Gallium nitride power device structure with novel field plate
By adopting a single-layer arc-shaped field plate structure in gallium nitride power devices, the gate and drain edge breakdown problems are solved, and higher breakdown voltages and lower parasitic capacitance are achieved, simplifying process steps.
Patent Information
- Application Number
- CN202422252759.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-13
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-09-13
AI Technical Summary
Existing gallium nitride power devices are prone to breakdown at the gate edge or drain edge, and the multi-layer field plate structure increases parasitic capacitance and process costs.
A single-layer arc field plate structure is adopted, and the field plate metal is located between the gate and drain and interconnected with the source metal. The arc structure is close to the gate and drain respectively to weaken the concentrated effect of the electric field.
Effectively reduce the electric field peak at the gate and drain edges, prevent breakdown, increase breakdown voltage, and reduce parasitic capacitance and process steps.
Smart Images
Figure CN223080398U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of semiconductors, and in particular, to a gallium nitride power device structure with a novel field plate. Background Art
[0002] As one of the representatives of the third-generation semiconductor materials, gallium nitride has significant advantages such as high electron mobility, wide bandgap, high thermal conductivity, and high electron saturation velocity compared with traditional silicon materials. Therefore, gallium nitride power semiconductor devices have higher saturation current density, higher breakdown voltage, lower on-resistance, and higher switching speed. Based on the above advantages, gallium nitride power semiconductor devices are gradually replacing silicon-based devices and are widely used in power supplies, automotive electronics, photovoltaics, communications, and other fields. The traditional Si MOS device relies on the reverse-biased PN junction formed between the drain and the substrate for voltage withstand, and breakdown usually occurs at the interface of this junction or the edge of the gate oxide layer.
[0003] The core structure of the gallium nitride power device is the AlGaN / GaN heterojunction. There is no PN junction in this device structure, and the device relies on the depletion region in the GaN channel layer for voltage withstand. Due to the electric field concentration effect, the electric field peak value at the gate edge or the drain edge is relatively large during voltage withstand of the gallium nitride power device, which further leads to breakdown at the gate edge or the drain edge.
[0004] In the design of gallium nitride power devices, a field plate structure is usually adopted to reduce the electric field spike at the gate or drain edge, thereby improving the breakdown voltage of the device. These field plate structures include source field plates, gate field plates, and drain field plates. These field plates are usually planar field plates, and one type of field plate can only improve the electric field spike on one side of the gate or drain. For example, the gate field plate can only reduce the electric field spike at the gate edge, while the drain field plate can only reduce the electric field spike at the drain edge. If a multi-layer field plate structure is adopted, it will greatly increase the parasitic capacitance of the device, and at the same time increase the process steps and process costs. Summary of the Utility Model
[0005] The purpose of the utility model is to provide a gallium nitride power device structure with a novel field plate to solve the problem of easy breakdown at the gate edge or the drain edge in the prior art.
[0006] The embodiments of the utility model are realized by the following technical solutions:
[0007] A gallium nitride power device structure with a novel field plate includes a substrate, a nucleation layer, a buffer layer, a doping layer, a channel layer, and a barrier layer which are sequentially arranged from bottom to top;
[0008] A first surface passivation layer, a source metal, and a drain metal are arranged on the upper part of the barrier layer, and the source metal and the drain metal are respectively arranged on both sides of the first surface passivation layer;
[0009] On the upper part of the first surface passivation layer, there are a gate metal and two second surface passivation layers, and the two second surface passivation layers are respectively arranged on both sides of the gate metal;
[0010] On the upper part of the first surface passivation layer, there is also a field plate metal, and the field plate metal is respectively interconnected with the source metal and the drain metal through an interconnect metal.
[0011] Preferably, the nucleation layer is an AlN nucleation layer.
[0012] Preferably, the doping layer is a C-doped GaN layer.
[0013] Preferably, the channel layer is a GaN channel layer.
[0014] Preferably, the barrier layer is an AlGaN barrier layer.
[0015] Preferably, the field plate metal includes a first field plate metal and a second field plate metal. The first field plate metal is interconnected with the source metal through an interconnect metal, and the second field plate metal is interconnected with the drain metal through an interconnect metal.
[0016] Preferably, the first field plate metal and the second field plate metal are in an arc structure.
[0017] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:
[0018] The present invention is a gallium nitride power device structure with a novel field plate. The field plate metal is located between the gate metal and the drain metal, and the field plate metal is interconnected with the source metal. The right side of the arc-shaped field plate is close to the drain. When the device withstands voltage, part of the power lines emitted by the drain fall on the field plate, which can effectively weaken the electric field concentration effect at the drain edge, thereby reducing the electric field peak value at the drain edge and preventing the drain from breaking down in advance.
[0019] The left side of the arc-shaped field plate metal is close to the gate. When the device withstands voltage, part of the power lines emitted by the drain fall on this side of the field plate, which can effectively weaken the electric field concentration effect at the gate edge, thereby reducing the electric field peak value at the gate edge and preventing the gate from breaking down in advance.
[0020] The gallium nitride power device structure with a novel field plate of the present invention has a single-field plate structure for the field plate metal, and the field plate is in an arc structure, which can simultaneously weaken the electric field concentration effects of the gate and the drain, make the electric field distribution in the GaN channel layer more uniform, and thus can achieve a higher breakdown voltage. In addition, the field plate is a single-field plate, which has the significant advantages of small parasitic capacitance and saving process steps compared with the commonly used multi-layer field plate structure. Description of the Drawings
[0021] To more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the attached drawings required for use in the embodiments. It should be understood that the following attached drawings only show certain embodiments of the present utility model and should not be regarded as a limitation of the scope. For those of ordinary skill in the art, without creative efforts, other relevant attached drawings can also be obtained based on these attached drawings.
[0022] Figure 1 It is a schematic structural diagram of Embodiment 1 of the present utility model;
[0023] Figure 2 It is a schematic structural diagram of Embodiment 2 of the present utility model.
[0024] Icon: 101 - Substrate, 102 - AlN nucleation layer, 103 - buffer layer, 104 - C-doped GaN layer, 105 - GaN channel layer, 106 - AlGaN barrier layer, 107 - Source metal, 108 - Gate metal, 109 - Drain metal, 110 - First surface passivation layer, 111 - Second surface passivation layer, 112 - First field plate metal, 113 - Second field plate metal, 114 - Field plate metal. Specific embodiments
[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present utility model in conjunction with the attached drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. Generally, the components of the embodiments of the present utility model described and shown in the attached drawings here can be arranged and designed in various different configurations.
[0026] Embodiment 1:
[0027] Please refer to Figure 1 , a gallium nitride power device structure with a novel field plate provided by the present utility model includes a substrate 101, a nucleation layer, a buffer layer 103, a doping layer, a channel layer, and a barrier layer arranged in sequence from bottom to top;
[0028] A first surface passivation layer 110, a source metal 107, and a drain metal 109 are provided on the upper part of the barrier layer. The source metal 107 and the drain metal 109 are respectively arranged on both sides of the first surface passivation layer 110;
[0029] Among them, the source metal 107 and the drain metal 109 respectively form ohmic contacts with the barrier layer.
[0030] On the upper part of the first surface passivation layer 110, there are a gate metal 108 and two second surface passivation layers 111, and the two second surface passivation layers 111 are respectively arranged on both sides of the gate metal 108;
[0031] Both the first surface passivation layer 110 and the second surface passivation layer 111 are insulating layers or insulating dielectrics.
[0032] On the upper part of the first surface passivation layer 110, there is also a field plate metal 114, and the field plate metal 114 is interconnected with the source metal 107 and the drain metal 109 through an interconnecting metal in the non-active region.
[0033] The utility model is a gallium nitride power device structure with a novel field plate 114. The field plate metal 114 is located between the gate metal 108 and the drain metal 109, and the field plate metal 114 is interconnected with the source metal 107. The right side of the arc-shaped field plate is close to the drain. When the device withstands voltage, part of the power lines emitted by the drain fall on the field plate, which can effectively weaken the electric field concentration effect at the drain edge, thereby reducing the electric field peak value at the drain edge and preventing the drain from breaking down prematurely.
[0034] In an exemplary embodiment of the utility model, the nucleation layer is an AlN nucleation layer 102, the doping layer is a C-doped GaN layer 104, the channel layer is a GaN channel layer 105, and the barrier layer is an AlGaN barrier layer.
[0035] The left side of the arc-shaped field plate metal 114 is close to the gate. When the device withstands voltage, part of the power lines emitted by the drain fall on this side of the field plate, which can effectively weaken the electric field concentration effect at the gate edge, thereby reducing the electric field peak value at the gate edge and preventing the gate from breaking down prematurely.
[0036] The gallium nitride power device structure with a novel field plate of the present invention, the field plate metal 114 of this structure is a single field plate, and this field plate is an arc-shaped structure, which can simultaneously weaken the electric field concentration effects of the gate and the drain, make the electric field distribution in the GaN channel layer 105 more uniform, and thus a higher breakdown voltage can be achieved. In addition, this field plate is a single field plate, which has the significant advantages of small parasitic capacitance and saving process steps compared with the commonly used multi-layer field plate structure.
[0037] The manufacturing method of this structure includes the following steps:
[0038] An AlN nucleation layer 102, a buffer layer 103, a C-doped GaN layer 104, a GaN channel layer 105, and an AlGaN barrier layer 106 are sequentially grown above the substrate 101. An insulating dielectric is deposited above the AlGaN barrier layer as a gate dielectric and a first surface passivation layer 110. The first surface passivation layer 110 is etched to form an opening, and ohmic metal is deposited at the position of the etched opening to form a source metal 107 and a drain metal 109. The ohmic contact metal is annealed so that 107 and 109 respectively form ohmic contacts with the AlGaN barrier layer 106. A gate metal 108 is deposited, and an insulating dielectric is deposited as a second surface passivation layer 111. An arc structure is formed on the second surface passivation layer 111 by photolithography. A field plate metal 114 is deposited on the second surface passivation layer 111. The field plate metal 114 is interconnected with the source metal 107 through an interconnect metal in the non-active region.
[0039] Embodiment 2:
[0040] Please refer to Figure 2 , on the basis of Embodiment 1, the field plate metal 114 can also be two separate first field plate metals 112 and second field plate metals 113. The first field plate metal 112 is interconnected with the source metal 107 through an interconnect metal, and the second field plate metal 113 is interconnected with the drain metal 109 through an interconnect metal.
[0041] The first field plate metal 112 and the second field plate metal 113 are arc structures.
[0042] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A gallium nitride power device structure with a novel field plate, characterized in that, It includes a substrate, a nucleation layer, a buffer layer, a doping layer, a channel layer, and a barrier layer that are sequentially arranged from bottom to top; A first surface passivation layer, a source metal, and a drain metal are provided on the upper part of the barrier layer, and the source metal and the drain metal are respectively arranged on both sides of the first surface passivation layer; A gate metal and two second surface passivation layers are provided on the upper part of the first surface passivation layer, and the two second surface passivation layers are respectively arranged on both sides of the gate metal; A field plate metal is further provided on the upper part of the first surface passivation layer, and the field plate metal is interconnected with the source metal and the drain metal through an interconnect metal.
2. The structure of a gallium nitride power device with a novel field plate according to claim 1, characterized in that, The nucleation layer is an AlN nucleation layer.
3. A gallium nitride power device structure with a novel field plate according to claim 1, characterized in that, The doping layer is a C-doped GaN layer.
4. A gallium nitride power device structure with a novel field plate according to claim 1, characterized in that, The channel layer is a GaN channel layer.
5. A gallium nitride power device structure with a novel field plate according to claim 1, characterized in that, The barrier layer is an AlGaN barrier layer.
6. The structure of a gallium nitride power device with a novel field plate according to claim 1, characterized in that, The field plate metal includes a first field plate metal and a second field plate metal. The first field plate metal is interconnected with the source metal through an interconnect metal, and the second field plate metal is interconnected with the drain metal through an interconnect metal.
7. The structure of a gallium nitride power device with a novel field plate according to claim 6, characterized in that, The first field plate metal and the second field plate metal are in an arc structure.