Stepped SiC trench field limiting ring terminal structure, preparation method and device thereof
A terminal structure and stepped technology, applied in the field of microelectronics, can solve the problems of increasing the terminal area and enhancing the expansion ability of the lateral space charge region, and achieve the effects of reducing the peak electric field, preventing premature breakdown, and reducing the terminal area
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Embodiment 1
[0036] See figure 1 , figure 1 It is a schematic diagram of a stepped SiC trench field limiting ring terminal structure provided by an embodiment of the present invention, including: a SiC substrate layer 1, a SiC epitaxial layer 2 on the SiC substrate layer 1, and a SiC epitaxial layer 2 on the surface Several trenches 3, ion implantation regions 4 located in the several trenches 3, and passivation layer 5 located on the SiC epitaxial layer 2, wherein the trench depths of the several trenches 3 start from the edge of the main junction It is distributed outwards in steps.
[0037] Further, the trench depths of the plurality of trenches 3 gradually decrease from the edge of the main junction outward.
[0038] Furthermore, the width of the first trench 301 close to the edge of the main junction among the plurality of trenches 3 is greater than that of the rest of the trenches, and the width of the rest of the trenches is the same. Wherein, the interval between each groove is ...
Embodiment 2
[0047] On the basis of the first implementation above, this embodiment provides a method for preparing a stepped SiC trench field-limiting ring termination structure, please refer to image 3 , image 3 It is a flowchart of a method for preparing a stepped SiC trench field-limiting ring terminal structure provided by an embodiment of the present invention, including:
[0048] S1: Get the SiC substrate.
[0049] Optionally, the SiC substrate can be 4H-SiC, 6H-SiC or 3C-SiC.
[0050] S2: growing a SiC epitaxial layer on the SiC substrate.
[0051] First, the selected SiC substrate is cleaned, and then the SiC epitaxial layer is grown on the SiC substrate by techniques such as molecular beam epitaxy (MBE), chemical vapor deposition (CVD) or liquid phase epitaxy (LPE).
[0052] S3: using multiple etching processes to sequentially form several grooves with different depths on the SiC epitaxial layer. Specifically include:
[0053]S31: Deposit SiO on the surface of SiC epitaxia...
Embodiment 3
[0080] In order to illustrate the preparation method of the present invention more clearly, the preparation process of the present invention will be described in detail below in conjunction with the accompanying drawings. See Figures 4a-4i , Figures 4a-4i It is a schematic diagram of the preparation process of the stepped SiC trench field-limiting ring terminal structure provided by the embodiment of the present invention, specifically including:
[0081] Step 1: Select SiC substrate 1, such as Figure 4a shown.
[0082] Step 2: grow SiC epitaxial layer 2 on SiC substrate 1 by CVD process, such as Figure 4b shown.
[0083] Step 3: Using PECVD process to grow SiO on the surface of the cleaned SiC epitaxial layer 2 2 , to form SiO 2 protective layer 101, such as Figure 4c shown.
[0084] Step 4: On SiO 2 A photoresist 102 is spin-coated on the protection layer 101, and the first photolithography is performed to form an etching mask window, such as Figure 4d shown....
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