial region 1, a second conductivity type well region 2 located within the first conductivity type epitaxial region 1, a first conductivity type source region 3 located within the second conductivity type well region 2, and a second conductivity type body region 4 located within the first conductivity type source region 3; wherein...

[0037] The second type of conductive body region 4 is convex;

[0038] Furthermore, along the vertical directions of the six sides of the hexagonal cell structure, the first conductive type epitaxial region 1, the second conductive type well region 2, and the first conductive type source region 3 are each provided with a plurality of protrusions of the same width and height, so as to form a plurality of protruding mesa 5a in each direction, and at the same time, a hexagonal mesa structure 6a intersecting with the second conductive type body region 4 is formed on the hexagonal cell structure.

[0039] In this embodiment, the width of each of the raised platforms 5a does not exceed the inner side length of the second conductive type well region 2, so as to ensure that the second conductive type well region 2 has raised platforms in both horizontal and vertical directions, thereby forming vertical and horizontal channels in the second conductive type well region 2.

[0040] Optionally, the width of the raised platform 5a is 1-5 μm and the height is 0.1-1 μm.

[0041] Specifically, this embodiment uses a hexagonal cell structure with a set of raised mesas as an example for detailed explanation. Please refer to [link to relevant documentation]. Figure 1 , Figure 1 This is a schematic diagram of a three-dimensional hexagonal cell structure with a set of raised mesa provided in Embodiment 1 of the present invention; wherein, the width d of the raised mesa 5a is the same as the side length of the second conductive type body region 4.

[0042] In this embodiment, the first conductivity type is N-type and the second conductivity type is P-type. Alternatively, the first conductivity type can be P-type and the second conductivity type N-type. Preferably, in this embodiment, the first conductivity type is N-type and the second conductivity type is P-type.

[0043] Furthermore, the N-type epitaxial region 1 and the P-type well region 2 are lightly doped regions, while the N-type source region 3 and the P-type body region 4 are heavily doped regions. Therefore, the three-dimensional hexagonal cell structure provided in this embodiment includes an N-epitaxial region 1, a P-well region 2, an N+ source region 3, and a P+ body region 4. Please refer to... Figures 2-3 , Figure 2 This is a top view of a three-dimensional hexagonal cell structure with a set of raised platforms provided in Embodiment 1 of the present invention; Figure 3 This is a cross-sectional view of a three-dimensional hexagonal cell structure with a set of raised platforms provided in Embodiment 1 of the present invention.

[0044] Since the hexagonal mesa structure in this embodiment includes a set of raised mesa, the total width of each arm of the hexagonal mesa structure 6a is the same as the width d of a single raised mesa 5a, both of which are equal to the side length of the second conductive type body region 4.

[0045] It should be noted that, in another embodiment of the present invention, the hexagonal platform structure may further include multiple sets of parallel raised platforms. For example, please refer to... Figure 4 , Figure 4 This is a schematic diagram of a three-dimensional hexagonal cell structure with two sets of raised mesa surfaces provided in an embodiment of the present invention. The edges of the two raised mesa surfaces 5a do not exceed the inner side length of the second conductivity type well region 2.

[0046] This embodiment creates a three-dimensional hexagonal cell structure by adding raised mesa structures to the surface of the cell structure. This allows the device to have not only parallel channels parallel to the cell surface but also vertical channels perpendicular to the cell surface. Compared to traditional two-dimensional cell structures where channels are only horizontal and cannot be further increased in width, this embodiment adds vertical channels (the sidewalls of the mesa are the vertical channels) without reducing the horizontal channels by adding mesa structures, thus effectively increasing the total channel width of the entire cell structure. Therefore, the height of the mesa sidewalls determines the width of the vertical channels. Similarly, the introduction of vertical channels effectively increases the cell channel density, reduces the channel on-resistance, and thus improves the device's current-carrying capacity.

[0047] Example 2

[0048] This embodiment provides a three-dimensional hexagonal cell structure with a groove structure, comprising: a first conductivity type epitaxial region 1, a second conductivity type well region 2 located within the first conductivity type epitaxial region 1, a first conductivity type source region 3 located within the second conductivity type well region 2, and a second conductivity type body region 4 located within the first conductivity type source region 3; wherein...

[0049] Along the vertical direction of the six sides of the hexagonal cell structure, the first conductive type epitaxial region 1, the second conductive type well region 2 and the first conductive type source region 3 around the second conductive type body region 4 are symmetrically provided with a plurality of grooves of the same width and depth, so as to form a plurality of grooves 5b in each direction, and at the same time, a hexagonal groove structure 6b intersecting the second conductive type body region 4 is formed on the hexagonal cell structure.

[0050] In this embodiment, the width of each groove 5b does not exceed the inner side length of the second conductive type well region 2, so as to ensure that the second conductive type well region 2 has both horizontal and vertical raised platforms, thereby forming vertical and horizontal channels in the second conductive type well region 2.

[0051] Optionally, the width of the groove 5a is 1-5 μm and the height is 0.1-1 μm.

[0052] Specifically, this embodiment uses a hexagonal cell structure with a set of grooves as an example for detailed explanation. Please refer to [link to relevant documentation]. Figure 5 , Figure 5 This is a schematic diagram of a three-dimensional hexagonal cell structure with a set of grooves provided in Embodiment 2 of the present invention; wherein, the width D1 of the groove 5b is the same as the side length of the second conductive type body region 4.

[0053] In this embodiment, the first conductivity type is preferably N-type, and the second conductivity type is P-type. Further, the N-type epitaxial region 1 and the P-type well region 2 are lightly doped regions, and the N-type source region 3 and the P-type body region 4 are heavily doped regions. Therefore, the three-dimensional hexagonal cell structure provided in this embodiment includes an N-epitaxial region 1, a P-well region 2, an N+ source region 3, and a P+ body region 4. Please refer to... Figures 6-7 , Figure 6 This is a top view of a three-dimensional hexagonal cell structure with a set of grooves provided in Embodiment 2 of the present invention; Figure 7 This is a cross-sectional view of a three-dimensional hexagonal cell structure with a set of grooves provided in Embodiment 2 of the present invention.

[0054] Since the hexagonal groove structure in this embodiment includes a set of grooves, the total width of each arm of the hexagonal groove structure 6b is the same as the width D of a single groove 5b, both of which are equal to the side length of the second conductive type body region 4.

[0055] It should be noted that, in another embodiment of the present invention, the hexagonal groove structure may further include multiple sets of parallel grooves. For example, please refer to... Figure 8 , Figure 8 This is a schematic diagram of a three-dimensional hexagonal cell structure with two sets of grooves provided in an embodiment of the present invention. The edges of the two grooves 5b do not exceed the inner side length of the second conductivity type well region 2.

[0056] This embodiment provides a method for creating a three-dimensional hexagonal cell structure by adding groove structures to the surface of the cell structure. This allows the device to have not only parallel channels parallel to the cell surface but also vertical channels perpendicular to the cell surface. Compared to traditional two-dimensional cell structures where channels are only horizontal and cannot be further increased in width, this embodiment adds vertical channels (the sidewalls of the mesa are the vertical channels) without reducing the horizontal channels by setting mesa structures, thereby effectively increasing the total channel width of the entire cell structure. It can be seen that the height of the mesa sidewalls determines the width of the vertical channels. Similarly, the introduction of vertical channels effectively increases the cell channel density, reduces the channel on-resistance, and thus improves the device's current-carrying capacity.

[0057] Example 3

[0058] Based on Embodiments 1 and 2 above, this embodiment provides a method for preparing a three-dimensional hexagonal cell structure. Please refer to... Figure 9 , Figure 9 This is a schematic flowchart of the preparation method of the three-dimensional hexagonal cell structure provided in Embodiment 3 of the present invention, which includes the following steps:

[0059] Step 1: Prepare an epitaxial region of the first conductivity type.

[0060] Generally, the epitaxial region is located on a conductive substrate of the same type, preferably with the first conductivity type being N-type.

[0061] Specifically, an N- epitaxial layer is formed on an N+ substrate. This embodiment does not specifically limit the thickness and doping concentration of the N- epitaxial layer; for example, the thickness of the N- epitaxial layer can be set to 35 μm and the doping concentration to 1 × 10⁻⁶. 15 cm -3 .

[0062] Step 2: Using ion implantation, a second conductivity type well region, a first conductivity type source region, and a second conductivity type body region are sequentially formed on the first conductivity type epitaxial region.

[0063] First, P-type ions are implanted into the N-epitaxial layer obtained in step 1 to form a P-well region. The junction depth of the P-well region can be 0.7 μm, and the doping concentration can be 4 × 10⁻⁶. 17 cm -3 .

[0064] Then, N-type ions are implanted onto the sample to form an N+ source region. The junction depth of the N+ source region can be 0.2 μm, and the doping concentration can be 1 × 10⁻⁶. 19 cm -3 .

[0065] Finally, P-type ions are implanted into the N+ source region in the middle of the sample to form a P+ bulk region. The junction depth of the P+ bulk region can be 0.2 μm, and the doping concentration can be 1 × 10⁻⁶. 19 cm -3 .

[0066] It should be noted that this embodiment does not specifically limit the order in which the second conductivity type well region, the first conductivity type source region, and the second conductivity type body region are formed, and those skilled in the art can adjust them arbitrarily as needed.

[0067] Step 3: Etch the obtained sample to form a hexagonal mesa structure or a hexagonal groove structure on the sample surface.

[0068] In this embodiment, depending on whether the epitaxial layer material is Si or SiC, the periphery of the sample obtained in step 2 can be etched using either Si etching or SiC etching processes to remove the epitaxial layer around the periphery, thereby forming a hexagonal mesa structure in the middle of the sample.

[0069] Alternatively, the middle of the sample obtained in step 2 can be etched to remove the epitaxial layer in the middle, so as to form a hexagonal groove structure in the middle of the sample.

[0070] It should be noted that the specific process parameters can be implemented by referring to existing etching processes, and this embodiment does not impose specific limitations.

[0071] The fabrication method provided in this embodiment can prepare the three-dimensional hexagonal cell structure provided in Embodiment 1 or Embodiment 2 above. As a result, the prepared device structure also has parallel channels parallel to the cell surface and vertical channels perpendicular to the cell surface, thereby increasing the channel density, reducing the channel on-resistance, and helping to improve the current carrying capacity of the device.

[0072] Example 4

[0073] Based on the above embodiments one and two, this embodiment provides a MOSFET device, which includes the three-dimensional hexagonal cell structure with a raised mesa structure provided in embodiment one, or the three-dimensional hexagonal cell structure with a groove structure provided in embodiment two.

[0074] In this embodiment, Si or SiC material can be used to form an epitaxial layer with a three-dimensional square cell structure.

[0075] Preferably, this embodiment uses SiC material to form a MOSFET device with a three-dimensional square cell structure. Specifically, in the SiC MOSFET device provided in this embodiment, the width of each mesa structure 5a can be 1-5 μm and the height can be 0.1-1 μm; or, the width of each groove structure 5b is 1-5 μm and the depth is 0.1-1 μm.

[0076] For other structural parameters of MOSFET devices, please refer to existing devices; they will not be described in detail in this embodiment.

[0077] Therefore, the SiC MOSFET device provided in this embodiment has a high channel density and a low channel resistance, thus having good current carrying capacity.

[0078] Example 5

[0079] Based on the above embodiments one and two, this embodiment provides an IGBT device, which includes the three-dimensional hexagonal cell structure with a raised mesa structure provided in embodiment one, or the three-dimensional hexagonal cell structure with a groove structure provided in embodiment two.

[0080] In this embodiment, the specific structural parameters of the IGBT device can be adapted and set by referring to the existing device structure and actual conditions. This embodiment will not describe them in detail here.

[0081] Therefore, the IGBT device provided in this embodiment also has a high channel density and a low channel resistance, thus having good current carrying capacity.

[0082] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0083] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0084] In the description of this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0085] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A three-dimensional hexagonal cell structure, characterized in that, include: A first conductivity type epitaxial region (1), a second conductivity type well region (2) located within the first conductivity type epitaxial region (1), a first conductivity type source region (3) located within the second conductivity type well region (2), and a second conductivity type body region (4) located within the first conductivity type source region (3); wherein, The second type of conductive body region (4) is convex; Furthermore, along the vertical directions of the six sides of the hexagonal cell structure, the first conductive type epitaxial region (1), the second conductive type well region (2), and the first conductive type source region (3) are each provided with a number of protrusions of the same width and height, so as to form a number of protruding mesa (5a) in each direction, and at the same time, a hexagonal mesa structure (6a) intersecting with the second conductive type body region (4) is formed on the hexagonal cell structure.

2. The three-dimensional hexagonal cell structure according to claim 1, characterized in that, The width of each of the raised platform (5a) does not exceed the inner side length of the second conductive type well region (2).

3. The three-dimensional hexagonal cell structure according to claim 1, characterized in that, The raised platform (5a) has a width of 1-5 μm and a height of 0.1-1 μm.

4. The three-dimensional hexagonal cell structure according to claim 1, characterized in that, The first conductivity type is N-type, and the second conductivity type is P-type.

5. A three-dimensional hexagonal cell structure, characterized in that, include: A first conductivity type epitaxial region (1), a second conductivity type well region (2) located within the first conductivity type epitaxial region (1), a first conductivity type source region (3) located within the second conductivity type well region (2), and a second conductivity type body region (4) located within the first conductivity type source region (3); wherein, Along the vertical direction of the six sides of the hexagonal cell structure, the first conductive type epitaxial region (1), the second conductive type well region (2) and the first conductive type source region (3) around the second conductive type body region (4) are symmetrically provided with a plurality of grooves of the same width and depth, so as to form a plurality of grooves (5b) in each direction, and at the same time, a hexagonal groove structure (6b) intersecting with the second conductive type body region (4) is formed on the hexagonal cell structure.

6. The three-dimensional hexagonal cell structure according to claim 5, characterized in that, The width of each groove (5b) does not exceed the inner side length of the second conductive type well region (2).

7. The three-dimensional hexagonal cell structure according to claim 5, characterized in that, The groove (5b) has a width of 1-5 μm and a depth of 0.1-1 μm.

8. A method for preparing a three-dimensional hexagonal cell structure, characterized in that, include: Prepare an epitaxial region of the first conductivity type; An ion implantation process is used to sequentially form a second conductivity type well region, a first conductivity type source region, and a second conductivity type body region on the first conductivity type epitaxial region. The obtained sample is etched to form a hexagonal mesa structure or a hexagonal groove structure on the sample surface; The hexagonal mesa structure includes: the second conductive type body region is protruding; and along the vertical direction of the six sides of the hexagonal cell structure, the first conductive type epitaxial region, the second conductive type well region, and the first conductive type source region are each provided with a plurality of protrusions of the same width and height, so as to form a plurality of protruding mesa in each direction, and at the same time, a hexagonal mesa structure intersecting with the second conductive type body region is formed on the hexagonal cell structure; The hexagonal groove structure includes: along the vertical direction of the six sides of the hexagonal cell structure, a plurality of grooves with the same width and depth are symmetrically provided on the first conductive type epitaxial region, the second conductive type well region and the first conductive type source region around the second conductive type body region, so as to form a plurality of grooves in each direction, and at the same time, a hexagonal groove structure intersecting the second conductive type body region is formed on the hexagonal cell structure.

9. A MOSFET device, characterized in that, Includes the three-dimensional hexagonal cell structure as described in any one of claims 1-4 or the three-dimensional hexagonal cell structure as described in any one of claims 5-7.

10. An IGBT device, characterized in that, Includes the three-dimensional hexagonal cell structure as described in any one of claims 1-4 or the three-dimensional hexagonal cell structure as described in any one of claims 5-7.

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