An improved method for improving the resolution of a lithography machine

Abstract

An improved method for improving the resolution of a photolithography machine is disclosed. The present invention places an optical storage unit between an objective lens and a wafer. During exposure, after the signal light passes through a lens system, it is temporarily stored in the optical storage unit in the form of atomic spin waves. The energy of the light is converted into the energy of the atoms in the medium of the optical storage unit. Subsequently, the stored optical information is released in the original direction and can be regarded as an ideal point light source. This point light source propagates in the original direction. Since the propagation path is not limited by the lens aperture, the effective aperture becomes larger, the corresponding Airy disk becomes smaller, and the minimum resolvable size is reduced. When this point light source reaches the wafer, the width of the Airy disk becomes narrower, and the resolution of the photolithography machine is greatly improved. The benefit of this is that the aperture requirement for the photolithography machine can be reduced. In order to achieve the same resolution requirement, the lens imaging system can adopt a small aperture, which invisibly reduces the difficulty and cost of manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of lithography machines, and particularly relates to an improved method for improving the resolution of lithography machines. Background Art

[0002] In the field of chip manufacturing, a lithography machine (Lithography can also be called a mask aligner, an exposure system, a lithography system, etc.) is a very crucial piece of equipment. It uses optical projection imaging technology to project the pattern on a photomask (also called a reticle) onto a wafer, which is the key to realizing mass production of chips.

[0003] With the development of the chip industry, more and more components and wirings need to be accommodated on the same chip area, and the resolution of lithography machines needs to be continuously improved. In optical projection imaging, the diffraction limit of light is an important factor restricting the improvement of resolution. The diffraction limit means that when an ideal object point is imaged by an optical system, due to the limitation of diffraction, an ideal image point cannot be obtained, but a Fraunhofer diffraction image, that is, the so-called Airy disk (diffusion disk), is obtained. This is an important factor affecting the resolution of the optical projection imaging system. In optical imaging, when two object points are imaged, two diffusion disks are obtained. If they are too close, it is very difficult to distinguish them. The larger the diffusion disk, the lower the resolution. For the same optical system, the smaller the wavelength of light, the smaller the diffusion disk and the higher the resolution. Therefore, reducing the wavelength of the light source of the lithography machine can improve the resolution of the lithography machine.

[0004] Evolution route of the wavelength of the light source of the lithography machine:

[0005]

[0006] When the wavelength is reduced to 193 nm, the engineering difficulty of going further becomes increasingly large because light is easily absorbed, and the original lens, photoresist and other supporting materials can no longer be used and must all be re-developed. Therefore, at 193 nm, engineers developed a new technical solution, that is, immersion lithography technology. When light propagates in water, the refractive index of water is larger than that of air, so the wavelength becomes smaller. Using this solution, the wavelength of the light source can be shortened from 193 nm to 132 nm at one go. The effect after the application of immersion lithography is very good, and it is still a widely used successful solution.

[0007] To fabricate chips below 5 nanometers, the chip industry generally believes that an EUV light source with a wavelength of 13.5nm is required. EUV is classified as extreme ultraviolet light, but it is no longer strictly light radiation but a soft X-ray. Currently, no optical material can refract it, and even air can absorb it. Therefore, the EUV lithography machine must be evacuated. The optical path system of EUV uses mirrors coated with multilayer molybdenum-silicon interference optical films instead of refractive lenses, making the engineering implementation extremely difficult. Currently, there is only one manufacturer of EUV lithography machines, ASML in the Netherlands, and it is not available in China.

[0008] We deeply understand the underlying physical laws, think, and develop innovative technical routes, significantly reducing the technical difficulty and providing good performance.

[0009] The inventor has submitted the following Chinese patent applications on the same subject:

[0010] Patent 2 (Title: An Improved Method for Improving the Resolution of Lithography Machines, Application Number: 202311159318X, Application Date: September 10, 2023, Patent Number: ZL 2023 1 1159318.X, Authorization Announcement Date: July 2, 2024)

[0011] This invention application has made some technical improvements based on Patent 2 above. Since there are many correlations between the two, this invention application retains some content of Patent 2. For ease of reading, the improved parts in this invention application are marked with special labels: "The start of the improved part of this invention application", "The end of the improved part of this invention application". Summary of the Invention

[0012] This invention presents a new technical solution for improving the resolution of lithography machines.

[0013] The start of the improved part of this invention application 1

[0014] In subsequent research, we found that the patented method solves the interference between different photons. However, even for a single photon, when it passes through an optical system with a certain aperture, its inherent Airy disk is still restricted by the Rayleigh criterion. An ideal point source, passing through an aperture with a diameter of D (aperture), which can be a small hole or a lens system, will undergo diffraction, and its diffraction pattern is an Airy disk. Due to the Airy disk, the minimum resolvable angle is calculated by the following formula:

[0015]

[0016] In the formula, λ is the frequency of the point source, and D is the diameter size of the aperture.

[0017] The resolution of the lithography machine is limited by the Rayleigh criterion, and the minimum resolvable size of the lithography machine is calculated by the following formula:

[0018]

[0019] In the formula, λ is the wavelength of light, K1 is the process coefficient factor, NA is the numerical aperture of the lithography objective, NA=n.sinθ, n is the refractive index, that is, the refractive index of the medium between the wafer and the lens. If it is air, its refractive index is close to 1.0, if it is a vacuum, its refractive index is 1.0, and the immersion lithography machine uses a transparent liquid with a high refractive index, such as deionized water, whose refractive index is 1.46.

[0020] θ represents the incident angle.

[0021] In order to obtain the smallest possible minimum resolvable size, the current lithography machine has the following method: method 1 is to increase the aperture, so the lens size of the current lithography machine is very large, which invisibly increases the difficulty and cost of manufacturing. Method 2 is immersion, where a high refractive index medium is used between the wafer and the lens, such as deionized water, whose refractive index n is 1.46, which is about 1.46 times the refractive index of air and vacuum.

[0022] This application uses the electromagnetically induced transparency (EIT) effect. The frequency of the probe light (also called signal light) corresponds to the absorption transition frequency of the medium. When it is incident on the medium alone, the probe light cannot pass through the medium due to the strong resonance absorption of the medium at this frequency. Another beam of strong control light (also called coupled light) forms a three-level atomic system with the probe light. When the strong control light exists, the strong control light field causes quantum coherent interference, and the probe light is almost not absorbed and passes through the medium, that is, electromagnetically induced transparency (EIT) occurs, and the refractive index of the medium changes sharply (see the attached figure of the specification). Figure 12 ), which causes the group velocity of the detection light to slow down. The group velocity of the detection light can be adjusted by changing the intensity of the control light. The lower the intensity of the control light, the slower the group velocity of the detection light. When the control light is adiabatically turned off, the group velocity of the detection light becomes 0, that is, the detection light is saved to the medium in the form of atomic spin waves, and the optical information is stored in the medium. This is called the optical writing process, and the control light of this process is called the writing light. The process of reading the stored optical information is called the optical reading process, and the control light of this process is called the reading light. When the reading light is turned on again, if the frequency and direction of the reading light are the same as the writing light, the stored optical information will be released according to the original frequency and direction; if the frequency and direction of the reading light are different from the writing light, the stored optical information will be released according to the new frequency and new direction.

[0023] The detection light, control light writing light and readout light are Figure 1 The timing of the optical storage can be realized.

[0024] Detection light and control light according toFigure 2 The timing of light slow light can be achieved.

[0025] Method 1 of the present application is to place an optical storage unit between an objective lens and a wafer, and control the timing of control light and detection light. During exposure, after the detection light passes through the lens system, it is temporarily stored in the optical storage unit in the form of atomic spin waves, and the energy of the light is converted into the energy of the atoms in the medium of the optical storage unit, and then restored to light according to the original propagation direction. The process of light restoration is to convert the energy of the atoms in the medium of the optical storage unit into the energy of light. If the frequency and direction of the read light are the same as those of the write light, the stored optical information will be released according to the original frequency and direction; if the frequency and direction of the read light are different from those of the write light, the stored optical information will be released according to the new frequency and new direction. After the stored optical information is released, it can be regarded as a newly generated ideal point light source. This point light source propagates in the direction of generation. In this application, it will propagate in the original direction before writing. Since the propagation path is not limited by the lens aperture, the effective aperture becomes larger, the corresponding Airy disk becomes smaller, and the minimum resolvable size will be reduced. When this point light source reaches the wafer, the Airy disk width becomes narrower, and the resolution of the lithography machine is greatly improved. The benefit of this is that the aperture requirements for the lithography machine can be reduced. In order to achieve the same resolution requirements, the lens imaging system can adopt a small aperture, which invisibly reduces the difficulty and cost of manufacturing.

[0026] Method 2 of the present application is to place a light slow light unit between the objective lens and the wafer. During exposure, after the detection light passes through the lens system, in the light slow light unit, because its frequency corresponds to the absorption transition frequency of the medium, when it is incident on the medium alone, due to the medium's strong resonance absorption of this frequency, the detection light cannot pass through the medium. Another beam of strong control light (also called coupled light) forms a three-level atomic system with the detection light. When the strong control light exists, the strong control light field causes quantum coherent interference, and the detection light is almost not absorbed and passes through the medium, that is, electromagnetic induced transparency (EIT) occurs, and the refractive index of the medium changes sharply (see the attached manual). Figure 12 ), which causes the group velocity of the detection light to slow down. Here, our focus is on the refractive index of the medium. When a specific detection light frequency is selected, the group velocity of the detection light when passing through the medium is slowed down, the equivalent wavelength of the detection light becomes shorter, and the refractive index of the medium increases significantly. The medium becomes a super-refractive medium with a large refractive index, just like the working mechanism of an immersion lithography machine. The optical slow light unit narrows the width of the Airy disk, reduces the minimum resolvable size of the lithography machine, and improves the resolution.

[0027] End of the Improvement Part 1 of the Invention Application

[0028] The present invention is further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the working timing diagram of the optical storage unit. The incident detection light refers to the detection light before the optical storage into the medium (414), and the outgoing detection light refers to the detection light restored after being stored in the medium. The outgoing detection light is the detection light received by the photoresist (3102). The writing light refers to the control light (416) for storing the detection light into the medium, and the reading light and the reading light 2 refer to the control lights (416) for restoring the detection light stored in the medium. The difference between these two reading lights is that the amplitudes of the reading light and the writing light are the same, while the amplitude of the reading light 2 is greater than that of the writing light. The reading light, the reading light 2, and the writing light are all control lights (416), and they are subdivided due to different functions. The optical switch signal refers to the switch control signal of the optical switch (not shown in the figure). The opening and closing of the optical switch (not shown in the figure) are controlled by the optical switch signal. The abscissa of the curve in the figure represents time, and the ordinate represents the intensity of light. T1 - T8 represent the relevant nodes on the time axis in the figure.

[0030] At time point T1, the writing light is turned on. After a certain period of time, at time point T2, the incident detection light is turned on. Due to the existence of the writing light as a control light, the electromagnetically induced transparency (EIT) effect is generated, and the incident detection light can propagate in the medium. Due to the slow light effect, its group velocity in the medium is lower than the speed of light in vacuum. At time point T3, the writing light is turned off. Without the writing light as a control light, the propagation of the incident detection light in the medium stops and it is stored in the medium. At time point T4, the reading light is turned on. Due to the existence of the reading light as a control light, the incident detection light stored in the medium is restored to the outgoing detection light and continues to propagate. Due to the slow light effect, its group velocity in the medium is lower than the speed of light in vacuum. When the reading light is replaced by the reading light 2, since the amplitude of the reading light 2 is greater than that of the reading light, the restored outgoing detection light will be accelerated, thus realizing the compression of the outgoing detection light pulse on the time axis. If the amplitude of the reading light 2 is less than that of the reading light, the opposite effect will occur, and the outgoing detection light pulse will be stretched on the time axis. At time point T5, the outgoing detection light starts to leave the medium. At time point T6, the outgoing detection light completely leaves the medium. The optical switch signal of the optical switch (not shown in the figure) is turned on at time point T5 and turned off at time point T6, which is precisely aligned with the timing of the outgoing detection light, only selecting the photons within this specific time interval, so a large amount of noise can be filtered out to achieve the purpose of time filtering. At time point T7, the reading light (or the reading light 2) is turned off. At time point T8, one write - read cycle ends, and then the next cycle begins.

[0031] Figure 2It is the working timing diagram of the optical slow light unit. At time point T4, the control light is turned on. Due to the presence of the control light, the electromagnetically induced transparency (EIT) effect is generated, and the probe light can propagate in the medium. Due to the slow light effect, its group velocity in the medium is lower than the speed of light in vacuum. At time point T5, the probe light is turned on. Due to the electromagnetically induced transparency (EIT) effect, the probe light can propagate in the medium. At time point T6, the probe light completely leaves the medium. At time point T7, the control light is turned off. At time point T8, a timing cycle ends, and then the next cycle begins.

[0032] The improvement part of this invention application starts from 2

[0033] Figure 3 It is the schematic diagram of Airy disks with different widths of this invention.

[0034] Figure 3 Among them, the width of (a) is larger, and the width of (b) is smaller. The smaller the width of the Airy disk, the smaller the minimum resolvable size, and the higher the resolution of the lithography machine. The purpose of this invention application is to make the width of the Airy disk as small as possible, so as to improve the resolution of the lithography machine.

[0035] Figure 4 It is the schematic diagram showing the Rayleigh criterion limitation of this invention.

[0036] Figure 4 Among them, an ideal point light source (1501), the light rays (1502) emitted by it pass through an aperture (1503) with a diameter of D. This aperture is a small hole or a lens system. Due to the diffraction effect, its light spot is an Airy disk (1504). Because of the Airy disk, the minimum resolvable angle θ is calculated by the above formula 1.1.

[0037] Figure 5 It is the schematic diagram showing the principle of the minimum resolvable size of the lithography machine of this invention.

[0038] Figure 5 Among them, 1601 is a photomask, 1602 is the transmissive dot pattern on it, the light rays (1603) pass through the dot pattern (1602), the light rays (1603) diffract, the lens system consists of two lenses (1604 and 1605), 1605 is the lithography objective lens, the light rays (1603) propagate in the lens system, 1606 is the medium, n is its refractive index, 310 is the wafer, 3102 is the photoresist on the surface of the wafer (310), θ is the incident angle of the objective lens (1605), and the minimum resolvable size of the lithography machine is calculated by the above formula 1.2. After the point light source passes through the lens system of the lithography machine, due to the diffraction effect, its light spot is an Airy disk (1607). The smaller the width of the Airy disk, the higher the resolution of the lithography machine.

[0039] Figure 6It is a schematic diagram of the relevant part structure in the lithography machine in the embodiment of the present invention.

[0040] Figure 6 Among them, 301 is a laser, 302 is the output light of the laser (301), 303 is a mirror, 304 is a light processing unit for processing light such as filtering, homogenizing, and beam adjustment, 305 is a mirror, 306 is an optical storage unit in Embodiment 1 and an optical compression and optical slowdown unit in Embodiment 2, 307 is a photomask, 308 is a photomask positioning stage, 309 is a lens group, 310 is a wafer, 311 is a wafer stage, 312 is the core functional unit of the present invention, which is an optical storage unit in Embodiment 3 and an optical slow light unit in Embodiment 4. Compared with the existing lithography machine, the main improved parts of the present invention are: the laser (301) and the core functional unit (306 and 312) of the present invention. The improvement of the laser (301) mainly lies in the frequency, and the selected frequency is the resonance transition frequency of the medium atoms.

[0041] Figure 7 It is a schematic diagram of the principle of the side structure of a local structure magnification in the lithography machine in the embodiment of the present invention.

[0042] Figure 7 (a) shows the side structure of a local structure magnification in the lithography machine. 309 is a lens group, 310 is a wafer, 311 is a wafer stage, 3102 is the photoresist on the surface of the wafer (310), and 312 is the core functional unit of the present invention, which is an optical storage unit in Embodiment 3 and an optical slow light unit in Embodiment 4. 415 is the probe light, and 416 is the control light beam.

[0043] Figure 7 (b) shows the structure of 312. 413 is a cryogenic cavity. In order to increase the aperture as much as possible and make the Airy disk width narrower, the cryogenic cavity uses a transparent material (preferably quartz material, including other available transparent materials) and has the largest possible diameter. The cryogenic cavity also includes a vacuum system and a liquid helium refrigeration system, which are not shown in the figure. The vacuum system provides the required vacuum environment, and the liquid helium refrigeration system reduces the temperature of the cryogenic cavity to 3.5 K and maintains it, making the temperature of the cryogenic cavity as close to absolute zero as possible. This can reduce the thermal motion of the medium and reduce noise. 414 is the medium, and praseodymium-doped yttrium orthosilicate crystal (Pr 3+ :Y2SiO5), or europium chloride hexahydrate (EuCl3.6H2O) single crystal can be selected.

[0044] Figure 8 It is a schematic diagram of the principle of the side structure of another local structure magnification in the lithography machine in the embodiment of the present invention.

[0045] Figure 8Among them, 309 is a lens group, 310 is a wafer, 311 is a wafer stage, 3102 is the photoresist on the surface of the wafer (310), 312 is the core functional unit of the present invention, which is an optical storage unit in Embodiment 3 and an optical slow light unit in Embodiment 4. 414 is a medium, and atomic vapor of a metal can be selected. 415 is a probe light, and 416 is a light beam for controlling light.

[0046] Figure 9 It is a schematic diagram of the principle for preparing a light beam of an optical storage unit in Embodiment 3 of the present invention.

[0047] Figure 9 Among them, 401 is an incident light ray, 402 is a half-wave plate, 403 is a beam splitter that divides one light beam into two light beams, 404 is a probe light focusing lens that focuses the light ray (401), 405 is a probe light collimating lens that collects the focused light ray (401) into a parallel light beam with a small diameter, 406 is an acousto-optic modulator (AOM) of the probe light, which is responsible for adjusting the frequency of the probe light to the required frequency and is also responsible for turning the light on and off to achieve timing control. 418 is a focusing lens that focuses the light beam (415) of the probe light, 419 is a collimating lens that collects the focused light beam (415) of the probe light into a parallel light beam with a large diameter, and 415 is the probe light.

[0048] 420 is a beam splitter that divides one light beam into two light beams, 408 is a control light focusing lens that focuses the light ray (401), 409 is a control light collimating lens that collects the focused light ray (401) into a parallel light beam with a small diameter, 410 is an acousto-optic modulator (AOM) of the control light, which is responsible for adjusting the frequency of the control light to the required frequency and is also responsible for turning the light on and off to achieve timing control, and 4161 is the writing light of the control light.

[0049] 429 is a beam splitter that divides one light beam into two light beams, 430 is a control light focusing lens that focuses the light ray (401), 431 is a control light collimating lens that collects the focused light ray (401) into a parallel light beam with a small diameter, 432 is an acousto-optic modulator (AOM) of the control light, which is responsible for adjusting the frequency of the control light to the required frequency and is also responsible for turning the light on and off to achieve timing control, and 4162 is the reading light of the control light.

[0050] 421 is a mirror, 422 is a pump light focusing lens that focuses the light beam (401), 423 is a pump light collimating lens that collects the focused light beam (401) into a parallel light beam with a small diameter, 424 is an acousto-optic modulator (AOM) of the pump light, which is responsible for adjusting the frequency of the pump light to the required frequency and at the same time responsible for turning the light on and off to achieve timing control, and 427 is the beam of the pump light. The components described in this paragraph constitute an auxiliary pump light beam splitting, simply referred to as pump light beam splitting. Its function is to pump the particles in the ground state energy level to a higher energy level during the initial state preparation of electromagnetically induced transparency (EIT). The pump light beam splitting is of an auxiliary nature and can be dispensed with in some application scenarios.

[0051] Figure 10 It is a schematic diagram of the principle of beam preparation for one type of optical slow light unit in Embodiment 4 of the present invention.

[0052] Figure 10 In it, 401 is the incident light beam, 402 is a half-wave plate, 403 is a beam splitter that divides one light beam into two light beams, 404 is a probe light focusing lens that focuses the light beam (401), 405 is a probe light collimating lens that collects the focused light beam (401) into a parallel light beam with a small diameter, 406 is an acousto-optic modulator (Acousto-Optic Modulators, simply referred to as AOM) of the probe light, which is responsible for adjusting the frequency of the probe light to the required frequency and at the same time responsible for turning the light on and off to achieve timing control. 418 is a focusing lens that focuses the light beam (415) of the probe light, 419 is a collimating lens that collects the focused light beam (415) of the probe light into a parallel light beam with a large diameter, and 415 is the probe light.

[0053] 420 is a beam splitter that divides one light beam into two light beams, 408 is a control light focusing lens that focuses the light beam (401), 409 is a control light collimating lens that collects the focused light beam (401) into a parallel light beam with a small diameter, 410 is an acousto-optic modulator (AOM) of the control light, which is responsible for adjusting the frequency of the control light to the required frequency and at the same time responsible for turning the light on and off to achieve timing control, and 416 is the control light.

[0054] 421 is a mirror, 422 is a pump light focusing lens that focuses the light beam (401), 423 is a pump light collimating lens that collects the focused light beam (401) into a parallel light beam with a small diameter, 424 is an acousto-optic modulator (AOM) of the pump light, which is responsible for adjusting the frequency of the pump light to the required frequency and at the same time responsible for turning the light on and off to achieve timing control, and 427 is the beam of the pump light. The components described in this paragraph constitute an auxiliary pump light beam splitting, simply referred to as pump light beam splitting. Its function is to pump the particles in the ground state energy level to a higher energy level during the initial state preparation of electromagnetically induced transparency (EIT). The pump light beam splitting is of an auxiliary nature and can be dispensed with in some application scenarios.

[0055] Figure 11 This is a schematic diagram of the principle of achieving the electromagnetically induced transparency (EIT) effect with a lower control light intensity through multiple reflections in an embodiment of the present invention.

[0056] Figure 11 In it, 312 is the core functional unit of the present invention. This figure shows its top view plan. In Embodiment 3, it is an optical storage unit, and in Embodiment 4, it is an optical slow light unit. 413 is a low-temperature cavity. There are quartz light-transmitting windows on two sides of the low-temperature cavity. The low-temperature cavity also includes a vacuum system and a liquid helium refrigeration system, which are not shown in the figure. The vacuum system provides the required vacuum environment, and the liquid helium refrigeration system reduces the temperature of the low-temperature cavity to 3.5 K and maintains it, making the temperature of the low-temperature cavity as close to absolute zero as possible. This can reduce the thermal motion of the medium and lower the noise. 414 is the medium, and praseodymium-doped yttrium silicate crystal (Pr 3+ :Y2SiO5), or europium(III) chloride hexahydrate (EuCl3·6H2O) single crystal can be selected. 4161 is the control light beam serving as the writing light, 4162 is the control light beam serving as the reading light, 427 is the light beam serving as the auxiliary light, 1803 and 1804 are half-reflecting mirrors that combine two beams of light into one beam of light. 1801 is a high-reflectivity mirror located on the left, and 1802 is a high-reflectivity mirror located on the right.

[0057] Figure 12 It shows the probe light passing rate curve of the medium and the refractive index curve of the medium when the electromagnetically induced transparency (EIT) effect occurs.

[0058] Figure 12 In it, a is the probe light passing rate curve, and b is the refractive index curve.

[0059] End of the improved part of the present invention application 2 Detailed implementation manners

[0060] Now, the specific implementation process of the present invention will be introduced in detail with reference to the above-mentioned drawings:

[0061] Start of the improved part of the present invention application 3

[0062] The medium form for the present invention to achieve the slow light effect, optical storage or quantum storage function can be gas, liquid, and solid. The gas-form medium includes but is not limited to: atomic vapors of metals such as rubidium (Rb), cesium (Cs), potassium (K), sodium (Na), strontium (Sr), lead (Pb), praseodymium (Pr), cerium (Ce), etc. When using gas, often a transparent gas chamber and a system for keeping the gas chamber at a constant temperature are required. Since gas and liquid will flow, it will cause storage distortion. Therefore, solid is the preferred storage medium.

[0063] The slow light effect is an important technical feature of the present invention. Any known method for achieving slow light can be applied to the present invention, including but not limited to: electromagnetically induced transparency (EIT), coherent population oscillation (CPO for short), spectral hole burning, Brillouin scattering, Raman scattering, and so on.

[0064] Optical quantum storage is an important technical feature of this embodiment. Currently, the reported solid optical storage or quantum storage functions in the literature are mostly realized in rare-earth doped crystals. The optical storage phenomenon in single crystals of pure rare-earth compound crystals has also been reported. For example, some literature has reported the realization of optical storage in EuCl3·6H2O (europium chloride hexahydrate) single crystals. Due to the lattice distortion caused by impurity rare-earth ions, it is usually difficult to directly increase the concentration of rare-earth ions to obtain a higher absorption depth. Using pure rare-earth compound crystals is a solution. Its lattice structure is perfect, without the lattice distortion caused by doping, and it has a very high optical density. To perfectly implement the present invention, the key lies in the perfect distribution of medium atoms. And for the atoms in the crystal to be perfectly distributed to form an orderly arranged substance, it is still difficult to manufacture nanostructures on a large scale in factories at present, and it is also difficult to ensure that each atom is evenly distributed during doping. Therefore, the optical storage medium of the lithography machine is preferably a monomer or a compound crystal, which is a key feature for the present invention to achieve good results. Those skilled in the art can understand that under the direct guidance of the core spirit of the present invention and inspired by the description of the present invention, along this direction, many suitable dielectric materials will continue to be discovered, including but not limited to single crystals of rare-earth element metal simple substances, pure rare-earth compound crystals, single crystals of non-rare-earth element simple substances, and non-rare-earth element compound crystals. All versions after various replacements, changes, and modifications within the scope of its patent protection can be successfully implemented, and such replacements, changes, and modifications should all fall within the scope of the patent protection of the present invention. Using pure rare-earth compound crystals also has an advantage that its lattice structure is perfect and there is no lattice distortion caused by doping, so the scattering noise can be effectively reduced. In the application of the lithography machine of the present invention, the noise of the light source will greatly affect the lithography effect. Therefore, in order to minimize the noise, it is preferred to use pure rare-earth compound crystals, and the chemical purity should be increased as much as possible, the crystal growth process control should be improved, and the lattice distortion should be reduced. In addition to chemical purity, the isotope purity should also be increased as much as possible. Atoms have different isotopes. It can be found in the published literature that after isotope purification of the chlorine (Cl) element among them, the inhomogeneous broadening of EuCl3·6H2O (europium chloride hexahydrate) can be effectively improved, and a very narrow linewidth can be obtained. The linewidth can be even narrower after isotope purification of all elements of the compound. The narrow linewidth can improve the efficiency of optical quantum storage. These methods can all be applied in the present invention, and many suitable dielectric materials with very narrow inhomogeneous broadening will continue to be discovered to achieve the best implementation effect.

[0065] It should be noted that for crystal dielectrics, their lattice structures are highly consistent and often have anisotropic characteristics. The incident directions of the probe light and the control light need to be precisely adjusted to maintain a certain angle with the lattice structure in order to achieve good results.

[0066] There are many optical storage solutions, including Electromagnetically Induced Transparency (EIT for short), Spectral Hole Burning (SHB for short) which is similar to it, Off-Resonant Raman-type excitations, Photo Echo, and Faraday Rotation of light. Under the category of Photo Echo, there are many subdivided types, including Controlled Reversible Inhomogeneous Broadening (CRIB for short), Atomic Frequency Comb (AFC for short), Gradient Echo Memory (GEM for short), Hybrid Photo Echo (HYPER for short), and so on. The principles of Electromagnetically Induced Transparency (EIT) and Off-Resonant Raman-type excitations are relatively similar, and light is stored in the medium in the form of atomic spin waves. The optical storage of the present invention can adopt all known optical storage technical solutions, including but not limited to the above-mentioned optical storage technical solutions, and is not limited to Electromagnetically Induced Transparency (EIT).

[0067] The frequency of the probe light (415) corresponds to the resonant absorption frequency of the slow light unit or the medium of the optical storage unit. This frequency is determined by the transition absorption frequency of the energy levels selected by the medium (414). If the medium is a praseodymium-doped yttrium orthosilicate crystal (Pr 3+ :Y2SiO5), and the 3H4→1D2 energy level transition is selected, the wavelength corresponding to the transition frequency is 605.78 nm (nanometers). If the medium is a single crystal of europium chloride hexahydrate (EuCl3·6H2O), and the 7F0→5D0 energy level transition is selected, the wavelength corresponding to the transition frequency is 579.7033 nm.

[0068] Example 3: In this example, the optical storage unit is placed between the objective lens and the wafer. Figure 7 One type of optical storage unit of this example is shown. Figure 8 Another type of optical storage unit of this example is shown.

[0069] Figure 1It is the working timing diagram of the optical storage unit. At time point T1, the writing light (4161) of the control light (416) is turned on. After a certain period of time, at time point T2, the incident detection light is turned on. Due to the existence of the writing light as the control light, the electromagnetically induced transparency (EIT) effect is generated, and the incident detection light can propagate in the medium. Due to the slow light effect, its group velocity in the medium is lower than the speed of light in vacuum. At time point T3, the writing light is turned off. Since the writing light no longer exists as the control light, the propagation of the incident detection light in the medium stops and is stored in the medium. At time point T4, the reading light (4162) of the control light (416) is turned on. Due to the existence of the reading light as the control light, the incident detection light stored in the medium is restored to the outgoing detection light and continues to propagate. Due to the slow light effect, its group velocity in the medium is lower than the speed of light in vacuum. When the reading light is replaced by the reading light 2, since the amplitude of the reading light 2 is greater than that of the reading light, the restored outgoing detection light will be accelerated, so that the outgoing detection light pulse is compressed on the time axis. If the amplitude of the reading light 2 is less than that of the reading light, the opposite effect will occur, and the outgoing detection light pulse will be stretched on the time axis. At time point T5, the outgoing detection light starts to leave the medium. At time point T6, the outgoing detection light completely leaves the medium. At time point T7, the reading light (or the reading light 2) is turned off. At time point T8, a write-read cycle ends, and then the next cycle starts.

[0070] The control light (416) includes the writing light (4161) and the reading light (4162). The frequencies, intensities, and Airy disk widths of the writing light and the reading light can be the same or different. When they are different, there can be a very large number of matching options, and any of these combinations can be applied in the present invention. When the intensity of the reading light is greater than that of the writing light, after the stored optical information is released, the optical group velocity will increase. Conversely, when the intensity of the reading light is less than that of the writing light, after the stored optical information is released, the optical group velocity will decrease. The writing light and the reading light can be modulated by optical systems with different apertures, so they have different Airy disk widths. By using different Airy disk widths, the release process of the stored optical information can be finely adjusted and intervened to achieve the best effect. Any of the above combinations can be applied in the present invention. By finely adjusting and intervening in the release process of the stored optical information, the most suitable parameter combination can be found to achieve the best effect. The present invention places no restrictions on the combination of parameters.

[0071] During exposure, after the detection light (415) passes through the lens system, it is temporarily stored in the optical storage unit (312) in the form of atomic spin waves, and the energy of the light is converted into the energy of the atoms in the optical storage unit medium, and then restored to light in the original propagation direction. The process of light restoration is to convert the energy of the atoms in the optical storage unit medium into the energy of light. If the frequency and direction of the read light are the same as those of the write light, the stored optical information will be released in the original frequency and direction; if the frequency and direction of the read light are different from those of the write light, the stored optical information will be released in the new frequency and new direction. After the stored optical information is released, it can be regarded as an ideal point light source. This point light source propagates in the direction of generation. In this application, it will propagate in the original direction before writing. Ideally, since the propagation path has no lens aperture limitation and no other aperture limitation, the aperture is almost infinite. According to the above formula 1.1, the minimum resolvable angle will be infinitesimal. In the actual physical world, infinitesimal does not exist because this leads to infinite energy density, which is a very small unit, much smaller than the resolution target nanometer we need to achieve. We call it the limit small, and the corresponding Airy disk is the limit small. The minimum resolvable size will be reduced to the limit small. When this point light source reaches the wafer, the influence of the Airy disk on the resolution can be ignored, and the resolution of the lithography machine is greatly improved. The above is the most ideal situation. In practical applications, the medium (414) requires support (not shown in the figure) and a low-temperature cavity (413), and the aperture cannot be infinite. The cryogenic cavity is made of transparent material (preferably quartz material, including other available transparent materials), and the diameter is as large as possible. After the light information stored in the medium (414) is released, it can be regarded as an ideal point light source. This point light source propagates in the direction of generation. The propagation path is not limited by the lens aperture. The propagation path is a transparent quartz material with a diameter as large as possible. The aperture limit becomes smaller, the Airy disk becomes narrower, and the resolution of the lithography machine is improved. As long as the aperture is large enough, the Airy disk will be narrow enough, and the resolution of the lithography machine will be high enough to meet the design requirements. It should be noted that the features described in this paragraph are not only applicable to Example 3, but also to Example 4. The optical storage unit can reduce the minimum resolvable size. The benefit of this is that the aperture requirement for the lithography machine can be reduced. In order to achieve the same resolution requirement, a small aperture can be used, which virtually reduces the difficulty and cost of manufacturing.

[0072] In the description of this embodiment, the optical storage unit (312) is placed between the objective lens and the wafer. However, since the light travels in a straight line in the form of a point source after leaving the optical storage unit and there is no aperture limitation anymore, the optical storage unit can be placed at any position between the photomask and the wafer. Considering that the stored optical information is released in the original direction with a certain deviation in direction, which is called the beam direction deviation in the present invention, the smaller the distance between the medium (414) in the optical storage unit (312) and the wafer, the better. This can reduce the exposure position deviation caused by the direction deviation, and this also applies to Embodiment 4, which will be elaborated later. At the microscopic level, Embodiment 4 essentially belongs to Embodiment 3. When light passes through the fine patterns on the photomask, diffraction occurs. Therefore, in this embodiment, the optical storage unit is not suitable to be placed in front of the photomask on the optical path. The optical storage unit can be in close contact with the photomask and the wafer. In fact, there are examples, such as the well-known near-field optical microscopy technology, which makes the distance between the probe and the object to be detected as small as possible, thereby being able to break through the diffraction limit and achieve nanoscale resolution.

[0073] Embodiment 4: In this embodiment, the optical slow light unit is placed between the objective lens and the wafer. Figure 7 One type of optical slow light unit of this embodiment is shown. Figure 8 Another type of optical slow light unit of this embodiment is shown.

[0074] Figure 2 It is the working timing diagram of the optical slow light unit. At time point T4, the control light (416) is turned on. Due to the presence of the control light, the electromagnetically induced transparency (EIT) effect is generated, and the probe light (415) can propagate in the medium (414). Due to the slow light effect, its group velocity in the medium is lower than the speed of light in vacuum. At time point T5, the probe light (415) is turned on. Due to the electromagnetically induced transparency (EIT) effect, the probe light can propagate in the medium. At time point T6, the probe light completely leaves the medium. At time point T7, the control light is turned off. At time point T8, one timing cycle ends, and then the next cycle starts.

[0075] During exposure, after the probe light (415) passes through the lens system and enters the optical slow light unit, because its frequency corresponds to the absorption transition frequency of the medium, when it is incident on the medium (414) alone, the probe light cannot pass through the medium due to the strong resonant absorption of the medium at this frequency. Another control light (416), together with the probe light, forms a three-level atomic system. When the control light is present, the control light field causes quantum coherence interference, and the probe light can pass through the medium with almost no absorption, that is, electromagnetically induced transparency (EIT) appears, and the refractive index of the medium changes sharply (see the attached Figure 12) As a result, the group velocity of the probe light slows down. Here, our focus is on the refractive index of the medium. We select the frequency of the probe light at which the refractive index is at its maximum value. According to Equation 1.2, when the refractive index of the medium increases, its minimum resolvable size decreases. When the refractive index increases, the frequency of the light remains unchanged, the group velocity of the light slows down, and the effective wavelength of the light decreases. All of these lead to a narrowing of the Airy disk width.

[0076] In the description of this embodiment, the slow light unit is placed between the objective lens and the wafer. However, since the slow light unit allows the light to exchange energy with the medium and the width of the Airy disk of the light has already narrowed, the slow light unit can be placed at any position between the photomask and the wafer. However, due to the deviation of the light beam direction, the smaller the distance between the medium (414) in the optical storage unit (312) and the wafer, the better.

[0077] When light passes through the fine patterns on the photomask, diffraction occurs. Therefore, in this embodiment, the slow light unit should not be placed in front of the photomask in the optical path. The slow light unit can be in close contact with the photomask and the wafer. In fact, there are examples of this, such as the well-known near-field optical microscopy technology, which makes the distance between the probe and the object to be detected as small as possible, thereby being able to break through the diffraction limit and achieve nanoscale resolution.

[0078] It should be particularly noted that other descriptions in this specification, or the descriptions in the following patents:

[0079] Patent 2 (Title: An Improved Method for Improving the Resolution of a Lithography Machine, Application Number: 202311159318X, Application Date: 20230910, Patent Number: ZL 2023 1 1159318.X, Authorization Announcement Date: July 02, 2024)

[0080] Unless otherwise specified, the features in these descriptions also apply to Embodiment 3 and Embodiment 4, and these descriptions will not be repeated below. The following is a summary of some common features of the above-mentioned Embodiment 3 and Embodiment 4:

[0081] In the above embodiments, in order to make the width of the Airy disk as narrow as possible to achieve better resolution, the measures taken include: 1) Refer to Figure 7(b), in order to maximize the aperture as much as possible, the low-temperature cavity (413) is made of a transparent material (preferably quartz material, including other available transparent materials), and its diameter is as large as possible. The manufacturing difficulty of its parallel-plate structure is lower than that of a lens; 2) the distance between the medium (414) and the wafer (310) is minimized; 3) a medium (414) available at room temperature is developed, so that containers can be dispensed with, including the low-temperature cavity (413) and a constant-temperature heating container (not shown in the figure); 4) the support structure of the medium (414) (not shown in the figure) is made of a transparent material (preferably quartz material, including other available transparent materials), and its diameter is as large as possible. At the same time, the pressing structure for fixing the medium (414) is designed to be as small as possible, and the interference with light propagation is minimized as much as possible.

[0082] In the above embodiments, according to the existing lithography technology, the area order of magnitude of the exposure area of the wafer is 33 mm x 26 mm, and the area of the medium (414) is larger than this. To achieve the electromagnetically induced transparency (EIT) effect within such a large area, the intensity of the control light (416) required is very high. To reduce the requirement for the intensity of the control light, it is preferably to use Figure 11 the structure in

[0083] which is called the control light of multiple reflections to reduce the requirement for the intensity of the control light. The control light (416) includes the writing light (4161) and the reading light (4162). By using high-reflectivity mirrors (1801 and 1802), the control light (416) is made to reflect multiple times inside the medium (414). The mirrors (1801 and 1802) in the figure can be discrete or integrated. The mirror (1801) on the left in the figure is connected into one large mirror, and the mirror (1802) on the right in the figure is connected into one large mirror.

[0084] In the above embodiments, the core spirit of the present invention is expounded with a transmissive lens system. The EUV lithography machine uses a reflective projection system. This type of reflective projection system can also apply the present invention to improve the resolution.

[0085] In the above embodiments, the exposure light passes through a slow light or optical storage unit and then the Airy disk width becomes narrower in and after leaving the medium. In the above embodiments, the feature that the Airy disk width becomes narrower after the medium is utilized. However, in fact, the feature that the Airy disk width becomes narrower already exists in the medium and can also be utilized.

[0086] In the above embodiments, for the slow light or optical storage unit, the feature of the narrowing of the Airy disk width already exists in the medium and can also be utilized. Therefore, the slow light or optical storage unit can be integrated into the photoresist, making the photoresist itself a slow light or optical storage unit, which can narrow the Airy disk width by itself, thereby improving the resolution.

[0087] In the above embodiments, for the slow light or optical storage unit, its medium form includes gas, liquid and solid. The slow light or optical storage unit can be in direct contact with the wafer, similar to the immersion lithography technology where a high refractive index liquid is in direct contact with the wafer. In this application environment, containers for carrying the medium, medium filtration, medium circulation, and medium recovery need to be added; when the medium is gas, auxiliary equipment for achieving a vacuum in the medium environment is required. The vacuum environment can be a locally enclosed vacuum in the wafer stage or a completely enclosed vacuum in the entire lithography machine; in non-vacuum applications, heating and insulation equipment for maintaining a constant temperature of the medium need to be added. In practical applications, when containers need to be added, follow Figure 7 the design in (b) therein. The containers are made of transparent materials (preferably quartz materials, including other available transparent materials), and the diameter should be made as large as possible. The light propagating in the medium (414) includes: a) the originally propagating light; b) or after the stored optical information is released, it can be regarded as an ideal point light source, and this point light source propagates in the generated direction. For the light propagating in the medium (414), the path of propagation is a transparent quartz material with as large a diameter as possible, without a lens aperture, the aperture limitation becomes smaller, the Airy disk width becomes narrower, the resolution of the lithography machine is improved. As long as the aperture is large enough, the Airy disk width is narrow enough, and the resolution of the lithography machine is high enough to meet the design requirements. It should be noted that these features in this paragraph apply to all embodiments.

[0088] In the above embodiments, for the slow light or optical storage unit, the directions of controlling the light include the same direction as the detection light, the opposite direction to the detection light, perpendicular to the detection light, and at an arbitrary angle to the detection light. One more factor needs to be added to the considerations for selecting the direction of controlling the light, that is, it cannot interfere with the exposure of the wafer. When the control light will directly enter or indirectly reflect onto the exposure area of the wafer, anti-interference measures need to be taken. Method 1 is not to select the frequency of the control light within the photosensitive frequency range of the photoresist.

[0089] In the above embodiments, the measures for reducing optical noise include: 1) In order to prevent the noise of the control light and the detection light from interfering with the exposure process of the photoresist, a shutter switch of physical machinery or electronic structures such as liquid crystals can be set at the optical path position above the wafer. The switching time of the shutter switch is precisely coordinated with the switching timing of the control light, and the shutter switch is opened and closed when needed; 2) Increasing the absorption depth. Using a pure rare earth compound crystal is a solution. Its lattice structure is perfect, without lattice distortion caused by doping, and it has an extremely high optical density; 3) Increasing the physical thickness of the medium (414). 4) Leaving a greater redundancy during timing control; 5) Precisely regulating the intensities of the control light and the detection light.

[0090] In the above embodiments, in order to improve efficiency, the optical storage process can be arranged during the unready time of the workbench. At this time, the workbench is not ready for lithography exposure, but the optical storage step can be carried out first. After the workbench is ready, the stored optical information is released for the exposure process.

[0091] In the above embodiments, the write light of the control light, the read light of the control light, and the detection light can come from the same laser light source or from different laser light sources.

[0092] In the above embodiments, the write light (4161) of the control light, the read light (4162) of the control light, and the auxiliary light (427) share one optical path. It can be changed to that the write light and the read light of the control light share one optical path, and the auxiliary light replicates another similar optical path separately on the other two sides of the optical slow light or the optical storage unit (312). If the parameters of the write light and the read light of the control light are exactly the same, only one needs to be retained.

[0093] In the above embodiments, the direction stability of the control light determines the accuracy of the direction in which the stored optical information is released. Calculated based on the effective average distance L between the medium of the optical slow light or the optical storage unit and the wafer being 3 cm, to achieve a deviation accuracy Δ of 1 nm, the maximum allowable deviation of the direction angle is

[0094]

[0095] It can be deduced that the maximum allowable deviation of the direction angle is 3.33x10 -8 radians. To reduce the deviation, the measures are: a) increasing the size of the laser resonator of the control light and increasing the size of the base of the laser resonator mirror; b) improving the anti-vibration ability; c) the optical slow light unit or the optical storage unit includes a laser direction feedback correction device. According to the above calculation, for a 10-meter optical path of the laser, the direction deviation cannot be greater than 3.33x10 -7In meters, which is 0.333 micrometers, the function of the feedback correction device is to measure the direction deviation in real time. When a direction deviation occurs, it fine-tunes the angle of the mirror of the laser resonator in real time in the reverse direction, and always controls the direction deviation within the target range; d) Small temperature changes can cause materials to deform, and precise temperature control needs to be achieved for all relevant components on the laser optical path; e) When light propagates in a medium - after the light and the medium undergo energy exchange, the light energy is converted into the atomic spin wave energy of the medium for storage - the stored atomic spin wave energy of the medium is converted back into light in the original direction and continues to propagate. The shorter the interval of this energy conversion process, the less affected it will be by the controlled light deviation. Therefore, a shorter pulse timing sequence and a faster frequency switching speed for light turning on and off are used to achieve this goal. The most ideal effect is that this interval is small enough to be negligible, that is, when transitioning from the mode of Embodiment 3 to the mode of Embodiment 4, during the continuous propagation of light in the medium, this energy conversion is a continuous process. Therefore, controlling the direction stability of the light is equally important for both Embodiment 3 and Embodiment 4. Essentially, Embodiment 4 is a type of Embodiment 3, except that its light energy conversion process is very fast. For the macroscopically intensity - continuous control light, its photons are also discrete. Microscopically, there are also on - off states for the photons in the instantaneous light intensity of the medium atoms, and this is more obvious when the control light intensity is low.

[0096] In the above - mentioned Embodiment 3, if the frequency of the read - out light is different from that of the write - in light, the stored optical information will be released at the new frequency. After the stored optical information is released, it can be regarded as an ideal point light source. This point light source propagates in the generated direction. Since there is no lens system on the propagation path at this time and chromatic aberration does not need to be considered, lights of different frequencies all propagate in the same direction. Therefore, the difference in the frequency between the read - out light and the write - in light will not cause chromatic aberration problems.

[0097] The essential differences between the above - mentioned Embodiment 3 and Embodiment 4 and Embodiment 1 and Embodiment 2 are as follows: a) Regarding the position, the preferred positions of Embodiment 3 and Embodiment 4 are between the objective lens and the wafer, while the preferred positions of Embodiment 1 and Embodiment 2 are in front of the photomask; b) Regarding the physical characteristics utilized, Embodiment 3 and Embodiment 4 mainly utilize the characteristics of slow light or the medium of the optical storage unit to narrow the Airy disk, while Embodiment 1 and Embodiment 2 mainly utilize the characteristics of slow light or the medium of the optical storage unit to slow down the light.

[0098] End of the improved part of this invention application - 3

[0099] The method of the invention and specific embodiments have been described above in conjunction with the accompanying drawings and embodiments. Those skilled in the art can understand that the present invention can have many different implementation manners. Therefore, it should be understood that the present invention is not limited to the described preferred embodiments, and as the spirit of the present invention given in the appended claims, the present invention includes various replacements, changes and modifications within the scope of its patent protection.

Claims

1. An improved method for improving the resolution of a photolithography machine, comprising a light slow light or light storage unit, characterized in that: In the application of lithography machines, the unit is placed at any position between the mask and the wafer, and after the exposure light is processed by the light slowing or light storage unit, the width of the Airy disk becomes narrower in the medium and after leaving the medium.

2. The method according to claim 1, characterized in that The feature "after the exposure light is processed by the optical slow light or the optical storage unit, its Airy disk width becomes narrower in the medium and after leaving the medium" is replaced by the feature "after the exposure light is processed by the optical storage unit, its Airy disk width becomes narrower in the medium and after leaving the medium".

3. The method according to claim 1, characterized in that The feature "after the exposure light is processed by the optical slow-light unit, the Airy disk width becomes narrower in the medium and after leaving the medium" is replaced by the feature "after the exposure light is processed by the optical slow-light or optical storage unit, the Airy disk width becomes narrower in the medium and after leaving the medium".

4. The method according to claim 1, characterized in that The feature "the exposure frequency corresponds to the absorption frequency of the medium of the optical slow-light or optical storage unit, and the Airy disk width of the exposed light becomes narrower in the medium and after leaving the medium after being processed by the optical slow-light or optical storage unit" is replaced by the feature "the exposure frequency corresponds to the absorption frequency of the medium of the optical slow-light or optical storage unit, and the Airy disk width of the exposed light becomes narrower in the medium and after leaving the medium after being processed by the optical slow-light or optical storage unit".

5. The method according to claim 1, characterized in that The feature "the optical storage medium of the optical slow-light or optical storage unit is a monomer or compound crystal, the material is a rare earth element, and the Airy disk width of the exposed light becomes narrower in the medium and after leaving the medium after being processed by the optical slow-light or optical storage unit" is used to replace the feature "the Airy disk width of the exposed light becomes narrower in the medium and after leaving the medium after being processed by the optical slow-light or optical storage unit".

6. The method according to claim 1 or 2 or 3 or 4 or 5, wherein the optical slow light or optical storage unit is characterized by any one of the following features: (a) The light slow light or light storage unit described above controls the direction of the light including the same direction as the detection light, the opposite direction to the detection light, the perpendicular direction to the detection light, and any other angle to the detection light. (b) The optical storage schemes selected include Electromagnetically Induced Transparency (EIT), Off-Resonant Raman-type excitations storage or PhotoEcho storage.

7. The method according to claim 1 or 2 or 3 or 4 or 5, wherein the optical slow light or optical storage unit is characterized by any one of the following features: a) Light Slowing Schemes for slowing down the speed of light or optical storage units include Electromagnetically Induced Transparency (EIT), Coherent Population Oscillation (CPO), Spectral Hole Burning, Brillouin Scattering or Raman Scattering b) The optical slow light or optical storage unit, whose medium form includes gas, liquid and solid c) The optical slow light or optical storage unit can be integrated into the photoresist d) Multiple reflections of the control light to reduce the requirements for the control light intensity e) Contains a laser direction feedback correction device to monitor and correct the direction deviation of the control light or detection light in real time f) The medium of the optical slow light or optical storage unit is isotopically purified for some or all elements to obtain a narrow inhomogeneous broadening.

8. A chip, characterized in that: The chip is prepared by any one of the methods of claims 1 to 7.

9. An optical imaging system, characterized in that: The optical imaging system is obtained by applying any one of the methods of claims 1 to 7.

10. The optical imaging system according to claim 9, wherein the optical imaging system comprises a microscope, a telescope, a radar, a camera and a video camera.

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