Ultraviolet metasurface projection optical system
Through the ultraviolet metasurface projection optical system, point light sources and superstructure surfaces are used to replace the beam expansion lens in traditional optical systems, spot expansion and focus are achieved, and the huge volume problem of the ultraviolet projection lithography system is solved, and the system is miniaturized and efficient.
Patent Information
- Application Number
- CN202510534580.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-27
- Publication Date
- 2025-07-08
AI Technical Summary
Traditional ultraviolet projection lithography systems have cumbersome structures and huge volumes, making it difficult to achieve miniaturization and efficiency.
UV metasurface projection optical system is adopted, and a point light source and the first superstructure surface are used to replace the traditional beam expanding lens. The spot diameter expansion and reflection are achieved through the first superstructure surface, the second superstructure surface realizes beam focusing, and the photosensitive material is imaged at the focal position.
Significantly reduce the system size and weight, reduce manufacturing costs and maintenance difficulties, improve lithography accuracy and flexibility, and realize the miniaturization and efficiency of the system.
Smart Images
Figure CN120276218A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of ultraviolet metasurface projection lithography, and particularly to an ultraviolet metasurface projection optical system. Background Art
[0002] Ultraviolet lithography is a key technology in microelectronics manufacturing. Its core mechanism is that through ultraviolet light irradiation, the fine patterns on the mask are projected onto the silicon wafer coated with photoresist through an optical system, causing a photochemical reaction in the photoresist. After subsequent process steps such as development and etching, the patterns are finally transferred to the silicon wafer, thereby constructing precise structures at the micron and even nanometer scales.
[0003] As a strong candidate for the next-generation lithography technology, ultraviolet lithography technology shows broad development prospects. However, with the stringent requirements for pattern feature sizes in manufacturing processes, the requirements for the resolution of lithography technology are also increasing. In this context, traditional contact and proximity lithography technologies are increasingly unable to meet production needs and are gradually being replaced by projection lithography technologies. The innovation of projection lithography technology lies in the ingenious introduction of a projection objective lens between the mask and the photoresist. Light first penetrates the mask, then enters the projection objective lens, and finally the projection objective lens focuses and images it onto the photoresist. This innovative projection exposure method not only significantly improves the resolution of lithography but also effectively avoids the problems of contamination and damage that may be caused by direct contact between the mask and the photoresist.
[0004] The projection exposure system is the core component of the ultraviolet lithography system. The design of ultraviolet lithography projection objective lenses and illumination systems is one of the important research contents of ultraviolet lithography technology and is of great significance and role in the development of semiconductor manufacturing equipment.
[0005] However, traditional ultraviolet projection lithography systems often rely on complex combinations of mirrors and lens barrels, which not only result in a cumbersome optical system structure but also make the entire system bulky. How to achieve the miniaturization and high efficiency of the projection lithography system has become an important issue that needs to be urgently addressed. Summary of the Invention
[0006] The purpose of the present invention is to provide an ultraviolet metasurface projection optical system that can achieve the miniaturization and high efficiency of the projection lithography system.
[0007] To achieve the above objective, the present invention provides the following solutions:
[0008] One aspect of the present invention provides an ultraviolet metasurface projection optical system, which includes: a point light source for emitting electromagnetic waves; a first metasurface disposed on the optical path of the point light source for modulating the phase and amplitude of the electromagnetic waves to obtain collimated light with an expanded spot diameter and reflecting the collimated light at a preset reflection angle; a mask disposed on the reflection optical path of the first metasurface; a second metasurface disposed on the optical path of the light emitted from the mask for focusing the incident laser light; and a photosensitive material disposed at the focal position of the second metasurface for obtaining the pattern on the reduced mask.
[0009] According to an embodiment of the present invention, the first metasurface includes a first substrate and a first sub-wavelength array disposed on the first substrate; the material of the first substrate is a material with a reflectivity greater than a first preset reflectivity in the ultraviolet light band; the material of the first sub-wavelength array is a material with a transmittance greater than a first preset transmittance in the ultraviolet light band; and the refractive index of the first sub-wavelength array is greater than the refractive index of the first substrate.
[0010] According to an embodiment of the present invention, the material of the first substrate is a metal material; the metal material includes at least one of Ag, Al, Ti, Co, and Ni.
[0011] According to an embodiment of the present invention, the first sub-wavelength array is an array of rectangular columns or elliptical columns with birefringence effect.
[0012] According to an embodiment of the present invention, the material of the first sub-wavelength array is a dielectric material; the dielectric material includes at least one of Nb2O5, HfO2, Ta2O5, SiO2, MgF2, MgO, Y2O3, sapphire, AlN, PMMA, and PS.
[0013] According to an embodiment of the present invention, the second metasurface includes a second substrate and a second sub-wavelength array disposed on the second substrate; the material of the second substrate is a material with a transmittance greater than a second preset transmittance in the ultraviolet light band; and the material of the second sub-wavelength array is a material with a transmittance greater than the first preset transmittance in the ultraviolet light band.
[0014] According to an embodiment of the present invention, the second sub-wavelength array is a polarization-insensitive cylindrical array, an array of rectangular columns with birefringence effect, or an array of elliptical columns with birefringence effect.
[0015] According to an embodiment of the present invention, the material of the second sub-wavelength array at least includes one of Nb2O5, HfO2, Ta2O5, SiO2, MgF2, MgO, Y2O3, sapphire, AlN, PMMA, and PS; wherein, the refractive index of the material of the second sub-wavelength array is greater than the refractive index of the material of the second substrate.
[0016] According to an embodiment of the present invention, the material of the second substrate at least includes one of Nb2O5, HfO2, Ta2O5, SiO2, MgF2, MgO, Y2O3, sapphire, AlN, PMMA, and PS.
[0017] According to an embodiment of the present invention, the wavelength range of the above point light source is 10 nm - 380 nm.
[0018] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:
[0019] The present invention provides an ultraviolet metasurface projection optical system, including: a point light source, a first metasurface, a mask, a second metasurface, and a photosensitive material; the point light source is used to emit electromagnetic waves; the first metasurface is arranged on the optical path of the point light source and is used to regulate the phase and amplitude of the electromagnetic waves to obtain collimated light with an expanded spot diameter and reflect the collimated light at a preset reflection angle; the mask is arranged on the reflection optical path of the first metasurface; the second metasurface is arranged on the optical path of the outgoing light of the mask and is used to focus the incident laser; the photosensitive material is arranged at the focal position of the second metasurface and is used to obtain the pattern on the reduced mask. In the present invention, the point light source and the first metasurface are used to replace the large-sized and complex-structured beam expander set in the traditional optical system, and the beam expansion function can be realized only by the first metasurface. In the present invention, only the second metasurface is used to realize reduced mask imaging on the photosensitive material, which not only significantly reduces the volume and weight of the ultraviolet metasurface projection optical system, but also reduces the manufacturing cost and maintenance difficulty, opening up a new path for the wide application of the ultraviolet lithography system. Description of the Drawings
[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0021] Figure 1 It is the optical path diagram of the present invention for realizing a micro ultraviolet metasurface projection lithography system using a metasurface;
[0022] Figure 2Schematic diagram of the optical field where the divergent light beam becomes parallel light after passing through the metasurface in the present invention;
[0023] Figure 3 Schematic diagram of the metasurface in the present invention that can focus the object light beam;
[0024] Figure 4 Schematic diagram of different unit structures of the present invention. Detailed implementation manners
[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.
[0026] The emergence of metasurface technology has provided unprecedented possibilities for simplifying the structure of optical systems and realizing system miniaturization. Metasurfaces can flexibly control the amplitude, phase, and polarization characteristics of light at the sub-wavelength scale, which makes it the key to solving the miniaturization problem of projection lithography systems. Therefore, deeply exploring and making full use of metasurface technology to achieve the miniaturization and high efficiency of projection lithography systems has become an important topic that needs to be urgently overcome at present.
[0027] The purpose of the present invention is to provide an ultraviolet metasurface projection optical system, aiming to achieve the miniaturization and high efficiency of projection lithography systems.
[0028] Ultraviolet lithography is an important microelectronic manufacturing technology. Its principle is to transfer the pattern of photosensitive materials onto a silicon wafer by using ultraviolet light to form micron- and nanoscale structures.
[0029] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.
[0030] Embodiment 1
[0031] As Figures 1 to 4 shown, an ultraviolet metasurface projection optical system in this embodiment includes: a point light source for emitting electromagnetic waves; a first metasurface disposed on the optical path of the point light source for regulating the phase and amplitude of the electromagnetic waves to obtain parallel light with an expanded spot diameter and reflecting the parallel light at a preset reflection angle; a mask disposed on the reflection optical path of the first metasurface; a second metasurface disposed on the optical path of the light emitted from the mask for focusing the incident laser; and a photosensitive material disposed at the focal position of the second metasurface for obtaining the pattern on the reduced mask.
[0032] According to an embodiment of the present invention, the first metasurface includes a first substrate and a first sub-wavelength array disposed on the first substrate; the material of the first substrate is a material with a reflectivity greater than a first preset reflectivity in the ultraviolet light band. For example, the first preset reflectivity is set to 70%; the material of the first sub-wavelength array is a material with a transmittance greater than a first preset transmittance in the ultraviolet light band. For example, the first preset transmittance is set to 70%. On this basis, the refractive index of the first sub-wavelength array is greater than the refractive index of the first substrate.
[0033] Among them, the first substrate is a high-reflection substrate. The first sub-wavelength array is an array of rectangular columns or elliptical columns with birefringence effect. The material of the first sub-wavelength array can be one of Nb2O5, HfO2, Ta2O5, SiO2, MgF2, MgO, Y2O3, sapphire, AlN, PMMA, and PS.
[0034] According to an embodiment of the present invention, the second metasurface includes a second substrate and a second sub-wavelength array disposed on the second substrate; the material of the second substrate is a material with a transmittance greater than a second preset transmittance in the ultraviolet light band; the material of the second sub-wavelength array is a material with a transmittance greater than a first preset transmittance in the ultraviolet light band.
[0035] Among them, the second substrate is a high-transmission substrate. The high-transmission substrate results in less loss of electromagnetic waves in the substrate material. Relatively speaking, the transmittance will be relatively higher. It can be considered that within the ultraviolet working bandwidth, the transmittance of the material of the second substrate is greater than 70%. The second sub-wavelength array is a polarization-insensitive cylindrical array, an array of rectangular columns with birefringence effect, or an array of elliptical columns with birefringence effect. The material of the second sub-wavelength array includes Nb2O5, HfO2, Ta2O5, SiO2, MgF2, MgO, Y2O3, sapphire, AlN, PMMA, and PS, etc., and one of them can be selected as the material of the second sub-wavelength array; among them, the refractive index of the material of the second sub-wavelength array is greater than the refractive index of the material of the second substrate.
[0036] According to an embodiment of the present invention, the wavelength range of the point light source is 10nm - 380nm.
[0037] In practical applications, when the electromagnetic wave emitted by the point light source reaches the first metasurface, the first metasurface uses its sub-wavelength structure to finely adjust the phase and amplitude of the incident divergent object beam wavefront. This process involves reshaping the electromagnetic wave wavefront so that it is directionally reflected at a preset reflection angle. After the precise adjustment of the first metasurface, the originally divergent beam is converted into a parallel light with an expanded spot diameter through this process. This conversion process demonstrates the excellent ability of the metasurface to manipulate the electromagnetic wave wavefront.
[0038] In the optical path after the first metasurface, a mask plate matching the diameter of the expanded light spot is placed. The mask plate carries specific pattern information, which is set according to actual needs. When the object beam carrying this information continues to move forward, it will undergo further focusing by the second metasurface. The second metasurface, with its unique sub-wavelength structure, performs phase modulation on the incident electromagnetic wave, achieving the focusing effect of the light beam.
[0039] The photosensitive material is precisely placed near the focal position of the second metasurface to ensure that the focused light beam can achieve reduced imaging of the pattern here. This process utilizes the basic principle of optical imaging and realizes precise control of the pattern size by adjusting the focal length and magnification of the imaging system.
[0040] The first metasurface proposed in the present invention not only has the ability to reflect the light beam diverging from one side as parallel light to the other side, and in the overall process, the parallel light with an expanded beam diameter is obtained. This characteristic is Figure 1 intuitively reflected in the schematic diagram of the first metasurface shown, where the first metasurface finely regulates the wavefront of the incident electromagnetic wave through additional phase and amplitude information.
[0041] Figure 2 Then, it further shows the schematic diagram of the second metasurface that can focus the expanded object beam in this embodiment. By precisely designing the sub-wavelength structure of the metasurface, the fine regulation of the electromagnetic wavefront is realized, and then the focusing and imaging functions of the light beam are achieved.
[0042] The first metasurface is composed of a first substrate and a first sub-wavelength array. The second metasurface is composed of a second substrate and a second sub-wavelength array.
[0043] As a specific implementation manner, the materials of the second substrate, the first sub-wavelength array, and the second sub-wavelength array are all high-transmittance materials in the ultraviolet light band. The high-transmittance materials can be materials such as Nb2O5, HfO2, Ta2O5, SiO2, MgF2, MgO, Y2O3, sapphire, AlN, PMMA, PS, etc. The materials of the second substrate, the first sub-wavelength array, and the second sub-wavelength array can select the same material from the high-transmittance materials or different materials. For example, in order to ensure the regulation of electromagnetic waves, the material of the second substrate is SiO2, the material of the first sub-wavelength array is sapphire, and the material of the second sub-wavelength array is Ta2O5.
[0044] The material of the first substrate in the first metasurface is a material with high reflectivity in the ultraviolet light band, such as materials like Ag, Al, Ti, Co, Ni, etc.
[0045] In practical applications, the first substrate is a high-reflection substrate. The high-reflection substrate can be considered to have a reflectivity greater than 70%, that is, the reflected electromagnetic wave accounts for 70% of the incident electromagnetic wave. The first sub-wavelength arrays are all arrays of rectangular columns or elliptical columns with birefringence effects.
[0046] The second substrate is a high-transmission substrate. The second sub-wavelength array can be an array of cylinders insensitive to polarization, an array of rectangular columns with birefringence effects, or an array of elliptical columns with birefringence effects.
[0047] The length and width of each unit structure in the first sub-wavelength array and the second sub-wavelength array are both less than the working wavelength, where the working wavelength is the working wavelength of the ultraviolet metasurface projection optical system during current operation. The wavelength range of the point light source is the ultraviolet band (10 nm - 380 nm).
[0048] The present invention aims to address the complexity challenges faced by current micro-ultraviolet metasurface projection lithography systems. Through innovative design ideas, a micro-ultraviolet metasurface projection lithography system solution is proposed. The core of this solution lies in the ingenious use of the precise and efficient modulation ability of the metasurface on the electromagnetic properties of light waves. Based on this, a high degree of functional integration and a significant simplification of the system structure are achieved. Specifically, the present invention draws on the advanced design concept of the Huygens electromagnetic metasurface and selects dielectric artificial atoms with flexibly adjustable phases as the basic units for constructing the metasurface. These carefully designed unit structures not only ensure the effective transmission of light waves but also make it possible to achieve complex optical functions. In the embodiment of the present invention, a point light source and a first metasurface are used to replace the large-volume and complex-structured beam expander lens group in the traditional optical system, and the beam expansion function can be achieved only through the first metasurface. In the present invention, only the second metasurface is used to achieve a reduced mask imaging on the photosensitive material. This innovation not only significantly reduces the volume and weight of the system but also reduces the manufacturing cost and maintenance difficulty, opening up a new path for the wide application of ultraviolet lithography systems.
[0049] As Figure 1 shown, the light beam emitted by the point light source shows a gradually divergent trend. The first metasurface at a certain distance from the point light source modulates the wavefront of the light and finally emits it as parallel light. This process ingeniously uses the modulation of the wavefront of light by the point light source and the first metasurface to achieve an expansion of the diameter of the parallel light spot. Subsequently, this parallel light beam is projected onto the mask, and after the patterning process of the mask, a light beam with specific information is formed. Then, this light beam passes through the second metasurface, and through its precise focusing and imaging effects, the pattern is finally mapped onto the photosensitive material in a reduced form.
[0050] It is worth noting that since the final pattern on the photoresist is the image formed by the lens, the pattern can be scaled by adjusting the magnification of the projection metalens. This feature allows the selection of a mask larger than the size of the desired pattern when making a mask, reducing the difficulty and error caused by the small size of the pattern. At the same time, this feature also enables the same mask to be used multiple times, further saving costs.
[0051] The present invention can achieve the parallel reflection and beam expansion effect of the divergent light beam only by the first metasurface, which greatly simplifies the traditional beam expansion device. The present invention also uses the second metasurface to achieve the reduction of the light beam and the scaling of the corresponding magnification image, further improving the flexibility and practicality of the system.
[0052] The present invention cleverly replaces the complex beam expansion device with a mirror by virtue of the fine design of the metasurface structure and its excellent ability in wavefront control. At the same time, the second metasurface is used to achieve focusing imaging of the corresponding magnification of the object beam. This greatly simplifies the structure of the system and significantly reduces its volume, injecting new vitality into the development of ultraviolet lithography technology.
[0053] The core of the present invention is to cleverly use the metasurface technology to achieve simplification and efficiency of beam processing and regulation. The first metasurface proposed in the present invention can precisely control the wavefront of the divergent light beam, so that the light beam can be expanded and emitted in the form of parallel light. The second metasurface can accurately focus the light beam on the target position, providing a stable energy input for the lithography process. The uniqueness of the present invention lies in that parallel light with an enlarged spot diameter is obtained by using a point light source and the first metasurface, which effectively reduces the processing difficulty and error of the mask size and improves the accuracy and reliability of lithography. At the same time, the reduced imaging of the mask by the second metasurface further enhances the flexibility and applicability of the system, allowing the system to be applied in a wider range of fields.
[0054] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0055] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.
Claims
1. An ultraviolet metasurface projection optical system, characterized in that, The system includes: A point light source for emitting electromagnetic waves; A first metasurface disposed on the optical path of the point light source for modulating the phase and amplitude of the electromagnetic waves to obtain collimated light with an expanded spot diameter and reflecting the collimated light at a preset reflection angle; A mask disposed on the reflection optical path of the first metasurface; A second metasurface disposed on the optical path of the light emitted from the mask for focusing the incident laser light; A photosensitive material disposed at the focal position of the second metasurface for obtaining the pattern on the reduced mask.
2. The ultraviolet metasurface projection optical system according to claim 1, wherein The first metasurface includes a first substrate and a first sub-wavelength array disposed on the first substrate; the material of the first substrate is a material with a reflectivity greater than a first preset reflectivity in the ultraviolet band; the material of the first sub-wavelength array is a material with a transmittance greater than a first preset transmittance in the ultraviolet band; the refractive index of the first sub-wavelength array is greater than the refractive index of the first substrate.
3. The ultraviolet metasurface projection optical system according to claim 2, characterized in that, The material of the first substrate is a metal material; the metal material includes at least one of Ag, Al, Ti, Co, and Ni.
4. The ultraviolet metasurface projection optical system according to claim 2, wherein The first sub-wavelength array is an array of rectangular columns or elliptical columns with birefringence effect.
5. The ultraviolet metasurface projection optical system according to claim 2, characterized in that The material of the first sub-wavelength array is a dielectric material; the dielectric material includes at least one of Nb2O5, HfO2, Ta2O5, SiO2, MgF2, MgO, Y2O3, sapphire, AlN, PMMA, and PS.
6. The ultraviolet metasurface projection optical system according to claim 2, wherein The second metasurface includes a second substrate and a second sub-wavelength array disposed on the second substrate; the material of the second substrate is a material with a transmittance greater than a second preset transmittance in the ultraviolet band; the material of the second sub-wavelength array is a material with a transmittance greater than the first preset transmittance in the ultraviolet band.
7. The ultraviolet metasurface projection optical system according to claim 6, characterized in that, The second sub-wavelength array is an array of cylinders insensitive to polarization, an array of rectangular columns with birefringence effect, or an array of elliptical columns with birefringence effect.
8. The ultraviolet metasurface projection optical system according to claim 6, characterized in that, The material of the second sub-wavelength array includes at least one of Nb2O5, HfO2, Ta2O5, SiO2, MgF2, MgO, Y2O3, sapphire, AlN, PMMA, and PS; wherein the refractive index of the material of the second sub-wavelength array is greater than the refractive index of the material of the second substrate.
9. The ultraviolet metasurface projection optical system according to claim 6, characterized in that, The material of the second substrate includes at least one of Nb2O5, HfO2, Ta2O5, SiO2, MgF2, MgO, Y2O3, sapphire, AlN, PMMA, and PS.
10. The ultraviolet metasurface projection optical system according to claim 1, characterized in that, The wavelength range of the point light source is 10nm - 380nm.