EPITAXIAL SUBSTRATE WITH 2D MATERIAL INTERPOSER, MANUFACTURING METHOD, AND MANUFACTURING ASSEMBLY

Abstract

Disclosed is an epitaxial substrate with a 2D material interposer on a surface of a polycrystalline substrate. The ultra-thin 2D material interposer is grown by van der Waals epitaxy. The lattice constant of a surface layer of the ultra-thin 2D material interposer and the coefficient of thermal expansion of the substrate base are highly fit with those of AlGaN or GaN. The ultra-thin 2D material interposer is of a single-layer structure or a composite-layer structure. An AlGaN or GaN single crystalline epitaxial layer is grown on the ultra-thin 2D material interposer by virtue of the van der Waals epitaxy. Therefore, the large-size substrate may be manufactured with far lower costs than related single crystal wafers.

Claims

1. An epitaxial substrate with a two-dimensional (2D) material interposer on a surface of a polycrystalline substrate, wherein the ultra-thin 2D material interposer is grown by van der Waals epitaxy; a lattice constant of a surface layer of the ultra-thin 2D material interposer and a coefficient of thermal expansion of the polycrystalline substrate base are highly fit with those of AlGaN or GaN respectively; the ultra-thin 2D material interposer is of a single-layer structure or a composite-layer structure; and an AlGaN or GaN single crystalline epitaxial layer is grown on the ultra-thin 2D material interposer by the van der Waals epitaxy.

2. The epitaxial substrate with a 2D material interposer according to claim 1, wherein a thickness of the ultra-thin 2D material interposer ranges from 0.5 nm to 1000 nm.

3. The epitaxial substrate with a 2D material interposer according to claim 1, wherein the ultra-thin 2D material interposer is a 2D layer applicable to AlGaN or GaN epitaxy.

4. The epitaxial substrate with a 2D material interposer according to claim 1, wherein the ultra-thin 2D material interposer is a composite-layer structure formed by a top layer and a bottom layer, the top layer is a 2D layer applicable to AlGaN or GaN epitaxy, and the bottom layer is a 2D material suitable as a single crystalline base layer.

5. The epitaxial substrate with a 2D material interposer according to claim 1, wherein a lattice constant misfit is not more than 5% between a lattice constant of AlN or GaN and a lattice constant of a single-layer structure or a top layer of a composite-layer structure of the ultra-thin 2D material interposer applicable to AlGaN or GaN epitaxy.

6. The epitaxial substrate with a 2D material interposer according to claim 1, wherein differences between the coefficient of thermal expansion of the polycrystalline substrate base and coefficients of thermal expansion of AlN or GaN in a direction parallel to a van der Waals epitaxy interface is not more than 1.5×10.sup.−6° C..sup.−1.

7. The epitaxial substrate with a 2D material interposer according to claim 1, wherein a manufacturing method comprises the following steps: step 1: pretreat a polished polycrystalline substrate to comply with a starting material ready for an epitaxial growth in subsequent manufacturing procedures; step 2: grow a single crystalline 2D material layer by existing manufacturing processes and cover a surface of the polished polycrystalline substrate with the single crystalline 2D material layer of a single-layer structure or a van der Waals epitaxially grown composite-layer structure with a heterojunction to serve as an interposer; alternatively, transfer a non-single crystalline 2D material layer applicable to AlGaN and GaN epitaxy to the surface of the the polished polycrystalline substrate material by existing procedures to serve as the interposer, and form the epitaxial substrate, wherein the lattice constant of the surface layer and the coefficient of thermal expansion of the epitaxial substrate are highly fit with those of AlGaN or GaN respectively; and step 3: grow the AlGaN or GaN single crystalline epitaxial layer on the interposer by utilizing the van der Waals epitaxy to finish the epitaxial substrate with the 2D material interposer.

8. The epitaxial substrate with a 2D material interposer according to claim 7, wherein in the step 2, the processes involved in the 2D material interposer include thin film growth, deposition, mechanical transfer, and coating; and a total thickness of the 2D material interposer of the single-layer structure or the composite-layer structure is in a range of 0.5 nm to 1000 nm.

9. The epitaxial substrate with a 2D material interposer according to claim 7, wherein in the step 2, the ultra-thin single crystalline 2D material interposer is manufactured by the following steps starting with a metal foil as an initial substrate. step A: make polycrystalline metal foils slowly pass through a hot zone at a temperature slightly lower than a nominal melting point of copper in an established procedure in order to form single crystalline metal foils; and select the single crystalline metal foils with a crystal orientation suitable for later 2D material growth; step B: cut one selected metal foil in step A to form a foil with a sharp tip at one end in the crystal orientation; step C: physically joint the sharp-tipped foil in step B with an untreated polycrystalline metal foil; step D: repeat the thermal treatment of step A on the jointed metal foil from step C to form a single crystalline metal foil with the crystal orientation; step E: epitaxially grow a thin single crystalline 2D material interposer on top of the metal foil from step D; and step F: transfer the grown single crystalline 2D material interposer from a surface of the metal foil in step E to the surface of the pretreated polycrystalline substrate by established procedures, supplemented by necessary clamping fixtures to align a lattice orientation to a substrate flat or a substrate notch.

10. Apply the epitaxial substrate with a 2D material interposer made by claim 1 for a subsequent epitaxial device growth toward manufacture of AlGaN-based wide bandgap components or the GaN-based laser diode components.

11. Apply the epitaxial substrate with a 2D material interposer made by claim 2 for a subsequent epitaxial device growth toward manufacture of AlGaN-based wide bandgap components or the GaN-based laser diode components.

12. Apply the epitaxial substrate with a 2D material interposer made by claim 3 for a subsequent epitaxial device growth toward manufacture of AlGaN-based wide bandgap components or the GaN-based laser diode components.

13. Apply the epitaxial substrate with a 2D material interposer made by claim 4 for a subsequent epitaxial device growth toward a manufacture of AlGaN-based wide bandgap components or the GaN-based laser diode components.

14. Apply the epitaxial substrate with a 2D material interposer made by claim 5 for a subsequent epitaxial device growth toward a manufacture of AlGaN-based wide bandgap components or the GaN-based laser diode components.

15. Apply the epitaxial substrate with a 2D material interposer made by claim 6 for a subsequent epitaxial device growth toward a manufacture of AlGaN-based wide bandgap components or the GaN-based laser diode components.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0033] FIG. 1 is a schematic diagram of a zinc oxide substrate corroded during the epitaxy;

[0034] FIG. 2 is a schematic structural diagram of a two-dimensional material transition metal dichalcogenides (TMDs);

[0035] FIG. 3 is a schematic structural diagram of a two-dimensional material hexagonal boron nitride (hBN);

[0036] FIGS. 4A and 4B are schematic diagrams of mechanically formed stacks;

[0037] FIGS. 5A and 5B are schematic diagrams of physical and chemical vapor deposition;

[0038] FIG. 6 is a hexagonal symmetry structure diagram of a crystalline structure on an epitaxial junction;

[0039] FIG. 7 is a schematic diagram of intrinsic or hetero epitaxy on a surface of an existing high-quality single crystalline substrate;

[0040] FIG. 8 is a schematic structural diagram of a first embodiment of the present disclosure;

[0041] FIG. 9 is a schematic structural diagram of a second embodiment of the present disclosure; and

[0042] FIG. 10 is a flowchart of a manufacturing method of the present disclosure.

DESCRIPTION OF EMBODIMENTS

[0043] The present disclosure is further described below with reference to the accompanying drawings and specific embodiments.

[0044] Referring to FIG. 8 and FIG. 9, the present disclosure provides an epitaxial substrate with a 2D material interposer on a surface of a polycrystalline substrate 1, wherein the ultra-thin 2D material interposer 2 is grown by van der Waals epitaxy; the lattice constant of a surface layer of the ultra-thin 2D material interposer 2 and the coefficient of thermal expansion of the substrate base are highly fit with those of AlGaN or GaN; the ultra-thin 2D material interposer 2 is of a single-layer structure (as shown in FIG. 9) or a composite-layer structure (heterogeneous material bonding, as shown in FIG. 8); and an AlGaN or GaN single crystalline epitaxial layer 3 is grown on the ultra-thin 2D material interposer 2 by virtue of the van der Waals epitaxy.

[0045] The polycrystalline substrate 1 adopts sintered AlN, other ceramic or metal substrates.

[0046] The thickness of the ultra-thin 2D material interposer 2 ranges from 0.5 nm to 1000 nm.

[0047] The ultra-thin 2D material interposer 2 is a 2D layer applicable to AlGaN or GaN epitaxy, such as a WS.sub.2 or MoS.sub.2 single-layer structure, as shown in FIG. 9.

[0048] The ultra-thin 2D material interposer 2 is of a composite-layer structure formed by a top layer 21 and a bottom layer 22, the top layer 21 is a 2D layer applicable to AlGaN or GaN epitaxy, such as WS.sub.2 or MoS.sub.2, and the bottom layer 22 is a 2D material suitable as a single crystalline base layer, such as hexagonal boron nitride (hBN). The lattice constant misfit is not more than 5% between the lattice constant of AlN or GaN and the lattice constant (a) of a single-layer structure or the top layer 21 of a composite-layer structure of the ultra-thin 2D material interposer 2 applicable to AlGaN or GaN epitaxy, such as WS.sub.2, MoS.sub.2 or other 2D materials.

[0049] The differences between the coefficients of thermal expansion (CTE) of the polycrystalline substrate base and AlN or GaN in the direction parallel to the van der Waals epitaxy interface is not more than 1.5×10.sup.−6° C..sup.−1. The stable material quality may be maintained in AlGaN and GaN epitaxial procedures without adverse effects or damage.

TABLE-US-00002 TABLE 2 Material Lattice constant a (nm) Hexagonal boron nitride (hBN) 0.25 Graphene 0.246 WS.sub.2 0318 MoS.sub.2 0.3161 WSe.sub.2 0.3297 MoSe.sub.2 0.3283

[0050] According to the single crystalline 2D material interposer with a heterojunction in the present disclosure, a single crystalline hBN layer is manufactured by existing processes and is transferred to the surface of the polycrystalline substrate 1 by the existing processes, and then a 2D material of the top layer is completed on the surface layer. The adopted hBN is an embodiment, which is not limited to the hBN.

[0051] The present disclosure further provides a new method. A lattice orientation of the single crystalline 2D material interposer is dependent on a wafer flat or wafer notch of an original substrate to ensure that the manufactured single crystalline substrate and a traditional substrate keep the consistency of lattice orientation or customization requirements of customers.

[0052] The present disclosure provides a manufacturing method of the epitaxial substrate with the 2D material interposer, including the following steps:

[0053] step 1: a polished polycrystalline substrate 1 (wafer) is pretreated to comply with an epitaxial growth grade and is subjected to appropriate pretreatment (including wafer cleaning) as a starting material ready for an epitaxial growth in subsequent manufacturing procedures;

[0054] step 2: a single crystalline 2D material layer is grown by existing manufacturing processes, and the surface of a polycrystalline substrate material is covered with the 2D material layer of a single-layer structure or a van der Waals epitaxially grown composite-layer structure with a heterojunction to serve as an interposer 2; alternatively, a non-single crystalline 2D material layer applicable to AlGaN and GaN epitaxy is grown on the surface of sapphire and then is peeled off and transferred to the surface of the polycrystalline substrate material by existing procedures to serve as an interposer 2, and the substrate is formed, wherein the lattice constant of a surface layer and the coefficient of thermal expansion of the substrate base are highly fit with those of AlGaN and GaN respectively; and

[0055] step 3: an AlGaN or GaN single crystalline epitaxial layer 3 is grown on the interposer 2 by utilizing the van der Waals epitaxy to finish the epitaxial substrate with the 2D material interposer.

[0056] In the step 2, the processes involved in the 2D material interposer include but not limited to the thin film growth, deposition, mechanical transfer, and coating; and the total thickness of the 2D material interposer of a single-layer structure or a composite-layer structure is in the range of 0.5 nm to 1000 nm.

[0057] As shown in FIG. 10, in the step 2, the ultra-thin single crystalline 2D material interposer is manufactured by the following steps starting with a metal foil as the initial substrate: step A: polycrystalline copper foils are enabled to slowly pass through a hot zone at a temperature slightly lower than the nominal melting point of copper in an established procedure in order to form single crystalline metal foils; and the single crystalline copper foils (such as Cu(110) applicable to the growth of single crystalline hBN) with the preferred crystal orientation suitable for later 2D material growth are selected; step B: orientational characterization and cutting: one selected metal foil in step A is cut to form a foil with a sharp tip at one end in the preferred (specific) crystal orientation; step C: the sharp-tipped foil in step B is physically jointed with an untreated polycrystalline metal foil; step D: the thermal treatment of step A is repeated on the jointed metal foil from step C to form a single crystalline metal foil with the preferred crystal orientation; step E: a thin single crystalline 2D material interposer (such as Cu(110) applicable to the growth of single crystalline hBN) is epitaxially grown/deposited on top of the metal foil from step D; step F: the thin single crystalline 2D material interposer is transferred from the surface of the metal foil in step E to the surface of the pretreated polycrystalline substrate by established procedures, supplemented by necessary clamping fixtures to align the lattice orientation to the substrate flat or the substrate notch; and step G: other types of thin single crystalline 2D materials are epitaxially grown as needed to meet the lattice fitting requirements of subsequent epitaxial procedures.

[0058] Further, subsequent epitaxial and other necessary manufacturing procedures may be continued on the epitaxial substrate with the 2D material interposer, for example, components including wide bandgap optoelectronic and electronic components such as AlGaN UVC LEDs (but not limited to UVC LEDs) and GaN-based laser diodes are manufactured, and an AlGaN-based wide bandgap component or a GaN-based laser diode component (AlGaN is used for C-band LEDs in UVC LEDs; and GaN is used for blue laser diodes) may be formed.

[0059] The present disclosure solves the problems of epitaxial substrates of existing UVC LEDs and GaN-based laser diodes and is capable of significantly reducing procedure costs, effectively improving the efficiency of the AlGaN-based wide bandgap optoelectronic and electronic components and the GaN-based laser diode components and reducing manufacturing costs.

[0060] The above are only preferred embodiments of the present disclosure, and are not intended to limit the present disclosure. It should be pointed out that after this description is read, the equivalent changes made by those skilled in the art according to the design idea of the present disclosure all fall into the scope of protection of the present disclosure.