A method for manufacturing a radio frequency transistor with a self-alignment structure

Abstract

The present invention relates to a method for fabricating a radio frequency transistor with a self-alignment structure, comprising: graphene growth, spin-coating two photoresists, depositing aluminum and gold, Lift-off, natural oxidation, depositing gold to form a self-alignment structure, spin-coating a transfer adhesive, attaching a transition substrate, mechanical peeling (accompanied by self-oxidation of aluminum), attaching a target substrate, van der Waals bonding, and dissociation cleaning. The present invention first pre-fabricates the device structure on a substrate, and then integrally peels and transfers it onto the target substrate. The whole process does not cause any pollution or damage to the target substrate, greatly improving the electrical performance of the device. Moreover, this method is compatible with semiconductor processes and is suitable for large-scale applications.

Description

Technical Field

[0001] The present invention belongs to the field of integrated circuit manufacturing, and particularly relates to a method for fabricating a radio frequency transistor with a self-aligned structure. Background Art

[0002] In recent years, wireless network technology has been revolutionized to 4G / 5G. The huge demand for information transmission and high transmission rate requirements pose higher demands on the transmission rate of high-speed transistors. Currently, the radio frequency electronics industry is basically satisfied by Si-based transistors such as MOSFETs, SiGe HBTs, and HEMTs. However, the common problems faced by current technologies such as Si MOSFETs are the continuous reduction of the process scale, which brings about short-channel effects, low operating voltage, large surface scattering and other effects, making the field effect transistor reach its optimal performance and it is difficult to further significantly improve in future expectations.

[0003] The radio frequency transistor, which is the core foundation of the communication field, requires high-speed and high-gain characteristics. In addition, the further development of radio frequency electronics technology requires very small sizes and new materials. Two-dimensional materials represented by graphene have excellent carrier transport properties. Combining its high mobility and high saturation velocity characteristics, 2D materials represented by graphene have become strong candidates for radio frequency electronic products.

[0004] In the stages of long metals and the like in traditional semiconductor devices, high-energy metal ions will cause structural damage to the channel material, thus deteriorating the electrical performance of the device. A new fabrication method needs to be found for radio frequency transistors. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for fabricating a radio frequency transistor with a self-aligned structure. This method first pre-fabricates the device structure on a substrate, and then integrally peels and transfers it to the target substrate. The whole process does not cause any pollution and damage to the target substrate, greatly improving the electrical performance of the device. Moreover, this method is compatible with semiconductor processes and is suitable for large-scale applications.

[0006] The present invention provides a method for fabricating a radio frequency transistor with a self-aligned structure, including the following steps:

[0007] Provide a substrate;

[0008] Grow a graphene layer on the upper surface of the substrate;

[0009] Spin-coat two photoresists with different photosensitive characteristics on the upper surface of the graphene layer;

[0010] Perform photolithography on the two photoresists to form a pattern;

[0011] Deposit aluminum and gold on the upper surface of the pattern;

[0012] Perform the Lift-off operation to remove the two photoresists;

[0013] In an air atmosphere, the aluminum surface is naturally oxidized to form an alumina dielectric layer;

[0014] Continue to deposit gold to form a self-aligned structure;

[0015] Spin-coat a transfer glue on the surface of the above self-aligned structure;

[0016] In a vacuum environment, attach a transition rigid substrate to the transfer glue,

[0017] Peel the transition temporary rigid substrate from the substrate by mechanical peeling, and the exposed aluminum surface undergoes self-oxidation to form a self-oxidized dielectric layer. At this time, the self-aligned structure (i.e., the device layer, including the source, drain, dielectric layer, etc.) and the laminated structure formed by the transfer glue are peeled off from the substrate;

[0018] In a vacuum environment, complete the van der Waals bonding of the laminated structure with the target substrate;

[0019] Separate the transition temporary rigid substrate by debonding;

[0020] Clean to remove the transfer glue, and obtain a radio frequency transistor with a self-aligned structure.

[0021] The substrate includes at least one of copper, nickel, germanium, titanium, platinum, gold, iron, silver, etc.

[0022] The method for obtaining the graphene layer includes at least one of chemical vapor deposition and plasma-enhanced chemical vapor deposition.

[0023] The two photoresists are PMMA and P(MMA / MAA) or two other photoresists with different photosensitive characteristics.

[0024] The transfer glue includes at least one of PVA, EVA, PMMA, thermosensitive glue, photosensitive glue, chemical sensitive glue, soluble glue, thermal slip glue, mechanical peeling glue, laser glue.

[0025] The transition temporary rigid substrate includes at least one of glass, sapphire, ceramic, metal, hard polymer.

[0026] The target substrate is a hard semiconductor substrate, and the hard semiconductor substrate is at least one of materials such as silicon, silicon dioxide, germanium, silicon carbide, silicon nitride, III-V, II-V, sapphire, ITO, SrTiO3, etc., or a flexible substrate, and the flexible substrate is at least one of materials such as polyimide, polyethylene naphthalate, polycarbonate, elastomeric polymer, thermoplastic polymer, etc.

[0027] The surface of the target substrate has two-dimensional materials grown thereon or two-dimensional materials transferred thereto. These two-dimensional materials include, but are not limited to, graphene layers, boron nitride, two-dimensional transition metal carbonitrides (including, but not limited to, Ti3C2, Ti2C, Nb2C, Ti3AlC2, etc.), two-dimensional metal borides (Fe2B2, Cr2B2), transition metal dichalcogenide (TMDCs) materials (including, but not limited to, MoS2, MoSe2, WSe2, MoTe2, PtSe2, etc.), metal-organic framework compound (MOFs) materials, perovskite (CsPbCl3, CsPbI3, FaPbI3) materials, and two-dimensional materials formed by arranging one-dimensional materials (including, but not limited to, Ag nanowire thin film materials, carbon nanotube thin film materials, etc.).

[0028] The debonding method includes at least one of thermal debonding, laser debonding, mechanical peeling debonding, and chemical immersion debonding.

[0029] Beneficial effects

[0030] In the present invention, the pre-preparation of the device structure is first completed on a substrate, and then the whole is peeled off and transferred onto the target substrate. The target substrate is not contaminated or damaged throughout the process, and the electrical performance of the device is greatly improved. Moreover, this method is compatible with semiconductor processes and is suitable for large-scale applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic flow chart of the present invention.

[0032] Figure 2 It is a process flow chart of Embodiment 1 of the present invention.

[0033] Figure 3 It is an SEM photograph of a radio frequency transistor with a self-aligned structure obtained in Embodiment 2.

[0034] Figure 4 For Figure 3 The enlarged SEM photograph within the white wireframe marked as a in the figure.

[0035] Figure 5 For Figure 3 The enlarged SEM photograph within the white wireframe marked as b in the figure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0037] Example 1

[0038] This example provides a graphene transfer method, as Figure 1 and 2 shown, including the following steps:

[0039] S1: Provide a substrate;

[0040] S2: Grow a graphene layer on the upper surface of the substrate;

[0041] S3: Spin-coat two photoresists with different photosensitive characteristics on the upper surface of the graphene layer;

[0042] S4: Perform photolithography on the two photoresists to form a pattern;

[0043] S5: Deposit aluminum and gold on the upper surface of the pattern;

[0044] S6: Perform a Lift-off operation to remove the two photoresists;

[0045] S7: In an air atmosphere, the aluminum is naturally oxidized to form a layer of alumina dielectric layer;

[0046] S8: Continue to deposit gold to form a self-aligned structure;

[0047] S9: Spin-coat a transfer glue on the surface of the above self-aligned structure;

[0048] S10: In a vacuum environment, attach a transition rigid substrate to the transfer glue;

[0049] S11: By mechanical peeling, the transition temporary rigid substrate is peeled off from the substrate, and the exposed aluminum surface undergoes self-oxidation to form a self-oxidation dielectric layer. At this time, the laminated structure formed by the self-aligned structure and the transfer glue is peeled off from the substrate;

[0050] S12: In a vacuum environment, the laminated structure is completed with a van der Waals bond to the target substrate;

[0051] S13: By debonding, the transition temporary rigid substrate is separated;

[0052] S14: Clean to remove the transfer glue to obtain a radio frequency transistor with a self-aligned structure.

[0053] S1: Provide a substrate; As an example, the substrate includes at least one of copper, nickel, germanium, titanium, platinum, gold, iron, silver, etc. The substrate provides good support for the subsequent layers of materials to be fabricated.

[0054] S2: Grow a graphene layer on the upper surface of the substrate; as an example, the method for growing the graphene layer includes at least one of chemical vapor deposition and plasma-enhanced chemical vapor deposition. In this embodiment, a germanium substrate is preferably used, and a single-layer graphene is grown on the surface of the germanium substrate by chemical vapor deposition.

[0055] S3: Spin-coat two photoresists with different light-sensitive characteristics on the upper surface of the graphene layer; as an example, PMMA and P(MMA / MAA) are taken as examples.

[0056] S9: Spin-coat a transfer glue on the surface of the above self-aligned structure; as an example, the transfer glue includes at least one of PVA, EVA, PMMA, thermosensitive glue, photosensitive glue, chemical-sensitive glue, soluble glue, thermal-slip glue, mechanical peeling glue, and laser glue.

[0057] S10: Attach a transition rigid substrate to the transfer glue in a vacuum environment; as an example, the transition temporary rigid substrate includes at least one of glass, sapphire, ceramic, metal, and hard polymer.

[0058] S12: In a vacuum environment, complete van der Waals bonding between the stacked structure and the target substrate; as an example, the target substrate is a hard semiconductor substrate, and the hard semiconductor substrate is at least one of materials such as silicon, silicon dioxide, germanium, silicon carbide, silicon nitride, III-V, II-V, sapphire, ITO, SrTiO3, etc., or a flexible substrate, and the flexible substrate is at least one of materials such as polyimide, polyethylene naphthalate, polycarbonate, elastomeric polymer, and thermoplastic polymer.

[0059] There are two-dimensional materials grown on the surface of the target substrate or two-dimensional materials transferred. These two-dimensional materials include, but are not limited to, graphene layers, boron nitride, two-dimensional transition metal carbonitrides (including, but not limited to, Ti3C2, Ti2C, Nb2C, Ti3AlC2, etc.), two-dimensional metal borides (Fe2B2, Cr2B2), transition metal dichalcogenide (TMDCs) materials (including, but not limited to, MoS2, MoSe2, WSe2, MoTe2, PtSe2, etc.), metal-organic framework compound MOFs materials, perovskite (CsPbCl3, CsPbI3, FaPbI3) materials, and two-dimensional materials formed by arranging one-dimensional materials (including, but not limited to, Ag nanowire thin film materials, carbon nanotube thin film materials, etc.).

[0060] S13: Separate the transition temporary rigid substrate by debonding; as an example, the debonding method includes at least one of thermal debonding, laser debonding, mechanical peeling debonding, and chemical immersion debonding.

[0061] Example 2

[0062] (1) Graphene is grown on a Ge substrate to form a Gr / Ge structure;

[0063] (2) Two kinds of photoresists, namely 60 nm PMMA950 A2 and 500 nm Copolymer EL11, are spin-coated on the Gr / Ge respectively;

[0064] (3) Photolithography is performed on the two kinds of photoresists to form patterns;

[0065] (4) 580 nm of aluminum and 50 nm of gold are deposited on the upper surface of the patterns;

[0066] (5) A Lift-off operation is carried out to remove the two kinds of photoresists;

[0067] (6) In an air atmosphere, the aluminum is naturally oxidized to form a layer of alumina dielectric layer;

[0068] (7) Another 50 nm of gold is continuously deposited to form a self-aligned structure;

[0069] (8) A phenolic resin transfer glue is spin-coated on the surface of the above self-aligned structure;

[0070] (9) In a vacuum environment, a transition rigid glass substrate is attached to the transfer glue;

[0071] (10) The transition temporary rigid substrate is peeled off from the substrate by mechanical peeling, and the exposed aluminum surface undergoes self-oxidation to form a self-oxidized dielectric layer; at this time, the laminated structure formed by the self-aligned structure and the transfer glue is peeled off from the substrate;

[0072] (11) In a vacuum environment, the laminated structure is bonded to the target substrate by van der Waals bonding;

[0073] (12) The transition temporary rigid substrate is separated by debonding;

[0074] (13) Cleaning is carried out to remove the transfer glue, and a radio frequency transistor with a self-aligned structure is obtained.

[0075] Figure 3 is the SEM photo of the finally obtained radio frequency transistor with a self-aligned structure.

[0076] Figure 4 is Figure 3 the enlarged SEM photo within the white wireframe marked as a in Figure 5 is Figure 3 the enlarged SEM photo within the white wireframe marked as b in

Claims

1. A method for fabricating a radio frequency transistor with a self-aligned structure, comprising the following steps: Providing a substrate; Growing a graphene layer on the upper surface of the substrate; Spin-coating two photoresists with different photosensitive characteristics on the upper surface of the graphene layer; Performing photolithography on the two photoresists to form a pattern; Depositing aluminum and gold on the upper surface of the pattern; Performing a Lift-off operation to remove the two photoresists; In an air atmosphere, the aluminum surface is naturally oxidized to form a layer of aluminum oxide dielectric layer; Continuing to deposit gold to form a self-aligned structure; Spin-coating a transfer adhesive on the surface of the above self-aligned structure; In a vacuum environment, attaching a transition rigid substrate to the transfer adhesive; Peeling the transition rigid substrate from the substrate by mechanical peeling. At this time, the laminated structure formed by the self-aligned structure and the transfer adhesive is peeled from the substrate; In a vacuum environment, completing van der Waals bonding of the laminated structure with a target substrate on which the channel material has been pre-patterned; Separating the transition temporary rigid substrate by debonding; Cleaning to remove the transfer adhesive to obtain a radio frequency transistor with a self-aligned structure.

2. The method according to claim 1, wherein: The substrate comprises at least one of copper, nickel, germanium, titanium, platinum, gold, iron, and silver.

3. The method according to claim 1, wherein: The method for growing the graphene layer comprises at least one of chemical vapor deposition and plasma-enhanced chemical vapor deposition.

4. The method according to claim 1, characterized in that: The two photoresists are PMMA and P(MMA / MAA) or two other photoresists with different photosensitive characteristics.

5. The method according to claim 1, characterized in that: The transfer adhesive comprises at least one of PVA, EVA, PMMA, thermosensitive adhesive, photosensitive adhesive, chemical-sensitive adhesive, soluble adhesive, thermal slip adhesive, mechanical peeling adhesive, and laser adhesive.

6. The method according to claim 1, characterized in that: The transition temporary rigid substrate comprises at least one of glass, sapphire, ceramic, metal, and hard polymer.

7. The method according to claim 1, characterized in that: The target substrate is a hard semiconductor substrate, and the hard semiconductor substrate is at least one of silicon, silicon dioxide, germanium, silicon carbide, silicon nitride, III-V, II-V, sapphire, ITO, SrTiO3 materials, or a flexible substrate, and the flexible substrate is at least one of polyimide, polyethylene naphthalate, polycarbonate, elastomeric polymer, and thermoplastic polymer.

8. The method according to claim 1, characterized in that: There is a two-dimensional material grown on the surface of the target substrate or a two-dimensional material is transferred.

9. The method according to claim 1, wherein: The debonding method comprises at least one of thermal debonding, laser debonding, mechanical peeling debonding, and chemical immersion debonding.

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