Optical system, method for forming same, and laser direct writing method

Abstract

Various embodiments may relate to an optical system. The optical system may include a laser source for emitting one or more laser beams. The optical system may also include a super lens, a first base mounted with the super lens, a first motor configured to move the first base, a second base carrying a sample, and a second motor configured to move the second base. The optical system may include an objective lens; a third base configured to carry the objective lens; and a third motor configured to move the third base. The optical system may also include a detector and a baffle including or having an aperture between the objective lens and the detector. The optical system may also include a processor in electrical communication with the first motor, the second motor, and the third motor.

Description

Technical Field

[0001] Various embodiments of the present disclosure may be directed to an optical system. Various embodiments of the present disclosure may be directed to a method of forming an optical system. Various embodiments of the present disclosure may be directed to a laser direct writing method. Background Art

[0002] Nanopatterning is a key step in many materials and device applications. A variety of nanopatterning techniques have been developed, such as electron beam lithography (EBL), focused ion beam (FIB) lithography, dip-pen lithography, and scanning probe lithography, which have high resolution but high cost and low throughput. Nanoimprint lithography (NIL) can be used for large-area patterning, with the advantages of low cost and high throughput, but there is still room for improvement in terms of accuracy, alignment, and uniformity. In addition, its master mold must be prepared by other lithography methods.

[0003] Optical lithography, or photolithography, has dominated the semiconductor industry for decades due to its large-scale processing capabilities and high throughput characteristics. By pushing the wavelength of light used in lithography toward deep ultraviolet (DUV) and extreme ultraviolet (EUV), its resolution can compete with electron beam and ion beam lithography. However, optical lithography, or photolithography, faces the problem of rising costs for the associated tools and processes.

[0004] Laser direct writing (DLW) is a maskless lithography technology that, in addition to being used in mask manufacturing in the semiconductor industry, is also a very important laboratory tool for scientists working in nanotechnology research. Resolution is a key factor in DLW systems because many applications, such as optics, micro-electromechanical systems (MEMS), sensors, etc., require miniaturization.

[0005] However, due to the diffraction limit of traditional objective lenses in DLW systems (Rayleigh criterion - 0.61λ / NA), the lithography resolution is still insufficient for many applications, especially high value-added applications. The minimum feature size of DLW on the market is currently over 300 nanometers. This bottleneck greatly limits the market space for DLW systems. Summary of the invention

[0006] Various embodiments may relate to an optical system. The optical system may include a laser source for emitting one or more laser beams. The optical system may also include a metalens. The optical system may further include a first base for mounting the metalens. The optical system may additionally include a first motor configured to move the first base. The optical system may further include a second base for carrying a sample. The optical system may also include a second motor configured to move the second base. The optical system may include an objective lens. The optical system may further include a third base configured to carry the objective lens. The optical system may additionally include a third motor configured to move the third base. The optical system may also include a detector. The optical system may include a baffle including or having a small hole thereon, the baffle being located between the objective lens and the detector. The optical system may also include a processor in electrical communication with the first motor, the second motor, and the third motor. The metalens may be configured to allow at least a portion of the laser beam to pass through to write the sample during a laser direct writing process. The processor may be configured to determine the distance between the metalens and the sample based on an image captured by the detector before the laser direct writing process. The processor may be further configured to control the second motor to move the second base stage, thereby controlling the exposure time of the sample during the laser direct writing process.

[0007] Various embodiments may be directed to a method of forming an optical system. The method may include providing a laser source for emitting one or more laser beams. The method may include forming or providing a metalens. The method may also include providing a first base for mounting the metalens. The method may further include providing a first motor configured to move the first base. The method may additionally include providing a second base for carrying a sample. The method may include providing a second motor configured to move the second base. The method may also include providing an objective lens. The method may also include providing a third base configured to carry the objective lens. The method may further include providing a third motor configured to move the third base. The method may additionally include providing a detector. The method may also include providing a baffle including or having a small hole therein, the baffle being located between the objective lens and the detector. The method may further include providing a processor in electrical communication with the first motor, the second motor, and the third motor. The metalens may be configured to allow at least a portion of the laser beam to pass through to write to the sample during a laser direct writing process. The processor may be configured to determine the distance between the metalens and the sample based on an image captured by the detector before the laser direct writing process. The processor may be further configured to control the second motor to move the second base stage, thereby controlling the exposure time of the sample during the laser direct writing process.

[0008] Various embodiments may relate to a laser direct writing method. The method may include providing an optical system. The optical system may include a laser source for emitting one or more laser beams. The optical system may also include a metalens. The optical system may further include a first base for mounting the metalens. The optical system may additionally include a first motor configured to move the first base. The optical system may also include a second base for carrying a sample. The optical system may further include an objective lens. The optical system may additionally include a third base configured to carry the objective lens. The optical system may also include a third motor configured to move the third base. The optical system may further include a detector. The optical system may additionally include a baffle including a pinhole thereon, the baffle being located between the objective lens and the detector. The optical system may also include a processor in electrical communication with the first motor, the second motor, and the third motor. The method may include providing a sample. The method may also include: prior to the laser direct writing process, determining a distance between the metalens and the sample based on an image captured by the detector, wherein the metalens is configured to allow at least a portion of the one or more laser beams to pass through to write the sample. The method may additionally include moving the second stage using a second motor to control an exposure time of the sample during the laser direct writing process.

[0009] BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the accompanying drawings, the same reference numerals generally represent the same parts in different views. The drawings are not necessarily drawn to scale, and emphasis is generally placed on illustrating the principles of various embodiments. In the following description, various embodiments of the present invention will be described with reference to the following drawings.

[0011] Figure 1 is an overall schematic diagram of an optical system according to various embodiments.

[0012] Figure 2 is an overall schematic diagram of a method for forming an optical system according to various embodiments.

[0013] Figure 3 is an overall schematic diagram of a laser direct writing method according to various embodiments.

[0014] Figure 4 The resolution, cost, and writing speed of various lithography methods including direct laser writing (DLW) according to various embodiments are demonstrated.

[0015] Figure 5 Scanning electron microscope (SEM) images of two types of two-dimensional lenses are shown: (a) a scanning electron microscope (SEM) image of a Fresnel zone plate (FZP) lens according to various embodiments; (b) a scanning electron microscope (SEM) image of a supercritical lens (SCL) lens according to various embodiments.

[0016] Figure 6 Schematic diagrams of optical systems are shown according to various embodiments.

[0017] Figure 7 Shown are (a) an optical image of a snake ladder pattern generated by an optical system according to various embodiments, with a feature size of approximately 270 nanometers; and (b) an atomic force microscope (AFM) measurement image of the snake ladder pattern generated by an optical system according to various embodiments.

[0018] Figure 8 Shown are (a) a scanning electron microscope (SEM) image of a dense grating pattern written by an optical system according to various embodiments; and (b) a magnified view of the portion of the image shown in (a).

[0019] Fig. 9 Potential applications for laser direct writing using optical systems according to various embodiments are demonstrated.

[0020] Fig.10 is a table comparing an embodiment with two conventional systems.

[0021] describe

[0022] The following detailed description refers to the accompanying drawings, which illustrate specific details and embodiments in which the present invention may be implemented. These embodiments have been described in sufficient detail to enable those skilled in the art to implement the present invention. Other embodiments may also be used, and structural, logical and electrical changes may be made without departing from the scope of the present invention. The various embodiments are not necessarily mutually exclusive, as certain embodiments may be combined with one or more other embodiments to form new embodiments.

[0023] Embodiments described in the context of one optical system are equally valid for other optical systems. Similarly, embodiments described in the context of a method are equally valid for optical systems, and vice versa.

[0024] Features described in the context of a certain embodiment may also be applicable to the same or similar features in other embodiments. Features described in the context of a certain embodiment may also be applicable to other embodiments even if they are not explicitly described in other embodiments. In addition, additions, combinations and / or alternatives to features described in the context of a certain embodiment may also be applicable to the same or similar features in other embodiments.

[0025] In the context of various embodiments, reference to a feature or element referred to by the terms "a", "an", and "the" includes one or more references to that feature or element.

[0026] In the context of various embodiments, the term "about" or "approximately" when applied to a numerical value encompasses the exact value and a reasonable range of variation thereof.

[0027] As used herein, the term "and / or" includes any and all combinations of the listed items.

[0028] Various embodiments may be directed to optical systems for laser writing that include planar metalenses. Various embodiments may solve problems faced by traditional lithography systems.

[0029] Figure 1 is an overall schematic diagram of an optical system according to various embodiments. The optical system may include a laser source 102 for emitting one or more laser beams. The optical system may also include a metalens 104. The optical system may further include a first base 106 for mounting the metalens 104. The optical system may additionally include a first motor 108, which is configured to move the first base 106. The optical system may further include a second base 110 for carrying a sample. The optical system may also include a second motor 112, which is configured to move the second base 110. The optical system may include an objective lens 114 (i.e., an object end lens). The optical system may further include a third base 116, which is configured to carry the objective lens 114. The optical system may additionally include a third motor 118, which is configured to move the third base 116. The optical system may also include a detector 120. The optical system may include a baffle 122, which includes a small hole or has a small hole, and the baffle 122 is located between the objective lens 114 and the detector 120. The optical system may further include a processor 124 that is in electrical communication with the first motor 108, the second motor 112, and the third motor 118. The metalens 104 may be configured to allow at least a portion of one or more laser beams to pass through to write to the sample during the laser direct writing process. The processor 124 may be configured to determine the distance between the metalens 104 and the sample based on the image captured by the detector 120 before the laser direct writing process. The processor 124 may be further configured to control the second motor 112 to move the second base 110, thereby controlling the exposure time of the sample during the laser direct writing process.

[0030] For the avoidance of doubt, Figure 1 It is only used to illustrate some features of various embodiments and is not intended to limit the arrangement, size, shape, direction, etc. of each feature.

[0031] In various embodiments, the optical system may be or may include a confocal microscope. The optical system may include three bases 106, 110, and 116, which are configured to be driven by motors 108, 112, and 118, respectively. The optical system may also include a laser source 102, a metalens 104, a baffle 122 with a small hole, and a detector 120. During operation, the first base 106 may move a first base carrying the metalens 104, the second motor 112 may move a second base carrying a sample, and the third motor 118 may move a third base 116 carrying an objective lens 114. The optical system may also include a processor 124, which is configured to control the first motor 108, the second motor 112, and the third motor 118. In various embodiments, the processor 124 may be part of the confocal microscope, while in various other embodiments, the processor 124 may be located outside the confocal microscope.

[0032] In various embodiments, the superlens 104 may be a planar superlens or a two-dimensional superlens. In various embodiments, the superlens 104 may be a super oscillation lens (also referred to as a superoscillatory lens). In various embodiments, the superoscillatory lens may include a plurality of metal rings arranged concentrically. These metal rings may be almost opaque to the laser beam. In other words, these metal rings may prevent the laser beam from passing through. However, when the laser beam passes through the transparent area between the metal rings, the laser beam may be allowed to pass through. In various other embodiments, the superoscillatory lens may include a plurality of grooves extending from a first surface of the lens through an opaque substrate to a second surface of the lens opposite to the first surface, and the plurality of grooves form a plurality of concentric ring structures. The superoscillatory lens may be configured to generate a sub-diffraction-limited focus when one or more laser beams are incident on the lens.

[0033] In various other embodiments, the metalens 104 may be a planar diffractive lens, such as a Fresnel zone plate (FZP) lens or a supercritical lens (SCL). The Fresnel zone plate (FZP) lens may be a lens comprising a plurality of concentric rings (referred to as Fresnel zones) that are alternately almost opaque or almost transparent to the laser beam. The supercritical lens (SCL) may include a plurality of concentric rings that are almost transparent to the laser beam.

[0034] In various embodiments, the focal point may be a focus that is not diffraction unlimited. In other words, the focal point size of the metalens 104 may not be limited by diffraction. The metalens 104 may exhibit sub-diffraction limited focusing. In various embodiments, the metalens 104 may employ amplitude modulation.

[0035] In various embodiments, the laser source may be a 405 nm laser source. The laser source may generate a laser beam having a wavelength of 405 nm. One or more laser beams may be continuous wave (CW) laser beams. Various embodiments may be able to achieve a feature size of only 180 nm on the photoresist using a 405 nm laser source. In various other embodiments, the laser source may be configured to generate a laser beam having any other suitable wavelength. In various embodiments, one or more laser beams may be any wavelength or wavelength range in the visible light region (400 nm to 700 nm). In various embodiments, the laser beam may be any wavelength or wavelength range in the infrared region or the ultraviolet region (e.g., about 200 nm to 280 nm in the deep ultraviolet region). In various embodiments, any suitable laser source may be used. Various embodiments may be able to achieve a feature size of less than 180 nm.

[0036] In various implementations, the first motor 108 , the second motor 112 , and the third motor 118 may be piezoelectric motors.

[0037] In various embodiments, the metalens 104 may include a substrate that is substantially transparent to the one or more laser beams. The metalens 104 may include a patterned metal layer on the substrate, the patterned metal layer being configured to allow at least a portion of the one or more laser beams to pass through while blocking the remaining portion of the one or more laser beams during the laser direct writing process. The patterned metal layer may be substantially opaque to the one or more laser beams.

[0038] For the avoidance of doubt, an element being "almost transparent" to one or more laser beams may mean that the element allows the laser beam to pass through without significantly reducing the intensity, such as greater than 50%, such as greater than 80%, such as greater than 90%, such as greater than 95%, such as greater than 99%. Conversely, an element being "almost opaque" to one or more laser beams may mean that the element is able to block the laser beam, or only allows the laser beam to pass through with significantly reduced intensity, such as less than 20%, such as less than 10%, such as less than 5%, such as less than 1%, such as less than 0.1%.

[0039] The detector 120 may be a charge coupled device (CCD) or a photodiode.

[0040] In various embodiments, the processor 124 may include suitable software to control the movement of the bases 106 , 110 , 118 by controlling the motors 108 , 112 , 118 .

[0041] Figure 2is an overall schematic diagram of a method of forming an optical system according to various embodiments. The method may include providing a laser source for emitting one or more laser beams, indicated at 202. The method may include forming or providing a metalens, indicated at 204. The method may also include providing a first base for mounting the metalens, indicated at 206. The method may further include providing a first motor configured to move the first base, indicated at 208. The method may additionally include providing a second base for carrying a sample, indicated at 210. The method may include providing a second motor configured to move the second base, indicated at 212. The method may also include providing an objective lens, indicated at 214. The method may also include providing a third base, configured to carry the objective lens, indicated at 216. The method may further include providing a third motor configured to move the third base, indicated at 218. The method may additionally include providing a detector, indicated at 220. The method may also include providing a baffle including or having a small hole therein, the baffle being located between the objective lens and the detector, indicated at 222. The method may further include providing a processor in electrical communication with the first motor, the second motor, and the third motor, as indicated at 224. The metalens may be configured to allow at least a portion of the laser beam to pass through to write to the sample during the laser direct writing process. The processor may be configured to determine the distance between the metalens and the sample based on the image captured by the detector before the laser direct writing process. The processor may be further configured to control the second motor to move the second base to control the exposure time of the sample during the laser direct writing process.

[0042] For the avoidance of doubt, Figure 2 The purpose is to illustrate some of the steps according to various embodiments, and the order of the steps is not intended to be limited. For example, step 202 may occur before, at the same time, or after step 204.

[0043] In various embodiments, metalenses can be formed by focused ion beam (FIB), electron beam lithography (EBL), or photon lithography.

[0044] In various embodiments, a metalens can be formed based on parameters provided by a binary particle swarm optimization algorithm. The binary particle swarm optimization algorithm can be used to construct supercritical focusing based on a predefined distance (z=f) and full width at half maximum (FWHM) spot size, taking into account a specific wavelength. The wavelength can be adjusted in the algorithm. A merit function in the focal region can be defined. The diffraction field can then be calculated by the scalar angular spectrum method, which provides a good approximation. Due to the radial symmetry of the ring structure, the calculation can be simplified to a one-dimensional (1D) Hankel transform, saving memory and time. The final design can be obtained when the intensity variance between the calculated field and the target merit function is minimized.

[0045] In various embodiments, the metalens can be a super-oscillating lens. In various embodiments, the metalens can be a Fresnel zone plate lens or a supercritical lens.

[0046] In various embodiments, a metalens can have a focal point that is not limited by the diffraction limit.

[0047] In various embodiments, the laser source may be a 405 nm laser source. In various other embodiments, the laser source may be configured to generate one or more laser beams having any other suitable wavelength.

[0048] In various implementations, the first motor, the second motor, and the third motor may be piezoelectric motors.

[0049] In various embodiments, a metalens may include a substrate that is transparent to one or more laser beams. The metalens may include a patterned metal layer on the substrate that is configured to allow at least a portion of the one or more laser beams to pass through while blocking the remaining portion of the one or more laser beams during laser direct writing.

[0050] Figure 3 is an overall schematic diagram of a laser direct writing method according to various embodiments. The method may include providing an optical system, represented by 302. The optical system may include a laser source for emitting one or more laser beams. The optical system may also include a metalens. The optical system may further include a first base for mounting the metalens. The optical system may additionally include a first motor configured to move the first base. The optical system may also include a second base for carrying a sample. The optical system may further include an objective lens. The optical system may additionally include a third base configured to carry the objective lens. The optical system may also include a third motor configured to move the third base. The optical system may further include a detector. The optical system may additionally include a baffle including a pinhole thereon, the baffle being located between the objective lens and the detector. The optical system may also include a processor, the processor being in electrical communication with the first motor, the second motor, and the third motor. The method may include providing a sample, represented by 304. The method may further include determining, prior to the laser direct writing process, a distance between the metalens and the sample based on an image captured by the detector, wherein the metalens is configured to allow at least a portion of the one or more laser beams to pass through to write the sample, as indicated at 306. The method may additionally include moving the second stage using a second motor to control an exposure time of the sample during the laser direct writing process, as indicated at 308.

[0051] In various embodiments, the sample can include a photoresist. The photoresist can be any suitable photoresist.

[0052] In various embodiments, writing the sample may include controlling an optical system so that at least a portion of the one or more laser beams irradiates a portion of the photoresist, thereby polymerizing the portion of the photoresist.

[0053] Various embodiments can be used for high-resolution laser direct writing, which is suitable for various optical applications, such as patterning of diffractive optical elements (DOEs) and other planar optical elements.

[0054] In various embodiments, the metalens can form a needle-shaped focal point on the sample.

[0055] Various embodiments can be used to write or form arbitrary patterns on a sample (e.g., photoresist). In various embodiments, a metalens can focus (i.e., without passing through other optical elements) a portion of one or more laser beams directly onto the sample while blocking the remaining portion of one or more laser beams.

[0056] Figure 4 The resolution, cost, and writing speed of various lithography methods including direct laser writing (DLW) according to various embodiments are demonstrated.

[0057] Various embodiments may involve super-oscillating lenses operating under supercritical conditions (0.38λ / NA) (where λ is the operating wavelength and NA is the numerical aperture) using the super-oscillation concept, which have demonstrated sub-diffraction-limited focusing, no significant side lobes, and long working distances. Various embodiments may have prospects for super-resolution scanning optical confocal imaging and optical lithography. Various embodiments may involve using super-oscillating lenses for laser direct writing (DLW) optical lithography. By incorporating a super-oscillating lens into an optical confocal microscope with a moving base and using a 405 nm laser, patterns with a feature size of only 180 nm have been created on photoresist, far superior to the benchmark product Heidelberg DWL 66+, which can only produce patterns of 300 nm.

[0058] The super-oscillating lens is the core component in this super-resolution optical lithography technology. Figure 5 Scanning electron microscope (SEM) images of two types of two-dimensional lenses are shown: (a) a scanning electron microscope (SEM) image of a Fresnel zone plate (FZP) lens according to various embodiments; (b) a scanning electron microscope (SEM) image of a supercritical lens (SCL) lens according to various embodiments. The two types of two-dimensional lenses can operate at a wavelength of 405nm. The full width at half maximum (FWHM) of the Fresnel zone plate (FZP) lens can be 0.65λ, while the full width at half maximum (FWHM) of the supercritical lens (SCL) can be 0.46λ.

[0059] Compared to supercritical lenses, Fresnel zone plate lenses can be designed with longer working distances and larger focal spots. Longer working distances may facilitate the positioning process between the 2D lens and the photoresist layer, but may reduce the resolution of direct laser writing (DLW). The above lenses can be used to form patterns with different desired feature sizes on the photoresist. Various implementations can be manufactured by focused ion beam (FIB), while in large-scale production, electron beam lithography or photon lithography can be suitable for manufacturing these lenses.

[0060] Figure 6 Schematic diagram of an optical system according to various embodiments is shown. The optical system may be a device based on a photon scanning tunneling microscope (PSTM) system. The optical system may include a laser source 602, such as a 25 mW laser diode, which is used to emit one or more laser beams (e.g., 405 nm wavelength), and a super lens (or two-dimensional lens) 604. The optical system may include a first base 606 for mounting the super lens 604. More specifically, the optical system may include a lens holder 626, which may be mounted on the first base 606. The first base 606 may be a piezoelectric base, that is, the base 606 may be driven by a first piezoelectric motor ( Figure 6 (not shown) drive.

[0061] The optical system may further include a second base 610 for carrying a sample (eg, photoresist). The optical system may include a second piezoelectric motor ( Figure 6 ), which is configured to move the second base 610. The optical system may further include an objective lens 614. The optical system may further include: a third piezoelectric base 616, which is configured to carry the objective lens 614; and a third piezoelectric motor ( Figure 6 The optical system may further include a detector 620 and a baffle ( Figure 6 ), the baffle is located between the objective lens 614 and the detector 620. The optical system may further include a processor 624, which is in electrical communication with the first motor, the second motor, and the third motor.

[0062] During operation, the first base 606 on which the lens holder 626 and the two-dimensional lens 604 are mounted can be adjusted (using the first piezoelectric motor) to align with one or more laser beams emitted from the laser source 602. The optical system may include a lens 630 for changing the direction of the one or more laser beams before being directed to the two-dimensional lens 604. During the alignment stage of operation, one or more laser beams pass through the two-dimensional lens 604, the objective lens 614, the tube lens 628 and the pinhole 622, and are irradiated onto the detector 620 (forming a confocal microscope), which can be used to determine the desired distance between the two-dimensional lens 604 and the sample. The first piezoelectric motor can move the first base 606 until the distance between the two-dimensional lens 604 and the sample reaches a desired value. The desired distance can be the distance between the two-dimensional lens 604 and the sample, which corresponds to the desired focus to be formed on the sample during the laser direct writing process. The desired focus can be determined or measured by the detector 620. After the distance is set, during the writing phase, the second base 610 carrying the sample (e.g., photoresist) may be moved to control the exposure of the sample (e.g., photoresist). A pattern may be formed on the surface of the sample (e.g., photoresist). The third base 616 carrying the objective lens 614 may also be moved during operation. The objective lens 614 may be moved to focus on objects such as the two-dimensional lens 604 and the sample (e.g., photoresist wafer).

[0063] In the experiment, the sample was a silicon substrate with AZ5214e photoresist spun on the surface at 6000 rpm. The thickness of the photoresist film was about 1 μm to 1.5 μm. All samples exposed to the laser beam had been pre-baked at 90°C for 60 seconds. The exposed pattern was developed in AZ developer diluted with water at a ratio of 1:3 for 10 seconds. Thinner photoresist can help improve writing resolution.

[0064] The photolithographic pattern generated by this optical system is shown below. Figure 7 (a) an optical image of a snake ladder pattern generated by an optical system according to various embodiments, with a feature size of approximately 270 nm; and (b) an atomic force microscope (AFM) measurement image of a snake ladder pattern generated by an optical system according to various embodiments. The depth of these structures is approximately 40 nm, as measured by atomic force microscopy (AFM). The writing speed is set to 1 μm / s and the incident laser power is set to 2.3 μW. The numerical aperture (NA) of the two-dimensional lens used here is 0.66 and the working distance is 50 μm. Considering that the photon scanning tunneling microscope may be damaged by a high-power laser beam, a relatively low laser power and a slow writing speed are used. Various embodiments may relate to specific lithography systems that are suitable for higher laser powers, which can increase the writing speed.

[0065] Figure 8 Shown are (a) a scanning electron microscope (SEM) image of a dense grating pattern written by an optical system according to various embodiments; and (b) a magnified view of the portion of the image shown in (a). The dense grating structure can be formed by a two-dimensional lens with a numerical aperture (NA) of 0.89 and a working distance of 20 µm. The laser power and writing speed used can be similar to those used for writing Figure 7 The laser power and writing speed of the pattern shown in are similar. The pattern consists of lines with a spacing of 2 μm. Figure 8 (b) shows a line width of about 180 nm. These results demonstrate the resolution advantage of this optical system using two-dimensional lenses over commercial products currently on the market (such as Heidelberg DWL 66+, with a minimum feature size of 300 nm). The resolution can be further improved by using shorter wavelength lasers, such as deep ultraviolet light.

[0066] Fig. 9 Potential applications of laser direct writing using optical systems according to various embodiments are demonstrated. The next stage of consumer-grade electronic optics technology is planar optics, which has overwhelming performance advantages over traditional optics, and most of these planar optical elements (such as diffractive optical elements, DOEs) require more advanced optical lithography with a resolution requirement of 100 - 300 nm. There is currently no economically viable solution on the market. Various embodiments can enable optical systems to achieve a resolution of 100 - 300 nm. Various embodiments can enable entry into the camera optics market, thereby promoting the "planar transformation".

[0067] The lithography method used in the semiconductor industry is optical projection lithography, which requires masks for mass production of chips. The cost of producing a set of masks for a chip can be more than 2 million, but in most cases, only a small number of wafers will be produced. Therefore, for low-volume production, direct laser writing (DLW) may be an ideal alternative to save costs and achieve more flexible production.

[0068] As the research trend is towards smaller structural features and larger pattern areas, the research industry urgently needs a lithography tool with higher writing speeds, higher resolution and lower cost. A variety of implementations can meet this demand.

[0069] Fig.10 is a table comparing an embodiment with two conventional systems.

[0070] Various embodiments can achieve sub-diffraction-limited focusing for lithography. Various embodiments can improve resolution. Although there are many ways to improve resolution, such as using objectives with shorter wavelengths and higher numerical apertures, the objectives used in traditional laser direct writing systems are essentially diffraction-limited (Rayleigh criterion 0.61λ / NA). This limitation inhibits any other attempts to improve the lithography resolution of laser direct writing. Various embodiments can use the concept of superoscillation to design a two-dimensional lens for laser direct writing that achieves sub-diffraction-limited focusing, thereby breaking through the resolution limitation.

[0071] By combining this 2D lens into an optical confocal microscope with a moving stage and using a 405 nm laser, patterns with a feature size of only 180 nm have been created on photoresist, far better than the resolution achieved by the benchmark product HeidelbergDWL 66+, which can only produce patterns of 300 nm. The resolution can be further improved by using a shorter wavelength laser and placing the lens in a higher refractive index environment to obtain a larger numerical aperture.

[0072] The focus of the two-dimensional lens can be needle-shaped and the focal depth can be micrometer-level, which is very advantageous for manufacturing structures with high aspect ratios. This is impossible to achieve with traditional objective lenses.

[0073] Conventional optical lithography objectives cannot provide sub-diffraction-limited focus, which is limited by fundamental physics. There are several ways to improve lithography resolution, such as using shorter wavelengths (ArF 193nm stepper), increasing the numerical aperture through immersion objectives, or optimizing photoresists and lithography processes. However, these alternatives are still limited by the diffraction limit.

[0074] Various embodiments involving lenses that are not diffractive limited may have advantages over these alternatives. Furthermore, two-dimensional lenses that are not diffractive limited may also be combined with these alternatives to achieve better lithography resolution than conventional lenses.

[0075] Various implementations can replace traditional spherical lenses with two-dimensional lenses in laser direct writing systems through knowledge and experience in optical design, optical packaging, automatic control and optoelectronic system design, thereby achieving higher performance, more compact systems and lower costs.

[0076] The word "include" means including but not limited to the items listed after "include". Therefore, the use of the word "include" indicates that the listed elements are required or mandatory, but other elements are optional and may or may not be present.

[0077] The term “consisting of…” means including and being limited to the items listed in “consisting of…” Thus, the term “consisting of…” indicates that the listed elements are required or mandatory, and no other elements may be present.

[0078] The invention described herein can be properly implemented in the absence of any other elements or limitations that are not specifically disclosed. Thus, for example, the terms "comprises", "includes", "containing", etc. should be understood broadly and without limitation. In addition, the terms and expressions used herein are descriptive terms rather than restrictive terms, and the use of these terms and expressions is not intended to exclude any equivalents of the features shown and described or parts thereof, but it is also recognized that various modifications can be made within the scope of the claimed invention. Therefore, it should be understood that although the present invention has been specifically disclosed through preferred embodiments and optional features, a skilled technician can still make modifications and changes to the invention embodied therein, and these modifications and changes should be considered within the scope of the present invention.

[0079] When referring to given values ​​(eg, temperature and time period), the use of the term "about" means that the value is within a range of 10% above and below the specified value.

[0080] The invention has been described broadly and generically herein. Each of the narrower classes and subclasses that fall within the generic disclosure also form part of the invention. This includes the generic description of the invention, but with certain preconditions or negative limitations excluding any subject matter falling within that class, whether or not the excluded matter is specifically mentioned herein.

[0081] Other embodiments are included in the following claims and non-limiting examples. In addition, where features or aspects of the invention are described in terms of Markush groups, the skilled artisan will recognize that the invention is also thereby described in terms of any individual member or subgroup of members of the Markush group.

Claims

1. An optical system comprising A laser source for emitting one or more lasers; Superlens; A first base, on which the super lens is mounted; a first motor configured to move the first base; A second base, used for carrying the sample; a second motor configured to move the second base; Objective lens; a third base, configured to carry the objective lens; a third motor configured to move the third base; detector; a baffle plate including a small hole, the baffle plate being located between the objective lens and the detector; as well as a processor in electrical communication with the first motor, the second motor, and the third motor; wherein the metalens is configured to allow at least a portion of the one or more laser beams to pass through to write to the sample in a laser direct writing process; Wherein, the processor is configured to determine the distance between the metalens and the sample according to the image captured by the detector before the laser direct writing process; and Wherein, the processor is further configured to control the second motor to move the second base, thereby controlling the exposure time of the sample during the laser direct writing process.

2. The optical system according to claim 1, in, The superlens is a super-oscillating lens.

3. The optical system according to claim 1, in, The metalens is a Fresnel zone plate lens or a supercritical lens.

4. The optical system according to claim 1, in, The metalens has a focal point that is not limited by the diffraction limit.

5. The optical system according to claim 1, in, The laser source is a 405 nm laser source.

6. The optical system according to claim 1, in, The first motor, the second motor and the third motor are piezoelectric motors.

7. The optical system according to claim 1, in, The metalens comprises a substrate transparent to the one or more laser beams; and The metal lens comprises a patterned metal layer on the substrate, and the patterned metal layer is configured to allow at least part of the one or more laser beams to pass through during the laser direct writing process, while blocking the remaining part of the one or more laser beams.

8. A method of forming an optical system, the method comprising: Providing a laser source, the laser source for emitting one or more lasers; forming a superlens; Providing a first base, wherein the first base is mounted with the metalens; providing a first motor configured to move the first base; Providing a second base, wherein the second base is used to carry the sample; providing a second motor configured to move the second base; Provide objective lens; providing a third base, the third base being configured to carry the objective lens; providing a third motor configured to move the third base; Provide detectors; providing a baffle plate including a small hole, the baffle plate being located between the objective lens and the detector; as well as Providing a processor, the processor is in electrical communication with the first motor, the second motor and the third motor; wherein the metalens is configured to allow at least a portion of the one or more laser beams to pass through to write to the sample in a laser direct writing process; Wherein, the processor is configured to determine the distance between the metalens and the sample according to the image captured by the detector before the laser direct writing process; and Wherein, the processor is further configured to control the second motor to move the second base, thereby controlling the exposure time of the sample during the laser direct writing process.

9. The method according to claim 8, in, The metalens is formed by focused ion beam, electron beam lithography or photon lithography.

10. The method according to claim 8, in, The metalens is formed based on parameters provided by a binary particle swarm optimization algorithm.

11. The method according to claim 8, in, The superlens is a super-oscillating lens.

12. The method according to claim 8, in, The metalens is a Fresnel zone plate lens or a supercritical lens.

13. The method according to claim 8, in, The metalens has a focal point that is not limited by the diffraction limit.

14. The method according to claim 8, in, The laser source is a 405 nm laser source.

15. The method according to claim 8, in, The first motor, the second motor and the third motor are piezoelectric motors.

16. The method of claim 8, in, The metalens comprises a substrate transparent to the one or more laser beams; and The metal lens comprises a patterned metal layer on the substrate, and the patterned metal layer is configured to allow at least the portion of the one or more laser beams to pass through during the laser direct writing while blocking the remaining portion of the one or more laser beams.

17. A method for laser direct writing, the method comprising: An optical system is provided, the optical system comprising A laser source for emitting one or more lasers; Superlens; A first base, on which the super lens is mounted; a first motor configured to move the first base; A second base, used for carrying the sample; a second motor configured to move the second base; Objective lens; a third base, configured to carry the objective lens; a third motor configured to move the third base; detector; a baffle plate including a small hole, the baffle plate being located between the objective lens and the detector; as well as a processor in electrical communication with the first motor, the second motor, and the third motor; providing the sample to the second base station; Prior to the laser direct writing process, determining a distance between the metalens and the sample based on an image captured by the detector, wherein the metalens is configured to allow at least a portion of the one or more laser beams to pass through to write to the sample; The second motor is used to move the second base stage, thereby controlling the exposure time of the sample during the laser direct writing process.

18. The method of claim 17, in, The sample includes photoresist.

19. The method of claim 18, in, Writing the sample includes controlling the optical system so that at least the portion of the one or more laser beams irradiates a portion of the photoresist, thereby polymerizing the portion of the photoresist.

20. The method of claim 17, in, The superlens forms a needle-shaped focus on the sample.

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