High-precision AlScN micro-nano structure laser etching process

Abstract

The invention relates to a high-precision AlScN micro-nano structure laser etching process, which comprises the following steps of: designing a micro-nano graphical track of a laser beam by adopting an ultrashort pulse laser system; a focusing assembly is arranged on the path of the laser beam, and the laser beam is focused on the surface of the AlScN thin film through the focusing assembly to be ablated to form a focal spot; and the laser beam is controlled to move according to the graphical track, and a focal spot formed in the moving process forms a high-precision AlScN micro-nano structure. According to the invention, a micro-nano structure can be formed in the AlScN film, fine regulation and control of ferroelectricity and piezoelectricity of the material are realized, and an optimization path is provided for application of a ferroelectric memory. Compared with wet etching, the etching speed of the AlScN thin film is remarkably increased through ultra-short pulse laser etching, and the machining efficiency is improved. Meanwhile, mask pollution of a traditional photoetching process is avoided, the process cleanliness and stability are improved, the AlScN thin film has higher durability and integration reliability, and the method is suitable for constructing novel electronic devices with high performance and low power consumption.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor technology, and particularly relates to a high-precision AlScN micro-nano structure laser etching process. Background Art

[0002] As the contradiction between the circuit performance and data computing volume of the traditional von Neumann architecture becomes increasingly serious, in-memory computing has become a key solution for the liberation of computing power. Ferroelectric memory devices have higher read and write speeds and lower power consumption, and have the advantages of high integration and high efficiency in building in-memory computing circuits. AlScN materials have several times higher remnant polarization intensity (Pr) and coercive electric field (Ec) than many traditional ferroelectric materials. Larger Ec not only provides a significantly better storage window, but also effectively resists the depolarization field, thereby achieving a longer retention time. In addition, the lower dielectric constant of AlScN is also conducive to improving the sensing accuracy and durability of ferroelectric memory, and its preparation process is compatible with the CMOS back-end preparation process, providing a new path for memory devices. However, the preparation process of AlScN ferroelectric memory still faces many challenges. The chemical stability of group III nitrides hinders the etching rate of wet and dry etching of AlN-based materials, and Sc doping further increases the difficulty of etching AlScN, thereby hindering the precise preparation of micro-nanostructure AlScN devices. In addition, patterning involves many processing steps, and the impact of process instability on the device cannot be ignored. Summary of the invention

[0003] In order to overcome the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a high-precision AlScN micro-nano structure laser etching process to reduce the influence of the etching process on the performance of the micro-nano structure AlScN device.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: A high-precision AlScN micro-nano structure laser etching process comprises the following steps: Step 1, using an ultrashort pulse laser system to design a graphical trajectory of the laser beam at the micro-nano level; Step 2, setting a focusing component on the path of the laser beam, and focusing the laser beam on the surface of the AlScN film to ablate and form a focal spot through the focusing component; Step 3: Control the movement of the laser beam according to the graphical trajectory, and the focal spot formed during the movement constitutes a high-precision AlScN micro-nano structure.

[0005] The high precision mentioned in the present invention refers to the etching depth, shape and edge quality at the micro-nano level.

[0006] In one embodiment, the pulse width of the laser beam is 170 fs-1 μs, the wavelength is 248 nm-10.8 μm, and the pulse energy is 0.0698 J / cm 2 -15J / cm 2 , etching depth 10nm-1μm.

[0007] In one embodiment, the etching linear speed of the laser beam is 5 mm / s-100 mm / s.

[0008] In one embodiment, the design of the graphical trajectory of the laser beam at the micro-nano level is achieved by: According to the pattern of the high-precision AlScN micro-nano structure, the movement trajectory of the emission end of the ultrashort pulse laser system is controlled, and the emission end is used to emit the laser beam.

[0009] In one embodiment, the focusing component is arranged on the path of the laser beam, and the implementation method is as follows: The focusing assembly is connected to the emission end of the ultrashort pulse laser system through a connector or directly installed to make the focusing assembly move synchronously with the emission end of the ultrashort pulse laser system, or the focusing assembly is fixed to the emission end of the ultrashort pulse laser system to make the AlScN film move; The laser beam is vertically incident on the focusing assembly to achieve focusing, and the angle between the laser emission direction after focusing and the substrate normal direction is less than 90°.

[0010] In one embodiment, the focusing assembly is a microscope objective.

[0011] In one embodiment, the magnification of the microscope objective is 5-50.

[0012] In one embodiment, the aperture of the microscope objective lens is 0.3-0.7.

[0013] In one embodiment, step 1, step 2 and step 3 are all performed in a vacuum or nitrogen environment.

[0014] By using the high-precision AlScN micro-nano structure laser etching process of the present invention, a variety of high-precision micro-nano structures can be directly etched. For example, a nanometer-level periodic groove structure can be accurately processed and applied to high-frequency surface acoustic wave devices, which is beneficial to improving filtering efficiency and performance stability; a regular micro-dot array can also be etched, which is suitable for photonic crystals, MEMS devices, etc.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention utilizes the characteristics of ultrashort pulse lasers, and directly performs micro-nano-level high-precision patterned etching on the AlScN film by regulating the etching linear velocity and power of the laser beam, thereby forming a controllable structure on the film surface and protecting the substrate. Through this method, a micro-nano structure can be formed in the AlScN film, and the ferroelectricity and piezoelectricity of the material can be finely regulated, providing an optimized path for the application of ferroelectric memory. Compared with wet etching, ultrashort pulse laser etching significantly improves the etching speed of the AlScN film and improves the processing efficiency. At the same time, the present invention avoids the mask contamination of the traditional photolithography process, improves the process cleanliness and stability, and makes the AlScN film have higher durability and integrated reliability, which is suitable for building high-performance, low-power new electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the high-precision AlScN micro-nano structure laser etching process flow of the present invention.

[0017] Figure 2 Schematic diagram of the principle of the high-precision AlScN micro-nano structure laser etching process of the present invention.

[0018] Figure 3 It is a cross-sectional diagram and irradiation schematic diagram of the high-precision AlScN micro-nano structure etching of the present invention.

[0019] In the figure: 1. Focusing component, 2. Laser beam, 3. Focus spot, 4. AlScN film. DETAILED DESCRIPTION

[0020] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0021] In response to the demand for high-quality AlScN ferroelectric films in high-density integrated memory devices, the present invention provides a high-precision AlScN micro-nanostructure laser etching process, which uses an ultrashort pulse laser to directly etch the surface of the AlScN film, focuses the ultrashort pulse energy on the AlScN surface, and forms a micro-nanostructure with high precision. By adjusting variables such as the etching linear velocity and power of the laser beam, patterns of different depths and morphologies can be obtained on the surface of the AlScN film, achieving precise control and efficient processing of nanoscale microstructures. Compared with traditional etching methods, the etching speed of ultrashort pulse lasers is faster, and in-situ etching can be directly integrated during the growth of the AlScN film, which simplifies the steps while avoiding mask contamination, effectively improving the quality and reliability of the device, making the AlScN film more suitable for use in ferroelectric memory and promoting its application in high-density integrated memory devices.

[0022] like Figure 1 As shown, the high-precision AlScN micro-nanostructure laser etching process of the present invention mainly includes the following steps: Step 1: Use an ultrashort pulse laser system to design a graphical trajectory of laser beam 2 at the micro-nano level, and adjust the etching linear speed and power of laser beam 2 within a reasonable range.

[0023] Step 2, focusing the laser beam 2 onto the surface of the AlScN film 4 through the focusing component 1, generating a local ablation phenomenon in a very short time to remove the AlScN material and forming a focal spot 3 on the surface.

[0024] Step 3, controlling the movement of the laser beam 2 according to the graphical trajectory, and the focal spot 3 formed during the movement constitutes a high-precision AlScN micro-nano structure.

[0025] like Figure 2 FIG. 1 is a schematic diagram of the laser etching process principle of the present invention. Figure 2 In the laser etching process, the pattern processed by the laser can be effectively transferred to the substrate material, thereby realizing the efficient preparation of the target structure. Ultrashort pulse laser focuses on the surface of AlScN film 4 through the action of short pulses and high energy, locally evaporates or peels off the material to remove specific areas and form the required micro-nano structure.

[0026] In the embodiment of the present invention, the focusing component 1 can specifically adopt a microscope objective lens. The laser beam 2 emitted by the ultrashort pulse laser system is a high-energy pulse, which is focused on the surface of the AlScN film 4 through the microscope objective lens. The high energy density of the laser beam 2 causes the AlScN material to decompose and generate gaseous aluminum (Al), gaseous scandium (Sc) and nitrogen (N2) or gaseous aluminum scandium nitrogen (AlScN). The chemical reaction equation is as follows: AlScN(s) → Al(g) + Sc(g) + 1 / 2 N2(g) +Δ H AlScN(s) → AlScN(g) +Δ H Where (s) and (g) represent the solid phase and gas phase, respectively. The principle can be described as: Due to Coulomb attraction, the free electrons generated by the pulse are confined to the focal area. When the femtosecond laser is focused on the substrate, nonlinear absorption will occur. For single-photon absorption, electron excitation will only occur when the photon energy exceeds the band gap of the material. In the femtosecond scale, the electric field intensity of the laser pulse is high, and the pulse photons have a high degree of degeneracy. The bound electrons in the valence band of the material can absorb multiple photons at the same time, that is, multi-photon absorption. When the photon density is high enough, electron excitation will occur even if the photon energy is lower than the band gap. Through multi-photon ionization, tunnel ionization and avalanche ionization, the AlScN surface absorbs photon energy to generate free electrons, and the electron energy is transferred to the lattice. The AlScN surface material is removed by melting, gasification or Coulomb explosion. In the nanosecond scale, the thermal diffusion effect is significant, and the pressure or shock wave is separated from the dense thermal focus area. In the microsecond scale, thermal diffusion is fully unfolded, the heat energy diffuses out of the focus area, and a phase change occurs.

[0027] Because the ultrashort pulse laser has a high instantaneous power density, it can directly etch the material without chemical doping and masking, greatly simplifying the etching process, reducing production costs and complexity, and effectively reducing the contamination of the AlScN film. Specifically, fast and efficient etching can decompose the AlScN material in a high-precision etching area, effectively reducing the lateral diffusion phenomenon during the etching process, thereby avoiding the loss of structural integrity caused by lateral drilling in traditional etching technology.

[0028] However, oxidation will inevitably occur on the surface of the AlScN film 4. Specifically, the gaseous aluminum and gaseous scandium generated during the etching process are easily oxidized when exposed to air, generating aluminum oxide (Al2O3) and scandium oxide (Sc2O3), respectively, forming oxide residues on the etched surface. These oxide residues will form impurities in the etched area, resulting in an uneven etched surface, which will affect the surface quality of the AlScN film and the accuracy of subsequent processes. For this reason, necessary post-processing is required to remove the impurities generated by etching. For example, the surface of the AlScN film 4 after laser etching is completed is cleaned to remove some of the existing oxidized substances.

[0029] If the laser etching is performed in a vacuum or nitrogen environment, surface oxidation will not occur, and other effects caused by cleaning can be avoided.

[0030] The preferred process conditions of the present invention include: The pulse width of the laser beam 2 is 170 fs-1 μs, and the wavelength is 248 nm-10.8 μm. The pulse width and wavelength are more preferably 110 fs and 790 nm.

[0031] The pulse energy of laser beam 2 is 0.0698 J / cm 2 -15J / cm 2 The pulse energy is further preferably 0.0698 J / cm 2 .

[0032] The above-mentioned pulse width, wavelength and pulse energy together constitute the power control of the laser beam 2 .

[0033] The etching linear speed of the laser beam 2 is 5 mm / s-100 mm / s, and the etching linear speed is more preferably 5 mm / s.

[0034] By controlling the above parameters, the etching depth of the laser beam 2 of the present invention can reach 10 nm-1 μm.

[0035] The magnification of the microscope objective lens is 5-50, the aperture is 0.3-0.7, and the aperture is more preferably 0.42.

[0036] like Figure 3 The etching profile and irradiation schematic diagram show that by moving the AlScN material at a certain rate, the etching process can be precisely controlled to produce AlScN etching lines with different characteristics. By adjusting the laser power, pulse width and other conditions, etching lines of different widths, depths and shapes can be produced in a wide range to meet diverse manufacturing needs.

[0037] In summary, by using ultrashort pulse laser to etch AlScN materials, the etching depth and pattern shape of the AlScN film can be precisely controlled, micro-nanoscale structural processing can be achieved by adjusting the laser parameters, and the physical properties of the film can be regulated by the surface characteristics after etching, so that the AlScN film has high-precision structural control capabilities in device applications. In addition, it is also possible to achieve in-situ processing of multiple different patterns in the same film, which has significant advantages of high efficiency and flexibility. Its advantages can be described as follows: 1) Induce adjustable etching of materials with high precision within an ideal controllable range; 2) Compared with traditional etching, laser etching is faster and significantly improves etching efficiency; 3) The etching process does not require mask materials, which reduces the operation steps, operation difficulty and cost; 4) It avoids the contamination caused by transferring the platform and provides a technically feasible path for in-situ etching.

[0038] The present invention uses a short-pulse laser to accurately etch an AlScN film, and uses the high energy density of the laser to achieve micro-nanoscale patterning of the material. By adjusting the etching line speed and power of the laser, the etching depth and surface morphology of the AlScN film can be controlled, thereby effectively regulating the physical and electrical properties of the film. At the same time, the present invention realizes the precise control of the AlScN film in in-situ processing, so that different regions can form a variety of micro-nano structures to meet the design requirements of different devices. Secondly, the high-precision AlScN etching process of the present invention has high selectivity and high etching rate, avoids the problem of too low etching rate in traditional etching, and improves the processing efficiency and processing stability of the microstructure. The present invention has significant advantages such as high precision, high efficiency and flexibility, and is expected to be widely used in the fields of high-performance ferroelectric memory devices and integrated circuit manufacturing.

[0039] Specific examples of AlScN etching technology based on different parameters are given below.

[0040] Embodiment 1 Step 1: Design the micro-nano patterning trajectory of laser beam 2 through an ultrashort pulse laser system, and adjust the etching linear speed and power of laser beam 2.

[0041] In this step, the etching linear speed of laser beam 2 is 5 mm / s, the pulse width is 110 fs, the wavelength is 790 nm, and the pulse energy is 0.0698 J / cm 2 Under these parameter conditions, the femtosecond laser can etch AlScN film 4 to a depth of 20 nm, which can achieve high-precision micro-nano patterning processing, ensure etching quality and reduce pollution.

[0042] Step 2: Through the focusing component 1, the engraving laser beam 2 pulse is focused to the surface of the AlScN film 4 in the track to ablate and form a focal spot 3.

[0043] In this step, the focusing component 1 uses a high-power microscope objective lens with a magnification of 50 and an aperture of 0.42 to focus the engraving laser beam 2 onto the material surface to form a focal spot 3, thereby removing part of the material on the AlScN film 4. The laser beam 2 is controlled to move according to the graphical trajectory, and the focal spot 3 formed during the movement constitutes a high-precision AlScN micro-nano structure.

[0044] Step three, post-treating the surface of the treated AlScN film 4 to remove impurities generated by etching.

[0045] Embodiment 2 Step 1: Design a micro-nano patterned trajectory of the laser beam 2 by using an ultrashort pulse laser system, and adjust the etching linear speed and power of the laser beam 2.

[0046] In this step, the etching linear speed of laser beam 2 is 25 mm / s, the pulse width is 10 ns, the wavelength is 248 nm, and the pulse energy is 0.43 J / cm 2 Under these parameter conditions, nanosecond laser etching of AlScN film 4 can reach an etching depth of 100nm, which can achieve high-precision micro-nano patterning processing, ensure etching quality and reduce pollution.

[0047] Step 2: Through the focusing component 1, the engraving laser beam 2 pulse is focused to the surface of the AlScN film 4 in the track to ablate and form a focal spot 3.

[0048] In this step, the focusing component 1 uses a high-power microscope objective lens with a magnification of 20 and an aperture of 0.35 to focus the laser beam 2 on the material surface to form a focal spot 3, thereby removing part of the material on the AlScN film 4. The laser beam 2 is controlled to move according to the graphical trajectory, and the focal spot 3 formed during the movement constitutes a high-precision AlScN micro-nano structure.

[0049] Step three, post-treating the surface of the treated AlScN film 4 to remove impurities generated by etching.

[0050] Embodiment 3 Step 1: Design the micro-nano patterning trajectory of laser beam 2 through an ultrashort pulse laser system, and adjust the etching linear speed and power of laser beam 2.

[0051] In this step, the etching linear speed of laser beam 2 is 100 mm / s, the pulse width is 1 μs, the wavelength is 10.8 μm, and the pulse energy is 15 J / cm 2 Under these parameter conditions, the microsecond laser can etch AlScN film 4 to a depth of 1 μm, which can achieve high-precision micro-nano patterning processing, ensure etching quality and reduce pollution.

[0052] Step 2: Through the focusing component 1, the laser beam 2 pulse is focused to the surface of the AlScN film 4 in the track to form a focal spot 3 by ablation.

[0053] In this step, the focusing component 1 uses a high-power microscope objective lens with a magnification of 5 and an aperture of 0.3 to focus the laser beam 2 on the surface of the material to form a focal spot 3, thereby removing part of the material on the AlScN film 4. The movement of the laser beam 2 is controlled according to the graphical trajectory, and the focal spot 3 formed during the movement constitutes a high-precision AlScN micro-nano structure.

[0054] Step three, post-treating the surface of the treated AlScN film 4 to remove impurities generated by etching.

[0055] In summary, the present invention realizes the integrated operation of thin film deposition and etching by integrating the laser system into the AlScN thin film growth equipment. The laser system is located directly opposite the substrate, and the angle between the emission direction and the substrate normal is less than 90°, which can accurately etch or perform graphic processing while the film is growing. The laser parameters and the growth process parameters are precisely controlled by the system to ensure the synchronization of film growth and etching. Combined with the monitoring system, the film state can be monitored, and it is started when the film reaches the set thickness, realizing in-situ, high-precision etching operation.

[0056] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A high-precision AlScN micro-nanostructure laser etching process, characterized in that: The steps include: Step 1, using an ultrashort pulse laser system, designing a patterned trajectory of the laser beam (2) at the micro-nano level; Step 2, arranging a focusing component (1) on the path of the laser beam (2), and focusing the laser beam (2) on the surface of the AlScN film (4) through the focusing component (1) to ablate and form a focal spot (3); Step 3, controlling the movement of the laser beam (2) according to the graphic trajectory, and forming a focal spot (3) during the movement to form a high-precision AlScN micro-nano structure.

2. The high-precision AlScN micro-nanostructure laser etching process according to claim 1, characterized in that: The laser beam (2) has a pulse width of 170 fs-1 μs, a wavelength of 248 nm-10.8 μm, and a pulse energy of 0.0698 J / cm 2 -15J / cm 2 , etching depth 10nm-1μm.

3. The high-precision AlScN micro-nanostructure laser etching process according to claim 1 or 2, characterized in that: The etching linear speed of the laser beam (2) is 5 mm / s-100 mm / s.

4. The high-precision AlScN micro-nanostructure laser etching process according to claim 1, characterized in that: The design of the graphical trajectory of the laser beam (2) at the micro-nano level is achieved by: According to the pattern of the high-precision AlScN micro-nano structure, the movement trajectory of the emission end of the ultrashort pulse laser system is controlled, and the emission end is used to emit the laser beam (2).

5. The high-precision AlScN micro-nanostructure laser etching process according to claim 1, characterized in that: The focusing component (1) is arranged on the path of the laser beam (2), and the implementation method is as follows: The focusing assembly (1) is connected to the emission end of the ultrashort pulse laser system through a connecting piece or is directly installed so that the focusing assembly (1) and the emission end of the ultrashort pulse laser system move synchronously, or the focusing assembly (1) is fixed to the emission end of the ultrashort pulse laser system so that the AlScN film (4) moves; The laser beam (2) is vertically incident on the focusing component (1) to achieve focusing, and the angle between the laser emission direction after focusing and the substrate normal direction is less than 90°.

6. The high-precision AlScN micro-nanostructure laser etching process according to claim 1 or 5, characterized in that: The focusing component (1) is a microscope objective lens.

7. The high-precision AlScN micro-nanostructure laser etching process according to claim 6, characterized in that: The magnification of the microscope objective lens is 5-50, and the aperture is 0.3-0.

7.

8. The high-precision AlScN micro-nanostructure laser etching process according to claim 1, characterized in that: The steps 1, 2 and 3 are all carried out in a vacuum or nitrogen environment.

9. A high-frequency surface acoustic wave device comprising a nanoscale periodic groove structure, characterized in that: The nanoscale periodic groove structure is obtained by the high-precision AlScN micro-nanostructure laser etching process described in claim 1.

10. A photonic crystal or MEMS device comprising a regular array of microdots, characterized in that: The regular micro-dot array is obtained by the high-precision AlScN micro-nanostructure laser etching process described in claim 1.

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