Silicon carbide MOSFET junction terminal structure

Abstract

The utility model discloses a silicon carbide MOSFET junction terminal structure, and belongs to the technical field of semiconductor devices. Comprising a first passivation layer, an N-drift region, an N + substrate, a cathode metal electrode layer, a Pwell cellular transition region, a Pplus main junction region, a Pplus field limiting ring region, a Pwell main junction region, a Pwell field limiting ring region, a JTE main junction region, a JTE field limiting ring region, an anode metal electrode layer and a second passivation layer. And the Pwell cell transition region, the Pplus main junction region, the Pplus field limiting ring region, the Pwell main junction region, the Pwell field limiting ring region, the JTE main junction region and the JTE field limiting ring region are sequentially manufactured on the N-drift region from left to right. And the junction area of every two junction termination extension structures is a field limiting ring. The problems that a field limiting ring structure of an existing silicon carbide MOSFET is large in occupied area, and a junction terminal expansion structure is complex in process are solved. The method is widely applied to the silicon carbide MOSFET design and manufacturing technology.

Description

Technical Field

[0001] This utility model belongs to the field of semiconductor device technology, and more specifically to the field of MOSFET technology. In particular, it relates to a silicon carbide MOSFET junction termination structure and its manufacturing method. Background Technology

[0002] For silicon carbide MOSFET devices, junction termination technology typically employs either a field-limiting ring (FLR) structure or a multi-region junction termination extension (JTE) structure. The advantage of FLR technology lies in its simple fabrication process, as it can be formed simultaneously with cell implantation. However, with increasing reverse breakdown voltage, the termination area occupied by the FLR also increases, and each ring requires precise design, increasing manufacturing costs. On the other hand, the advantage of JTE technology is its simple structure and small footprint, making it suitable for high-voltage and ultra-high-voltage applications. However, due to the unique fabrication process of silicon carbide, JTE structures can only be formed through individual ion implantation. Therefore, the fabrication process for JTE structures becomes increasingly complex with the increase in ion zones, and the concentration variations between the multi-zone boundaries can easily lead to electric field concentration, affecting termination efficiency.

[0003] The main drawback of existing silicon carbide MOSFET junction termination structures is that they are usually single field-limiting ring structures or multi-region junction termination extension structures. Field-limiting ring structures occupy a large termination area, while multi-region junction termination structures are complex to manufacture and prone to electric field concentration problems.

[0004] While the advantages and disadvantages of the two mainstream junction termination technologies mentioned above are obvious, they are still adopted by the vast majority of silicon carbide MOSFET devices. In order to solve the problems highlighted in the above technologies and further optimize the junction termination structure of silicon carbide MOSFET devices, this invention proposes a multi-region hybrid field-limiting ring and junction termination extension structure, which combines the technical advantages of field-limiting ring structure and junction termination extension structure, optimizes the termination structure and ion implantation method, and thus solves the problems of large area occupation of field-limiting ring structure and complex process of junction termination extension structure.

[0005] In view of the above, this utility model is hereby proposed. Summary of the Invention

[0006] The technical problem to be solved by this utility model is to address the issues of large area occupied by the field limiting ring structure and complex process of the junction termination extension structure of existing silicon carbide MOSFETs.

[0007] The inventive concept of this utility model is as follows: Addressing the aforementioned problems, this utility model proposes a multi-region hybrid field-limiting ring and junction termination extension structure. In this termination structure, both a field-limiting ring structure and a junction termination extension structure coexist. The field-limiting ring structure is located at the boundary region between every two junction termination extension structures, serving as a transition and providing an electric field modulation effect, thereby mitigating the problem of electric field concentration in the transition regions of multiple junction termination extension structures. The junction termination extension structure employs three different implantation concentrations, forming a multi-region junction termination extension structure and increasing its efficiency. Furthermore, the first two regions of the multi-region junction termination extension structure are implanted with the same impurities as the cell region, reducing process complexity. This structure can reduce the terminal area occupied and increase junction termination utilization efficiency while only adding one photolithography pattern, bringing the breakdown voltage of the silicon carbide MOSFET device close to the ideal value.

[0008] Therefore, this utility model provides a silicon carbide MOSFET junction termination structure, such as... Figure 1 As shown. Includes:

[0009] 1. First passivation layer; 2. N- drift region; 3. N+ substrate; 4. Cathode metal electrode layer; 5. Pwell cell transition region; 6. Pplus main junction region; 7. Pplus field confinement ring region; 8. Pwell main junction region; 9. Pwell field confinement ring region; 10. JTE main junction region; 11. JTE field confinement ring region; 12. Anode metal electrode layer; 13. Second passivation layer.

[0010] The cathode metal electrode layer 4 is located on the bottom surface of the N+ substrate 3.

[0011] The N-drift region 2 is located on the top surface of the N+ substrate 3.

[0012] The Pwell cell transition region 5, Pplus main junction region 6, Pplus field limiting ring region 7, Pwell main junction region 8, Pwell field limiting ring region 9, JTE main junction region 10, and JTE field limiting ring region 11 are fabricated sequentially on top of the N-drift region 2 from left to right. The Pwell cell transition region 5 is adjacent to the Pplus main junction region 6, the Pplus field limiting ring region 7 is adjacent to the Pwell main junction region 8, and the Pwell field limiting ring region 9 is adjacent to the JTE main junction region 10.

[0013] The first passivation layer 1 is fabricated above the Pwell cell transition region 5 and part of the Pplus main junction region 6.

[0014] The second passivation layer 13 is fabricated above a portion of the Pplus main junction region 6, the Pplus field-limiting ring region 7, the Pwell main junction region 8, the Pwell field-limiting ring region 9, the JTE main junction region 10, and the JTE field-limiting ring region 11.

[0015] The anode metal electrode layer 12 is fabricated above a portion of the Pplus main junction region 6, located between the first passivation layer 1 and the second passivation layer 13.

[0016] The beneficial effects of this invention are as follows: This invention integrates the field limiting ring structure and the junction termination extension structure into a single junction termination structure. The field limiting ring structure alleviates the problem of electric field concentration in the transition region of the multi-region junction termination structure. At the same time, by utilizing the natural concentration difference between Pwell injection and Pplus injection in the cell region, only one additional JTE region injection is needed to form a three-region junction termination extension structure, which greatly simplifies the process flow and reduces complexity. This termination structure also reduces the area occupied by the termination and improves the termination efficiency.

[0017] It can be widely used in silicon carbide MOSFET design and manufacturing technology. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the silicon carbide MOSFET junction termination structure of this utility model.

[0019] Figure 2 This diagram shows the ion implantation locations in the Pwell cell transition region, Pwell main junction region, and Pwell field-confined ring region.

[0020] Figure 3 This is a schematic diagram of the ion implantation locations in the Pplus main junction region and the Pplus field-confined ring region.

[0021] Figure 4 This is a schematic diagram of the ion implantation locations in the JTE main junction region and the JTE field-confined ring region.

[0022] Figure 5 This is a schematic diagram of the passivation layer deposition structure.

[0023] Figure 6 This is a schematic diagram of the anode metal deposition layer structure.

[0024] Figure 7 This is a schematic diagram of the cathode metal deposition layer structure.

[0025] In the figure: 1 is the first passivation layer, 2 is the N- drift region, 3 is the N+ substrate, 4 is the cathode metal electrode layer, 5 is the Pwell cell transition region, 6 is the Pplus main junction region, 7 is the Pplus field confinement ring region, 8 is the Pwell main junction region, 9 is the Pwell field confinement ring region, 10 is the JTE main junction region, 11 is the JTE field confinement ring region, 12 is the anode metal electrode layer, and 13 is the second passivation layer. Detailed Implementation

[0026] like Figure 1-7 As shown, the specific implementation of the silicon carbide MOSFET junction termination structure and its manufacturing method is as follows:

[0027] (1) Epitaxial wafer cleaning;

[0028] (2) High-temperature ion implantation of Pwell cell transition region 5, Pwell main junction region 8 and Pwell field confinement ring region 9, with aluminum ions as impurities. The three regions are implanted in the same way in this step and are formed together with the Pwell base region of the silicon carbide MOSFET cell region, without the need for additional photomasks.

[0029] (3) High-temperature ion implantation of Pplus main junction region 6 and Pplus field confinement ring region 7, with aluminum ions as impurities. The two regions are implanted in the same way in this step and are formed together with the Pplus ohmic contact region of the silicon carbide MOSFET cell region, without the need for additional photomasks.

[0030] (4) High-temperature ion implantation of JTE main junction region 10 and JTE field confinement ring region 11, with aluminum ions as impurities. The two regions are implanted in the same way in this step, requiring only a single JTE photomask.

[0031] (5) High-temperature annealing activates impurity ions;

[0032] (6) Deposition of polycrystalline silicon;

[0033] (7) Deposition medium layer;

[0034] (8) Depositing anode metal;

[0035] (9) Deposition of passivation layer;

[0036] (10) The substrate is thinned and cathode metal is deposited.

[0037] The doping concentration range of the N-drift region 2 is 1×10⁻⁶. 14 cm -3 Up to 5×10 15 cm -3 The thickness of the N-drift region 2 ranges from 5 to 200 μm.

[0038] The Pwell cell transition region 5, Pplus main junction region 6, Pplus field confinement ring region 7, Pwell main junction region 8, Pwell field confinement ring region 9, JTE main junction region 10, and JTE field confinement ring region 11 were all formed by multiple ion implantations.

[0039] The single-implantation doping dose range for the Pplus main junction region 6 and the Pplus field-confined ring region 7 is 1×10⁻⁶. 14 cm -2 Up to 5×10 15 cm -2 The energy range for injection is 50keV-500keV.

[0040] The doping dose range for a single implantation of the Pwell cell transition region 5, Pwell main junction region 8, and Pwell field confinement region 9 is 1 × 10⁻⁶. 11 cm -2 Up to 5×10 14 cm -2 The energy range for injection is 50keV-500keV.

[0041] The doping dose range for a single implantation of the JTE main junction region 10 and the JTE field-confined ring region 11 is 1×10⁻⁶. 11 cm -2 Up to 5×10 13 cm -2 The energy range for injection is 50keV-500keV.

[0042] The injection depth of the Pwell cell transition region 5, Pplus main junction region 6, Pplus field confinement ring region 7, Pwell main junction region 8, Pwell field confinement ring region 9, JTE main junction region 10 and JTE field confinement ring region 11 is 0.4μm-1μm.

[0043] All regions containing Pwell doping types are formed in the same batch of processes as the Pwell base regions in the cell regions of silicon carbide MOSFETs, without the need for additional photolithography and process steps; such as Pwell cell transition region 5, Pwell main junction region 8, Pwell field confinement ring region 9, etc.

[0044] All regions containing Pplus doped types are formed in the same batch of processes as the Pplus ohmic contact regions of the cell regions in silicon carbide MOSFETs, without the need for additional photolithography and process steps; such as Pplus main junction region 6, Pplus field confinement ring region 7, etc.

[0045] The JTE main junction region 10 and the JTE field limiting ring region 11 can be compatible with the JTE region injection process in conventional silicon carbide MOSFETs using a single JTE injection photomask.

[0046] The Pwell field-limiting ring region 9 contains 1-5 Pwell-doped field-limiting rings, with the width of the Pwell field-limiting rings ranging from 2-3 μm and the spacing ranging from 1-3 μm.

[0047] The Pplus field confinement ring region 7 contains 1-5 Pplus-doped field confinement rings, with the width of the Pplus field confinement rings ranging from 2-3 μm and the spacing ranging from 1-3 μm.

[0048] The JTE field confinement ring region 11 contains 1-5 JTE-doped field confinement rings, with the width of the JTE field confinement rings ranging from 2-3 μm and the spacing ranging from 1-3 μm.

[0049] The materials of the N+ substrate 3, N- drift region 2, Pwell cell transition region 5, Pplus main junction region 6, Pplus field confinement ring region 7, Pwell main junction region 8, Pwell field confinement ring region 9, JTE main junction region 10 and JTE field confinement ring region 11 are all silicon carbide.

[0050] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A silicon carbide MOSFET junction termination structure, characterized in that: It includes a first passivation layer (1), an N- drift region (2), an N+ substrate (3), a cathode metal electrode layer (4), a Pwell cell transition region (5), a Pplus main junction region (6), a Pplus field confinement ring region (7), a Pwell main junction region (8), a Pwell field confinement ring region (9), a JTE main junction region (10), a JTE field confinement ring region (11), an anode metal electrode layer (12), and a second passivation layer (13). The cathode metal electrode layer (4) is located on the bottom surface of the N+ substrate (3); The N-drift region (2) is located on the top surface of the N+ substrate (3); The Pwell cell transition region (5), Pplus main junction region (6), Pplus field limiting ring region (7), Pwell main junction region (8), Pwell field limiting ring region (9), JTE main junction region (10), and JTE field limiting ring region (11) are fabricated on top of the N-drift region (2) from left to right. The Pwell cell transition region (5) is adjacent to the Pplus main junction region (6), the Pplus field limiting ring region (7) is adjacent to the Pwell main junction region (8), and the Pwell field limiting ring region (9) is adjacent to the JTE main junction region (10). The first passivation layer (1) is fabricated above the Pwell cell transition region (5) and part of the Pplus main junction region (6); The second passivation layer (13) is fabricated above a portion of the Pplus main junction region (6), the Pplus field-limiting ring region (7), the Pwell main junction region (8), the Pwell field-limiting ring region (9), the JTE main junction region (10), and the JTE field-limiting ring region (11); The anode metal electrode layer (12) is fabricated above a portion of the Pplus main junction region (6) and is located between the first passivation layer (1) and the second passivation layer (13).

2. The silicon carbide MOSFET junction termination structure as described in claim 1, characterized in that: The thickness of the N-drift region (2) ranges from 5 μm to 200 μm.

3. The silicon carbide MOSFET junction termination structure as described in claim 1, characterized in that: The injection depth of the Pwell cell transition region (5), Pplus main junction region (6), Pplus field confinement ring region (7), Pwell main junction region (8), Pwell field confinement ring region (9), JTE main junction region (10) and JTE field confinement ring region (11) is 0.4μm-1μm.

4. The silicon carbide MOSFET junction termination structure as described in claim 1, characterized in that: The Pwell field-limiting ring region (9) contains 1-5 Pwell-doped field-limiting rings, with the width of the Pwell field-limiting rings ranging from 2μm to 3μm and the spacing ranging from 1μm to 3μm.

5. The silicon carbide MOSFET junction termination structure as described in claim 1, characterized in that: The Pplus field confinement ring region (7) contains 1-5 Pplus-doped field confinement rings, with the width of the Pplus field confinement rings ranging from 2μm to 3μm and the spacing ranging from 1μm to 3μm.

6. The silicon carbide MOSFET junction termination structure as described in claim 1, characterized in that: The JTE field confinement ring region (11) contains 1-5 JTE-doped field confinement rings, with the width of the JTE field confinement rings ranging from 2μm to 3μm and the spacing ranging from 1μm to 3μm.

7. The silicon carbide MOSFET junction termination structure as described in claim 1, characterized in that: The materials of the N+ substrate (3), N- drift region (2), Pwell cell transition region (5), Pplus main junction region (6), Pplus field confinement ring region (7), Pwell main junction region (8), Pwell field confinement ring region (9), JTE main junction region (10) and JTE field confinement ring region (11) are all silicon carbide.

Images