Lithography system and method thereof

Abstract

In some embodiments of the present disclosure, a lithography system and a method thereof are provided. The lithography system includes a radiation source, a mask stage, a reflective mask, and an optical element. The radiation source is configured to generate a radiation light. The mask stage includes a base and a photocatalyst layer on the base. The reflective mask is disposed on the base, wherein the photocatalyst layer is disposed on one side of the reflective mask. The optical element is configured to irradiate the radiation light onto the reflective mask.

Description

TECHNICAL FIELD

[0001] Some embodiments of the disclosure relate to a lithography system and a method thereof. BACKGROUND

[0002] Lithography operation is one of the key systems in semiconductor manufacturing process, including ultraviolet lithography, deep ultraviolet lithography, and extreme ultraviolet lithography. In the lithography operation, the exposure process is an important step to transfer the pattern on the mask to the substrate. In the exposure process, the reflection state of the reflected mark on the mask stage after the irradiation of the radiation light is detected, and the mask stage and the radiation light are corrected, which is an important step in the lithography operation. SUMMARY

[0003] In some embodiments of the disclosure, a lithography system is provided, including a radiation source, a mask stage, a reflective mask, and an optical element. The radiation source is configured to generate radiation light. The mask stage includes a base and a photocatalyst layer on the base. The reflective mask is disposed on the base, wherein the photocatalyst layer is disposed on one side of the reflective mask. The optical element is configured to irradiate the radiation light onto the reflective mask.

[0004] In some embodiments of the disclosure, a lithography method is provided, including generating radiation light using a radiation source to irradiate a reflective mask on a mask stage and a photocatalyst layer disposed on one side of the reflective mask, wherein the photocatalyst layer reflects a first portion of the radiation light to a sensor, wherein the first portion of the radiation light further decomposes contaminants on the surface of the photocatalyst layer, and the reflective mask reflects a second portion of the radiation light to a substrate to form a pattern on the substrate.

[0005] In some embodiments of the disclosure, a method for cleaning a lithography system is provided, including generating first radiation light using a radiation source to irradiate a reflective mask on a mask stage, the reflective mask reflecting the first radiation light to a substrate to form a pattern on the substrate; and generating second radiation light using the radiation source to irradiate a photocatalyst layer on the mask stage to decompose contaminants on the surface of the photocatalyst layer, wherein the volume of the photocatalyst layer remains the same. BRIEF DESCRIPTION OF DRAWINGS

[0006] The various features illustrated in the drawings can not be drawn to scale. Accordingly, the dimensions of the various features can be arbitrarily increased or decreased for the ease of discussion. In addition, it is noted that the various features illustrated in the drawings can be combined with each other in any manner.

[0007] FIG. 1A A cross-sectional view illustrating part of the elements of the lithography system in some embodiments of the disclosure is shown;

[0008] FIG. 1BFIG. 3A is a bottom view illustrating some elements of a lithography system in some embodiments of the present disclosure;

[0009] FIG. 2A FIG. 3B is a cross-sectional schematic view illustrating some elements of a lithography system in some embodiments of the present disclosure;

[0010] FIG. 2B FIG. 4A is a bottom view illustrating some elements of a lithography system in some embodiments of the present disclosure;

[0011] FIG. 3A FIG. 4B is a cross-sectional schematic view illustrating some elements of a lithography system in some embodiments of the present disclosure;

[0012] FIG. 3B FIG. 5A is a bottom view illustrating some elements of a lithography system in some embodiments of the present disclosure;

[0013] FIG. 4 FIG. 6 is a flowchart illustrating a lithography method in some embodiments of the present disclosure;

[0014] FIG. 5A to FIG. 5B FIG. 7 is a cross-sectional schematic view illustrating some steps of a lithography method in some embodiments of the present disclosure;

[0015] FIG. 6 FIG. 8 is a flowchart illustrating a lithography method in some embodiments of the present disclosure;

[0016] FIG. 7A to FIG. 7C FIG. 9 is a cross-sectional schematic view illustrating some steps of a lithography method in some embodiments of the present disclosure.

[0017]

Symbol Explanation

[0018] 100: lithography system

[0019] 110: reticle stage

[0020] 112: base

[0021] 112a: first surface

[0022] 112b: second surface

[0023] 114: photocatalyst layer

[0024] 120: sensing element

[0025] 200: lithography system

[0026] 210: reticle stage

[0027] 212: base

[0028] 212a: first surface

[0029] 212b: second surface

[0030] 214: photocatalyst layer

[0031] 216: reflective marker

[0032] 216a: first surface

[0033] 216b: second surface

[0034] 216c: side surface

[0035] 220: sensing element

[0036] 300: lithography system

[0037] 310: reticle stage

[0038] 312: base

[0039] 312a: first surface

[0040] 312b: second surface

[0041] 314: photocatalyst layer

[0042] 316: reflective marker

[0043] 316a: first surface

[0044] 316b: second surface

[0045] 316c: side surface

[0046] 320: sensing element

[0047] 400: method

[0048] 500: method

[0049] S410: step

[0050] S422: step

[0051] S424: step

[0052] S510: step

[0053] S520: step

[0054] S530: step

[0055] B1: radiation light

[0056] B2: radiation light

[0057] B3: radiation light

[0058] B1a, B1b: radiation light

[0059] B1c: first radiation light

[0060] B1d: second radiation light

[0061] E: energy

[0062] M1, M2, M3: reflective mask

[0063] P1: contaminant

[0064] P2: particle

[0065] IL1, IL2, IL3: optical element

[0066] RS1, RS2, RS3: radiation source

[0067] W: substrate

[0068] WT: substrate table

[0069] POB: projection optical module DETAILED DESCRIPTION

[0070] The following disclosure provides many different embodiments, or examples, for implementing different characteristics of the application. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows can include embodiments in which the first and second features are formed in direct contact, and can also include embodiments in which additional features can be formed between the first and second features, such that the first and second features can not be in direct contact. In addition, the present disclosure can repeat use of reference numerals in the various examples as a matter of convenience and clarity. This repetition of reference numerals is not to be construed as a limitation with respect to the scope of the various embodiments or any other embodiments of the present disclosure.

[0071] Still further, to facilitate the description hereinafter, spatially relative terms, such as "beneath", "below", "lower", "above", "upper" are used to describe the relative relationship of one element or feature to another element or feature as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0072] As used herein, the term "optical component" is intended to be understood broadly to include, and is not necessarily limited to, one or more components that reflect incident light and / or transmit incident light and / or operate on incident light, and includes, but is not limited to, one or more lenses, windows, filters, wedges, prisms, prisms, gratings, transmissive fibers, collimators, diffusers, uniformizers, detector and other instrument components, apertures, axicons, and mirrors (including multilayer mirrors, near-normal incidence mirrors, grazing incidence mirrors), specular reflectors, diffuse reflectors, and combinations thereof. Furthermore, the term "optical component" as used herein is not intended to be limited to components that operate alone or to be advantageous in one or more specific wavelength ranges, such as at extreme ultraviolet output light wavelengths, illumination laser wavelengths, wavelengths suitable for metrology, or any other particular wavelengths, unless otherwise stated.

[0073] See FIG. 1A and FIG. 1B . FIG. 1A FIG. 1 illustrates a cross-sectional view of a portion of a lithography system 100 in accordance with some embodiments of the present disclosure. FIG. 1B FIG. 2 illustrates a bottom view of a portion of a lithography system in accordance with some embodiments of the present disclosure. The lithography system 100 includes a radiation source RSI, a reflective mask Ml, a mask stage 110, and an optical element ILl. The mask stage 110 includes a base 112 and a photo-catalytic layer 114 disposed on the base 112, and the reflective mask Ml is disposed on the base 112, wherein the photo-catalytic layer 114 is disposed on one side of the reflective mask Ml.

[0074] The lithography system 100 is designed to generate radiation light B 1 using the radiation source RSI, which is guided through the optical element ILl, and through the reflective mask Ml that is fixed on the mask stage 110, to expose a photoresist layer (a material sensitive to radiation light) on a substrate and to image on the substrate coated with the photoresist layer (not shown in the figure).

[0075] The lithography system 100 generates radiation B1, such as deep ultraviolet (DUV), extreme ultraviolet (EUV), etc., where EUV has a wavelength that varies between about 1 nm and about 100 nm. In some implementations, the radiation source RSI utilizes a laser-produced plasma element to generate the radiation B1. In some implementations, the lithography system 100 is an extreme ultraviolet lithography system, and the radiation source RSI generates the radiation B1 (i.e., EUV) having a wavelength centered at about 13.5 nm. In some implementations, the radiation source RSI is a laser-produced plasma that heats a metal (e.g., tin, lithium, etc.) target droplet to ionize the droplet into a plasma that emits EUV light. In some implementations, when the lithography system 100 performs an exposure process, the temperature of the surface of the irradiation location that is irradiated by the radiation B1 can increase due to the high energy of the radiation B1, such as a temperature range of about 350 °C to about 1000 °C, including but not limited to about 350 °C, about 400 °C, about 450 °C, about 500 °C, about 550 °C, about 600 °C, about 650 °C, about 700 °C, about 750 °C, about 800 °C, about 850 °C, about 900 °C, about 950 °C, about 1000 °C, or a value within any of the ranges recited. The temperature can vary depending on the type of radiation B1 that is generated and the energy that is released by the radiation B1. For example, when the radiation B1 is EUV, the temperature of the surface of the irradiation location that is irradiated by the radiation B1 can range from about 600 °C to about 1000 °C, including but not limited to about 600 °C, about 650 °C, about 700 °C, about 750 °C, about 800 °C, about 850 °C, about 900 °C, about 950 °C, about 1000 °C, or a value within any of the ranges recited.

[0076] The reflective mask M1 is disposed on the base 112 of the mask stage 110. In other implementations, the base 112 includes a first surface 112a and a second surface 112b opposite the first surface 112a, and an electrostatic chuck is disposed on the second surface 112b of the base 112, and the reflective mask M1 is disposed on the electrostatic chuck.

[0077] The reflective mask M1 of the lithography system 100 includes a substrate (e.g., a low thermal expansion glass substrate) having a suitable material, such as a low thermal expansion material or fused quartz. In some implementations, the low thermal expansion substrate emits light at visible wavelengths, a portion of near-infrared wavelengths that are close to the visible spectrum, and a portion of ultraviolet wavelengths. In some implementations, the low thermal expansion substrate absorbs extreme ultraviolet wavelengths and deep ultraviolet wavelengths that are close to the extreme ultraviolet wavelengths. In some implementations, the low thermal expansion material includes titania-doped silica or other suitable material having low thermal expansion.

[0078] In some embodiments, the reflective photomask Ml of the lithography system 100 can include a reflective film stack deposited on a substrate. The reflective film stack includes a plurality of pairs of films, such as pairs of molybdenum-silicon (Mo / Si) films (e.g., pairs of films with a molybdenum layer over or under a silicon layer). Alternatively, the reflective film stack can include pairs of molybdenum-beryllium (Mo / Be) films or other suitable materials configured to highly reflect extreme ultraviolet light. In some embodiments, the molybdenum-silicon film pair multilayer stack includes from about 30 to about 60 alternating layers of silicon and molybdenum. In some embodiments, the silicon and molybdenum layers are formed by chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), atomic layer deposition (ALD), physical vapor deposition (PVD) (sputtering), or any other suitable film formation method, with each layer of the silicon and molybdenum layers having a thickness of about 2 nanometers to about 10 nanometers. In some embodiments, the silicon and molybdenum layers are the same thickness. In other embodiments, the silicon and molybdenum layers are different thicknesses.

[0079] In the reflective film stack, the alternating layers of the two materials act as a Bragg reflector for maximizing the reflection of the radiation B 1, such as extreme ultraviolet light. The combination of the two materials of the alternating layers is chosen to provide a large difference in the reflection coefficients between the two layers (e.g., to provide a large optical reflectivity at the interface between the two layers according to the Fresnel equations) while providing a small extinction coefficient (e.g., to minimize absorption). The thickness of each layer of the bilayer groups of the reflective film stack is adjusted according to the wavelength and angle of incidence of the radiation B 1, such as extreme ultraviolet light, that is incident on the reflective photomask Ml so that the light reflected from the different interfaces of the reflective film stack can achieve maximum constructive interference. In general, the optical reflectivity of the reflective film stack increases with the number of bilayer groups in the reflective film stack. In principle, if the number of bilayer groups is large enough and the extinction coefficient of the materials of the layers approaches zero, the optical reflectivity of the reflective film stack can approach 100% regardless of the difference in the reflection coefficients of the materials of the layers in the bilayer groups. In some embodiments, to achieve an optical reflectivity of the reflective film stack of greater than 90% and to minimize the manufacturing time and cost of the reflective photomask Ml, the reflective film stack includes about 40 bilayer groups, such as 40 groups of molybdenum-silicon bilayer groups.

[0080] The reticle stage 110 is configured to hold the reflective reticle Ml, including a base 112 and a photocatalyst layer 114 disposed on the base 112. The base 112 includes a first surface 112a and a second surface 112b opposite the first surface 112a, and the photocatalyst layer 114 is disposed on the second surface 112b and directly contacts the base 112. In some embodiments, the photocatalyst layer 114 is disposed on a periphery (e.g., a corner) of the second surface 112b of the base 112.

[0081] The photocatalyst layer 114 is made of a photocatalyst material having an excellent light reflectance (e.g., a light reflectance greater than about 95%) and is configured to reflect the radiation B1. In some embodiments, the photocatalyst layer 114 is disposed on one side of the reflective reticle Ml. In other embodiments, the photocatalyst layer 114 abuts the reflective reticle Ml. In some embodiments, the lithography system 100 further includes a sensing element 120 configured to detect the radiation B1 reflected by the photocatalyst layer 114 for adjusting the intensity and the incident angle of the radiation B1 and the position of the reticle stage 110.

[0082] In some embodiments, the difference between the light reflectance of the photocatalyst layer 114 and the light reflectance of the reflective reticle Ml is between about 0% and about 5%, including but not limited to about 0%, about 1%, about 2%, about 3%, about 4%, about 5%, or any range of values between the foregoing. For example, the light reflectance of the reflective reticle Ml is about 98% and the light reflectance of the photocatalyst layer 114 is about 97%, and the difference between the light reflectance of the two is about 1%. In some embodiments, the light reflectance of the photocatalyst layer 114 is the same as the light reflectance of the reflective reticle Ml.

[0083] It is noted that during the use of the lithography system 100, some of the reactants (e.g., photoresist) in the process can be decomposed or evaporated due to high temperature processing, forming contaminants. The contaminants adhere to the surface of the photocatalyst layer 114 by Van der Waals forces, contaminating the photocatalyst layer 114. The contaminants can absorb the radiation source RS1, causing the radiation B1 reflected by the photocatalyst layer 114 to weaken or even disappear, resulting in deviation in the correction of the reticle stage 110 and the radiation source RS1.

[0084] In other embodiments, the source of the contaminants can be from the reactants in each step (e.g., exposure or development) of the lithography process, debris (e.g., skin or cleaning cloth) left over from the manual maintenance of the lithography system 100, particles or suspended particles attracted by the Van der Waals forces of the high concentration of metal atoms of the reflective reticle Ml. In some embodiments, the contaminants can include carbon-containing substances, such as hydrocarbons.

[0085] The photocatalyst layer 114 is made of a photocatalyst material having excellent light reflectivity. The photocatalyst material is a catalyst that catalyzes a reaction using light energy. In detail, the photocatalyst material forms an electron-hole pair when irradiated with ultraviolet light, extreme ultraviolet light, or visible light. When the electron meets an oxygen molecule (O2) in the air or a medium, a negative oxygen ion (·O 2- ) is generated. When the hole meets water vapor, a hydroxyl radical (·OH) is generated through a photochemical reaction. The negative oxygen ion and the hydroxyl radical oxidize and decompose other substances, such as carbon-containing substances, for example, hydrocarbons, into water and carbon dioxide upon contact. The photocatalyst material can include zinc oxide (ZnO), titanium dioxide (TiO2), tin dioxide (SnO2), cadmium sulfide (CdS), or the like. In addition to irradiation with radiation light, other methods of providing additional energy can be used to cause the photocatalyst material to catalyze the oxidation-reduction reaction of the contacted substance and decompose the contacted substance.

[0086] Therefore, the photocatalyst layer 114 made of the photocatalyst material having excellent light reflectivity can serve as a reference mark for the reticle stage 110 and the radiation light B1, and can also catalyze and decompose the contaminants accumulated on the surface of the photocatalyst layer 114 by providing sufficient additional energy (for example, irradiating the reticle stage 110 with high-energy light) to the photocatalyst layer 114. Thus, the photocatalyst layer 114 has a self-cleaning surface effect. In some embodiments, different photocatalyst materials and properties of the contaminants can be used to provide appropriate reaction pressure while providing energy to the photocatalyst layer 114 to improve the effect of decomposition of the contaminants.

[0087] In some embodiments, the material of the photocatalyst layer 114 can use titanium dioxide. Titanium dioxide has the same light reflectivity as the reflective film stack of the reflective reticle M1 and has a good effect of decomposition of contaminants among photocatalyst materials. Thus, the photocatalyst layer 114 formed of titanium dioxide can serve as a mark for the reticle stage 110, provide a reference for correction of the reticle stage 110 and the radiation light B1, and simulate the state in which the radiation light B1 irradiates the reflective reticle M1 to adjust the radiation light B1 and the reticle stage 110 based on the desired condition in which the radiation light B1 enters the reflective reticle M1. In some embodiments, if appropriate energy is provided to the photocatalyst layer 114 formed of titanium dioxide (for example, the photocatalyst layer 114 is irradiated with extreme ultraviolet light) while the pressure is in a range of about 200 Pa to about 500 Pa (for example, about 200 Pa, about 250 Pa, about 300 Pa, about 350 Pa, about 400 Pa, about 450 Pa, about 500 Pa, or a value in any of the above ranges), the suspended particles in the air can have a good decomposition effect.

[0088] In some embodiments, the reticle stage 110 includes an electrostatic chuck (e-chuck) to hold the reflective reticle Ml. In some embodiments, the lithography system 100 is maintained in a vacuum environment to avoid loss of intensity of the radiation B 1 (e.g., extreme ultraviolet light) due to absorption by gas molecules. Thus, the e-chuck can stably hold the reflective reticle Ml on the reticle stage 110 based on electrostatic forces generated, regardless of the vacuum environment.

[0089] The optical element ILl is configured to direct the radiation B 1 from the radiation source RSl to the reflective reticle Ml on the reticle stage 110 or to the reflective reticle Ml held on the reticle stage 110. In some embodiments, the optical element ILl includes a refractive optical component such as a single lens or a lens system having multiple lenses (zone plates), or a reflective optical component such as a single mirror or a mirror system having multiple mirrors (e.g., for an extreme ultraviolet lithography system).

[0090] In some embodiments, the lithography system 100 also includes a projection optics module (or projection optics box). The lithography system 100 collects and directs the radiation B 1 from the reflective reticle Ml defining the pattern of the reflective reticle Ml through the projection optics module and images it onto a substrate on the substrate stage (e.g., as shown in FIG. 1). FIG. 5A or FIG. 7A In some embodiments, the projection optics module has reflective optical components (e.g., for an extreme ultraviolet lithography system).

[0091] In some embodiments, the lithography system 100 also includes a substrate stage to hold a substrate. In some embodiments, the substrate can be a silicon wafer or other type of wafer to be patterned. The surface of the substrate is coated with a photoresist layer (not shown) that is sensitive to the radiation B 1 (e.g., extreme ultraviolet light).

[0092] In some embodiments, the lithography system 100 is integrated with the above-described elements and is operated to perform a lithography process. In some other embodiments, the lithography system 100 can further include or be integrated with (or coupled to) other modules. In some embodiments, the lithography system 100 can include a gas supply module to provide hydrogen gas inside the lithography system 100. In some embodiments, the lithography system 100 can include a pressure control module configured to provide the lithography system 100 to perform the lithography process at a suitable pressure.

[0093] FIG. 2A and FIG. 2B Another aspect of a lithography system in some embodiments of the present disclosure is provided. FIG. 2A A cross-sectional view of a lithography system in some embodiments of the present disclosure is shown, FIG. 2BFIG. 2A shows a bottom view of a lithography system in some embodiments of the present disclosure (i.e. FIG. 2A FIG. 2B shows a bottom view of a portion of the elements in FIG. 2A, FIG. 2A The lithography system 200 of FIG. 2A includes a radiation source RS2, a reticle stage 210, a reflective reticle M2, and an optical element IL1, where the reticle stage 210 includes a base 212, a reflective mark 216 disposed on the base 212, and a photocatalyst layer 214 disposed on the reflective mark 216.

[0094] The base 212 in the reticle stage 210 includes a first surface 212a and a second surface 212b opposite to the first surface 212a, and the reflective mark 216 is located on the second surface 212b. The reflective mark 216 includes a first surface 216a contacting the base 212 and a second surface 216b opposite to the first surface 216a, and the photocatalyst layer 214 is only disposed on the second surface 216b of the reflective mark 216, but not disposed on a side surface 216c of the reflective mark 216 adjacent to the second surface 216b.

[0095] FIG. 2A and FIG. 2B The main difference between the lithography system 200 of FIG. 2A and the lithography system 100 of FIG. 1A is that the reflective mark 216 is disposed between the photocatalyst layer 214 and the base 212. FIG. 1A FIG. 2A The reflective mark 216 is configured to reflect the radiation B2, and can be used as a reference for adjusting the intensity and incident angle of the radiation B2, and the position of the reticle stage 210. In some embodiments, the reflective mark 216 is a coating of a reflective material on the second surface 212b of the base 212. In some embodiments, the material of the reflective mark 216 can be the same as the reflective film stack of the reflective reticle M2. In some embodiments, the reflective mark 216 is located on the periphery (e.g., corners) of the second surface 212b of the base 212. In some embodiments, the side surface 216c of the reflective mark 216 does not contact the reflective reticle M2 (e.g. FIG. 2B In other embodiments, the side surface 216c of the reflective mark 216 contacts the reflective reticle M2.

[0096] FIG. 2A The radiation source RS2, the reflective reticle M2, and the optical element IL2 in the lithography system 200 of FIG. 2A can be the same as or similar to those in the lithography system 100 of FIG. 1A, and are not described again here. FIG. 1A

[0097] The reflective mark 216 is configured to reflect the radiation B2, and can be used as a reference for adjusting the intensity and incident angle of the radiation B2, and the position of the reticle stage 210. In some embodiments, the reflective mark 216 is a coating of a reflective material on the second surface 212b of the base 212. In some embodiments, the material of the reflective mark 216 can be the same as the reflective film stack of the reflective reticle M2. In some embodiments, the reflective mark 216 is located on the periphery (e.g., corners) of the second surface 212b of the base 212. In some embodiments, the side surface 216c of the reflective mark 216 does not contact the reflective reticle M2 (e.g. FIG. 2A FIG. 2B In other embodiments, the side surface 216c of the reflective mark 216 contacts the reflective reticle M2.

[0098] ​​​In some embodiments, the light reflectance of the reflective mark 216 is the same as the light reflectance of the reflective film stack of the reflective mask M2. Thus, the sensing element 220 can be used to detect the intensity and angle of the reflected radiation B2 after the radiation B2 is reflected off the reflective mark 216, and the state of the radiation B2 when the radiation B2 is reflected off the reflective mask M2 can be inferred. Based on the desired intensity and position of the radiation B2 that is desired to be incident on the reflective mask M2, the energy intensity, angle of incidence, and position of the mask stage M2 can be adjusted. In some embodiments, the mask stage 210 includes an electrostatic chuck (e-chuck) to secure the reflective mask M2. In some embodiments, the lithography system 200 is maintained in a vacuum environment to avoid loss of intensity of the radiation B2 (e.g., extreme ultraviolet light) due to absorption by gas molecules. Thus, the e-chuck can stably secure the reflective mask M2 on the mask stage 210 based on electrostatic forces generated, regardless of the vacuum environment.

[0099] The photocatalyst layer 214 is disposed on the second surface 216b of the reflective mark 216 and is configured to activate and decompose pollutants via the photocatalyst material. To avoid interference with the performance of the reflective mark 216, the photocatalyst layer 214 can be made of the same or similar material as the photocatalyst layer 114 in the reflective mask 100, i.e., made of a photocatalyst material having excellent light reflectance (e.g., light reflectance higher than about 95%). FIG. 1A

[0100] In some embodiments, the difference between the light reflectance of the photocatalyst layer 214 and the light reflectance of the reflective mask M2 is between about 0% and about 5%, including but not limited to about 0%, about 1%, about 2%, about 3%, about 4%, about 5%, or any range of values between the foregoing.

[0101] In some embodiments, the material of the photocatalyst layer 214 is different from the material of the reflective mark 216. The material of the photocatalyst layer 214 has photocatalyst activity, while the material of the reflective mark 216 does not have photocatalyst activity.

[0102] ​In some embodiments, the photocatalyst layer 214 may be made of titanium dioxide. Titanium dioxide has the same stack as the reflective film of the reflective photomask M2 and exhibits relatively good pollutant decomposition effects among photocatalyst materials. Therefore, the radiation light B2 reflected by the photocatalyst layer 214 formed by titanium dioxide can also serve as a positioning reference for the photomask stage 210, and can simulate the state of radiation light B2 irradiating the reflective photomask M2. Based on the desired conditions of radiation light B2 incident on the reflective photomask M2, the radiation light B2 and the photomask stage 210 can be adjusted. For example, extreme ultraviolet light can be used to irradiate the photocatalyst layer 214 to decompose surface pollutants (e.g., carbonaceous substances). In some embodiments, if appropriate energy is simultaneously provided to the photocatalyst layer 214 formed of titanium dioxide within a pressure range of about 200 Pa to about 500 Pa (for example, about 200 Pa, about 250 Pa, about 300 Pa, about 350 Pa, about 400 Pa, about 450 Pa, about 500 Pa, or any value in the aforementioned range), it can have a good decomposition effect on suspended particles in the air.

[0103] Therefore, according to FIG. 2A By applying energy to the photocatalyst layer 214 (e.g., irradiating the photocatalyst layer 214 with a high-energy light source), contaminants can be decomposed, maintaining the cleanliness of the surface of the photocatalyst layer 214 opposite to the substrate.

[0104] FIG. 2A The radiation source RS2, reflective photomask M2, and optical element IL2 in the lithography system 200 can be connected with... FIG. 1A The same or similar lithography system 100 will not be described in detail here.

[0105] FIG. 3A as well as FIG. 3B Another form of the lithography system is provided in some embodiments of this disclosure. FIG. 3A A cross-sectional schematic diagram of a lithography system in some embodiments of the present disclosure is shown. FIG. 3B A bottom view of the lithography system in some embodiments of the present disclosure is shown (i.e., FIG. 3A (Lower view of the middle part of the components). FIG. 3A The lithography system 300 includes a radiation source RS3, a photomask stage 310, a reflective photomask M3, and an optical element IL3. The photomask stage 310 includes a base 312, a reflective mark 316 disposed on the base 312, and a photocatalyst layer 314 disposed on the reflective mark 316.

[0106] FIG. 3A and FIG. 2A The materials and setups are largely similar; the difference lies in... FIG. 3AThe photocatalyst layer 314 is disposed not only on the second surface 316b of the reflective mark 316, but also extends to the side surface 316c of the reflective mark 316 adjacent to the second surface 316b. That is, FIG. 3A The photocatalytic layer 314 covers the surface of the reflective mark 316 that is not in contact with the base 312.

[0107] FIG. 3A The radiation source RS3, reflective photomask M3, and optical element IL3 in the lithography system 300 can be connected with... FIG. 1A The same or similar lithography system 100 will not be described in detail here.

[0108] Therefore, according to FIG. 3A By applying energy to the photocatalyst layer 314 (e.g., irradiating the photocatalyst layer 314 with a high-energy light source (e.g., radiation light B3), contaminants can be decomposed, and the surface of the photocatalyst layer 314 opposite to the substrate can be kept clean. In addition, other surfaces of the photocatalyst layer 314 can be further cleaned.

[0109] In other embodiments, the photocatalyst layer may also be selectively applied to different locations of the reflective mark as needed (e.g., the second surface of the reflective mark, any one side surface, multiple side surfaces, or a combination thereof).

[0110] The following describes one aspect of the lithography method in some embodiments of this disclosure.

[0111] FIG. 4 A flowchart illustrating a lithography method 400 in some embodiments of the present disclosure is shown. Method 400 includes step S410, using a radiation source to generate radiation light to illuminate a reflective photomask on a photomask stage and a photocatalyst layer disposed on one side of the reflective photomask; step S422, the photocatalyst layer reflects a first portion of the radiation light to a sensor; and step S424, the reflective photomask reflects a second portion of the radiation light to a substrate.

[0112] To explain in more detail FIG. 4 Please refer to the following procedures: FIG. 5A to FIG. 5B . FIG. 5A to FIG. 5B by FIG. 1A Taking the lithography system 100 as an example, a cross-sectional schematic diagram of some steps of the lithography method in some embodiments of the present disclosure is shown. However, the lithography system here may also use... FIG. 2A Microfilm system 200, FIG. 3A The Microfilm 300 or other suitable Microfilm system.

[0113] FIG. 5AIn some embodiments, the radiation source RS1 is configured to generate the radiation light B1 to irradiate the reflective mask M1 (i.e., the first portion of the radiation light B1a irradiates the reflective mask M1) and the photocatalyst layer 114 (i.e., the second portion of the radiation light B1b irradiates the photocatalyst layer 114) on the reticle stage 110.

[0114] The radiation light B1a and the radiation light B1b provide the irradiated irradiation position with the energy E, such that the temperature of the irradiation position surface is increased, for example, the temperature range can be about 350°C to about 1000°C, and the temperature includes, but is not limited to, about 350°C, about 400°C, about 450°C, about 500°C, about 550°C, about 600°C, about 650°C, about 700°C, about 750°C, about 800°C, about 850°C, about 900°C, about 950°C, about 1000°C, or a value within any of the aforementioned ranges.

[0115] The contaminant P1 is a reaction substance of the lithography process, a debris left over from the artificial maintenance of the lithography system 100, or a particle or a suspended particle attracted by the Van der Waals force of the high-concentration metal atoms of the reflective mask M1, which can be generated during the operation of the lithography system 100. In some embodiments, the contaminant can include a carbon-containing substance, such as a hydrocarbon. The contaminant P1 covers the surface of the photocatalyst layer 114, and the contaminant P1 absorbs the radiation light B1, causing the light reflection ability of the photocatalyst layer 114 to weaken or even disappear, interfering with the signal of the radiation light B1a reflected by the photocatalyst layer 114 detected by the sensing element 120, and affecting the correction of the radiation light B1 and the reticle stage 110.

[0116] Next, please see FIG. 5B The radiation light B1a is guided by the optical element IL1, passes through the reflective mask M1 fixed on the reticle stage 110, reflects the radiation light B1a, exposes the photoresist layer (a material sensitive to the radiation light) on the substrate W, images on the substrate W coated with the photoresist layer fixed on the substrate stage WT, and reflects the radiation light B1a through the photocatalyst layer 114 made of a photocatalyst material with excellent light reflectivity (for example, the light reflectivity is higher than about 95%). In some embodiments, at this time, the radiation light B1b reflected by the photocatalyst layer 114 can be detected by the sensing element 120 for correcting the intensity and the incident angle of the radiation light B1 and the position of the reticle stage 110.

[0117] After the light catalyst layer 114 receives the high energy E, the light catalyst layer 114 catalyzes the pollutants P1 on the surface to undergo a redox reaction to decompose the pollutants P1 into particles P2. Compared to the pollutants P1, the van der Waals force between the particles P2 and the light catalyst layer 114 is low, and the particles P2 leave the surface of the light catalyst layer 114. Therefore, the surface of the light catalyst layer 114 is restored to be clean through the irradiation of the irradiation light B1b. In some embodiments, if the pollutants P1 are hydrocarbons, they can be decomposed into water and carbon dioxide (i.e., particles P2). It is worth mentioning that during the reaction, the light catalyst layer 114 acts as a catalyst to catalyze the decomposition of the pollutants P1, and the volume of the light catalyst layer 114 remains the same and does not decrease.

[0118] FIG. 5A The irradiation light B1 is used to irradiate the reflective mask M1 and the light catalyst layer 114 on the side of the reflective mask M1 at the same time. That is, when the photolithography process of exposing the substrate W1 through the reflective mask M1 using the irradiation light B1 is performed, the light catalyst layer 114 can be irradiated at the same time. Not only the reflected light reflected by the light catalyst layer 114 corrects the irradiation source B1 and the mask table 110, but also the irradiation light B1 provides energy to promote the light catalyst layer 114 to catalyze and decompose the pollutants P1 on the surface, thereby omitting the additional cleaning process and saving manpower and resources for maintaining the photolithography system.

[0119] The irradiation sequence and the number of times of the reflective mask M1 and the light catalyst layer 114 are not particularly limited and can be flexibly adjusted according to actual needs. In some embodiments, the irradiation of the reflective mask M1 is performed before the irradiation of the light catalyst layer 114. In some embodiments, the irradiation of the reflective mask M1 is performed after the irradiation of the light catalyst layer 114. In some embodiments, the irradiation of the reflective mask M1 can be performed multiple times, and then the light catalyst layer 114 is irradiated. In some embodiments, the light catalyst layer 114 can be irradiated multiple times, and then the reflective mask M1 is irradiated. In some embodiments, the reflective mask M1 and the light catalyst layer 114 can be irradiated once respectively, and they are regarded as a group, and multiple groups of irradiation cycles are performed.

[0120] In some embodiments, an extreme ultraviolet light source can be used as the irradiation source RS1 to generate extreme ultraviolet light as the irradiation light B1 to irradiate the reflective mask M1 and the light catalyst layer 114. It can be understood that compared to other irradiation sources such as a deep ultraviolet light source or an ultraviolet light source, the extreme ultraviolet light source provides higher energy when it emits extreme ultraviolet light. However, the irradiation source RS1 can also be adjusted to a suitable type of irradiation source corresponding to the type of pollutants to be decomposed.

[0121] In some implementations, after the contaminant P1 on the surface of the photocatalyst layer 114 is decomposed, the particles P2 resulting from the decomposition of contaminant P1 can be removed, for example, by performing appropriate treatments such as vacuuming the lithography system (e.g., removing carbon dioxide from hydrocarbon decomposition), drying (e.g., removing water from hydrocarbon decomposition), or other removable particle P2 treatments, to improve the cleanliness inside the lithography system.

[0122] The following describes another aspect of the lithography method in some embodiments of this disclosure.

[0123] FIG. 6 A flowchart illustrating a lithography method 500 in some embodiments of this disclosure is shown. Method 500 includes step S510, using a radiation source to generate first radiation light to irradiate a reflective photomask on a photomask stage, the reflective photomask reflecting the first radiation light onto a substrate to form a pattern on the substrate; step S520, using a radiation source to generate second radiation light to irradiate a photocatalyst layer on the photomask stage; and step S530, decomposing contaminants on the surface of the photocatalyst layer, wherein the volume of the photocatalyst layer remains constant.

[0124] To explain in more detail FIG. 6 Please refer to the following procedures: FIG. 7A to FIG. 7B . FIG. 7A to FIG. 7B by FIG. 1A Taking the lithography system 100 as an example, a cross-sectional schematic diagram of some steps of the lithography method in some embodiments of the present disclosure is shown. However, the lithography system here may also use... FIG. 2A Microfilm system 200, FIG. 3A The Microfilm 300 or other suitable Microfilm system.

[0125] FIG. 7A In the example, a radiation source RS1 is used to generate a first radiation light B1c. The first radiation light B1c is guided by an optical element IL1 to illuminate a reflective photomask M1 fixed to a photomask stage 110. The reflective photomask M1 reflects the first radiation light B1c, exposing the photoresist layer on the substrate W, and imaging is performed on the substrate W fixed to the substrate stage WT with the photoresist layer coated on it.

[0126] During operation, contaminant P1 will cover the surface of photocatalyst layer 114, causing the light reflection ability of photocatalyst layer 114 to weaken or even disappear, interfering with the signal of radiation light reflected by photocatalyst layer 114 detected by sensing element 120, and affecting the correction of radiation light B1 and photomask stage 110.

[0127] Next, please see FIG. 7BThe second radiation B1d is generated by the radiation source RS1 and is directed to the photocatalyst layer 114 on the reticle stage 110. The photocatalyst layer 114 can reflect the second radiation B1d, and the reflected second radiation B1d is detected by the sensing element 120 to correct the intensity and the incident angle of the radiation B1d and the position of the reticle stage 110. The second radiation B1d provides the irradiation position energy E to the irradiation position surface such that the temperature of the irradiation position surface is increased, for example, in a range from about 350°C to about 1000°C, including but not limited to about 350°C, about 400°C, about 450°C, about 500°C, about 550°C, about 600°C, about 650°C, about 700°C, about 750°C, about 800°C, about 850°C, about 900°C, about 950°C, about 1000°C, or a value within any of the above ranges.

[0128] Next, referring to FIG. 7C The photocatalyst layer 114 can use the energy E provided by the second radiation B1d to catalytically decompose the contaminants on the surface of the photocatalyst layer 114 into particles P2, and the volume of the photocatalyst layer 114 remains the same before and after the decomposition. The Van der Waals force between the particles P2 and the photocatalyst layer 114 is low, and the particles P2 leave the surface of the photocatalyst layer 114. Thus, the surface of the photocatalyst layer 114 is cleaned by the irradiation of the radiation B1d, and the volume of the photocatalyst layer 114 remains unchanged. In some embodiments, if the contaminants are hydrocarbons, they can be decomposed into water and carbon dioxide (i.e., particles P2).

[0129] It can be understood that some embodiments of the present disclosure use the photocatalyst layer 114 as a correction mark, so that after the routine exposure process, the photocatalyst layer is irradiated to decompose the contaminants on the surface of the photocatalyst layer 114, thereby simplifying the manpower and resources required for maintaining the lithography system.

[0130] The order and number of times of irradiating the reflective reticle M1 and the photocatalyst layer 114 are not particularly limited and can be flexibly adjusted according to actual needs. For example, in some embodiments, irradiating the reflective reticle M1 is performed before irradiating the photocatalyst layer 114. In some embodiments, irradiating the reflective reticle M1 is performed after irradiating the photocatalyst layer 114. In some embodiments, irradiating the reflective reticle M1 can be performed multiple times, and then irradiating the photocatalyst layer 114. In some embodiments, irradiating the photocatalyst layer 114 can be performed multiple times, and then irradiating the reflective reticle M1. In some embodiments, irradiating the reflective reticle M1 and irradiating the photocatalyst layer 114 can be performed once, respectively, and they are regarded as a group, and multiple groups of irradiation cycles are performed.

[0131] In some embodiments, the radiation source RSI can be an extreme ultraviolet radiation source to generate extreme ultraviolet light as the radiation B1d to irradiate the photocatalyst layer 114. It can be appreciated that the extreme ultraviolet radiation source provides higher energy when generating extreme ultraviolet light compared to other radiation sources such as deep ultraviolet radiation sources or ultraviolet radiation sources. However, the radiation source RSI can also be adjusted to a suitable type of radiation source corresponding to the type of pollutants to be decomposed.

[0132] In some embodiments, the particles P2 after decomposition of the pollutants P1 on the surface of the photocatalyst layer 114 can be removed, for example, by vacuuming (e.g., removing carbon dioxide after decomposition of hydrocarbons), drying (e.g., removing water after decomposition of hydrocarbons), or other suitable processes to remove the particles P2 to improve the cleanliness of the lithography system.

[0133] In some embodiments of the present disclosure, a lithography system and a method thereof are provided, in which a photocatalyst layer is disposed on a surface of a reticle stage base or a reflective mark. The photocatalyst layer can reflect radiation light for calibration of the reticle stage and the radiation light, and can also catalyze decomposition of pollutants with the aid of external energy to avoid interference of the pollutants with detection of the reflected light, improve calibration accuracy of the reticle stage and the radiation light, and simplify cleaning steps of the pollutants to save manpower and resources for maintaining the lithography system.

[0134] In some embodiments of the present disclosure, a lithography system is provided, including a radiation source, a reticle stage, a reflective reticle, and an optical element. The radiation source is configured to generate radiation light. The reticle stage includes a base and a photocatalyst layer disposed on the base. The reflective reticle is disposed on the base, and the photocatalyst layer is disposed on one side of the reflective reticle. The optical element is configured to irradiate the radiation light onto the reflective reticle.

[0135] In some embodiments, the reflective reticle includes a reflective film stack, and the photocatalyst layer has the same light reflectivity as the reflective film stack.

[0136] In some embodiments, the photocatalyst layer directly contacts the base.

[0137] In some embodiments, the reticle stage further includes a reflective mark, and the reflective mark is disposed on the base. The reflective mark includes a first surface contacting the base and a second surface opposite to the first surface, and the photocatalyst layer is disposed on the second surface of the reflective mark.

[0138] In some embodiments of the disclosure, a lithography method is provided, comprising: using a radiation source to generate radiation light to irradiate a reflective photomask on a photomask stage and a photocatalyst layer disposed on a side of the reflective photomask, wherein the photocatalyst layer reflects a first portion of the radiation light to a sensor, wherein the first portion of the radiation light further decomposes contaminants on a surface of the photocatalyst layer, and the reflective photomask reflects a second portion of the radiation light to a substrate to form a pattern on the substrate.

[0139] In some embodiments, the step of using the radiation light to irradiate the reflective photomask and the photocatalyst layer includes a temperature range of the irradiation position of the photocatalyst layer irradiated by the radiation light is about 350°C to about 1000°C.

[0140] In some embodiments, after the step of decomposing the contaminants on the surface of the photocatalyst layer, further comprising removing particles after decomposition of the contaminants.

[0141] In some embodiments of the disclosure, a lithography method is provided, comprising: using a radiation source to generate first radiation light to irradiate a reflective photomask on a photomask stage, the reflective photomask reflecting the first radiation light to a substrate to form a pattern on the substrate; and using a radiation source to generate second radiation light to irradiate a photocatalyst layer on the photomask stage to decompose contaminants on a surface of the photocatalyst layer, wherein a volume of the photocatalyst layer remains the same.

[0142] In some embodiments, the step of using the radiation source to generate the first radiation light to irradiate the reflective photomask on the photomask stage is performed before the step of using the radiation source to generate the second radiation light to irradiate the photocatalyst layer on the photomask stage.

[0143] In some embodiments, the step of using the radiation source to generate the first radiation light to irradiate the reflective photomask on the photomask stage is performed after the step of using the radiation source to generate the second radiation light to irradiate the photocatalyst layer on the photomask stage.

[0144] The foregoing outlines features of several embodiments so that those skilled in the art can better understand the various aspects of the disclosure. Those skilled in the art should appreciate that they can readily use the disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and / or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the disclosure, and that they can make various changes, substitutions and alterations herein without departing from the spirit and scope of the disclosure.

Claims

1. A lithography system, comprising: The lithography system comprises: a radiation source configured to generate a radiation light; a reticle stage comprising a base and a photocatalyst layer disposed on the base; a reflective reticle disposed on the base, wherein the photocatalyst layer is disposed on a side of the reflective reticle, the reflective reticle comprising a reflective film stack, wherein a light reflectivity of the photocatalyst layer is the same as a light reflectivity of the reflective film stack; and an optical element configured to irradiate the radiation light onto the reflective reticle.

2. The lithography system of claim 1, wherein, The optical element is further configured to irradiate the radiation light onto the photocatalyst layer, and the lithography system further comprises a sensing element configured to detect a portion of the radiation light reflected from the photocatalyst layer.

3. The lithography system of claim 1, wherein, The photocatalyst layer directly contacts the base.

4. The lithography system of claim 1, wherein, The reticle stage further comprises a reflective mark, wherein the reflective mark is disposed on the base, the reflective mark comprising a first surface contacting the base and a second surface opposite to the first surface, wherein the photocatalyst layer is disposed on the second surface of the reflective mark.

5. A lithography method, characterized by, The lithography system comprises: generating a radiation light using a radiation source to irradiate onto a reflective reticle comprising a reflective film stack and a photocatalyst layer disposed on a side of the reflective reticle on a reticle stage, wherein the photocatalyst layer reflects a first portion of the radiation light to a sensor, wherein the first portion of the radiation light further decomposes a contaminant on a surface of the photocatalyst layer, the reflective reticle reflects a second portion of the radiation light to a substrate to form a pattern on the substrate, wherein a light reflectivity of the photocatalyst layer is the same as a light reflectivity of the reflective film stack.

6. The method of claim 5, wherein, The step of irradiating the reflective reticle and the photocatalyst layer using the radiation light comprises a temperature range of an irradiation location of the photocatalyst layer irradiated by the radiation light is within 350°C to 1000°C.

7. The method of claim 5, wherein, The step of decomposing the contaminant on the surface of the photocatalyst layer further comprises removing a particle after the contaminant is decomposed.

8. A lithography method, characterized by, The lithography system comprises: generating a first radiation light using a radiation source to irradiate onto a reflective reticle comprising a reflective film stack on a reticle stage, the reflective reticle reflects the first radiation light to a substrate to form a pattern on the substrate; and generating a second radiation light using the radiation source to irradiate onto a photocatalyst layer on a reticle stage to decompose a contaminant on a surface of the photocatalyst layer, wherein a volume of the photocatalyst layer remains the same, wherein a light reflectivity of the photocatalyst layer is the same as a light reflectivity of the reflective film stack.

9. The lithography method of claim 8, wherein, The step of generating the first radiation light using the radiation source to irradiate onto the reflective reticle on the reticle stage is performed before the step of generating the second radiation light using the radiation source to irradiate onto the photocatalyst layer on the reticle stage.

10. The lithography method of claim 8, wherein, The step of generating the first radiation light using the radiation source to irradiate onto the reflective reticle on the reticle stage is performed after the step of generating the second radiation light using the radiation source to irradiate onto the photocatalyst layer on the reticle stage.

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