Bipolar gallium nitride heterojunction material and preparation method and device thereof

Abstract

The invention relates to a bipolar gallium nitride heterojunction material, a preparation method thereof and a device. The preparation method comprises the following steps: S1, sequentially growing a first buffer layer, a first Ga polar gallium nitride channel layer, a first insertion layer and a first barrier layer on the upper surface of a first substrate from bottom to top; sequentially growing a second buffer layer, a second Ga polar gallium nitride channel layer, a second insertion layer and a second barrier layer on the upper surface of the second substrate from bottom to top; the upper surfaces of the first Ga polar gallium nitride channel layer and the second Ga polar gallium nitride channel layer are Ga polar; s2, aligning the lower surface of the first substrate with the upper surface of the second barrier layer, and performing bonding to obtain a bipolar bonding structure; s3, the second substrate and the second buffer layer in the bipolar bonding structure are removed, the lower surface of the second Ga polar gallium nitride channel layer is exposed, and a bipolar gallium nitride heterojunction material is obtained; and the lower surface of the second Ga polarity gallium nitride channel layer is N polarity.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductors, and particularly relates to a bipolar gallium nitride heterojunction material, a preparation method thereof, and a device. Background Art

[0002] As a third-generation wide-bandgap semiconductor material, gallium nitride has advantages such as a high breakdown electric field, a high electron mobility, and a high electron saturation velocity. Thanks to these advantages, optoelectronic devices and microwave devices based on gallium nitride semiconductor materials have played a huge role in many fields. The epitaxial growth process of gallium-polar gallium nitride materials is relatively mature, and it is easier to obtain a high-quality crystal structure and a low background carrier concentration. Therefore, current gallium nitride electronic devices mainly rely on gallium-polar heterostructure materials.

[0003] However, compared with traditional gallium-polar gallium nitride heterojunction materials, nitrogen-polar gallium nitride heterojunction materials have many natural advantages in improving the operating frequency and output frequency of devices.

[0004] However, directly epitaxially growing nitrogen-polar gallium nitride heterojunction materials is extremely difficult. When directly epitaxially growing nitrogen-polar gallium nitride, the difficult control of the nitrogen-polar gallium nitride polarity will lead to a poor surface morphology, the strong ability of the nitrogen-polar surface to adsorb oxygen atoms will lead to a large background carrier concentration, and the large stress under large mismatch will lead to film cracking. The preparation difficulty of nitrogen-polar gallium nitride heterojunction materials has greatly limited the application of nitrogen-polar gallium nitride materials. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a bipolar gallium nitride heterojunction material, a preparation method thereof, and a device. The technical problems to be solved by the present invention are realized through the following technical solutions:

[0006] The first aspect of the present invention provides a preparation method of a bipolar gallium nitride heterojunction material, including the following steps:

[0007] S1: A first buffer layer, a first Ga-polar gallium nitride channel layer, a first insertion layer, and a first barrier layer are sequentially grown from bottom to top on the upper surface of a first substrate; a second buffer layer, a second Ga-polar gallium nitride channel layer, a second insertion layer, and a second barrier layer are sequentially grown from bottom to top on the upper surface of a second substrate; the upper surfaces of the first Ga-polar gallium nitride channel layer and the second Ga-polar gallium nitride channel layer are both Ga-polar;

[0008] S2: Align the lower surface of the first substrate and the upper surface of the second barrier layer, and perform bonding to obtain a bipolar bonding structure;

[0009] S3: Remove the second substrate and the second buffer layer in the bipolar bonding structure to expose the lower surface of the second Ga-polar gallium nitride channel layer, obtaining a bipolar gallium nitride heterojunction material; the lower surface of the second Ga-polar gallium nitride channel layer is N-polar.

[0010] In an achievable manner, step S2 includes:

[0011] S201: Grow an insulating layer on the lower surface of the first substrate and the upper surface of the second barrier layer respectively;

[0012] S202: Bond the insulating layer on the lower surface of the first substrate and the insulating layer on the upper surface of the second barrier layer together through bonding glue or a metal bonding process to obtain a bipolar bonding structure.

[0013] In an achievable manner, step S3 includes:

[0014] S301: Peel or etch the second substrate in the bipolar bonding structure to expose the lower surface of the second buffer layer;

[0015] S302: Etch the second buffer layer in the bipolar bonding structure to expose the lower surface of the second Ga-polar gallium nitride channel layer.

[0016] In an achievable manner, the materials of the first substrate and the second substrate are sapphire or silicon.

[0017] In an achievable manner, when the material of the second substrate is sapphire, the specific operation of step S301 is:

[0018] Perform laser lift-off on the second substrate in the bipolar bonding structure to remove the second substrate and expose the lower surface of the second buffer layer.

[0019] In an achievable manner, when the material of the second substrate is silicon, the specific operation of step S301 is:

[0020] Perform dry etching or wet etching on the second substrate in the bipolar bonding structure to remove the second substrate and expose the lower surface of the second buffer layer.

[0021] In an achievable manner, the materials of the first buffer layer and the second buffer layer include gallium nitride;

[0022] The materials of the first insertion layer and the second insertion layer include aluminum nitride;

[0023] The materials of the first barrier layer and the second barrier layer include aluminum gallium nitride.

[0024] The second aspect of the present invention provides a bipolar gallium nitride heterojunction material, which is prepared according to the preparation method of the bipolar gallium nitride heterojunction material provided in the first aspect of the present invention, and includes a second Ga-polar gallium nitride channel layer, a second insertion layer, a second barrier layer, a first substrate, a first buffer layer, a first Ga-polar gallium nitride channel layer, a first insertion layer, and a first barrier layer sequentially arranged from bottom to top;

[0025] The upper surfaces of the first Ga-polar gallium nitride channel layer and the second Ga-polar gallium nitride channel layer are both Ga-polar;

[0026] The lower surface of the second Ga-polar gallium nitride channel layer is N-polar.

[0027] In an implementable manner, an insulating layer is further included between the second barrier layer and the first substrate.

[0028] The third aspect of the present invention provides a bipolar gallium nitride heterojunction device, including: the bipolar gallium nitride heterojunction material provided in the second aspect of the present invention;

[0029] A first device structure, including one of an ultraviolet detector structure, a biosensor structure, and a gas sensor structure, is located on the upper surface of the bipolar gallium nitride heterojunction material;

[0030] A second device structure, including a HEMT device structure, is located on the lower surface of the bipolar gallium nitride heterojunction material.

[0031] Compared with the prior art, the beneficial effects of the present invention:

[0032] A preparation method of a bipolar gallium nitride heterojunction material provided by the present invention bonds a first Ga-polar gallium nitride channel layer and a second Ga-polar gallium nitride channel layer into the same structure, and by removing the second substrate and the second buffer layer under the second Ga-polar gallium nitride channel layer, the lower surface of the second Ga-polar gallium nitride channel layer is exposed. Since the upper surfaces of the first Ga-polar gallium nitride channel layer and the second Ga-polar gallium nitride channel layer are both Ga-polar, therefore, the exposed lower surface of the second Ga-polar gallium nitride channel layer is N-polar, realizing the appearance of two polarities of polar semiconductors in a single structure. By preparing different device structures on the N-polar surface and the Ga-polar surface, the electronic, photon, and acoustic functions can be simultaneously realized on the opposite surfaces (upper and lower surfaces) of the same wafer. Description of the Drawings

[0033] Figure 1 is a step flow chart of a preparation method of a bipolar gallium nitride heterojunction material provided by an embodiment of the present invention;

[0034] Figures 2a to 2cIt is a step structure diagram of a method for preparing a bipolar gallium nitride heterojunction material provided by an embodiment of the present invention;

[0035] Figure 3 It is a schematic structural diagram of a bipolar gallium nitride heterojunction device provided by an embodiment of the present invention. Specific embodiments

[0036] The present invention will be further described in detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0037] Embodiment 1

[0038] Please refer to Figure 1 , Figure 1 It is a step flow diagram of a method for preparing a bipolar gallium nitride heterojunction material provided by an embodiment of the present invention.

[0039] In the first aspect of this embodiment, a method for preparing a bipolar gallium nitride heterojunction material is provided, including the following steps:

[0040] S1: A first buffer layer, a first Ga-polar gallium nitride channel layer, a first insertion layer, and a first barrier layer are sequentially grown from bottom to top on the upper surface of the first substrate; a second buffer layer, a second Ga-polar gallium nitride channel layer, a second insertion layer, and a second barrier layer are sequentially grown from bottom to top on the upper surface of the second substrate; the upper surfaces of the first Ga-polar gallium nitride channel layer and the second Ga-polar gallium nitride channel layer are both Ga-polar.

[0041] Specifically, as Figure 2a shown, the materials of the first substrate and the second substrate are sapphire or silicon. When the upper surfaces of the first Ga-polar gallium nitride channel layer and the second Ga-polar gallium nitride channel layer are both Ga-polar, the lower surfaces of the first Ga-polar gallium nitride channel layer and the second Ga-polar gallium nitride channel layer are both N-polar. By growing a buffer layer, a Ga-polar gallium nitride channel layer, an insertion layer, and a barrier layer on the substrate, an epitaxial GaN heterostructure is obtained. In this embodiment, two epitaxial GaN heterostructures with the same structure are obtained. One is the first epitaxial GaN heterostructure, including: the first substrate, the first buffer layer, the first Ga-polar gallium nitride channel layer, the first insertion layer, and the first barrier layer; the other is the second epitaxial GaN heterostructure, including: the second substrate, the second buffer layer, the second Ga-polar gallium nitride channel layer, the second insertion layer, and the second barrier layer. The corresponding layer structures in the first epitaxial GaN heterostructure and the second epitaxial GaN heterostructure are the same. Here, the first and the second are only for easy distinction. The materials of the first buffer layer and the second buffer layer include gallium nitride, the materials of the first insertion layer and the second insertion layer include aluminum nitride, and the materials of the first barrier layer and the second barrier layer include aluminum gallium nitride (AlGaN).

[0042] S2: Align the lower surface of the first substrate with the upper surface of the second barrier layer and bond them to obtain a bipolar bonding structure.

[0043] In this embodiment, as Figure 2b shown, step S2 includes:

[0044] S201: Grow an insulating layer on the lower surface of the first substrate and the upper surface of the second barrier layer respectively.

[0045] Specifically, deposit a layer of SiN x on the lower surface of the first substrate and the upper surface of the second barrier layer as the insulating layer to relieve the stress and thermal adaptation problems of bonding, protect the nitride epitaxial film on the surface of the epitaxial GaN heterostructure, and at the same time ensure the mutual insulation between the first epitaxial GaN heterostructure and the second epitaxial GaN heterostructure.

[0046] S202: Bond the insulating layer on the lower surface of the first substrate and the insulating layer on the upper surface of the second barrier layer together through a bonding adhesive or a metal bonding process to obtain a bipolar bonding structure.

[0047] Specifically, the bipolar bonding structure includes a second substrate, a second buffer layer, a second Ga-polarity gallium nitride channel layer, a second insertion layer, a second barrier layer, an insulating layer, a first substrate, a first buffer layer, a first Ga-polarity gallium nitride channel layer, a first insertion layer, and a first barrier layer, which are arranged in sequence from bottom to top.

[0048] S3: Remove the second substrate and the second buffer layer in the bipolar bonding structure to expose the lower surface of the second Ga-polarity gallium nitride channel layer, obtaining a bipolar gallium nitride heterojunction material; the lower surface of the second Ga-polarity gallium nitride channel layer is N-polarity.

[0049] In this embodiment, as Figure 2c shown, step S3 includes:

[0050] S301: Peel or etch the second substrate in the bipolar bonding structure to expose the lower surface of the second buffer layer.

[0051] Specifically, when the material of the second substrate is sapphire, the specific operation of step S301 is:

[0052] Perform laser lift-off on the second substrate in the bipolar bonding structure to remove the second substrate and expose the lower surface of the second buffer layer.

[0053] Specifically, when the material of the second substrate is silicon, the specific operation of step S301 is:

[0054] Dry etch or wet etch the second substrate in the bipolar bonding structure to remove the second substrate and expose the lower surface of the second buffer layer.

[0055] Furthermore, the silicon substrate can be etched by acid, so the silicon substrate can be removed by wet etching. Dry etching can also be used. First, the silicon substrate is thinned, and then the silicon substrate is removed by deep silicon etching.

[0056] S302: Etch the second buffer layer in the bipolar bonding structure to expose the lower surface of the second Ga-polar gallium nitride channel layer.

[0057] Specifically, since the upper surface of the second Ga-polar gallium nitride channel layer is Ga-polar, after etching the second buffer layer, the lower surface of the exposed second Ga-polar gallium nitride channel layer is N-polar, and thus a bipolar gallium nitride heterojunction material can be obtained. The upper surface of the bipolar gallium nitride heterojunction material is Ga-polar, and the lower surface is N-polar.

[0058] The second aspect of this embodiment provides a bipolar gallium nitride heterojunction material, which is prepared according to the preparation method of the bipolar gallium nitride heterojunction material provided in the first aspect of this embodiment, and includes a second Ga-polar gallium nitride channel layer, a second insertion layer, a second barrier layer, a first substrate, a first buffer layer, a first Ga-polar gallium nitride channel layer, a first insertion layer, and a first barrier layer arranged in sequence from bottom to top. Among them, the upper surfaces of the first Ga-polar gallium nitride channel layer and the second Ga-polar gallium nitride channel layer are both Ga-polar, and the lower surface of the second Ga-polar gallium nitride channel layer is N-polar.

[0059] In an implementable manner, an insulating layer is further included between the second barrier layer and the first substrate.

[0060] Please refer to Figure 3 , Figure 3It is a schematic structural diagram of a bipolar gallium nitride heterojunction device provided by an embodiment of the present invention. The third aspect of this embodiment provides a bipolar gallium nitride heterojunction device, including: the bipolar gallium nitride heterojunction material, the first device structure, and the second device structure provided by the second aspect of this embodiment. Among them, the first device structure includes one of an ultraviolet detector structure, a biosensor structure, and a gas sensor structure, and is located on the upper surface (Ga-polarity surface) of the bipolar gallium nitride heterojunction material; the second device structure includes a HEMT device structure and is located on the lower surface (N-polarity surface) of the bipolar gallium nitride heterojunction material. Further, by using the preparation methods of ultraviolet detectors, biosensors, gas sensors, and HEMT device structures in the prior art, one of an ultraviolet detector, a biosensor, and a gas sensor is prepared on the upper surface of the bipolar gallium nitride heterojunction material, and a HEMT device structure is prepared on the lower surface of the bipolar gallium nitride heterojunction material, so that devices with two functions can be realized in the same semiconductor structure. Exemplarily, the HEMT device structure includes: a source electrode, a drain electrode, a gate dielectric layer, and a gate electrode. Among them, the source electrode and the drain electrode are respectively located at both ends of the lower surface of the bipolar gallium nitride heterojunction material, the gate dielectric layer is located on the lower surface of the bipolar gallium nitride heterojunction material between the source electrode and the drain electrode, and the gate electrode is located on the lower surface of the gate dielectric layer.

[0061] The preparation method of the bipolar gallium nitride heterojunction material provided by this embodiment bonds the first Ga-polarity gallium nitride channel layer and the second Ga-polarity gallium nitride channel layer into the same structure, and by removing the second substrate and the second buffer layer under the second Ga-polarity gallium nitride channel layer, the lower surface of the second Ga-polarity gallium nitride channel layer is exposed. Since the upper surfaces of the first Ga-polarity gallium nitride channel layer and the second Ga-polarity gallium nitride channel layer are both Ga-polarity, the exposed lower surface of the second Ga-polarity gallium nitride channel layer is N-polarity, realizing two polarities of polar semiconductors in a single structure. By preparing different device structures on the N-polarity surface and the Ga-polarity surface, electronic, photonic, and acoustic functions can be simultaneously realized on the opposite surfaces (upper and lower surfaces) of the same wafer.

[0062] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for preparing a bipolar gallium nitride heterojunction material, characterized in that: The following steps are involved: S1: growing a first buffer layer, a first Ga-polarity gallium nitride channel layer, a first insertion layer and a first barrier layer in sequence from bottom to top on the upper surface of the first substrate; growing a second buffer layer, a second Ga-polarity gallium nitride channel layer, a second insertion layer and a second barrier layer in sequence from bottom to top on the upper surface of the second substrate; the upper surfaces of the first Ga-polarity gallium nitride channel layer and the second Ga-polarity gallium nitride channel layer are both Ga-polarity; S2: aligning the lower surface of the first substrate and the upper surface of the second barrier layer, and bonding them to obtain a bipolar bonding structure; S3: removing the second substrate and the second buffer layer in the bipolar bonding structure to expose the lower surface of the second Ga-polarity gallium nitride channel layer, thereby obtaining a bipolar gallium nitride heterojunction material; The lower surface of the second Ga-polarity gallium nitride channel layer is N-polarity.

2. The method for preparing the bipolar gallium nitride heterojunction material according to claim 1, characterized in that: Step S2 includes: S201: growing an insulating layer on the lower surface of the first substrate and the upper surface of the second barrier layer; S202: Bonding the insulating layer on the lower surface of the first substrate and the insulating layer on the upper surface of the second barrier layer together by bonding glue or metal bonding process to obtain a bipolar bonding structure.

3. The method for preparing the bipolar gallium nitride heterojunction material according to claim 1, characterized in that: Step S3 includes: S301: peeling or etching the second substrate in the bipolar bonding structure to expose the lower surface of the second buffer layer; S302: etching the second buffer layer in the bipolar bonding structure to expose the lower surface of the second Ga-polarity gallium nitride channel layer.

4. The method for preparing the bipolar gallium nitride heterojunction material according to claim 3, characterized in that: The first substrate and the second substrate are made of sapphire or silicon.

5. The method for preparing the bipolar gallium nitride heterojunction material according to claim 4, characterized in that: When the material of the second substrate is sapphire, the specific operation of step S301 is: The second substrate in the bipolar bonding structure is subjected to laser stripping to remove the second substrate and expose the lower surface of the second buffer layer.

6. The method for preparing the bipolar gallium nitride heterojunction material according to claim 4, characterized in that: When the material of the second substrate is silicon, the specific operation of step S301 is: The second substrate in the bipolar bonding structure is dry-etched or wet-etched to remove the second substrate and expose the lower surface of the second buffer layer.

7. The method for preparing the bipolar gallium nitride heterojunction material according to claim 1, characterized in that: The materials of the first buffer layer and the second buffer layer include gallium nitride; The materials of the first insertion layer and the second insertion layer include aluminum nitride; The materials of the first barrier layer and the second barrier layer include aluminum gallium nitride.

8. A bipolar gallium nitride heterojunction material, characterized in that: The bipolar gallium nitride heterojunction material is prepared according to the method for preparing the bipolar gallium nitride heterojunction material according to any one of claims 1 to 7, comprising a second Ga-polar gallium nitride channel layer, a second insertion layer, a second barrier layer, a first substrate, a first buffer layer, a first Ga-polar gallium nitride channel layer, a first insertion layer and a first barrier layer arranged in sequence from bottom to top; The upper surfaces of the first Ga-polarity gallium nitride channel layer and the second Ga-polarity gallium nitride channel layer are both Ga-polarity; The lower surface of the second Ga-polarity gallium nitride channel layer is N-polarity.

9. The bipolar gallium nitride heterojunction material according to claim 8, characterized in that: An insulating layer is further included between the second barrier layer and the first substrate.

10. A bipolar gallium nitride heterojunction device, characterized in that: include: The bipolar gallium nitride heterojunction material according to claim 8 or 9; A first device structure, including one of an ultraviolet detector structure, a biosensor structure, and a gas sensor structure, is located on the upper surface of the bipolar gallium nitride heterojunction material; The second device structure, including a HEMT device structure, is located on the lower surface of the bipolar gallium nitride heterojunction material.

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