HEMT device and preparation method thereof
By forming a patterned hydrogen diffusion barrier layer on a P-type GaN layer and performing local annealing, a gradual distribution of Mg activation rate is achieved, which solves the problems of excessive electric field at the edge of the P-type GaN epitaxial layer and etching damage, and improves the reliability of HEMT devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI XINWEI SEMICON CO LTD
- Filing Date
- 2026-02-06
- Publication Date
- 2026-05-01
AI Technical Summary
In existing technologies, excessively strong edge electric fields at the edges of P-type GaN epitaxial layers and damage introduced during etching processes lead to increased gate leakage current and decreased device reliability.
A patterned hydrogen diffusion barrier layer is formed on the P-type GaN layer, and the P-type GaN layer is locally annealed through an annealing window to make the activation rate of Mg gradually decrease from the source to the drain, forming a gradient distribution, thereby reducing the electric field strength and leakage current on the drain side.
By varying the activation rate of Mg, the leakage current and electric field strength of the P-type GaN layer near the drain are reduced, thus improving the reliability of the device.
Smart Images
Figure CN121968620A_ABST
Abstract
Description
HEMT devices and their fabrication methods Technical Field
[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a HEMT device and its fabrication method. Background Technology
[0002] Compared to first- and second-generation semiconductor materials, third-generation semiconductor materials, especially gallium nitride (GaN)-based materials, have advantages such as large bandgap, high breakdown field strength, high electron mobility, and strong radiation resistance. GaN-based high electron mobility transistors (HEMTs) have great development potential in high-frequency and high-power fields such as wireless communication base stations, radar, and automotive electronics.
[0003] P-type gate technology is a common method for realizing enhancement-mode devices. It involves adding a P-type GaN epitaxial layer between the gate metal and the barrier layer, lowering the barrier height. Due to the conduction band difference between the P-type GaN epitaxial layer and the barrier layer, the conduction band of the entire heterojunction rises above the Fermi level, depleting the two-dimensional electron gas (2DEG) in the channel below the gate, thus achieving enhancement mode. However, during device operation, the edge electric field of the P-type GaN epitaxial layer is relatively strong. Furthermore, during device fabrication, the P-type GaN epitaxial layer between the gate source and gate drain needs to be etched away, making it difficult to control etching precision and introducing etching damage. Ultimately, this leads to increased gate leakage current and decreased device reliability. Summary of the Invention
[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a HEMT device and its fabrication method, which solves the problems of excessively strong edge electric field of P-type GaN epitaxial layer and damage introduced during etching process leading to increased gate leakage current and deteriorated device reliability in the prior art.
[0005] To achieve the above and other related objectives, the present invention provides a method for fabricating a HEMT device, the method comprising:
[0006] A substrate is provided, and a channel layer, a barrier layer and an in-situ Mg-doped P-type GaN layer are sequentially formed on the substrate; wherein, a Mg-H structure with Mg and H bonds is formed in the P-type GaN layer;
[0007] A patterned hydrogen diffusion barrier layer is formed on the P-type GaN layer. The patterned hydrogen diffusion barrier layer has a plurality of annealing windows in a preset gate region. The planar size of the annealing windows gradually decreases from the preset source region to the preset drain region. The preset gate region is located between the preset source region and the preset drain region.
[0008] The P-type GaN layer is annealed based on the annealing window of the patterned hydrogen diffusion barrier layer, so that the Mg in the Mg-H structure in the P-type GaN layer not covered by the patterned hydrogen diffusion barrier layer is activated, thereby gradually reducing the activation rate of Mg in the preset gate region from the preset source region to the preset drain region.
[0009] Remove the patterned hydrogen diffusion barrier layer;
[0010] A gate metal layer is formed on the predetermined gate region of the P-type GaN layer, and the P-type GaN layer outside the predetermined gate region is removed;
[0011] A source metal layer is formed on the predetermined source region of the barrier layer, and a drain metal layer is formed on the predetermined drain region of the barrier layer.
[0012] Optionally, the substrate material includes one of Si, SiC, and sapphire.
[0013] Optionally, the channel layer is made of GaN, and the barrier layer is made of AlGaN.
[0014] Optionally, a buffer layer is also formed between the substrate and the channel layer.
[0015] Optionally, the patterned hydrogen diffusion barrier layer may be made of silicon nitride or silicon oxide.
[0016] Optionally, the method for annealing the P-type GaN layer based on the annealing window of the patterned hydrogen diffusion barrier layer includes laser annealing.
[0017] The present invention also provides a HEMT device, the HEMT device comprising:
[0018] A substrate and a channel layer and a barrier layer sequentially stacked on the substrate;
[0019] A Mg-doped P-type GaN layer is located on the barrier layer;
[0020] A gate metal layer located in a predetermined gate region on the P-type GaN layer, a source metal layer located in a predetermined source region on the barrier layer, and a drain metal layer located in a predetermined drain region; wherein, the gate metal layer is located between the source metal layer and the drain metal layer, and the doping rate of Mg in the P-type GaN layer gradually decreases from the source metal layer to the drain metal layer.
[0021] Optionally, a buffer layer is also formed between the substrate and the channel layer.
[0022] Optionally, the substrate material includes one of Si, SiC, and sapphire.
[0023] Optionally, the channel layer is made of GaN, and the barrier layer is made of AlGaN.
[0024] As described above, the HEMT device and its fabrication method of the present invention have the following beneficial effects: by forming a patterned hydrogen diffusion barrier layer on the P-type GaN layer and using the annealing window of the barrier layer to perform local annealing treatment on the P-type GaN layer, a gradual distribution of Mg activation rate in the gate region is achieved, that is, the Mg activation rate gradually decreases from the source to the drain. Correspondingly, the Mg-H concentration in the P-type GaN layer closer to the drain is higher, and the resistivity of the corresponding P-type GaN layer material is also higher. Therefore, the leakage current of the P-type GaN layer near the drain side in the off state can be reduced, and the electric field strength on the drain side can be reduced, thereby improving the reliability of the device. Attached Figure Description
[0025] Figure 1 shows a schematic flowchart of the fabrication method of the HEMT device of the present invention.
[0026] Figures 2 to 8 show schematic cross-sectional views of each step in the fabrication method of the HEMT device of the present invention.
[0027] Component labeling explanation: 10 Substrate, 11 Channel layer, 12 Barrier layer, 13 P-type GaN layer, 131 Mg-H structure, 132 Activated Mg, 14 Patterned hydrogen diffusion barrier layer, 141 Annealing window, 15 Gate metal layer, 16 Source metal layer, 17 Drain metal layer, 18 Buffer layer, 21 Preset gate region, 22 Preset source region, 23 Preset drain region, Steps S1~S6. Detailed Implementation
[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0029] Please refer to Figures 1 to 8. It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0030] This embodiment provides a method for fabricating a HEMT device, as shown in Figure 1. The fabrication method includes:
[0031] S1, a substrate is provided, and a channel layer, a barrier layer and an in-situ Mg-doped P-type GaN layer are sequentially formed on the substrate; wherein, a Mg-H structure with Mg and H bonds is formed in the P-type GaN layer;
[0032] S2, a patterned hydrogen diffusion barrier layer is formed on the P-type GaN layer. The patterned hydrogen diffusion barrier layer has a plurality of annealing windows in a preset gate region. The planar size of the annealing windows gradually decreases from the preset source region to the preset drain region. The preset gate region is located between the preset source region and the preset drain region.
[0033] S3, the P-type GaN layer is annealed based on the annealing window of the patterned hydrogen diffusion barrier layer, so that the Mg in the Mg-H structure in the P-type GaN layer not covered by the patterned hydrogen diffusion barrier layer is activated, thereby making the activation rate of Mg in the preset gate region gradually decrease from the preset source region to the preset drain region.
[0034] S4, Remove the patterned hydrogen diffusion barrier layer;
[0035] S5, a gate metal layer is formed on the preset gate region of the P-type GaN layer, and the P-type GaN layer outside the preset gate region is removed;
[0036] S6, a source metal layer is formed on the preset source region of the barrier layer, and a drain metal layer is formed on the preset drain region of the barrier layer.
[0037] The HEMT device fabrication method of this embodiment achieves a gradual distribution of Mg activation rate in the preset gate region by forming a patterned hydrogen diffusion barrier layer on the P-type GaN layer and using the annealing window of the barrier layer to perform local annealing treatment on the P-type GaN layer. That is, the Mg activation rate gradually decreases from the source to the drain. Correspondingly, the concentration of Mg-H structure in the P-type GaN layer closer to the drain is higher, and the resistivity of the corresponding P-type GaN layer material is also higher. This can reduce the leakage current of the P-type GaN layer near the drain in the off state and reduce the electric field strength on the drain side, thereby improving the reliability of the device.
[0038] The fabrication method of the HEMT device in this embodiment will be described in detail below with reference to the specific accompanying drawings.
[0039] As shown in Figure 2, step S1 is performed first, a substrate 10 is provided, and a channel layer 11, a barrier layer 12 and an in-situ Mg-doped P-type GaN layer 13 are sequentially formed on the substrate 10; wherein, a Mg-H structure 131 in which Mg and H are bonded is formed in the P-type GaN layer 13.
[0040] As an example, the material of the substrate 10 includes one of silicon (Si), silicon carbide (SiC) and sapphire, and the specific material can be selected according to actual needs, without excessive restrictions here.
[0041] Specifically, the channel layer 11 and the barrier layer 12 are made of different materials. A two-dimensional electron gas is formed at the interface between the channel layer 11 and the barrier layer 12. This two-dimensional electron gas serves as the channel of the HEMT device, providing a conductive channel between the source and drain of the device. The formation method and materials of the channel layer 11 and the barrier layer 12 can be designed according to actual needs, and no excessive restrictions are imposed here. The material of the channel layer 11 includes, but is not limited to, GaN, and the material of the barrier layer 12 includes, but is not limited to, aluminum gallium nitride (AlGaN).
[0042] As an example, a buffer layer 18 is also formed between the substrate 10 and the channel layer 11. Other transition layers may also be formed between the buffer layer 18 and the channel layer 11, which can be designed according to actual needs, and no excessive restrictions are imposed here.
[0043] Specifically, during the epitaxial growth of the P-type GaN layer 13, byproduct hydrogen (H) atoms from ammonia or hydrogen gas form bonds with the dopant Mg to form the Mg-H structure 131, causing the Mg in the Mg-H structure 131 to lose its activity and not participate in the formation of holes by doping GaN.
[0044] As shown in Figure 3, step S2 is then performed, in which a patterned hydrogen diffusion barrier layer 14 is formed on the P-type GaN layer 13. The patterned hydrogen diffusion barrier layer 14 has a plurality of annealing windows 141 in the preset gate region 21. The planar size of the annealing windows 141 gradually decreases from the preset source region 22 to the preset drain region 23. The preset gate region 21 is located between the preset source region 22 and the preset drain region 23.
[0045] As an example, the material of the patterned hydrogen diffusion barrier layer 14 includes, but is not limited to, silicon nitride or silicon oxide.
[0046] As shown in Figure 4, step S3 is then performed, in which the P-type GaN layer 13 is annealed based on the annealing window 141 of the patterned hydrogen diffusion barrier layer 14, so that the Mg in the Mg-H structure 131 in the P-type GaN layer 13 not covered by the patterned hydrogen diffusion barrier layer 14 is activated to form activated Mg132, thereby causing the activation rate of Mg in the preset gate region 21 to gradually decrease from the preset source region 22 to the preset drain region 23.
[0047] Specifically, step S3 is a selective annealing process, in which the patterned hydrogen diffusion barrier layer 14 selects the activated annealing region and performs annealing treatment on the P-type GaN layer 13 exposed by the annealing window 141. After annealing, the Mg-H structure 131 will effectively reduce and release hydrogen to obtain the activated Mg132. The activated Mg132 is used as a dopant to dop the P-type GaN layer 13 to form holes. Since the planar size of the annealing window 141 gradually decreases from the preset source region 22 to the preset drain region 23, after annealing, the concentration of the Mg-H structure 131 in the P-type GaN layer 13 in the preset gate region 21 gradually increases from the preset source region 22 to the preset drain region 23. That is, the closer to the preset drain region 23, the higher the concentration of the Mg-H structure 131 in the P-type GaN layer 13, and the higher the resistivity of the corresponding P-type GaN layer 13 material. This can reduce the leakage current of the P-type GaN layer 13 near the drain when the device is off, and can also reduce the electric field strength on the drain side, thereby improving the reliability of the device.
[0048] As an example, the method of annealing the P-type GaN layer 13 based on the annealing window 141 of the patterned hydrogen diffusion barrier layer 14 includes laser annealing, which efficiently activates Mg in a precisely controlled area while avoiding unnecessary thermal damage to the surrounding materials. This annealing method is not limited to this embodiment.
[0049] As shown in Figure 5, step S4 is then performed to remove the patterned hydrogen diffusion barrier layer 14.
[0050] As shown in Figures 6 and 7, step S5 is then performed, in which a gate metal layer 15 is formed on the preset gate region 21 of the P-type GaN layer 13, and the P-type GaN layer 13 outside the preset gate region 21 is removed.
[0051] As shown in Figure 8, step S6 is then performed, in which a source metal layer 16 is formed on the preset source region 22 of the barrier layer 12, and a drain metal layer 17 is formed on the preset drain region 23 of the barrier layer 12.
[0052] Thus, as shown in Figure 8, the fabrication of the HEMT device in this embodiment is complete.
[0053] This embodiment also provides a HEMT device, as shown in Figure 8, the HEMT device comprising:
[0054] Substrate 10 and channel layer 11 and barrier layer 12 sequentially stacked on substrate 10;
[0055] A Mg-doped P-type GaN layer 13 is located on the barrier layer 12;
[0056] A gate metal layer 15 is located in a predetermined gate region 21 on the P-type GaN layer 13, a source metal layer 16 is located in a predetermined source region 22 on the barrier layer 12, and a drain metal layer 17 is located in a predetermined drain region 23; wherein, the gate metal layer 15 is located between the source metal layer 16 and the drain metal layer 17, and the doping rate of Mg in the P-type GaN layer 13 gradually decreases from the source metal layer 16 to the drain metal layer 17.
[0057] The HEMT device can be prepared using the above-described method, but it is not limited to this method. Other suitable preparation methods are also possible, and their beneficial effects can be found in the detailed description of the preparation methods, which will not be repeated here.
[0058] As an example, the material of the substrate 10 includes one of Si, SiC and sapphire, and can be selected according to actual needs, without excessive restrictions here.
[0059] Specifically, the channel layer 11 and the barrier layer 12 are made of different materials. A two-dimensional electron gas is formed at the interface between the channel layer 11 and the barrier layer 12. This two-dimensional electron gas serves as the channel of the HEMT device, providing a conductive channel between the source and drain of the device. The formation method and materials of the channel layer 11 and the barrier layer 12 can be designed according to actual needs, and no excessive restrictions are imposed here. The material of the channel layer 11 includes, but is not limited to, GaN, and the material of the barrier layer 12 includes, but is not limited to, AlGaN.
[0060] As an example, a buffer layer 18 is also formed between the substrate 10 and the channel layer 11. Other transition layers may also be formed between the buffer layer 18 and the channel layer 11, which can be designed according to actual needs, and no excessive restrictions are imposed here.
[0061] In summary, the HEMT device and its fabrication method of the present invention achieve a gradual distribution of Mg activation rate in the predetermined gate region by forming a patterned hydrogen diffusion barrier layer on a P-type GaN layer and using the annealing window of the barrier layer to perform local annealing treatment on the P-type GaN layer. Specifically, the Mg activation rate gradually decreases from the source to the drain. Correspondingly, the Mg-H concentration in the P-type GaN layer closer to the drain is higher, and the resistivity of the corresponding P-type GaN layer material is also higher. This can reduce the leakage current of the P-type GaN layer near the drain in the off-state and reduce the electric field strength on the drain side, thus improving the reliability of the device. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial applicability.
[0062] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A method for fabricating a HEMT device, characterized in that, The fabrication method includes: providing a substrate, and sequentially forming a channel layer, a barrier layer, and an in-situ Mg-doped P-type GaN layer on the substrate; wherein, a Mg-H structure with Mg and H bonds is formed in the P-type GaN layer; forming a patterned hydrogen diffusion barrier layer on the P-type GaN layer, wherein the patterned hydrogen diffusion barrier layer has a plurality of annealing windows in a predetermined gate region, the planar size of the annealing windows gradually decreasing from a predetermined source region to a predetermined drain region, wherein the predetermined gate region is located between the predetermined source region and the predetermined drain region; and the annealing windows based on the patterned hydrogen diffusion barrier layer... The P-type GaN layer is annealed to activate the Mg in the Mg-H structure of the P-type GaN layer not covered by the patterned hydrogen diffusion barrier layer, thereby gradually decreasing the activation rate of Mg in the preset gate region from the preset source region to the preset drain region; the patterned hydrogen diffusion barrier layer is removed; a gate metal layer is formed on the preset gate region of the P-type GaN layer, and the P-type GaN layer outside the preset gate region is removed; a source metal layer is formed on the preset source region of the barrier layer, and a drain metal layer is formed on the preset drain region of the barrier layer.
2. The method for fabricating a HEMT device according to claim 1, characterized in that: The substrate material includes one of Si, SiC, and sapphire.
3. The method for fabricating a HEMT device according to claim 1, characterized in that: The channel layer is made of GaN, and the barrier layer is made of AlGaN.
4. The method for fabricating a HEMT device according to claim 1, characterized in that: A buffer layer is also formed between the substrate and the channel layer.
5. The method for fabricating a HEMT device according to claim 1, characterized in that: The patterned hydrogen diffusion barrier layer is made of silicon nitride or silicon oxide.
6. The method for fabricating a HEMT device according to claim 1, characterized in that: The method for annealing the P-type GaN layer based on the annealing window of the patterned hydrogen diffusion barrier layer includes laser annealing.
7. A HEMT device, characterized in that, The HEMT device includes: a substrate and a channel layer and a barrier layer sequentially stacked on the substrate; a Mg-doped P-type GaN layer located on the barrier layer; a gate metal layer located in a predetermined gate region on the P-type GaN layer; a source metal layer located in a predetermined source region on the barrier layer; and a drain metal layer located in a predetermined drain region. The gate metal layer is located between the source metal layer and the drain metal layer, and the Mg doping rate in the P-type GaN layer gradually decreases from the source metal layer to the drain metal layer.
8. The HEMT device according to claim 7, characterized in that: A buffer layer is also formed between the substrate and the channel layer.
9. The HEMT device according to claim 7, characterized in that: The substrate material includes one of Si, SiC, and sapphire.
10. The HEMT device according to claim 7, characterized in that: The channel layer is made of GaN, and the barrier layer is made of AlGaN.