CN118112886B - Method and equipment for cleaning photoetching mask plate - Google Patents
Method and equipment for cleaning photoetching mask plate Download PDFInfo
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- CN118112886B CN118112886B CN202311642923.2A CN202311642923A CN118112886B CN 118112886 B CN118112886 B CN 118112886B CN 202311642923 A CN202311642923 A CN 202311642923A CN 118112886 B CN118112886 B CN 118112886B
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- 238000000034 method Methods 0.000 title claims abstract description 60
- 238000001259 photo etching Methods 0.000 title claims abstract description 55
- 238000004140 cleaning Methods 0.000 title claims abstract description 47
- 239000011261 inert gas Substances 0.000 claims abstract description 65
- 239000007789 gas Substances 0.000 claims abstract description 28
- 239000001307 helium Substances 0.000 claims abstract description 25
- 229910052734 helium Inorganic materials 0.000 claims abstract description 25
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000001257 hydrogen Substances 0.000 claims abstract description 20
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 20
- 239000000126 substance Substances 0.000 claims abstract description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 23
- 239000008367 deionised water Substances 0.000 claims description 10
- 229910021641 deionized water Inorganic materials 0.000 claims description 10
- 238000010926 purge Methods 0.000 claims description 8
- 230000010363 phase shift Effects 0.000 claims description 5
- GALOTNBSUVEISR-UHFFFAOYSA-N molybdenum;silicon Chemical compound [Mo]#[Si] GALOTNBSUVEISR-UHFFFAOYSA-N 0.000 claims description 4
- 238000009423 ventilation Methods 0.000 claims description 3
- 210000002381 plasma Anatomy 0.000 abstract description 56
- 239000012535 impurity Substances 0.000 abstract description 46
- 150000002500 ions Chemical class 0.000 abstract description 36
- 239000010410 layer Substances 0.000 abstract description 33
- 230000008569 process Effects 0.000 abstract description 26
- 238000010521 absorption reaction Methods 0.000 abstract description 7
- 150000001875 compounds Chemical class 0.000 abstract description 7
- 239000011241 protective layer Substances 0.000 abstract description 6
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 14
- 238000000206 photolithography Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 7
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- 229910001220 stainless steel Inorganic materials 0.000 description 7
- 239000010935 stainless steel Substances 0.000 description 7
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 6
- -1 SC1 Chemical class 0.000 description 6
- 238000010586 diagram Methods 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 5
- 238000001459 lithography Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 230000000670 limiting effect Effects 0.000 description 4
- 239000002344 surface layer Substances 0.000 description 4
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000001900 extreme ultraviolet lithography Methods 0.000 description 3
- 238000002513 implantation Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 239000006117 anti-reflective coating Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 239000005416 organic matter Substances 0.000 description 2
- 238000001020 plasma etching Methods 0.000 description 2
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 2
- 229910052707 ruthenium Inorganic materials 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 206010034972 Photosensitivity reaction Diseases 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- CXOWYMLTGOFURZ-UHFFFAOYSA-N azanylidynechromium Chemical compound [Cr]#N CXOWYMLTGOFURZ-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 1
- 229910001634 calcium fluoride Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000007943 implant Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 239000010954 inorganic particle Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000010849 ion bombardment Methods 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000036211 photosensitivity Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- MZLGASXMSKOWSE-UHFFFAOYSA-N tantalum nitride Chemical compound [Ta]#N MZLGASXMSKOWSE-UHFFFAOYSA-N 0.000 description 1
- 229910001936 tantalum oxide Inorganic materials 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
- G03F1/82—Auxiliary processes, e.g. cleaning or inspecting
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Preparing Plates And Mask In Photomechanical Process (AREA)
Abstract
The invention relates to a method and equipment for cleaning a photoetching mask plate, wherein the method comprises the following steps: placing a photoetching mask plate to be cleaned in a cavity of plasma equipment; the plasma apparatus has a radio frequency power supply for generating plasma; introducing inert gas into the cavity; the inert gas is helium and/or helium-hydrogen mixed gas; and keeping the temperature of the inert gas in the cavity below 50 ℃ so that the inert gas generates plasma and acts on the photoetching mask plate. According to the invention, the impurity ions on the photoetching mask plate are bombarded by the plasmas of helium and/or helium-hydrogen mixed gas, so that chemical bonds of the impurity ions are broken and converted into gaseous or water-soluble organic impurities, and the organic impurities can be removed easily in the follow-up process. The cleaning process can not damage the special compound oxide layer, the absorption layer and the protective layer structure on the surface of the EUV (extreme ultraviolet) high-end photomask, and can improve the chip yield.
Description
Technical Field
The invention relates to a semiconductor photoetching process, in particular to a method for cleaning a photoetching mask plate (also called a photomask and a photoetching plate), and further relates to a device for cleaning the photoetching mask plate.
Background
With the rapid development and technological progress of chip processing technology in recent years, the node of photolithography process is reaching below 10nm, so EUV (Extreme ultraviolet) lithography technology will be increasingly applied by various large wafer foundries (Fab). More and more EUV and high-end lithography masks (hereinafter EUV etc. high-end photomasks), such as OMOG mask (Opaque MoSi on Glass, opaque molybdenum silicon mask) and phase shift mask (PSM, phase Shift Mask), will also gradually replace the conventional lithography masks.
Impurities, contamination, etc. on the photolithographic reticle can affect the photolithographic process, resulting in a loss of yield of chips.
Disclosure of Invention
Based on this, it is necessary to provide a method for cleaning a photolithographic reticle.
A method of cleaning a photolithographic reticle, comprising: placing a photoetching mask plate to be cleaned in a cavity of plasma equipment; the plasma apparatus has a radio frequency power supply for generating plasma; introducing inert gas into the cavity; the inert gas is helium and/or helium-hydrogen mixed gas; and keeping the temperature of the inert gas in the cavity below 50 ℃ so that the inert gas generates plasma and acts on the photoetching mask plate.
According to the method for cleaning the photoetching mask, impurity ions on the photoetching mask are bombarded by plasmas of helium and/or helium-hydrogen mixed gas, chemical bonds of the impurity ions are broken and converted into gaseous or water-soluble organic impurities, and the gaseous or water-soluble organic impurities can be removed simply. The environment temperature of the photoetching mask plate is controlled in the cleaning process, the special compound oxide layer, the absorption layer and the protective layer on the surface of the EUV (extreme ultraviolet) and other high-end photomasks are not damaged, and the chip yield can be improved.
In one embodiment, the temperature is below 30 degrees celsius.
In one embodiment, the temperature is 10 to 30 degrees celsius.
In one embodiment, the cavity is a stainless steel cavity.
In one embodiment, in the step of generating the inert gas into plasma, the working power of the radio frequency power supply is 500W to 1500W.
In one embodiment, in the step of generating the inert gas into plasma, the plasma apparatus discharges to generate plasma for a working time of 1 to 5 minutes.
In one embodiment, in the step of introducing the inert gas, the total flow rate of the inert gas is 80-150NL/min.
In one embodiment, the flow rate ratio of the helium-hydrogen mixed gas to the introduced inert gas is not more than 30%.
In one embodiment, the helium accounts for not less than 70% of the flow of the inert gas.
In one embodiment, the step of causing the inert gas to generate a plasma further comprises the step of purging the photolithographic reticle with a gaseous species after the step of causing the inert gas to generate a plasma.
In one embodiment, the step of generating a plasma from the inert gas, after the step of acting on the photolithographic reticle, further comprises the step of rinsing the photolithographic reticle with deionized water.
In one embodiment, the photolithographic reticle is an opaque molybdenum silicon mask or a phase shift mask.
It is also desirable to provide a cleaning apparatus for a lithographic reticle.
A cleaning apparatus for a lithographic reticle, comprising: the cavity is used for placing a photoetching mask plate to be cleaned; the ventilation device is used for introducing inert gas into the cavity; a radio frequency power supply for generating plasma from the inert gas; the cleaning apparatus is configured to clean a photolithography reticle according to the cleaning method of any of the foregoing embodiments.
According to the cleaning equipment for the photoetching mask plate, impurity ions on the photoetching mask plate are bombarded by plasmas of helium and/or helium-hydrogen mixed gas, chemical bonds of the impurity ions are broken and converted into gaseous or water-soluble organic impurities, and the organic impurities can be removed simply. The environment temperature of the photoetching mask plate is controlled in the cleaning process, the special compound oxide layer, the absorption layer and the protective layer on the surface of the EUV (extreme ultraviolet) and other high-end photomasks are not damaged, and the chip yield can be improved.
In one embodiment, the cavity is a stainless steel cavity.
Drawings
For a better description and illustration of embodiments and/or examples of those inventions disclosed herein, reference may be made to one or more of the accompanying drawings. Additional details or examples used to describe the drawings should not be construed as limiting the scope of the disclosed invention, the presently described embodiments and/or examples, and any of the presently understood modes of carrying out the invention.
FIG. 1 is a flow chart of a method of cleaning a photolithographic reticle in an embodiment of the application;
FIG. 2 is a schematic diagram of an EUV lithography reticle in an embodiment of the application;
FIG. 3 is a schematic diagram of the principle of the present application for removing impurity ions by plasma;
FIG. 4 is a schematic diagram of a cleaning apparatus for a lithographic reticle in an embodiment of the application.
Detailed Description
In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
It will be understood that when an element or layer is referred to as being "on," "adjacent," "connected to," or "coupled to" another element or layer, it can be directly on, adjacent, connected, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
Spatially relative terms, such as "under," "below," "beneath," "under," "above," "over," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "under" or "beneath" other elements would then be oriented "on" the other elements or features. Thus, the exemplary terms "below" and "under" may include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
Embodiments of the invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. In this way, variations from the illustrated shape due to, for example, manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the present invention should not be limited to the particular shapes of the regions illustrated herein, but rather include deviations in shapes that result, for example, from manufacturing. For example, an implanted region shown as a rectangle typically has rounded or curved features and/or implant concentration gradients at its edges rather than a binary change from implanted to non-implanted regions. Also, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface over which the implantation is performed. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention.
In a process using a photolithographic reticle, an exemplary cleaning process would use an acid solution (e.g., high purity sulfuric acid), a strong oxidizing mixture (e.g., SPM, i.e., a mixture of sulfuric acid and hydrogen peroxide), and a portion of a strong base compound (e.g., SC1, i.e., a mixture of ammonia, hydrogen peroxide, and water, or TC1, i.e., a mixture of tetramethylammonium hydroxide, TMAH, hydrogen peroxide, and water). The series of acid-base mixtures can more or less leave ionic impurities (such as sulfate radicals, ammonium radicals, alkali ions and the like) on the photoetching mask plate after a cleaning process, and the ionic impurities can generate vaporous crystallization during the use process of the EUV high-end photomask so as to cause a large number of chip pattern defective products. Therefore, effectively controlling and removing such ion impurities will have a great impact on the process yield improvement of the whole EUV and other high-end photomasks.
Exemplary methods of removing ionic impurities from a photolithographic reticle fall into two broad categories. The first method is to use a wet method, i.e. soaking and flushing with hot water (about 60-95 ℃). Since this type of process requires spraying liquid via a pipeline and heating by a heater, it has the disadvantage of introducing additional inorganic particles. The cleanliness is limited by the capacity of the pipeline filtration equipment and the cleanliness of the heater's own hardware, and once the hardware ages, the filter fails, introducing new and more serious particle defect problems. In addition, excessive hot water cleaning can also form certain erosion to the nano-scale linewidth patterns on the surface of the EUV (extreme ultraviolet) high-end photomask. In addition, as the principle of the method is that the purpose of removing ions on the surface of the mask plate is achieved by diluting with hot water, the process time is limited by dilution efficiency, long process time is often required, and the average cleaning process time is different from half an hour to one hour.
The second method is to irradiate the photomask with Deep Ultraviolet (DUV) light of wavelength of 100-250nm to break sulfide and ammonium ion bonds. Although the cleaning efficiency of the method is improved to a great extent for the wet method, the irradiation process can generate high temperature of hundreds of degrees, and the high temperature can cause the detachment and fracture of the multi-layer composite oxide layer, the absorption layer and the protection layer for high-end photomasks such as EUV, thereby damaging the substrate structure of the mask and causing irreversible damage to products.
The object of the application is to effectively remove ionic impurities from the surface of a lithographic reticle while avoiding the above-mentioned disadvantages.
FIG. 1 is a flow chart of a method of cleaning a photolithographic reticle in an embodiment of the application, comprising the steps of:
s110, placing the photoetching mask plate to be cleaned in a cavity of plasma equipment.
FIG. 2 is a schematic diagram of an EUV lithography reticle in an embodiment of the application. The EUV lithography reticle comprises: an anti-reflective coating (ARC) 210, which is mainly tantalum oxide; an absorption layer (absorber) 220 made of tantalum nitride; a capping layer (coating) 230, made of ruthenium (Ru) and comprising a backside-coated metal coating; a composite mirror layer (multilayer mirror) 240, which is mainly made of molybdenum and silicon (MoSi); the substrate 250 is made of a material with Low Thermal Expansion (LTEM), and specifically may be quartz or calcium fluoride; the metal coating 260 is made of metal nitride, such as chromium nitride.
In order to avoid damage to the structure of EUV reticles, care must be taken to control the ambient temperature during cleaning not to be too high. In one embodiment of the application, the photolithographic reticle is maintained at a temperature of less than 50 degrees celsius while in the cavity.
And S120, introducing inert gas into the cavity.
The photolithography mask is placed in an inert gas environment by introducing an inert gas into the chamber of the plasma apparatus.
In one embodiment of the application, the inert gas is helium and/or a helium-hydrogen mixed gas. Specifically, the helium-hydrogen mixed gas may be a mixed gas of helium and a small amount of hydrogen. In one embodiment of the application, the hydrogen gas comprises 2 to 5 percent of the helium-hydrogen mixed gas.
The film layer of the EUV high-end photomask mainly comprises rare metals such as molybdenum, ruthenium and the like, and inert gas adopts helium and/or helium-hydrogen mixed gas, so that a certain protection effect can be achieved on the metal surface. Compared with the embodiment adopting helium and/or helium-hydrogen mixed gas, the scheme adopting argon, nitrogen, oxygen and related mixed gas as a plasma gas source is easy to cause the problems of loss and damage to the metal film layer of the photo-etching mask after a certain process time, so that the oxide layer of the photo-etching mask is fallen off, the photosensitivity and the transmission loss rate of the raw material of the photo-etching mask are reduced, and the photo-etching resolution is seriously affected if the process time is too long.
And S130, generating plasma by inert gas and acting on the photoetching mask plate.
In one embodiment of the application, the plasma apparatus is a plasma generating tool commonly used in Fab, such as a Plasma Enhanced Chemical Vapor Deposition (PECVD) tool, a High Density Plasma Chemical Vapor Deposition (HDPCVD) tool, a Reactive Ion Etching (RIE) tool, an Inductively Coupled Plasma (ICP) etching tool, or the like. And placing the photoetching mask plate to be cleaned in a cavity of the machine, applying an electric field to inert gas in the cavity to enable the inert gas to generate plasma and act on the photoetching mask plate, and keeping the temperature of the inert gas in the cavity to be lower than 50 ℃ in the process of generating the plasma. In other embodiments of the application, the generated plasma may also be applied to the photolithographic reticle by placing the photolithographic reticle to be cleaned in a plasma generator.
According to the method for cleaning the photoetching mask, impurity ions (such as sulfate ions, ammonium ions, alkali ions and the like) on the photoetching mask are bombarded by plasmas of helium and/or helium-hydrogen mixed gas, chemical bonds of the impurity ions are broken and converted into gaseous or water-soluble organic impurities, and the organic impurities can be removed simply. The environment temperature of the photoetching mask plate is controlled in the cleaning process, and the special compound oxide layer, the absorption layer and the protective layer structure (refer to figure 2) on the surface of the EUV (extreme ultraviolet) high-end photomask cannot be damaged, so that the chip yield can be improved.
The plasma formed by the inert gas molecules bombards the impurity ions mainly in a physical process. In one embodiment of the application, the plasma generating station has a radio frequency power source. Under the action of the radio frequency power source, the inert gas molecules generate interactions of metastable state, ions and electrons, the ions and electrons can be combined rapidly (before they reach the surface of the target object), and the metastable state substances need to collide with the solid to transfer energy. They can release energy there to this effect when reaching the object surface. The metastable species can of course also release energy during collisions with the process gas molecules and decompose directly at the point of contact and produce reactive species. Fig. 3 is a schematic diagram of the principle of removing impurity ions by the plasma of the present application.
For sulfate impurity ions (SO 4 2-), the sulfate impurity ions are mainly converted into oxygen molecules (O 2), sulfur dioxide molecules (SO 2), oxygen ions and the like after being bombarded by plasmas formed by inert gas molecules. For ammonium ions (NH 4 +), the ion bombardment by the plasma formed by inert gas molecules will mainly convert into ammonia molecules (NH 3), nitrogen molecules (N 2), hydrogen ions (H +), etc., and possibly also form small amounts of water vapor.
In one embodiment of the application, the ambient temperature within the chamber of the machine is controlled to be below 30 degrees celsius, such as 10 to 30 degrees celsius, during cleaning.
In one embodiment of the present application, the working power of the rf power supply of the machine during the process of generating the plasma in step S120 is 500W to 1500W. A conventional rf power supply with a frequency of 13.56Mhz may be selected with a power support range of 300W-3000W.
In one embodiment of the present application, the working time of the stage discharge to generate plasma in step S120 is 1 to 5 minutes. The method for cleaning the photoetching mask plate can finish the cleaning of the photoetching mask plate only in a short time.
In one embodiment of the application, the total flow of inert gas into the chamber is 80-150NL/min (standard liters per minute). In one embodiment of the application, the inert gas may be all helium. Or 70% -90% helium and 30% -10% helium-hydrogen mixed gas.
In an embodiment of the present application, step S120 further includes a step of rinsing the photolithography mask with deionized water, so as to further consolidate the removal effect.
In one embodiment of the present application, after step S120, and before rinsing the lithography reticle with deionized water, the method further comprises the step of purging the lithography reticle with a gaseous substance. In particular, the gaseous substance may be an inert gas, such as an inert gas. In one embodiment of the application, after ultra-pure nitrogen is introduced into the cavity for purging, the air in the cavity is pumped out and discharged into the waste gas pipeline through the air exhaust device of the machine table.
The technical scheme of the application is described below by means of several specific examples:
Example 1
The photolithographic reticle to be cleaned is placed in a stainless steel chamber equipped with a radio frequency power supply for generating plasma, the temperature in the chamber is controlled at 10-25 ℃, and a proper amount of helium is filled into the chamber at a flow rate of 80 NL/min. The radio frequency power supply ionizes helium gas with a power of 600W to generate plasma and acts on the surface of the photoetching mask plate, and the glow discharge time is controlled to be 5min. In this embodiment, the height of the photolithography mask from the rf emission source is 10mm. After the impurity ions on the surface layer of the photoetching mask plate are subjected to the bombardment effect of plasma energy combined with inert gas ions, chemical bonds in the impurity ions are broken or crushed, and are converted into gaseous or organic impurities which are very soluble in pure water. After the glow discharge is finished, ultra-pure nitrogen is introduced into the cavity for purging, then the air in the cavity is pumped out through an air exhaust device of the equipment cavity and is discharged into an exhaust pipeline, and finally the surface of the photoetching mask plate is flushed by deionized water and then dried.
Example 2
The photolithographic reticle to be cleaned is placed in a stainless steel chamber equipped with a radio frequency power supply for generating plasma, the temperature in the chamber is controlled at 10-25 ℃, and a proper amount of helium is filled into the chamber at a flow rate of 80 NL/min. The radio frequency power supply ionizes helium gas with 700W power glow discharge to generate plasma and act on the surface of the photoetching mask plate, and the glow discharge time is controlled to be 3min. In this embodiment, the height of the photolithography mask from the rf emission source is 10mm. After the impurity ions on the surface layer of the photoetching mask plate are subjected to the bombardment effect of plasma energy combined with inert gas ions, chemical bonds in the impurity ions are broken or crushed, and are converted into gaseous or organic impurities which are very soluble in pure water. After the glow discharge is finished, ultra-pure nitrogen is introduced into the cavity for purging, then the air in the cavity is pumped out through an air exhaust device of the equipment cavity and is discharged into an exhaust pipeline, and finally the surface of the photoetching mask plate is flushed by deionized water and then dried.
Example 3
The photolithographic reticle to be cleaned is placed in a stainless steel chamber equipped with a radio frequency power supply for generating plasma, the temperature in the chamber is controlled at 10-25 ℃, and a proper amount of helium is filled into the chamber at a flow rate of 120 NL/min. The radio frequency power supply ionizes helium gas with 800W power glow discharge to generate plasma and act on the surface of the photoetching mask plate, and the glow discharge time is controlled to be 1min. In this embodiment, the height of the photolithography mask from the rf emission source is 15mm. After the impurity ions on the surface layer of the photoetching mask plate are subjected to the bombardment effect of plasma energy combined with inert gas ions, chemical bonds in the impurity ions are broken or crushed, and are converted into gaseous or organic impurities which are very soluble in pure water. After the glow discharge is finished, ultra-pure nitrogen is introduced into the cavity for purging, then the air in the cavity is pumped out through an air exhaust device of the equipment cavity and is discharged into an exhaust pipeline, and finally the surface of the photoetching mask plate is flushed by deionized water and then dried.
Example 4
The photolithographic reticle to be cleaned is placed in a stainless steel chamber equipped with a radio frequency power supply for generating plasma, the temperature in the chamber is controlled at 10-25 ℃, and an appropriate amount of inert gas (helium 90% and helium-hydrogen mixed gas 10%) is filled into the chamber at a flow rate of 100 NL/min. The radio frequency power supply ionizes helium gas with 700W power glow discharge to generate plasma and act on the surface of the photoetching mask plate, and the glow discharge time is controlled to be 3min. In this embodiment, the height of the photolithography mask from the rf emission source is 10mm. After the impurity ions on the surface layer of the photoetching mask plate are subjected to the bombardment effect of plasma energy combined with inert gas ions, chemical bonds in the impurity ions are broken or crushed, and are converted into gaseous or organic impurities which are very soluble in pure water. After the glow discharge is finished, ultra-pure nitrogen is introduced into the cavity for purging, then the air in the cavity is pumped out through an air exhaust device of the equipment cavity and is discharged into an exhaust pipeline, and finally the surface of the photoetching mask plate is flushed by deionized water and then dried.
After the high-end photomask such as EUV is cleaned by adopting the cleaning method of the photoetching mask plate, the photoetching mask plate can be soaked in high-temperature deionized water to detect the concentration of residual ion impurities. Specifically, after the photoetching mask plate cleaned by the method is soaked in 100ml of hot water at ninety ℃ for one hour, the concentration of sulfate ions, ammonium ions and other impurity ions in the hot water is detected to be less than 0.2ppb, so that the online control requirement of EUV high-end wafer factory flow on the chip yield can be met. In contrast, a photolithographic reticle which is not cleaned by the cleaning method of the photolithographic reticle of the present application, even after being immersed in 100ml of ninety degrees celsius hot water for one hour under the conventional condition of very good process capability, has a sulfate ion concentration of about 2ppb and an ammonium ion concentration of about 4ppb to 8ppb, see table 1. Therefore, the application can lead the ion impurity residual quantity on the EUV high-end photomask to be lower than 0.2ppb under the condition that the special compound oxide layer and the protective layer on the surface of the photomask are not damaged, and can reduce the manufacturing cost and simultaneously lead the EUV high-end photomask not to generate fog defects in the life cycle to influence the chip yield.
The application correspondingly provides cleaning equipment for the photoetching mask plate. FIG. 4 is a schematic diagram of a cleaning apparatus for a photolithography mask according to an embodiment of the present application, which includes a chamber 310, a ventilator 320, and a RF power source 330. The chamber 310 is used to house a photolithographic reticle to be cleaned. The ventilation device 320 is used to introduce inert gas into the cavity 310. In other embodiments, other gas sources may be connected to the ventilator 320, and other gases may be provided to the chamber 310 and perform the corresponding functions. The rf power source 330 is used to generate a plasma from the inert gas, i.e., to apply an electric field to the chamber 310, thereby generating a plasma from the inert gas in the chamber 310. When generating plasma to clean the photolithography mask, the temperature of the inert gas environment is lower than 50 ℃.
According to the cleaning equipment for the photoetching mask plate, impurity ions on the photoetching mask plate are bombarded by plasma of inert gas, chemical bonds of the impurity ions are broken and converted into gaseous or water-soluble organic matter impurities, and the organic matter impurities can be removed simply later. The environment temperature of the photoetching mask plate is controlled in the cleaning process, the special compound oxide layer, the absorption layer and the protective layer on the surface of the EUV (extreme ultraviolet) and other high-end photomasks are not damaged, and the chip yield can be improved.
In one embodiment of the application, the inert gas is helium and/or a helium-hydrogen mixed gas.
In one embodiment of the application, the cavity 310 is a stainless steel cavity.
In one embodiment of the application, the temperature is below 30 degrees celsius.
In one embodiment of the present application, the RF power source 330 operates at a power of 500W to 1500W.
In one embodiment of the application, the cleaning apparatus of the photolithographic reticle is discharged to generate plasma for a working time of 1 to 5 minutes.
In one embodiment of the application, the total flow of inert gas into the chamber 310 by the ventilator 320 is 80-150NL/min.
In one embodiment of the application, the helium-hydrogen mixed gas accounts for no more than 30% of the flow of the introduced inert gas.
In one embodiment of the application, helium comprises no less than 70% of the flow of inert gas.
In one embodiment of the application, the photolithographic reticle is an opaque molybdenum silicon mask or a phase shift mask.
In one embodiment of the application, the cleaning apparatus of the lithographic reticle further comprises a rinsing device for rinsing the lithographic reticle with deionized water.
It should be understood that, although the steps in the flowcharts of the present application are shown in order as indicated by the arrows, these steps are not necessarily performed in order as indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least a portion of the steps in the flowcharts of this application may include a plurality of steps or stages that are not necessarily performed at the same time but may be performed at different times, the order in which the steps or stages are performed is not necessarily sequential, and may be performed in rotation or alternately with at least a portion of the steps or stages in other steps or others.
In the description of the present specification, reference to the terms "some embodiments," "other embodiments," "desired embodiments," and the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.
Claims (9)
1. A method of cleaning a photolithographic reticle, comprising:
placing a photoetching mask plate to be cleaned in a cavity of plasma equipment; the plasma apparatus has a radio frequency power supply for generating plasma;
Introducing inert gas into the cavity; the inert gas comprises helium and helium-hydrogen mixed gas, the helium-hydrogen mixed gas accounts for not more than 30% of the flow rate of the introduced inert gas, and the helium accounts for not less than 70% of the flow rate of the introduced inert gas;
And keeping the temperature of the inert gas in the cavity below 50 ℃ so that the inert gas generates plasma and acts on the photoetching mask plate.
2. The method of claim 1, wherein the temperature is below 30 degrees celsius.
3. The method of claim 1, wherein the rf power source is operated at a power of 500W to 1500W during the step of generating the inert gas to generate the plasma and applying the inert gas to the photolithographic reticle.
4. A method of cleaning a photolithographic reticle as claimed in any one of claims 1 to 3 wherein in the step of causing the inert gas to generate a plasma and act on the photolithographic reticle, the plasma apparatus is discharged to generate a plasma for a working time of 1 to 5 minutes.
5. The method of claim 1, wherein in the step of introducing an inert gas into the chamber, the total flow rate of the inert gas introduced is 80-150NL/min.
6. The method of cleaning a photolithographic reticle of claim 1, further comprising the step of purging the photolithographic reticle with a gaseous substance after the step of generating a plasma from the inert gas and acting on the photolithographic reticle.
7. The method of cleaning a photolithographic reticle of claim 1 or 6, further comprising the step of rinsing the photolithographic reticle with deionized water after the step of generating a plasma from the inert gas and acting on the photolithographic reticle.
8. The method of cleaning a photolithographic reticle of any of claims 1-3, 5-6, wherein the photolithographic reticle is an opaque molybdenum silicon mask or a phase shift mask.
9. A cleaning apparatus for a lithographic reticle, characterized in that it is used for cleaning a lithographic reticle according to the cleaning method of any one of claims 1-8, the cleaning apparatus comprising:
the cavity is used for placing a photoetching mask plate to be cleaned;
The ventilation device is used for introducing inert gas into the cavity;
And the radio frequency power supply is used for enabling the inert gas to generate plasma.
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| KR100712991B1 (en) * | 2005-06-08 | 2007-05-02 | 주식회사 하이닉스반도체 | How to remove growth foreign substances in photomask |
| US7767365B2 (en) * | 2006-08-31 | 2010-08-03 | Micron Technology, Inc. | Methods for forming and cleaning photolithography reticles |
| CN101699352B (en) * | 2009-11-06 | 2011-10-19 | 常州瑞择微电子科技有限公司 | Method for removing sulfate radicals from photomask |
| DE102013108872B4 (en) * | 2013-03-15 | 2018-05-09 | Taiwan Semiconductor Manufacturing Company, Ltd. | Ultraviolet light photovoltaic (EUV) photomasks and their manufacturing processes |
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