Preparation method of diamond color center array based on phase separation nano mask

Abstract

The invention belongs to the technical field of micro-nano machining, and particularly relates to a preparation method of a diamond color center array based on a phase separation nano mask. The invention comprises two schemes. The scheme I comprises the following steps: pretreating a diamond raw material; depositing a hard mask layer on the surface of the diamond; coating an adhesion layer; coating a phase-separable patterned block copolymer or assembling high polymer materials such as biological macromolecules and the like; the diamond is subjected to annealing treatment; forming a nano mask by selectively etching the surface film layer; injecting nitrogen ions to form an NV color center array; removing the hard mask; and surface carbon impurities are removed through vacuum high-temperature annealing and acid pickling, and the high-quality color center array is obtained. The second scheme comprises a deposition step of simplifying a hard mask, and a phase-separable patterned high polymer material thick film is directly coated on the surface of the diamond raw material. By adopting two different technological processes, the preparation of the nano mask ion implantation color center array which is low in cost, high in mask precision and resolution, high in flux, extensible and large in area is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nano processing, and in particular relates to a method for preparing a diamond color center array based on a phase separation nano mask. Background Art

[0002] Diamond NV color center is a type of optically active point defect inside diamond, formed by the replacement of two adjacent carbon atoms by a nitrogen atom and a vacancy, and then the capture of an electron. It can exist in two electronic states: ground state and excited state. Under certain conditions, it will selectively absorb specific wavelengths and emit fluorescent photons at the same time, and is sensitive to external magnetic fields. In particular, it has great application value in room temperature quantum sensors, magnetic sensors, integrated photonic quantum chips and quantum information processing. High-precision magnetic field measurements based on NV color centers still need to be improved, and it is still difficult to obtain accurate measurements of microtesla-level magnetic field vector strength and magnetic field gradient measurements at micron-level spacing. The preparation of single NV color center arrays with high consistency, large area and high sensitivity is crucial for high-precision static magnetic field vector and magnetic field gradient detection at extremely small spacing.

[0003] At present, the preparation methods of diamond NV color centers mainly include chemical vapor deposition, thermal annealing, electron beam treatment, ion implantation, ultrafast laser irradiation, etc. The ion beam implantation method is compatible with semiconductor processes and is suitable for large-area preparation. It is currently the most widely used method for preparing NV color centers. In type IIa high-purity diamond, an N ion beam is injected through a photolithography mask to generate NV color centers after annealing, and its planar position is controlled. However, relying on the mask ion implantation process, the depth of the NV color center is Gaussian, the amount of N ion implantation is difficult to control, and it is still difficult to control the formation of a single NV color center. In response to the above problems, it is necessary to develop a nano-mask ion implantation color center array manufacturing technology that has low cost, high mask accuracy and resolution, high throughput scalability, and large area or even wafer-level preparation area. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing a diamond color center array based on a polymer phase separation nanomask, so as to achieve the manufacture of nanomask ion implantation color center arrays with high mask accuracy and resolution, high throughput scalability, and large area or even wafer-level preparation area.

[0005] The method for preparing a diamond color center array based on a polymer phase separation nanomask provided by the present invention includes two schemes:

[0006] Scheme 1: Use polymer phase separation assembly to obtain a nanopore array pattern, transfer the nanopore array pattern to a hard mask layer on the diamond surface, and then use the nanopore array hard mask to prepare a color center array by ion implantation. The specific steps are as follows:

[0007] Step S1: pre-treating the diamond surface to remove organic and inorganic impurities on the diamond surface, providing a clean surface for subsequent processes, and obtaining a pre-treated diamond surface;

[0008] Step S2: preparing a hard mask layer on the pre-treated diamond surface, wherein the hard mask layer is made of a silicon film, or an oxide film or a metal film; the film thickness is less than 200 nm;

[0009] Step S3: coating an adhesive layer on the hard mask layer to enhance the adhesion between the polymer material and the hard mask;

[0010] Step S4: coating a phase-separable patterned polymer material on the adhesive layer, and utilizing its self-assembly property to form a nano-scale pattern;

[0011] Step S5: performing annealing treatment on the selected area of ​​the thin film formed in step S4 to induce and regulate the phase separation structure of the polymer material, form a uniform nano-mask, and enhance the pattern clarity;

[0012] Step S6: etching the sample after annealing, phase separation and assembly, transferring the obtained pattern to the substrate, etching the hard mask layer (oxide film or metal film or silicon film) to obtain a nanomask layer of the nanohole array;

[0013] Step S7: Under the protection of the nanomask, nitrogen ions are implanted into the diamond to form a regular array of NV color centers;

[0014] Step S8: using wet pickling or dry reactive ion etching to remove the hard mask and expose the diamond surface implantation area;

[0015] Step S9: perform nitrogen ion implantation and high temperature annealing in a vacuum environment to activate the color center and improve its optical properties;

[0016] Step S10: post-processing the diamond NV color center array to obtain a diamond NV color center array with a clear and stable pattern.

[0017] Further:

[0018] In step S2, in the hard mask layer, the silicon thin film is prepared by spin coating, and the film thickness is 50-100 nm; the oxide thin film or metal thin film is prepared by semiconductor thin film deposition processes such as thermal evaporation, ALD, CVD or magnetron sputtering, and the film thickness is 10-50 nm, and the preferred materials are oxides such as silicon dioxide and titanium dioxide or metals such as aluminum;

[0019] In step S3, the adhesion layer material is a molecular brush layer composed of two segments of the block copolymer of the polymer material used or a non-block homopolymer molecular felt layer, with a thickness of 10-20 nm;

[0020] In step S4, the phase-separable patterned polymer material may be a diblock copolymer such as PS-b-PMMA.

[0021] In step S5, the annealing may be performed by laser annealing, overall thermal annealing, solvent-induced phase separation annealing, etc.

[0022] In step S7, the energy of the nitrogen ion implantation is 10-200 keV, and the implantation dose is 1×10 12 -1×10 14 / cm 2 .

[0023] In step S8, the acid is selected from nitric acid, sulfuric acid, and perchloric acid, preferably a mixture of nitric acid, sulfuric acid, and perchloric acid, and preferably the ratio of nitric acid / sulfuric acid / perchloric acid is 1:1:1.

[0024] In step S9, the high temperature annealing temperature is 800-1100° C. and the time is 1-2 hours.

[0025] In the present invention, the size and spacing of the color center array can be controlled by controlling the polymer phase separation and ion implantation conditions; the size range of the color center distribution points is 10nm-100nm; the color center spacing range is 10nm-100nm.

[0026] Solution 2, the specific steps are:

[0027] Step S1: pre-treating the diamond surface to remove organic and inorganic impurities on the diamond surface to obtain a pre-treated diamond surface;

[0028] Step S2: directly coating a phase-separable patterned block copolymer polymer material film with a high Flory-Huggins interaction parameter value (high χ value), or a self-assembling biomacromolecule such as amyloid protein and DNA on the pretreated diamond surface to form a nanoscale pattern, and the film thickness is greater than 200 nm (relative to the film with a thickness of less than 200 nm in the first scheme, it is called a thick film);

[0029] Step S3: performing laser or solvent annealing on the block copolymer polymer material film to improve the phase separation structure of the block copolymer polymer material; annealing is not required for the biomacromolecule film.

[0030] Step S4: etching the assembled sample, etching the thin film, and obtaining a nano-mask layer of the nano-hole array;

[0031] Step S5: directly using the polymer thick film after phase separation, assembly and selective etching as a mask to perform nitrogen ion implantation to form color centers;

[0032] Step S6: After the nitrogen ion implantation, the polymer layer is removed by acid washing;

[0033] Step S7: performing high temperature annealing in a vacuum environment to activate the color center;

[0034] Step S8: acid-washing the diamond NV color center array to improve the color center quality.

[0035] Further:

[0036] In step S2, typical materials of the high-χ-value block copolymer polymer are PS-b-P2VP, PS-b-PDMS, etc., and the χ value at 150° C. is greater than 0.07 and less than 0.1.

[0037] In step S3, the biomacromolecule material self-assembles to form a nano-pattern, and the annealing in step S4 is not required.

[0038] In the present invention, the size and spacing of the color center array can be controlled by controlling the polymer phase separation and ion implantation conditions; the size range of the color center distribution points is 10nm-100nm; the color center spacing range is 10nm-100nm.

[0039] Compared with the prior art, the present invention mainly has the following technical effects:

[0040] (1) Through the self-assembled nanomask of polymer phase separation technology, the color center is successfully confined in the nanopore, achieving stable, low-cost, and large-area preparation of color center arrays in a wide area.

[0041] (2) By precisely controlling the polymer phase separation and ion implantation conditions, the size and spacing of the color centers can be precisely controlled, which simplifies the preparation process of the color center array and facilitates operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a block diagram of the method for preparing diamond color center array based on polymer phase separation nano mask of the present invention (Scheme 1).

[0043] Figure 2The present invention is a flowchart of the method for preparing a diamond color center array based on a polymer phase separation nanomask (Scheme 1). Among them, a is a schematic diagram of the diamond sample structure after pretreatment, b is a schematic diagram of the diamond sample structure deposited with a silicon film, an oxide film or a metal film, c is a schematic diagram of the diamond sample structure immediately coated with an adhesion layer, d is a schematic diagram of the diamond sample structure with a phase separation polymer material layer spin-coated on the adhesion layer, e is a schematic diagram of the diamond sample structure after annealing to form a phase separation, f is a schematic diagram of the diamond sample structure after selective etching to form holes, g is a schematic diagram of the diamond sample structure after ion implantation, and h is a schematic diagram of the diamond sample structure after removing the hard mask.

[0044] Figure 3 The diamond film samples are deposited on silicon wafers by chemical vapor deposition. (a) is a picture of a fully polished diamond, and (b) is a picture of a partially polished diamond.

[0045] Figure 4 This is a confocal scanning imaging result diagram of the diamond NV color center array in the present invention.

[0046] Numbers in the figure: 1 is the pre-treated diamond, 2 is the Si film or oxide film or metal film, 3 is the adhesion layer, 4 is the phase separation patterned polymer material layer, 5 is the injected ions, and 6 is the formed color center. DETAILED DESCRIPTION

[0047] The present invention is further described below by way of examples.

[0048] Example 1: Scheme 1, see Figure 2 As shown, the specific steps are:

[0049] Step S1: Pretreatment of diamond raw materials, see Figure 2 (a) A high-purity diamond sheet was placed in a beaker containing isopropyl alcohol and ultrasonically cleaned for 30 min using an ultrasonic cleaner to remove organic pollutants on the surface.

[0050] The diamond sheet can also be pickled by immersing the diamond in a mixed acid solution of HClO4 / HNO3 / H2SO4 (1:1:1) at room temperature for 10 minutes and then rinsing with deionized water.

[0051] Step S2: Hard mask deposition, see Figure 2 (b), using atomic layer deposition (ALD) technology to deposit a 100 nm thick silicon film on the diamond surface to obtain a hard mask layer;

[0052] Step S3: Adhesion layer coating, see Figure 2(c) coating an adhesion layer on the hard mask (for the block copolymer used, a molecular brush layer composed of two segments or a non-block homopolymer molecular felt layer is selected) to enhance the adhesion between the polymer material and the hard mask.

[0053] Step S4: coating of phase-separable patterned polymer material: see Figure 2 (d) A phase-separable patterned polymer material PS-b-PMMA diblock copolymer film was spin-coated on the adhesion layer.

[0054] Step S5: Annealing treatment to induce polymer phase separation assembly: see Figure 2 (e) The diamond sheet coated with the polymer material is heat treated to promote the phase separation of the polymer material and assemble into a nanoscale pattern.

[0055] Step S6: Selective etching: see Figure 2 (f) Using a plasma etcher to etch the silicon film, the nanohole array pattern is transferred to the hard mask layer.

[0056] Step S7: Nitrogen ion implantation: see Figure 2 (g) Load the diamond sheet into the ion implanter and control the energy and dose (a typical set of parameters is energy 10 keV, implant dose 4×10 13 / cm 2 ), forming color centers in diamond.

[0057] Step S8: Remove the hard mask: see Figure 2 (h), the hard mask layer was removed using a mixed acid (HClO4 / HNO3 / H2SO4 (1:1:1)) solution at room temperature for 30 min and then rinsed with deionized water.

[0058] Step S9: vacuum high temperature annealing: the diamond sheet is placed in a vacuum furnace and treated in a vacuum environment at 850°C for 2 hours to activate the color centers and improve their optical properties.

[0059] Step S10: Pickling to remove surface carbon impurities: Use a mixed acid solution to treat at room temperature for 10 minutes to remove surface carbon impurities, and then rinse with deionized water to obtain a high-quality color center array.

[0060] Embodiment 2: Scheme 2

[0061] This embodiment provides the preparation of a color center array for polymer phase separation assembled nanomask ion implantation. The preparation method is the same as that of Example 1, with the only difference being that steps S2, S3, S4 in Example 1 are changed to directly coating a phase-separable patterned PS-b-PMMA diblock copolymer polymer material thick film greater than 200 nm, and steps S6 and S8 in Example 1 are changed here to only etching the polymer layer and only removing the polymer layer. This thick film process can provide better mask protection and is suitable for more complex pattern transfer and deeper ion implantation.

[0062] Example 3: Adjusting annealing conditions

[0063] On the basis of Example 1 and Example 2, the annealing temperature and time are changed to study the influence of annealing conditions on the self-assembly effect of phase separation polymer materials. In particular, laser annealing technology is used to optimize parameters such as laser power and laser scanning speed, such as laser wavelength of 532nm or 980nm; when the laser is a continuous laser, the laser spot can be a Gaussian circular spot, the spot diameter is 10-50μm, the laser power is 2-20W, the scanning speed is 10-1000um / s, and when the laser is a nanosecond laser, the laser spot can be a Gaussian circular spot, the spot diameter is 10-50μm, the laser power is 100-500mW, the scanning speed is 250-1000nm / s, the laser pulse width is 100-200ns, and the laser repetition frequency is 100-300KHz. To improve the uniformity and repeatability of the nanohole array pattern, realize micro-nanoscale positioning and selective annealing, control the shape of the annealing area, and then control nanoassembly and patterning.

[0064] Example 4: Optimizing ion implantation parameters

[0065] This embodiment improves the formation efficiency and optical properties of color centers by optimizing ion implantation parameters. Based on Embodiment 1 or Embodiment 2, the energy and dose of ion implantation are adjusted. For example, at 10 KeV and 1*10 12 / cm 2 Ion implantation is performed at a dose of .

[0066] Example 5: Pattern design of nanohole array

[0067] This embodiment discusses the effect of different nanohole array patterns on the performance of color center arrays. On the basis of Embodiment 1 or Embodiment 2, nanohole arrays of different shapes and arrangements are designed and prepared mainly based on laser annealing micro-nano positioning and regional shape customization with light field shaping or action space control to meet the requirements of different spacing and size of color center arrays for specific applications.

Claims

1. A method for preparing a diamond color center array based on a polymer phase separation nanomask, characterized in that: There are two options: Scheme 1: Use polymer phase separation assembly to obtain a nanopore array pattern, transfer the nanopore array pattern to a hard mask layer on the diamond surface, and then use the nanopore array hard mask to prepare a color center array by ion implantation. The specific steps are as follows: Step S1: pre-treating the diamond surface to remove organic and inorganic impurities on the diamond surface, providing a clean surface for subsequent processes, and obtaining a pre-treated diamond surface; Step S2: preparing a hard mask layer on the pre-treated diamond surface, wherein the hard mask layer is made of a silicon film, or an oxide film or a metal film; the film thickness is less than 200 nm; Step S3: coating an adhesion layer on the hard mask layer to enhance the adhesion between the polymer material and the hard mask; Step S4: coating a phase-separable patterned polymer material on the adhesive layer, and utilizing its self-assembly property to form a nano-scale pattern; Step S5: performing annealing treatment on the selected area of ​​the thin film formed in step S4 to induce and regulate the phase separation structure of the polymer material, form a uniform nano-mask, and enhance the pattern clarity; Step S6: etching the sample after annealing, phase separation and assembly, transferring the obtained pattern to the substrate, etching the hard mask layer, and obtaining a nanomask layer of the nanohole array; Step S7: Under the protection of the nanomask, nitrogen ions are implanted into the diamond to form a regular array of NV color centers; Step S8: using wet pickling or dry reactive ion etching to remove the hard mask and expose the diamond surface implantation area; Step S9: perform nitrogen ion implantation and high temperature annealing in a vacuum environment to activate the color center and improve its optical properties; Step S10: post-processing the diamond NV color center array to obtain a diamond NV color center array with a clear and stable pattern; Solution 2, the specific steps are: Step S1: pre-treating the diamond surface to remove organic and inorganic impurities on the diamond surface to obtain a pre-treated diamond surface; Step S2: directly coating a phase-separable patterned high Flory-Huggins interaction parameter high χ value block copolymer polymer material film, or amyloid protein, DNA self-assembled biomacromolecules on the pretreated diamond surface to form a nanoscale pattern, the film thickness is greater than 200nm, relative to the film thickness less than 200nm in scheme 1, it is called a thick film; Step S3: performing laser or solvent annealing on the block copolymer polymer material film to improve the phase separation structure of the block copolymer polymer material; annealing is not required for the biomacromolecule film; Step S4: etching the assembled sample, etching the thin film, and obtaining a nano-mask layer of the nano-hole array; Step S5: directly using the polymer thick film after phase separation, assembly and selective etching as a mask to perform nitrogen ion implantation to form color centers; Step S6: After the nitrogen ion implantation, the polymer layer is removed by acid washing; Step S7: performing high temperature annealing in a vacuum environment to activate the color center; Step S8: acid-washing the diamond NV color center array to improve the color center quality.

2. The preparation method according to claim 1, characterized in that: In option 1: In step S2, in the hard mask layer, the silicon thin film is prepared by spin coating, and the film thickness is 50-100 nm; the oxide thin film or the metal thin film is prepared by thermal evaporation, ALD, CVD or magnetron sputtering process, and the film thickness is 10-50 nm, the oxide thin film material is silicon dioxide or titanium dioxide, and the metal thin film material is aluminum; In step S3, the adhesion layer material is a molecular brush layer composed of two segments of the block copolymer of the polymer material used or a non-block homopolymer molecular felt layer, with a thickness of 10-20 nm; In step S4, the phase-separable patterned polymer material is a diblock copolymer PS-b-PMMA; In step S5, the annealing is performed by laser annealing, overall thermal annealing or solvent-induced phase separation annealing; In step S7, the energy of the nitrogen ion implantation is 10-200 keV, and the implantation dose is 1×10 12 -1×10 14 / cm 2 ; In step S8, the acid is selected from nitric acid, sulfuric acid, and perchloric acid; In step S9, the high temperature annealing temperature is 800-1100° C. and the time is 1-2 hours.

3. The preparation method according to claim 1, characterized in that: By controlling polymer phase separation and ion implantation conditions, the size and spacing of the color center array can be controlled; The size range of the color center distribution points is 10nm-100nm; the color center spacing range is 10nm-100nm.

4. The preparation method according to claim 1, characterized in that: In option 2: In step S2, the high-χ value block copolymer polymer material is PS-b-P2VP or PS-b-PDMS, and the χ value at 150° C. is greater than 0.07 and less than 0.

1.

5. The preparation method according to claim 4, characterized in that: By controlling the polymer phase separation and ion implantation conditions, the size and spacing of the color center array can be controlled; The size range of the color center distribution points is 10nm-100nm; the color center spacing range is 10nm-100nm.

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