A monolithic integrated material and its preparation method

Abstract

The present invention discloses a monolithic integrated material and a preparation method thereof. The monolithic integrated material can further reduce the volume of a radio frequency front-end module and avoid problems such as parasitic loss, response delay, and noise introduced when discrete components of the front-end module are integrated. The preparation method of the monolithic integrated material is simple and efficient, laying the foundation for monolithic integration of radio frequency front-end modules. The use of the monolithic integrated material reduces the cost of the radio frequency front-end module. Compared with various existing discrete packages, the present invention provides a new idea for integrated packaging. The monolithic integrated material can be widely used in sensors, filters, and GaN switches.

Description

Technical Field

[0001] The present invention belongs to the field of electronic component materials, and in particular relates to a monolithic integrated material and a preparation method thereof. Background Art

[0002] Gallium nitride high-electron-mobility transistors (GaN HEMTs) and thin-film bulk acoustic resonators (FBARs) are RF devices with superior overall performance, emerging in recent years with the rapid development of modern wireless communication technology. GaN HEMTs offer the advantages of extremely high quality factors (Q) and integration on IC chips. Their compatibility with complementary metal oxide semiconductor (CMOS) processes facilitates device fabrication process optimization and the integration of diverse devices.

[0003] With the popularization of 5G mobile communication technology and the surge in mobile data traffic, the era of big data is also driving the growth of the communications terminal market. The higher demand for data transmission speeds is making RF front-end modules more diverse and complex. Existing RF front-end modules are constructed by assembling multiple discrete chip components on a single laminate or PC board. The disadvantage of this approach is that different chips must be interconnected, which leads to electrical connection loss and increased assembly complexity, size, and cost.

[0004] Monolithic integration technology solves the problem of RF front-end modules being assembled from multiple discrete chip components, and is therefore being used to optimize and improve RF front-end modules for electronic communications. However, existing monolithic integration technology suffers from technical issues such as poor RF front-end module integration, high losses, and high costs. Therefore, it is necessary to develop a new monolithic integration material to address these issues. Summary of the Invention

[0005] In order to overcome the problems existing in the above-mentioned prior art, one of the objects of the present invention is to provide a monolithic integrated material; the second object of the present invention is to provide a method for preparing such a monolithic integrated material; and the third object of the present invention is to provide an application of such a monolithic integrated material.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A first aspect of the present invention provides a monolithic integrated material, comprising:

[0008] a substrate and a bonding layer covering a surface area of ​​the substrate;

[0009] a first single crystal layer of AlN formed on and covering the bonding layer;

[0010] a channel layer GaN formed on and covering the first single crystal layer AlN;

[0011] A heterojunction formed on and covering the channel layer GaN;

[0012] The surface of the substrate has a groove; the groove is located on the surface of the substrate close to the first single crystal layer AlN; the monolithic integrated material also includes a Bragg reflection layer, which is embedded between the groove and the first single crystal layer AlN, and the Bragg reflection layer passes through the bonding layer.

[0013] Preferably, the bonding layer includes at least one of Au, Sn, Cr, Ti, Pt, and Ni; further preferably, the bonding layer includes at least one of Au and Sn.

[0014] Preferably, the Bragg reflection layer includes at least one of SiO2, AlN, W, and GaN; further preferably, the Bragg reflection layer is SiO2.

[0015] Preferably, the thickness of the first single crystal layer AlN is 0.01 μm-10 μm; further preferably, the thickness of the first single crystal layer AlN is 0.1 μm-5 μm; even further preferably, the thickness of the first single crystal layer AlN is 0.5 μm-3 μm.

[0016] Preferably, the thickness of the channel layer GaN is 0.5 μm-15 μm; further preferably, the thickness of the channel layer GaN is 1 μm-10 μm.

[0017] Preferably, the thickness of the heterojunction is 2 nm-40 nm; further preferably, the thickness of the heterojunction is 3 nm-30 nm; even further preferably, the thickness of the heterojunction is 5 nm-20 nm.

[0018] Preferably, the heterojunction includes at least one of AlN, AlGaN, InAlGaN, and InAlN; further preferably, the heterojunction includes at least one of AlN, AlGaN, and InAlGaN.

[0019] Preferably, the substrate includes at least one of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a diamond substrate, a zinc oxide substrate, and a LaAlO2 substrate; further preferably, the substrate includes at least one of a silicon substrate, a sapphire substrate, and a silicon carbide substrate; even further preferably, the substrate is a silicon substrate.

[0020] The second aspect of the present invention provides a method for preparing the monolithic integrated material according to the first aspect of the present invention, comprising the following steps:

[0021] 1) epitaxially growing a base layer, a stress transition layer, and a functional layer on a first substrate in sequence using a metal organic vapor phase epitaxy device to obtain an integrated epitaxial wafer; the functional layer sequentially includes a stacked first single crystal layer AlN, a channel layer GaN, and a heterojunction;

[0022] 2) Inverting the integrated epitaxial wafer, bonding the functional layer heterojunction of the integrated epitaxial wafer to a second substrate coated with bonding adhesive, and then using laser lift-off technology to decompose the stress transition layer and peel off the first substrate to obtain a peeled epitaxial material;

[0023] 3) etching the stress transition layer of the peeled epitaxial material, using the etch stop layer as a functional layer, to obtain the etched epitaxial material;

[0024] 4) preparing a cavity structure, a Bragg reflection layer and a bonding layer on a third substrate in sequence;

[0025] 5) Inverting the etched epitaxial material and bonding it to the bonding layer of the third substrate, and then peeling off the second substrate to obtain the monolithic integrated material.

[0026] Preferably, the first substrate includes at least one of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a diamond substrate, a zinc oxide substrate, and a LaAlO2 substrate; further preferably, the first substrate includes at least one of a silicon substrate, a sapphire substrate, and a silicon carbide substrate; even further preferably, the first substrate is a silicon substrate.

[0027] Preferably, the second substrate includes at least one of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a diamond substrate, a zinc oxide substrate, and a LaAlO2 substrate; further preferably, the second substrate includes at least one of a silicon substrate, a sapphire substrate, and a silicon carbide substrate; even further preferably, the second substrate is a silicon substrate.

[0028] Preferably, the third substrate includes at least one of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a diamond substrate, a zinc oxide substrate, and a LaAlO2 substrate; further preferably, the third substrate includes at least one of a silicon substrate, a sapphire substrate, and a silicon carbide substrate; even further preferably, the third substrate is a silicon substrate.

[0029] Preferably, the base layer is AlN.

[0030] Preferably, the stress transition layer includes at least one of AlGaN, AlN, and GaN.

[0031] Preferably, the thickness of the base layer is 1 nm-300 nm; further preferably, the thickness of the base layer is 100 nm-300 nm; even further preferably, the thickness of the base layer is 150 nm-200 nm.

[0032] Preferably, the thickness of the stress transition layer is 100 nm-17000 nm; further preferably, the thickness of the stress transition layer is 500 nm-8000 nm; even further preferably, the thickness of the stress transition layer is 1200 nm-3000 nm.

[0033] Preferably, the gas used in the organic vapor phase epitaxy equipment includes at least one of trimethylaluminum, triethylaluminum, trimethylgallium, triethylgallium, ammonia, hydrogen, and nitrogen.

[0034] Preferably, the gas used for the etching includes at least one of chlorine and boron trichloride.

[0035] Preferably, in the etching gas, the molar ratio of chlorine to boron trichloride is (0.3-100):1.

[0036] Preferably, the etching power is 100W-300W.

[0037] Preferably, in the preparation method, after obtaining the monolithic integrated material, the step of annealing the monolithic integrated material is further included.

[0038] Preferably, the annealing temperature is 400°C-800°C.

[0039] Preferably, the annealing atmosphere is a nitrogen atmosphere.

[0040] The third aspect of the present invention provides the use of the monolithic integrated material according to the first aspect of the present invention in sensors, filters, and GaN switches.

[0041] The beneficial effects of the present invention are:

[0042] The monolithic integrated material disclosed in the present invention can further reduce the volume of the RF front-end module and avoid problems such as parasitic loss, response delay and noise introduced when integrating discrete devices in the front-end module; the preparation method of the monolithic integrated material is simple and efficient, laying the foundation for the monolithic integration of the RF front-end module. The use of the monolithic integrated material reduces the cost of the RF front-end module. Compared with various existing discrete packages, the present invention provides a new idea for integrated packaging. The monolithic integrated material can be widely used in sensors, filters, and GaN switches. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the monolithic integrated epitaxial material structure of the GaN HEMT and filter device prepared in Example 1.

[0044] Figure 2 Schematic diagram of the monolithic integrated material structure of the GaN switch and filter device prepared in Example 1. DETAILED DESCRIPTION

[0045] The following examples further illustrate the specific implementation of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are readily achievable or understood by those skilled in the art with reference to the prior art. Materials or instruments used without manufacturer identification are assumed to be commercially available conventional products.

[0046] Example 1

[0047] The steps for preparing the monolithic integrated material in this example are as follows:

[0048] 1) Before bonding the GaN HEMT and filter device monolithic integration materials, a single-crystal AlN base layer with a thickness of 200 nm is grown on a sapphire single crystal substrate from bottom to top using an MOCVD device; a stress transition layer AlxGa1-xN with a thickness of 300 nm, where x is 10; a stress transition layer AlN / GaN superlattice with an AlN thickness of 2 nm, a GaN thickness of 6 nm, and a period of 100 periods; a stress transition layer AlN / AlGaN superlattice with an AlN thickness of 4 nm, an AlGaN thickness of 6 nm, and a period of 100 periods; a functional layer single-crystal AlN with a first single crystal layer of AlN and a thickness of 1 μm; a GaN channel layer with a thickness of 1 μm; and a heterojunction AlGaN with a thickness of 20 nm. Figure 1 Schematic diagram of the monolithic integrated epitaxial material structure of the GaN HEMT and filter device prepared in Example 1. Substrate represents a sapphire single crystal substrate, AlN seed layer represents an AlN base layer, AlGaN buffer represents an AlxGa1-xN stress transition layer, AlN / GaN SL buffer and AlN / AlGaN SL buffer represent a stress transition layer AlN / GaN superlattice and a stress transition layer AlN / AlGaN superlattice, respectively, AlN layer represents the first AlN single crystal layer, GaN channel layer represents a GaN channel layer, and barrier layer represents a heterojunction AlGaN layer. The heterojunction layer may optionally include at least one of AlGaN, AlN, InAlN, and InAlGaN.

[0049] 2) Taking another Si substrate 1, applying bonding glue on the Si substrate to bond the device functional layer in step 1) to the bonding layer on the Si substrate;

[0050] 3) The bonding material in step 2) is inverted with the Si substrate facing downward, and laser lift-off is used to decompose the GaN and remove the single crystal substrate;

[0051] 4) Based on the materials in step 3), the stress transition layer AlGaN, the stress transition layer AlN / GaN superlattice, and the stress transition layer AlN / AlGaN superlattice layer are etched away by adjusting the ICP dry etching process, the etching gas being chlorine and boron trichloride in a gas ratio of 100:20 and the etching power being 100 W;

[0052] 5) Prepare another Si substrate (II) and sequentially fabricate a cavity structure, a Bragg reflector layer, and a bonding layer in a fixed area on the Si substrate. Selectively etch the surface of the Si substrate to form a cavity, in which a first Bragg reflector layer or a second Bragg reflector layer is fabricated. The Bragg reflector layer comprises SiO2. Then, a bonding layer of Au / Sn is formed on the surface of the Si substrate. Bond the device functional layer from step 4) to the bonding layer on the Si substrate.

[0053] 6) The surface of the material from step 5) is smoothed and annealed at 400° C. in a nitrogen atmosphere. The etching damage on the surface of the material is repaired, and finally a monolithic integrated material for GaN HEMT and filter components in a radio frequency front-end module is prepared. Figure 2 Schematic diagram of the monolithic integrated material structure of the GaN switch and filter device prepared in Example 1. Here, substrate represents the second Si substrate, reflect layer represents the Bragg reflector layer, bonding layer represents the Au / Sn bonding layer, AlN layer represents the first AlN single crystal layer, GaN channel layer represents the GaN channel layer, and barrier layer represents the heterojunction.

[0054] Example 2

[0055] The steps for preparing the monolithic integrated material in this example are as follows:

[0056] 1) Before bonding the GaN HEMT and filter device monolithic integration materials, a single-crystal AlN base layer with a thickness of 150 nm is grown on a sapphire single crystal substrate from bottom to top using an MOCVD device; a peeling layer GaN with a thickness of 800 nm, a stress transition layer AlxGa1-xN with a thickness of 200 nm, where x is 15, a stress transition layer AlN / GaN superlattice with an AlN thickness of 4 nm, a GaN thickness of 4 nm, and an 80-period period; a stress transition layer AlN / AlGaN superlattice with an AlN thickness of 4 nm, an AlGaN thickness of 4 nm, and an 80-period period; a functional layer single-crystal AlN with a first single-crystal layer of AlN and a thickness of 1.5 μm; a GaN channel layer with a thickness of 5 μm and a heterojunction AlN with a thickness of 5 nm;

[0057] 2) Taking another Si substrate 1, applying bonding glue on the Si substrate to bond the device functional layer in step 1) to the bonding layer on the Si substrate;

[0058] 3) The bonding material in step 2) is inverted with the Si substrate facing downward, and laser lift-off is used to decompose the GaN and remove the single crystal substrate;

[0059] 4) Based on the materials in step 3), the stress transition layer AlGaN, the stress transition layer AlN / GaN superlattice, and the stress transition layer AlN / AlGaN superlattice layer are etched away by adjusting the ICP dry etching process, the etching gas being chlorine and boron trichloride in a gas ratio of 80:40 and the etching power being 150 W;

[0060] 5) Prepare another Si substrate (II) and sequentially prepare a cavity structure, a Bragg reflector layer, and a bonding layer in a fixed area on the Si substrate. Selectively etch the surface of the Si substrate to form a cavity. Prepare a first or second Bragg reflector layer comprising SiO2 in the cavity. Then, form a bonding layer of Ni on the surface of the Si substrate. Bond the device functional layer from step 4) to the bonding layer on the Si substrate.

[0061] 6) The surface of the material from step 5) is smoothed and annealed at 500° C. in a nitrogen atmosphere. The etching damage on the surface of the material is repaired, and finally a monolithic integrated material for GaN HEMT and filter components in a radio frequency front-end module is prepared.

[0062] Example 3

[0063] The steps for preparing the monolithic integrated material in this example are as follows:

[0064] 1) Before bonding the GaN HEMT and filter device monolithic integration materials, a single-crystal AlN base layer with a thickness of 200 nm is grown from bottom to top on a sapphire single crystal substrate using an MOCVD device; a peeling layer GaN with a thickness of 1200 nm, a stress transition layer AlxGa1-xN with a thickness of 500 nm, where x is 17, a stress transition layer AlN / GaN superlattice with an AlN thickness of 4 nm, a GaN thickness of 6 nm, and a period number of 120 periods, a stress transition layer AlN / AlGaN superlattice with an AlN thickness of 6 nm, an AlGaN thickness of 6 nm, and a period number of 90 periods, a functional layer single crystal AlN with a first single crystal layer of AlN and a thickness of 1.5 μm, a GaN channel layer with a thickness of 10 μm, and a heterojunction InAlGaN with a thickness of 7 nm;

[0065] 2) Taking another Si substrate 1, applying bonding glue on the Si substrate to bond the device functional layer in step 1) to the bonding layer on the Si substrate;

[0066] 3) The bonding material in step 2) is inverted with the Si substrate facing downward, and laser lift-off is used to decompose the GaN and remove the single crystal substrate;

[0067] 4) Based on the materials in step 3), the stress transition layer AlGaN, the stress transition layer AlN / GaN superlattice, and the stress transition layer AlN / AlGaN superlattice layer are etched away by adjusting the ICP dry etching process. The etching gas is chlorine and boron trichloride, the gas ratio is 90:30, and the etching power is 120W.

[0068] 5) Taking another Si substrate, a cavity structure, a Bragg reflector layer, and a bonding layer are sequentially prepared in a fixed area on the Si substrate. The Si substrate surface is selectively etched to form a cavity. A first Bragg reflector layer or a second Bragg reflector layer comprising SiO2 is prepared in the cavity. A bonding layer of Ti is then formed on the surface of the Si substrate. The device functional layer from step 1) is bonded to the bonding layer on the Si substrate.

[0069] 6) The surface of the material from step 5) is smoothed and annealed at 550° C. in a nitrogen atmosphere. The etching damage on the surface of the material is repaired, and finally a monolithic integrated material that meets the requirements of GaN HEMT and filter components in the RF front-end module is prepared.

[0070] The above examples are preferred implementations of the present invention, but the implementation of the present invention is not limited to the above examples. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A monolithic integrated material, characterized in that: The monolithic integrated material comprises: a substrate and a bonding layer covering a surface area of ​​the substrate; a first single crystal layer of AlN formed on and covering the bonding layer; a channel layer GaN formed on and covering the first single crystal layer AlN; A heterojunction formed on and covering the channel layer GaN; The surface of the substrate has a groove; the groove is located on the surface of the substrate close to the first single crystal AlN layer; the monolithic integrated material further includes a Bragg reflection layer, the Bragg reflection layer is embedded between the groove and the first single crystal AlN layer, and the Bragg reflection layer passes through the bonding layer; The method for preparing the monolithic integrated material comprises the following steps: 1) epitaxially growing a base layer, a stress transition layer, and a functional layer on a first substrate in sequence using a metal organic vapor phase epitaxy device to obtain an integrated epitaxial wafer; the functional layer sequentially includes a stacked first single crystal layer AlN, a channel layer GaN, and a heterojunction; 2) Inverting the integrated epitaxial wafer, bonding the functional layer heterojunction of the integrated epitaxial wafer to a second substrate coated with bonding adhesive, and then using laser lift-off technology to decompose the stress transition layer and peel off the first substrate to obtain a peeled epitaxial material; 3) etching the stress transition layer of the peeled epitaxial material, using the etch stop layer as a functional layer, to obtain the etched epitaxial material; 4) preparing a cavity structure, a Bragg reflection layer and a bonding layer on a third substrate in sequence; The etched epitaxial material is inverted and bonded to the bonding layer of the third substrate, and then the second substrate is peeled off to obtain the monolithic integrated material.

2. The monolithic integrated material according to claim 1, characterized in that: The bonding layer includes at least one of Au, Sn, Cr, Ti, Pt, and Ni; and the Bragg reflection layer includes at least one of SiO2, AlN, W, and GaN.

3. The monolithic integrated material according to claim 2, characterized in that: The thickness of the first single crystal layer AlN is 0.01 μm-10 μm.

4. The monolithic integrated material according to claim 1, wherein: The thickness of the GaN channel layer is 0.5 μm-15 μm; the thickness of the heterojunction is 2 nm-40 nm.

5. The monolithic integrated material according to claim 4, characterized in that: The heterojunction includes at least one of AlN, AlGaN, InAlGaN, and InAlN.

6. The monolithic integrated material according to claim 1, characterized in that: The substrate includes at least one of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a diamond substrate, a zinc oxide substrate, and a LaAlO2 substrate.

7. The method for preparing a monolithic integrated material according to any one of claims 1 to 6, characterized in that: The following steps are involved: 5) epitaxially growing a base layer, a stress transition layer, and a functional layer on the first substrate in sequence using a metal organic vapor phase epitaxial growth device to obtain an integrated epitaxial wafer; the functional layer sequentially includes a stacked first single crystal layer AlN, a channel layer GaN, and a heterojunction; 6) Inverting the integrated epitaxial wafer, bonding the functional layer heterojunction of the integrated epitaxial wafer to a second substrate coated with bonding adhesive, and then using laser lift-off technology to decompose the stress transition layer and peel off the first substrate to obtain a peeled epitaxial material; 7) etching the stress transition layer of the peeled epitaxial material, using the etch stop layer as a functional layer to obtain the etched epitaxial material; 8) preparing a cavity structure, a Bragg reflection layer and a bonding layer on a third substrate in sequence; 9) Inverting the etched epitaxial material and bonding it to the bonding layer of the third substrate, and then peeling off the second substrate to obtain the monolithic integrated material.

8. The preparation method according to claim 7, characterized in that: The first substrate includes at least one of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a diamond substrate, a zinc oxide substrate, and a LaAlO2 substrate; the base layer is AlN; and the stress transition layer includes at least one of AlGaN, AlN, and GaN.

9. The preparation method according to claim 8, characterized in that: The thickness of the base layer is 1 nm to 300 nm; the thickness of the stress transition layer is 100 nm to 17000 nm.

10. Use of the monolithic integrated material according to any one of claims 1 to 6 in sensors, filters, and GaN switches.

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