A method for preparing an interconnection line of a diamond device

Abstract

A method for preparing an interconnection line of a diamond device belongs to the field of processing and preparation of ultra-wide bandgap semiconductor electronic devices. It is characterized in that: designing a circuit layout and cleaning a diamond substrate (110); then performing a photolithography process to prepare device units (120) and an interconnection region (130); plating a metal catalyst (131) on the interconnection region of the diamond surface; and in-situ growing a conductive carbon nanomaterial (132) on the diamond surface as the interconnection line. The present invention obtains a low-resistance and stable ohmic contact interconnection line on the diamond substrate, effectively avoiding the limitation of device failure caused by the breakage of the interconnection line formed by an ultra-thin metal film at present; the carbon nanomaterial interconnection line can work normally under high-temperature and high-pressure conditions and can meet the requirements of the future working environment of diamond devices. The obtained interconnection line has a low contact resistance with the diamond substrate, strong bonding force, and can withstand high-temperature and high-pressure working environments, laying a good foundation for the back-end process of future diamond-based integrated circuit preparation.

Description

Technical Field

[0001] The present invention belongs to the field of processing and preparation of ultra-wide bandgap semiconductor electronic devices, and particularly relates to a method for preparing interconnections of diamond devices. Background Art

[0002] Ultra-wide bandgap semiconductor diamond materials have broad application prospects in the fields of next-generation high-temperature, high-frequency, high-power transistors, integrated circuits, power electronic devices, optoelectronic devices, etc. Accelerating the exploration of the research and development of ultra-wide bandgap semiconductor devices such as diamond is of great significance for our country to seize the strategic high ground and achieve overtaking on a curve in future communication, energy, national defense and military and other cutting-edge fields.

[0003] With the integration of diamond devices, the influence of interconnections on the performance of the entire integrated circuit will become increasingly prominent. At present, metal interconnection is the main interconnection material for high-performance silicon-based and silicon carbide-based integrated circuits. However, due to the high-resistance characteristics and strong chemical inertness of diamond materials, the contact resistance between common metals such as gold and platinum and diamond substrates is relatively high, and their specific contact resistivity is generally in the range of 10 -4 ~10 -5 Ωcm 2 , and usually long-time annealing treatment is required to form an ohmic contact. At the same time, the bonding strength between the two is also very limited. During the preparation process and normal operation of diamond electronic devices, metal interconnections are prone to phenomena such as peeling, tearing, and burning out, which not only affect the device performance but also affect chip interconnection. Therefore, exploring an interconnection with high bonding strength, low contact resistance, and resistance to extreme working environments is crucial for diamond devices.

[0004] Carbon nanomaterials such as graphene have high carrier mobility, low capacitance, high thermal conductivity, and resistance to electron migration, and are one of the ideal materials for manufacturing low-dimensional nanoelectronic devices. Graphene or carbon nanotubes directly converted from diamond will form strong chemical bonding at the interface, and both have high thermal conductivity and can withstand high-temperature and high-pressure working environments, and may become an effective solution for diamond device interconnections. Summary of the Invention

[0005] The present invention aims to provide a method for preparing interconnections of diamond devices, with the main purpose of reducing the contact resistance between metal and diamond, reducing parasitic effects, while improving the bonding strength between the metal thin film and the diamond substrate, avoiding interconnection failure, and enhancing the service life of diamond chips under high temperature and high pressure.

[0006] The present invention provides a method for preparing interconnections of diamond devices, which is characterized by including the following steps:

[0007] 1) Design a circuit layout and clean the diamond substrate (110);

[0008] 2) Perform a lithography process to fabricate device units (120) and interconnect regions (130);

[0009] 3) Deposit a metal catalyst (131) on the interconnect region of the diamond surface;

[0010] 4) In-situ grow conductive carbon nanomaterials (132) on the surface of the diamond substrate to form interconnect lines.

[0011] Further, in the step 1), the diamond substrate is single crystal or highly preferred orientation polycrystal.

[0012] Further, in the step 2), the device unit is one of a transistor, a Schottky diode, a MOS capacitor, and a sensor.

[0013] Further, in the step 3), the method for depositing the catalyst layer is one of magnetron sputtering, electron beam deposition, and thermal evaporation.

[0014] Further, in the step 3), the metal catalyst is a metal that can undergo a catalytic reaction with diamond at high temperature, such as one of iron, nickel, copper, manganese, and cobalt.

[0015] Further, in the step 4), the method for in-situ growth is rapid annealing or vapor deposition. The conditions for rapid annealing are that the heating and cooling rate ≥ 50 °C / s and the holding time ≤ 1 min; the vapor deposition is one of pyrolytic chemical vapor deposition and plasma-enhanced chemical vapor deposition.

[0016] Further, in the step 4), the conductive carbon nanomaterials are one of graphene and carbon nanotubes.

[0017] Further, one of the specific preparation processes and steps is: 1) Design a circuit layout and clean the diamond substrate: Use software to design a circuit layout, place the single crystal diamond substrate in a sulfuric acid: nitric acid (volume ratio 1:3) mixed solution and heat for 1 h, then clean it successively with acetone, ethanol, and deionized water and dry it for standby; 2) Perform a lithography process to fabricate the interconnect region: Spin-coat a negative photoresist on the single crystal diamond substrate, pre-bake, expose, post-bake, and develop; 3) Deposit a metal catalyst and perform patterning treatment: Place the developed single crystal diamond sample in a magnetron sputtering device to deposit a 50 nm nickel film; then place the single crystal diamond sample with the deposited nickel film in acetone for stripping; 4) Anneal to form a graphene structure: Place the stripped nickel-plated single crystal diamond sample in a rapid annealing furnace for heat treatment to form graphene interconnect lines.

[0018] Further, the second specific preparation process and steps are as follows: 1) Design the circuit layout and clean the diamond substrate: Use software to design the circuit layout. Place the single-crystal diamond substrate in a sulfuric acid:nitric acid (volume ratio 1:3) mixed solution and heat for 1 h. Then, successively clean it with acetone, ethanol, and deionized water, and dry it for later use; 2) Deposit the metal catalyst: Place the developed single-crystal diamond sample in a magnetron sputtering device and deposit 10 nm of metallic nickel.

[0019] 3) Prepare the carbon nanotube structure: First, place the nickel-plated single-crystal diamond sample in a heat treatment furnace to form nickel nanoparticles from the thin film catalyst, and then place it in a microwave plasma device to grow the carbon nanotube structure;

[0020] 4) Perform the photolithography process and form interconnects after dry etching: Spin-coat a negative photoresist on the single-crystal diamond substrate, pre-bake, expose, post-bake, develop, and use oxygen plasma for dry etching for 15 min. After removing the photoresist, carbon nanotube interconnects are obtained.

[0021] Further, the third specific preparation process and steps are as follows: 1) Design the circuit layout and clean the diamond substrate: Use software to design the circuit layout. Place the single-crystal diamond substrate in a sulfuric acid:nitric acid (volume ratio 1:3) mixed solution and heat for 1 h. Then, successively clean it with acetone, ethanol, and deionized water, and dry it for later use; 2) Deposit and grow a flaky graphene structure: Place the polycrystalline diamond sample in a microwave plasma device to grow the flaky graphene structure; 3) Perform the photolithography process and form interconnects after dry etching: Spin-coat a negative photoresist on the single-crystal diamond substrate, pre-bake, expose, post-bake, develop, and use oxygen plasma for dry etching for 10 min. After removing the photoresist, graphene interconnects are obtained.

[0022] Compared with the prior art, the advantages of the present invention are as follows: 1) Obtain low-resistance and stable ohmic contact interconnects on the diamond substrate, effectively avoiding the limitation of device failure caused by the breakage of interconnects formed by ultra-thin metal films at present; 2) The carbon nanomaterial interconnects can work normally under high-temperature and high-pressure conditions, meeting the requirements of the future working environment of diamond devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art.

[0024] Figure 1 It is a schematic diagram of the preparation process of a graphene interconnect provided in Embodiment 1 of the present invention.

[0025] Figure 2 It is a schematic diagram of the structure of the interconnect of the diamond device described in the present invention.

[0026] Figure 3Schematic diagram of a preparation process for carbon nanotube interconnects provided in Embodiment 2 of the present invention,

[0027] Figure 4 Schematic diagram of a preparation process for graphene interconnects provided in Embodiment 3 of the present invention. Detailed implementation manners

[0028] Embodiment 1

[0029] The specific preparation process and steps in this embodiment are as follows:

[0030] 1) Design the circuit layout and clean the diamond substrate (S100): Use L-ledit software to design the circuit layout. Place the single-crystal diamond substrate in a sulfuric acid:nitric acid (volume ratio 1:3) mixed solution and heat for 1 h. Then, successively clean it with acetone, ethanol, and deionized water and dry it for standby.

[0031] 2) Perform photolithography to prepare the interconnect area (S101): Spin-coat negative photoresist AZnloF2020 on the single-crystal diamond substrate, pre-bake at 110 °C for 90 s, expose for 5 s, post-bake at 110 °C for 90 s, and develop for 3 min.

[0032] 3) Deposit a metal catalyst and perform patterning (S102): Place the developed single-crystal diamond sample in a magnetron sputtering device to deposit a 50 nm nickel film. The sputtering parameters are: radio frequency power 200 W, pulsed bias voltage 100 V, time 15 min, and the protective atmosphere is argon; then place the single-crystal diamond sample with the deposited nickel film in acetone for stripping.

[0033] 4) Anneal to form a graphene structure (S103): Place the stripped nickel-coated single-crystal diamond sample in a rapid annealing furnace for heat treatment to form graphene interconnects. Among them, the annealing time is 1 min, the annealing temperature is 800 °C, and the annealing atmosphere is argon.

[0034] Embodiment 2

[0035] The specific preparation process and steps in this embodiment are as follows:

[0036] 1) Design the circuit layout and clean the diamond substrate (S200): Use L-ledit software to design the circuit layout. Place the single-crystal diamond substrate in a sulfuric acid:nitric acid (volume ratio 1:3) mixed solution and heat for 1 h. Then, successively clean it with acetone, ethanol, and deionized water and dry it for standby.

[0037] 2) Deposit a metal catalyst (S201): Place the developed single-crystal diamond sample in a magnetron sputtering device to deposit 10 nm of metal nickel. The sputtering parameters are: radio frequency power 200 W, pulsed bias voltage 100 V, time 3 min, and the protective atmosphere is argon.

[0038] 3) Preparation of carbon nanotube structure (S202): The nickel-plated single-crystal diamond sample is first placed in a heat treatment furnace to form nickel nanoparticles as the thin-film catalyst, and then placed in a microwave plasma device to grow the carbon nanotube structure. Among them, the heat treatment annealing time is 1 min, the annealing temperature is 800 °C, and the annealing atmosphere is argon; the carbon nanotube growth parameters are: temperature 700 °C, time 3 min, and the ratio of acetylene, hydrogen, and argon is 1:2:4.

[0039] 4) Perform photolithography process and form interconnects after dry etching (S203): Spin-coat negative photoresist AZnloF2020 on the single-crystal diamond substrate, pre-bake at 110 °C for 90 s, expose for 5 s, post-bake at 110 °C for 90 s, develop for 3 min, perform oxygen plasma dry etching for 15 min, and obtain carbon nanotube interconnects after removing the photoresist.

[0040] Example 3

[0041] The specific preparation process and steps in this example are as follows:

[0042] 1) Design the circuit layout and clean the diamond substrate (S300): Use L-ledit software to design the circuit layout. Place the single-crystal diamond substrate in a mixed solution of sulfuric acid: nitric acid (volume ratio 1:3) and heat for 1 h, then successively clean with acetone, ethanol, and deionized water and dry for standby.

[0043] 2) Deposit and grow a flaky graphene structure (S301): Place the polycrystalline diamond sample in a microwave plasma device to grow the flaky graphene structure. The growth parameters are: temperature 650 °C, time 2 min, and the ratio of methane to hydrogen is 1:2.

[0044] 3) Perform photolithography process and form interconnects after dry etching (S302): Spin-coat negative photoresist AZnloF2020 on the single-crystal diamond substrate, pre-bake at 110 °C for 90 s, expose for 5 s, post-bake at 110 °C for 90 s, develop for 3 min, perform oxygen plasma dry etching for 10 min, and obtain graphene interconnects after removing the photoresist.

[0045] The above embodiments are preferred cases of the present invention and are not used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing an interconnection line of a diamond device, characterized in that, It includes the following steps: 1) Design the circuit layout and clean the diamond substrate (110); 2) Perform the lithography process to fabricate device units (120) and interconnect regions (130). The interconnect regions (130) interconnect multiple device units (120), and the device unit is one of a transistor, a Schottky diode, a MOS capacitor, and a sensor; 3) Deposit a metal catalyst (131) on the interconnect region on the diamond surface; 4) In-situ grow a conductive carbon nanomaterial (132) on the surface of the diamond substrate to form an interconnect line. The conductive carbon nanomaterial is one of graphene or carbon nanotubes.

2. The method for preparing the interconnection line of the diamond device according to claim 1, wherein, In step 1), the diamond substrate is single crystal or highly preferentially oriented polycrystal.

3. The preparation method of the diamond device interconnection line according to claim 1, characterized in that, In step 3), the catalyst deposition method is one of magnetron sputtering, electron beam deposition, and thermal evaporation.

4. The preparation method of the diamond device interconnection line according to claim 1, characterized in that, In step 3), the metal catalyst includes one of iron, nickel, copper, manganese, and cobalt.

5. The method for preparing the interconnection line of the diamond device according to claim 1, wherein In step 4), the in-situ growth method is rapid annealing or chemical vapor deposition. The conditions for rapid annealing are that the heating and cooling rate ≥ 50 °C / s and the holding time ≤ 1 min; the chemical vapor deposition is one of pyrolytic chemical vapor deposition and plasma-enhanced chemical vapor deposition.

6. The method for preparing the interconnection line of the diamond device according to claim 1, characterized in that, One of the specific preparation processes and steps is: 1) Design the circuit layout and clean the diamond substrate: Use software to design the circuit layout. Put the single crystal diamond substrate into a mixed solution of sulfuric acid: nitric acid with a volume ratio of 1:3 and heat for 1 h, and then successively clean with acetone, ethanol, and deionized water and dry for standby; 2) Perform the lithography process to fabricate the interconnect region: Spin-coat a negative photoresist on the single crystal diamond substrate, pre-bake, expose, post-bake, and develop; 3) Deposit the metal catalyst and perform patterning treatment: Put the developed single crystal diamond sample into a magnetron sputtering device to deposit a 50 nm nickel film; then put the single crystal diamond sample coated with the nickel film into acetone for stripping; 4) Perform annealing treatment to form a graphene structure: Put the stripped nickel-coated single crystal diamond sample into a rapid annealing furnace for heat treatment to form a graphene interconnect line.

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