Patent Application
20250216769
The present application claims priority under 35 U.S.C. § 119 (a) to Korean Patent Application Number 10-2023-0197825, filed on Dec. 29, 2023, which is incorporated herein by reference in its entirety.
The embodiments of the present disclosure relate generally to semiconductor technology and, more in particular, to a blank mask and a method of fabricating the same.
Due to the high integration of semiconductor devices, etc., there is a demand for the refinement of circuit patterns of semiconductor devices. Thereby, the importance of lithography technology, a technology that develops circuit patterns on the surface of a wafer using a photomask, is attracting more attention.
To develop refined circuit patterns, a shorter wavelength of an exposure light source used in an exposure process is required. Examples of exposure light sources recently used include ArF excimer laser (wavelength: 193 nm), and the like.
Also, examples of a photomask include a binary mask, a phase shift mask, and the like.
A binary mask has a configuration wherein a light-shielding layer pattern is formed on a light-transmissive substrate. On the surface of a binary mask where patterns are formed, a light transmission part excluding a light-shielding layer transmits exposure light, and a light-shielding part including a light-shielding layer blocks exposure light, exposing a pattern on a resist film of a wafer surface. However, problems may occur in the fine pattern phenomenon due to light diffraction that occurs at the edges of a light transmission part during an exposure process as the pattern of a binary mask becomes finer.
Examples of a phase shift mask include a Levenson-type mask, an outrigger-type mask, and a half-tone-type mask. Among these masks, the half-tone-type phase shift mask has a pattern, which is made of a semi-transmissive film, formed on a light-transmissive substrate. On the patterned surface of the half-tone-type phase shift mask, a light transmission part excluding a semi-transmissive layer transmits exposure light, and a semi-transmissive part including a semi-transmissive layer transmits attenuated exposure light. The attenuated exposure light has a phase difference compared to the exposure light that has passed through the light transmission part. Accordingly, diffracted light occurring at the edge of the light transmission part is canceled out by exposure light that has transmitted through the semi-transmissive part, so that the phase shift mask can form a more elaborate fine pattern on a wafer surface.
Therefore, the embodiments of the present disclosure have been made in view of the above problems, and provide a blank mask that is precisely patterned to provide a photomask having low optical distortion, and a method of fabricating the blank mask.
In accordance with an embodiment of the present disclosure, the above and other objects can be accomplished by a method of fabricating a blank mask, the method including forming a light-shielding film on a light-transmissive substrate to form an optical substrate; preparing a nozzle for spraying a photoresist resin composition onto the optical substrate; filling the nozzle with the photoresist resin composition and maintaining a state where the photoresist resin composition is filled inside the nozzle; removing the photoresist resin composition inside the nozzle; and forming a photoresist layer on the light-shielding film using the nozzle.
In the method of fabricating a blank mask according to an embodiment, the photoresist layer may include a flat portion disposed on the light-shielding film; and optical irregularities having optical thicknesses different from the flat portion, wherein the optical irregularities are detected by a 532 nm laser and arranged in a number of less than 30/36 inch2 on the light-shielding film.
According to an embodiment, in maintaining the state where the photoresist resin composition is filled inside the nozzle according to the method of fabricating a blank mask, a portion of the photoresist resin composition may be formed to be exposed to an outside from an inlet of the nozzle.
In the method of fabricating a blank mask according to an embodiment, a state where the photoresist resin composition is filled inside the nozzle may be maintained for about 30 sec to about 300 minutes.
According to an embodiment, in maintaining the state where the photoresist resin composition is filled inside the nozzle according to the method of fabricating a blank mask, a residue attached to the inside of the nozzle may be detached from an inner surface of the nozzle.
In the method of fabricating a blank mask according to an embodiment, maintaining the state where the photoresist resin composition is filled inside the nozzle may be maintained until the residue is detached from the inner surface of the nozzle.
In the method of fabricating a blank mask according to an embodiment, the optical irregularities may be less than 20/36 inch2.
In accordance with another embodiment of the present disclosure, there is provided a blank mask, including a transparent substrate; a light-shielding film disposed on the transparent substrate; and a photoresist layer disposed on the light-shielding film, wherein the photoresist layer includes a flat portion disposed on the light-shielding film; and optical irregularities detected by a 532 nm laser, wherein the optical irregularities are arranged in a number of less than 30/36 inch2 on the light-shielding film.
In the blank mask according to an embodiment, the optical irregularities may be less than 20/36 inch2.
In the blank mask according to an embodiment, the optical irregularities may have a refractive index different from the photoresist layer.
In the blank mask according to an embodiment, the optical irregularities may have a thickness different from the photoresist layer.
In the blank mask according to an embodiment, the optical irregularities may have an optical thickness different from the flat portion.
In the blank mask according to an embodiment, the optical irregularities may include an optical path-changing part.
In the blank mask according to an embodiment, the optical path-changing part may have a refractive index different from the flat portion.
In accordance with yet another embodiment of the present disclosure, there is provided a method of fabricating a blank mask, the method including forming a light-shielding film on a light-transmissive substrate to form an optical substrate; preparing a nozzle for spraying a photoresist resin composition onto the optical substrate; filling the nozzle with the photoresist resin composition and detaching a residue from an inner surface of the nozzle; removing the photoresist resin composition and the detached residue from an inside of the nozzle; and forming a photoresist layer on the light-shielding film using the nozzle.
In the method of fabricating a blank mask according to an embodiment, the residue attached to the inner surface of the nozzle may be detached by the photoresist resin composition filled inside the nozzle.
In the method of fabricating a blank mask according to an embodiment, a state where the photoresist resin composition is filled inside the nozzle may be maintained for about 30 sec to about 300 minutes.
In the method of fabricating a blank mask according to an embodiment, the residue may have a refractive index different from the photoresist layer.
In the method of fabricating a blank mask according to an embodiment, the photoresist resin composition may be liquid, and the residue may be solid.
In the method of fabricating a blank mask according to an embodiment, the optical irregularities are less than 20/36 inch2.
A method of fabricating a blank mask according to an embodiment includes an operation of maintaining a state wherein a photoresist resin composition is filled inside a nozzle for spraying a photoresist resin composition. In addition, the method of fabricating the blank mask according to an embodiment includes an operation of removing the photoresist resin composition inside the nozzle. Accordingly, a residue attached to the inside of the nozzle can be easily removed.
Accordingly, the method of fabricating the blank mask according to an embodiment can prevent the residue from entering the photoresist layer.
Accordingly, the blank mask according to an embodiment can reduce the number of optical irregularities caused by the residue, etc. The blank mask according to an embodiment can include optical irregularities in a number of less than 30/36 inch2.
Accordingly, a method of fabricating the blank mask according to an embodiment can implement the photoresist layer having optical flatness overall. Accordingly, the photoresist layer can precisely pattern the light-shielding film.
In particular, since the photoresist layer has optical irregularities, detected by the 532 nm laser, in the above-mentioned number as described above, it can be precisely developed by ultraviolet rays.
Accordingly, the blank mask according to an embodiment can provide a photomask having a precise pattern.
These and other features and advantages of the embodiments of the present disclosure will become apparent from the following detailed description of specific examples of the embodiments in conjunction with the following drawings.
Hereinafter, embodiments of the present disclosure will be described in detail such that those skilled in the art can easily implement them. However, the embodiments may be implemented in various different forms and are not limited to embodiments described herein.
The terms “about,” “substantially,” and the like used in this specification are used to mean at or close to a presented numerical value when manufacturing and material tolerances inherent in stated meaning are presented, and are used to aid understanding of the embodiments.
Throughout this specification, the term “a combination thereof” included in the Markush format expression refers to a mixture or combination of one or more elements selected from the group consisting of components described in the Markush format expression, and to include one or more selected from the group consisting of the components.
Throughout this specification, the expression “A and/or B” means “A, B, or A and B”.
Throughout this specification, terms such as “first”, “second” or “A” and “B” are used to distinguish the same terms from each other unless otherwise specified.
In this specification, “B is located on A” means “B is located on A” or “B is located on A with another layer located therebetween”, and is not interpreted as limited to B being positioned in contact with the surface of A.
In this specification, singular expressions are interpreted to include singular or plural as interpreted in context, unless otherwise specified.
The blank mask according to an embodiment may be manufactured by the following fabrication process.
First, an optical substrate 10 may be provided, as shown in
The light-transmissive substrate 20 may have optical transparency to exposure light. For example, the light-transmissive substrate 20 may have a transmittance of greater than about 85% for exposure light having a wavelength of about 193 nm. The transmittance of the light-transmissive substrate 20 may be greater than about 87%. The transmittance of the light-transmissive substrate 20 may be less than 99.99%. Any suitable material may be used for the light-transmissive substrate 20. In an embodiment, light-transmissive substrate 20 may include a synthetic quartz substrate. In this case, the light-transmissive substrate 20 may suppress the attenuation of transmitted light.
Since the light-transmissive substrate 20 has surface characteristics such as appropriate flatness and appropriate illuminance, it may suppress distortion of transmitted light.
The light-shielding film 30 may be disposed on a top side of the light-transmissive substrate 20.
The light-shielding film 30 may at least selectively block exposure light incident on a bottom side of the light-transmissive substrate 20.
In an embodiment as illustrated in
The light-shielding film 30 may include a transition metal and at least one of oxygen and nitrogen.
The light-shielding film 30 may include chromium, oxygen, nitrogen and carbon. The content of each element in the entire light-shielding film 30 may vary in the thickness direction. The content of each element in the entire light-shielding film 30 may differ by layer in the case of a multi-layered light-shielding film 30.
The light-shielding film 30 may include chromium in a content of about 44 atom % to about 60 atom %. The light-shielding film 30 may include chromium in a content of about 47 atom % to about 57 atom %.
The light-shielding film 30 may include carbon in a content of about 5 atom % to 30 atom %. The light-shielding film 30 may include carbon in a content of about 7 atom % to about 25% atom %.
The light-shielding film 30 may include nitrogen in a content of about 3 atom % to about 20 atom %. The light-shielding film 30 may include nitrogen in a content of about 5 atom % to about 15 atom %.
The light-shielding film 30 may include oxygen in a content of about 20 atom % to about 45 atom %. The light-shielding film 30 may include oxygen in a content of about 25 atom % to about 40 atom %.
In this case, the light-shielding film 30 may have sufficient extinction properties.
As shown in
The second light-shielding layer 32 includes a transition metal. In addition, the second light-shielding layer 32 may include at least one of oxygen, nitrogen and carbon. The second light-shielding layer 32 may include a transition metal in a content of about 50 atom % to about 80 atom %. The second light-shielding layer 32 may include a transition metal in a content of about 55 atom % to about 75 atom %. The second light-shielding layer 32 may include a transition metal in a content of about 60 atom % to about 70 atom %.
In the second light-shielding layer 32, the content of an element corresponding to at least one of oxygen, nitrogen and carbon may be about 10 atom % to about 35 atom %. In the second light-shielding layer 32, the content of an element corresponding to at least one of oxygen, nitrogen and carbon may be about 15 atom % to about 25 atom %.
The second light-shielding layer 32 may include nitrogen in a content of about 5 atom % to about 20 atom %. The second light-shielding layer 32 may include nitrogen in a content of about 7 atom % to about 13 atom %.
The second light-shielding layer 32 may include oxygen in a content of about 5 atom % to about 20 atom %. The second light-shielding layer 32 may include oxygen in a content of about 7 atom % to about 13 atom %.
The second light-shielding layer 32 may include carbon in a content of about 2 atom % to about 10 atom %. The second light-shielding layer 32 may include nitrogen in a content of about 7 atom % to about 8 atom %.
The second light-shielding layer 32 may include all of nitrogen, oxygen and carbon.
In this case, the light-shielding film 30 may form a laminate with the phase shift film 40 to help substantially block exposure light.
The first light-shielding layer 31 may include a transition metal. The first light-shielding layer 31 may include oxygen and nitrogen. The first light-shielding layer 31 may include a transition metal in a content of 30 atom % or more and 60 atom % or less. The light-shielding layer 31 may include a transition metal in a content of 35 atom % or more and 55 atom % or less. The first light-shielding layer 31 may include a transition metal in a content of 40 atom % or more and 50 atom % or less.
The sum of the oxygen content and nitrogen content in the first light-shielding layer 31 may be 40 atom % or more and 70 atom % or less. The sum of the oxygen content and nitrogen content in the first light-shielding layer 31 may be 45 atom % or more and 65 atom % or less. The sum of the oxygen content and nitrogen content in the first light-shielding layer 31 may be 50 atom % or more and 60 atom % or less.
The first light-shielding layer 31 may include oxygen in a content of 20 atom % or more and 40 atom % or less. The first light-shielding layer 31 may include oxygen in a content of 23 atom % or more and 33 atom % or less. The first light-shielding layer 31 may include oxygen in a content of 25 atom % or more and 30 atom % or less.
The first light-shielding layer 31 may include nitrogen in a content of 5 atom % or more and 20 atom % or less. The first light-shielding layer 31 may include nitrogen in a content of 7 atom % or more and 17 atom % or less. The first light-shielding layer 31 may include nitrogen in a content of 10 atom % or more and 15 atom % or less.
In this case, the first light-shielding layer 31 can help the light-shielding film 30 have excellent extinction properties.
The transition metal may include at least one of Cr, Ta, Ti and Hf. The transition metal may be Cr.
The thickness of the first light-shielding layer 31 may be about 250 Å to about 650 Å. The thickness of the first light-shielding layer 31 may be about 350 Å to about 600 Å. The thickness of the first light-shielding layer 31 may be about 400 Å to about 550 Å. Within the above range, the first light-shielding layer 31 may help the light-shielding film 30 effectively block exposure light.
The thickness of the second light-shielding layer 32 may be about 30 Å to about 200 Å. The thickness of the second light-shielding layer 32 may be about 30 Å or more and about 100 Å. The thickness of the second light-shielding layer 32 may be about 40 Å to about 80 Å. Within the above range, the second light-shielding layer 32 may improve the extinction characteristics of the light-shielding film 30 and may help to more precisely control the side surface profile of a light-shielding pattern film 35 formed during the patterning of the light-shielding film 30.
A ratio of the thickness of the second light-shielding layer 32 to the thickness of the first light-shielding layer 31 may be about 0.05 to about 0.3. The ratio of the thickness of the second light-shielding layer 32 to the thickness of the first light-shielding layer 31 may be about 0.07 to about 0.25. The ratio of the thickness of the second light-shielding layer 32 to the thickness of the first light-shielding layer 31 may be about 0.1 to about 0.2.
In this case, the light-shielding film 30 has sufficient extinction characteristics and may more precisely control the side surface profile of a light-shielding pattern film 35 formed during the patterning of the light-shielding film 30.
The content of a transition metal in the second light-shielding layer 32 may be larger than the content of a transition metal in the first light-shielding layer 31.
To more precisely control the side surface profile of the light-shielding pattern film 35 formed by pattering the light-shielding film 30 and to ensure that the reflectance of the surface of the light-shielding film 30 for inspection light in defect inspection has a value suitable for inspection, the second light-shielding layer 32 may be required to have a larger transition metal content than the first light-shielding layer 31.
In this case, recovery, recrystallization, and grain growth may occur in a transition metal contained in the second light-shielding layer 32 during the heat treatment of the formed light-shielding film 30. If grain growth occurs in the second light-shielding layer 32 containing a high content of a transition metal, the illuminance characteristics of the surface of the light-shielding film 30 may excessively change due to excessively grown transition metal particles.
This may cause an increase in the number of pseudo defects detected when defects on the surface of the light-shielding film 30 are inspected with high sensitivity.
The light-shielding film 30, may have a transmittance of about 1% to about 2% for light with a wavelength of 193 nm. The light-shielding film 30 may have a transmittance of about 1.3% to about 2% for light with a wavelength of 193 nm. The light-shielding film 30 may have a transmittance of about 1.4% to about 2% for light with a wavelength of 193 nm.
The light-shielding film 30 may have an optical density of about 1.8 to about 3. The light-shielding film 30 may have an optical density of about 1.9 to about 3.
In this case, a thin film containing the light-shielding film 30 may effectively suppress the transmission of exposure light.
As shown in
The phase shift film 40 may be disposed between the light-transmissive substrate 20 and the light-shielding film 30. The phase shift film 40 may be a thin film that attenuates the light intensity of penetrating exposure light and adjusts a phase difference to substantially suppress the diffracted light occurring at the edge of a pattern.
The phase shift film 40 may have a phase difference of about 170° to about 190° for light with a wavelength of 193 nm. The phase shift film 40 may have a phase difference of about 175° to about 185° for light with a wavelength of 193 nm.
The phase shift film 40 may have a transmittance of about 3% to about 10% for light with a wavelength of 193 nm. The phase shift film 40 may have a transmittance of about 4% to about 8% for light with a wavelength of 193 nm. By keeping the transmittance within these ranges, the resolution of a photomask 200 containing the phase shift film 40 may be improved.
The phase shift film 40 may include a transition metal and silicon. The phase shift film 40 may include a transition metal, silicon, oxygen and nitrogen. The transition metal may be molybdenum.
A hard mask (not shown) may be placed on the light-shielding film 30. The hard mask may function as an etching mask film when etching the pattern of the light-shielding film 30. The hard mask may include silicon, nitrogen and oxygen.
A method of fabricating the optical substrate 10 includes an operation of forming the light-shielding film 30 on the light-transmissive substrate 20. The light-shielding film 30 may be formed by a sputtering process.
After the sputtering process proceeds, a heat treatment process may proceed.
The heat treatment may be performed at about 200° C. to about 400° C.
The heat treatment may be performed for about 5 minutes to about 30 minutes.
In addition, the method of fabricating the optical substrate 10 may further include cooling the light-shielding film 30 that has been subjected to the heat treatment process.
The sputtering target may be selected considering the composition of the light-shielding film 30 to be formed. The sputtering target may be applied with a single target containing a transition metal. The sputtering target may be applied with two or more targets including one target containing a transition metal. The target containing a transition metal may contain 90 atom % or more of a transition metal. The target containing a transition metal may contain 95 atom % or more of a transition metal. The target containing a transition metal may include 99 atom % of a transition metal.
The transition metal may include at least one of Cr, Ta, Ti and Hf. The transition metal may include Cr.
The atmospheric gas may include inert gas, reactive gas and sputtering gas. The inert gas does not contain elements constituting a formed thin film. The reactive gas contains elements constituting a formed thin film.
The sputtering gas ionizes in a plasma atmosphere and collides with a target. The inert gas may include helium.
The reactive gas may include a gas containing nitrogen element. The gas containing the nitrogen element may be, for example, N2, NO, NO2, N2O, N2O3, N2O4, N2O5 or the like. The reactive gas may include a gas containing an oxygen element.
The gas containing the oxygen element may be, for example, O2. The reactive gas may include a gas containing nitrogen element and a gas containing oxygen element. The reactive gas may include a gas containing both nitrogen element and oxygen element. The gas containing both the nitrogen element and the oxygen element may be, for example, NO, NO2, N2O, N2O3, N2O4, N2O5, or the like.
In addition, the reactive gas containing carbon and oxygen may be CO2.
The sputtering gas may be Ar gas.
A power source that applies power to the sputtering target may be either DC power or RF power.
Next, the cooled light-shielding film 30 may be cleaned. The cleaning process may include an ultraviolet irradiation process and/or a rinse process.
The ultraviolet irradiation process may include an operation of irradiating ultraviolet rays to the light-shielding film 30.
The rinse process includes an operation of treating the light-shielding film 30 with a cleaning solution. The cleaning solution may include at least one of deionized water, hydrogen water, ozone water and carbonated water. The cleaning solution may include the carbonated water.
As shown in
The chamber 100 accommodates the chuck 200. The chamber 100 may accommodate the optical substrate 10 to manufacture a blank mask. The inside of the chamber 100 may be isolated from the outside. The pressure inside the chamber 100 may be vacuumed to be lower than the atmospheric pressure.
In addition, the chamber 100 may include a door or cover that can be opened and closed. The chamber 100 may be equipped with a heater or the like that can control the temperature inside the chamber 100.
The chuck 200 may include a support part and a guide part.
The support part may support the guide part and a byproduct removal part. The support part supports the optical substrate 10. The support part may be disposed under the optical substrate 10.
The support part may temporarily fix the optical substrate 10. The support part may temporarily fix the optical substrate 10 by vacuum pressure or electrostatic force.
The guide part may be connected to the support part 210. The guide part may be formed integrally with the support part 210. The guide part may be disposed on a side surface of the optical substrate 10. The guide part may surround the side surface of the optical substrate 10.
An accommodating part that accommodates the optical substrate 10 may be formed by the support part and the guide part. That is, the support part may be disposed on the bottom side of the optical substrate 10, and the guide part may be disposed on the side surface of the optical substrate 10, thereby constituting the accommodating part.
The accommodating part may correspond to the planar shape of the optical substrate 10. The planar shape of the accommodating part may be almost similar to the planar shape of the optical substrate 10. The planar shape of the optical substrate 10 may be square, and the planar shape of the accommodating part may also be square.
The outer edge of the guide part may have a circular shape. The guide part and the support part may have a circular shape.
The exhaust part 400 may exhaust gas inside the chamber 100. In addition, the exhaust part 400 may discharge a photoresist resin composition remaining after being coated on the optical substrate 10. The exhaust part 400 may discharge a photoresist resin composition that is scattered to the side of the chuck 200.
The photoresist resin composition-supplying part 500 may supply the photoresist resin composition 510 to the top side of the optical substrate 10. The photoresist resin composition 510 may include a spray nozzle 520 disposed in the chamber 100. The photoresist resin composition 510 may be dropped onto the optical substrate 10 through the spray nozzle 520. That is, the photoresist resin composition-supplying part 500 may spray the photoresist resin composition 510 to the top side of the optical substrate 10.
The photoresist resin composition may be a negative-type actinic light-sensitive or radiation-sensitive resin composition. The photoresist resin composition may be a negative-type resist composition for pattern formation, a negative-type resist composition for organic solvent development or a negative-type resist composition for alkaline development. The photoresist resin composition may be typically a chemically amplified resist composition.
The photoresist resin composition may include a binder resin, a photosensitive agent (or photosensitizer) and an organic solvent.
Examples of the binder resin include novolac resin, phenolic resin, epoxy resin, polyimide resin, and the like. Examples of the binder resin include polyvinyl pyrrolidone, poly(acrylamide-co-diacetoneacrylamide), and the like.
For example, the photosensitizer may be selected from the group consisting of 4,4′-diazido-2,2′-stilbendisulfonate sodium salt, 4,4′-diazo-2,2′-dibenzalacetone disulfonate disodium salt, 2,5-bis(4-azido-2-sulfobenzylidene)cyclopentanone disodium salt and 4,4′-diazido 2,2′-dicinnamylideneacetone sulfonate salt (DACA).
For example, the solvent may be selected from the group consisting of ethyl acetate, butyl acetate, diethylene glycol dimethyl ether, diethylene glycol dimethyl ethyl ether, dipropylene glycol dimethyl ether, methyl methoxypropionate, ethyl ethoxy propionate (EEP), ethyl lactate, propylene glycol methyl ether acetate (PGMEA), propylene glycol methyl ether, propylene glycol propyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol methyl acetate, diethylene glycol ethyl acetate, acetone, methyl isobutyl ketone, cyclohexanone, dimethylformamide (DMF), N,N-dimethylacetamide (DMac), N-methyl-2-pyrrolidone (NMP), γ-butyrolactone, diethyl ether, ethylene glycol dimethyl ether, diglyme, tetrahydrofuran (THF), methanol, ethanol, propanol, iso-propanol, methyl cellosolve, ethyl cellosolve, diethylene glycol methyl ether, diethylene glycol ethyl ether, dipropylene glycol methyl ether, toluene, xylene, hexane, heptane and octane.
The content of solids, except for the solvent, of the photoresist resin composition may be about 3 wt % to about 20 wt % based on the total weight. The content of solids, except for the solvent, of the photoresist resin composition may be about 3 wt % to about 15 wt % based on the total weight. The content of solids, except for the solvent, of the photoresist resin composition may be about 5 wt % to about 10 wt % based on the total weight.
The photoresist resin composition may include the binder resin in a content of about 2 wt % to about 50 wt % based on the total weight. The photoresist resin composition may include the binder resin in a content of about 3 wt % to about 15 wt %.
The photoresist resin composition may include the photosensitive agent in a content of about 0.5 wt % to about 40 wt %. The photoresist resin composition may include the photosensitive agent in a content of about 0.5 wt % to about 20 wt %. The photoresist resin composition may include the photosensitive agent in a content of about 0.5 wt % to about 10 wt %. The photoresist resin composition may include the photosensitive agent in a content of about 0.5 wt % to about 5 wt %.
The viscosity of the photoresist resin composition may be about 0.5 cPs to about 10 cPs. The viscosity of the photoresist resin composition may be about 1 cPs to about 5 cPs. The viscosity of the photoresist resin composition may be about 0.5 cPs to about 5 cPs. The viscosity of the photoresist resin composition may be about 1 cPs to about 4 cPs.
The photoresist resin composition may further include an additive such as a leveling agent or an adhesion aid.
The operation of the coating device may be prepared so that the photoresist layer 50 is formed on the optical substrate 10.
First, the interior of the nozzle 520 of the coating device may be treated by the following method.
As shown in
The state where the interior of the nozzle 520 has been filled with the photoresist resin composition 512 may be maintained. The state where the interior of the nozzle 520 is filled with the photoresist resin composition 512 may be maintained for about 30 sec to about 30 minutes. The state where the interior of the nozzle 520 is filled with the photoresist resin composition 512 may be maintained for about 1 minute to about 30 minutes. The state where the interior of the nozzle 520 is filled with the photoresist resin composition 512 may be maintained for about 2 minutes to about 30 minutes. The state where the interior of the nozzle 520 is filled with the photoresist resin composition 512 may be maintained for about 3 minutes to about 30 minutes.
The photoresist resin composition 512 may be filled in a stationary state inside the nozzle 520. That is, the photoresist resin composition 512 may have little flow while being filled in the inside of the interior of the nozzle 520.
In addition, the photoresist resin composition 512 filled in the nozzle 520 may be in direct contact with a residue 513 inside the nozzle 520. The photoresist resin composition 512 may be in direct contact with the residue 513 attached to the inside of the nozzle 520.
Accordingly, the adhesive force between the residue 513 and the inner surface of the nozzle 520 may be reduced. In addition, the residue may be detached from the inner surface of the nozzle 520. That is, the state where the interior of the nozzle 520 is filled with the photoresist resin composition 512 may be maintained until the residue 513 is detached from the inner surface of the nozzle 520.
The residue 513 may be a foreign substance generated by the hardening of the photoresist resin composition remaining from the previous process. That is, the residue 513 may be a foreign substance other than the photoresist resin composition 512. In addition, the residue 513 may be a solid, and the photoresist resin composition 512 may be a liquid.
The residue 513 may have a different refractive index from a photoresist layer formed later.
Next, as shown in
That is, the residue 513 may become detached and may be removed together with the photoresist resin composition 512.
After the residue 513 is detached from the inner surface of the nozzle 520, it may be removed together with the sprayed photoresist resin composition 512. In addition, the residue 513 may be detached from the inner surface of the nozzle 520 by the spray pressure of the photoresist resin composition 512.
After the inner surface of the nozzle 520 is treated, the coating device may be prepared.
Next, the optical substrate 10 may be disposed in the chamber 100. The optical substrate 10 may be temporarily fixed to the chuck 200. The optical substrate 10 may be disposed in the receiving part. The optical substrate 10 may be seated on the chuck 200.
As shown in
To form the photoresist layer 50, the inside of the chamber 100 is isolated from the outside by a cover of the chamber 100. Next, in a state where the chuck 200 rotates at high speed, the photoresist resin composition is dropped and coated on the top surface of the optical substrate 10 by the photoresist resin composition supply part 500. Accordingly, a photoresist resin composition layer may be formed on the optical substrate 10.
Here, the chuck 200 may rotate the optical substrate 10 by the following method.
First, the optical substrate 10 may undergo a first rotation operation. The first rotation operation may be performed at about 20° C. to about 30° C. The first rotation operation may have a first rotation speed. The first rotation speed may be about 30 rpm to about 70 rpm. The first rotation operation may be performed for about 1 sec to about 5 sec.
In addition, in the first rotation operation, the photoresist resin composition may be dropped onto the optical substrate 10. The dropping rate of the photoresist resin composition may be about 0.5 ml/sec to about 5 ml/sec.
After the first rotation operation, the optical substrate 10 may undergo a second rotation operation. The second rotation operation may be performed at about 20° C. to about 30° C. The second rotation operation may have a second rotation speed. The second rotation speed may be about 50 rpm to about 100 rpm. The second rotation speed may be higher than the speed in the first rotation operation. The second rotation operation may be performed for about 3 sec to about 10 sec.
After the second rotation operation, the optical substrate 10 may undergo a third rotation operation. The third rotation operation may be performed at about 20° C. to about 30° C. The third rotation operation may have a third rotation speed. The third rotation speed may be about 100 rpm to about 150 rpm. The third rotation speed may be higher than the second rotation speed. The third rotation operation may be performed for about 5 sec to about 13 sec.
After the third rotation operation, the optical substrate 10 may undergo a fourth rotation operation. The fourth rotation operation may be performed at about 20° C. to about 30° C. The fourth rotation operation may have a fourth rotation speed. The fourth rotation speed may be about 800 rpm to about 3000 rpm. The fourth rotation speed may be about 800 rpm to about 1500 rpm. The fourth rotation speed may be about 1500 rpm to about 2500 rpm. The fourth rotation speed may be about 2000 rpm to about 3000 rpm. The fourth rotation speed may be higher than the third rotation speed. The fourth rotation speed may be about 500 rpm to about 2500 rpm higher than the third rotation speed. The fourth rotation operation may be performed for about 0.5 sec to about 2 sec.
After the fourth rotation operation, the optical substrate 10 may undergo a fifth rotation operation. The fifth rotation operation may be performed at about 20° C. to about 30° C. The fifth rotation operation may have a fifth rotation speed. The fifth rotation speed may be about 500 rpm to about 2500 rpm. The fifth rotation speed may be about 500 rpm to about 1200 rpm. The fifth rotation speed may be about 1000 rpm to about 2000 rpm. The fifth rotation speed may be about 1500 rpm to about 2500 rpm. The fifth rotation speed may be higher than the fourth rotation speed. The fifth rotation speed may be about 300 rpm to about 1500 rpm lower than the fourth rotation speed. The fifth rotation operation may be performed for about 1 sec to about 5 sec.
After the fifth rotation operation, the optical substrate 10 may undergo a sixth rotation operation. The sixth rotation operation may be performed at about 20° C. to about 30° C. The sixth rotation operation may have a sixth rotation speed. The sixth rotation speed may be about 100 rpm to about 500 rpm. The sixth rotation speed may be about 100 rpm to about 400 rpm. The sixth rotation speed may be about 100 rpm to about 300 rpm. The sixth rotation speed may be about 200 rpm to about 400 rpm. The sixth rotation operation may be performed for about 30 sec to about 60 sec.
In the sixth rotation operation, a photoresist resin composition layer formed on the optical substrate 10 may be dried, and the solvent may be removed.
Accordingly, as shown in
As shown in
The flat portion 51 may have a uniform thickness overall. In addition, the flat portion 51 may have a thickness variation of less than about 100 Å overall. The flat portion 51 may have a thickness variation of less than about 90 Å overall. The flat portion 51 may have a thickness variation of less than about 80 Å overall. The flat portion 51 may have a thickness variation of less than about 50 Å overall. The thickness variation may be a difference between the maximum thickness and minimum thickness of the flat portion 51.
The thickness of the flat portion 51 may be measured with an ellipsometer. The thickness of the flat portion 51 may be measured with the SE MG series, SE MF series, SE MH series or SE MI series, etc. manufactured by Nano-View Company.
The thickness of the flat portion 51 may be about 1000 Å to about 10000 Å. The thickness of the flat portion 51 may be about 1000 Å to about 5000 Å. The thickness of the flat portion 51 may be about 1000 Å to about 4000 Å.
The optical irregularities 52 and 53 may have optical thicknesses different from the flat portion 51. The optical thickness of the flat portion 51 may be derived from the product of the refractive index of the flat portion 51 and the thickness of the flat portion 51. In addition, the optical thickness of the optical irregularities 52 and 53 may be derived from the product of the refractive index of the optical irregularities 52 and 53 and the thickness of the optical irregularities 52 and 53.
The difference between the optical thickness of the flat portion 51 and the optical thickness of the optical irregularities 52 and 53 may be greater than about 5 nm. The difference between the optical thickness of the flat portion 51 and the optical thickness of the optical irregularities 52 and 53 may be greater than about 10 nm. The difference between the optical thickness of the flat portion 51 and the optical thickness of the optical irregularities 52 and 53 may be greater than about 15 nm. The difference between the optical thickness of the flat portion 51 and the optical thickness of the optical irregularities 52 and 53 may be greater than about 20 nm. The difference between the optical thickness of the flat portion 51 and the optical thickness of the optical irregularities 52 and 53 may be greater than about 30 nm. The difference between the optical thickness of the flat portion 51 and the optical thickness of the optical irregularities 52 and 53 may be greater than about 40 nm. The difference between the optical thickness of the flat portion 51 and the optical thickness of the optical irregularities 52 and 53 may be greater than about 50 nm.
The maximum value of the difference between the optical thickness of the flat portion 51 and the optical thickness of the optical irregularities 52 and 53 may be about 500 nm.
The diameters of the optical irregularities 52 and 53 may be greater than about 10 nm. The diameters of the optical irregularities 52 and 53 may be greater than about 20 nm. The diameters of the optical irregularities 52 and 53 may be greater than about 30 nm. The diameters of the optical irregularities 52 and 53 may be greater than about 40 nm. The diameters of the optical irregularities 52 and 53 may be greater than about 50 nm. The diameters of the optical irregularities 52 and 53 may be greater than about 70 nm. The diameters of the optical irregularities 52 and 53 may be greater than about 100 nm.
The maximum value of the diameters of the optical irregularities 52 and 53 may be about 500 nm.
In addition, the optical irregularities 52 and 53 may include an optical path-changing part. The optical path-changing part may change the path of incident light. The path of light incident on the optical irregularities 52 and 53 is distorted by the optical path-changing part, so that the incident angle of the light and the reflection angle on the optical irregularities 52 and 53 may be different from each other.
That is, for light incident at the same angle, the reflection angle of the flat portion 51 and the reflection angle of the optical irregularities 52 and 53 may be different from each other.
The optical irregularities 52 and 53 may include a curved surface. The optical path-changing part may include the curved surfaces of the optical irregularities 52 and 53.
As shown in
The first optical irregularity 52 may have a refractive index different from that of the flat portion 51. A difference between the refractive index of the first optical irregularity 52 and the refractive index of the flat portion 51 may be about 0.05 to about 0.7. Accordingly, the optical path may be changed at the boundary surface between the first optical irregularity 52 and the flat portion 51. That is, the reflection angle may be changed at the boundary surface between the first optical irregularity 52 and the flat portion 51.
That is, the optical path-changing part may include the boundary surface between the first optical irregularity 52 and the flat portion 51. That is, the optical path-changing part may include the curved surface of the first optical irregularity 52.
In addition, the optical irregularities may include a second optical irregularity 53. The second optical irregularity 53 may protrude from the top side of the photoresist layer 50. That is, the surface of the photoresist layer 50 may become irregular due to the second optical irregularity 53. That is, the height of the top side of the second optical irregularity 53 may be higher than the height of the top side of the flat portion 51. A difference between the height of the top side of the second optical irregularity 53 and the height of the top side of the flat portion 51 may be about 1 nm to about 100 nm.
In addition, a portion, which protrudes from the top side of the photoresist layer 50, of the second optical irregularity 53 may have a curved surface. That is, the top side of the second optical irregularity 53 may protrude from the photoresist layer 50 and may have a curved surface.
The optical path-changing part may include the curved surface of the second optical irregularity 53. The optical path-changing part may include the exposed top side of the second optical irregularity 53.
The optical irregularities 52 and 53 may be detected by light of about 532 nm. The optical irregularities 52 and 53 may be detected by a laser of about 532 nm. The laser is irradiated to the photoresist layer 50, and the optical irregularities 52 and 53 may be detected by analyzing light reflected from the photoresist layer 50.
After the laser is irradiated to the photoresist layer 50, the reflected light may be sensed through an image sensor. The light reflected from the photoresist layer 50 may be sensed by the image sensor through a confocal and spatial filter. Next, signals sensed through the image sensor may be processed into an image of 256 grayscales of 8 bits. The image may be processed into 640×480 pixels.
In addition, when a difference exceeding about 3 grayscales occurs in the pixels of the image, it may be detected as the optical irregularities 52 and 53. When a difference exceeding about 5 grayscales occurs in the pixels of the image, it may be detected as the optical irregularities 52 and 53. When a difference exceeding about 7 grayscales occurs in the pixels of the image, it may be detected as the optical irregularities 52 and 53. When a difference exceeding about 10 grayscales occurs in the pixels of the image, it may be detected as the optical irregularities 52 and 53.
In addition, the planar area of the optical irregularities 52 and 53 may be calculated by the number of pixels detected as the optical irregularities 52 and 53 in the image.
The optical irregularities 52 and 53 may be detected with optical surface inspection equipment. The optical irregularities 52 and 53 may be detected with M6640S or M6641S manufactured by LASERTEC.
In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be less than about 50/36 inch2. In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be less than about 40/36 inch2. In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be less than about 30/36 inch2. In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be less than about 20/36 inch2. In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be less than about 10/36 inch2.
In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be about 1/36 inch2 or more and less than about 50/36 inch2. In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be about 1/36 inch2 or more and less than about 40/36 inch2. In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be about 1/36 inch2 or more and less than about 30/36 inch2. In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be about 1/36 inch2 or more and less than about 20/36 inch2. In the photoresist layer 50, the number of the optical irregularities 52 and 53 may be about 1/36 inch2 or more and less than about 10/36 inch2.
Since the photoresist layer 50 includes the optical irregularities 52 and 53 in the above-mentioned number, the photoresist layer 50 may be precisely developed. That is, since the photoresist layer 50 includes the optical irregularities 52 and 53 in the above-mentioned number, the precision of the photoresist layer 50 in an exposure process may be improved. Accordingly, the method of fabricating a blank mask according to an embodiment may provide a precise photomask.
Light is selectively irradiated to the photoresist layer 50, and the light-shielding film is selectively etched, thereby forming the light-shielding pattern film 35. Accordingly, a photomask 2 including the light-transmissive substrate 20 and the light-shielding pattern film 35 disposed on the light-transmissive substrate 20 may be formed as shown in
The light-shielding pattern film 35 includes a transition metal and at least one of oxygen and nitrogen.
The light-shielding pattern film 35 may be formed by patterning the light-shielding film 30 of the blank mask 100 as described above.
Descriptions of the physical properties, composition and structure of the light-shielding pattern film 35 are omitted as they overlap with the descriptions of the light-shielding film 30 of the blank mask 1.
A method of fabricating a semiconductor device according to an embodiment includes an operation of placing a light source, a photomask 2 and a semiconductor wafer coated with a resist film; an exposure operation of selectively transmitting and emitting light, incident from the light source, onto a semiconductor wafer through the photomask 2; and a development operation of developing a pattern on the semiconductor wafer.
The photomask 2 includes the light-transmissive substrate 20, and the light-shielding pattern film 35 disposed on the light-transmissive substrate 20.
The light-shielding pattern film 35 includes a transition metal and at least one of oxygen, nitrogen and carbon.
In the preparation operation, the light source is a device capable of generating short-wavelength exposure light. The exposure light may be light having a wavelength of 200 nm. The exposure light may be arf light having a wavelength of 193 nm.
A lens may be additionally disposed between the photomask 2 and the semiconductor wafer. The lens has the function of reducing the circuit pattern shape on the photomask 2 and transferring it onto the semiconductor wafer. The lens is not limited as long as it can be generally applied to an Arf semiconductor wafer exposure process. For example, the lens may be a lens made of calcium fluoride (CaF2).
In the exposure operation, exposure light may be selectively transmitted onto the semiconductor wafer through the photomask 2. In this case, chemical degeneration may occur in a resist film part on which exposure light is incident.
In the development operation, the semiconductor wafer that has been subjected to the exposure operation may be treated with a developing solution to develop a pattern on the semiconductor wafer. When the applied resist film is a positive resist, a resist film part on which exposure light is incident may be dissolved by the developing solution. When the applied resist film is a negative resist, a resist film part on which exposure light is not incident may be dissolved by the developing solution. The resist film is formed into a resist pattern by treatment with the developing solution. A pattern may be formed on the semiconductor wafer using the resist pattern as a mask.
A description of the photomask 2 is omitted as it overlaps with the previous content.
A method of fabricating the blank mask according to an embodiment includes an operation of maintaining a state where a photoresist resin composition is filled inside a nozzle 520 that sprays a photoresist resin composition. In addition, the method of fabricating the blank mask according to an embodiment includes an operation of removing the photoresist resin composition inside the nozzle 520. Accordingly, a residue attached to the inside of the nozzle 520 may be easily removed.
Accordingly, the method of fabricating the blank mask according to an embodiment may prevent the residue 513 from being introduced into the photoresist layer 50.
Accordingly, the blank mask according to an embodiment may reduce the number of the optical irregularities 52 and 53 that may be caused by the residue, etc. The blank mask according to an embodiment may include the optical irregularities 52 and 53 in a number of less than 30/36 inch2.
Accordingly, a method of fabricating the blank mask according to an embodiment may implement the photoresist layer 50 having optical flatness overall. Accordingly, the photoresist layer 50 may precisely pattern the light-shielding film.
Accordingly, the blank mask according to an embodiment may provide a photomask having a precise pattern. The method of fabricating a blank mask according to an embodiment includes an operation of maintaining a state wherein a photoresist resin composition is filled inside a nozzle 520 for spraying a photoresist resin composition. In addition, the method of fabricating the blank mask according to an embodiment includes an operation of removing the photoresist resin composition inside the nozzle 520. Accordingly, a residue attached to the inside of the nozzle 520 may be easily removed.
Accordingly, the method of fabricating the blank mask according to an embodiment may prevent the residue 513 from entering the photoresist layer 50.
Accordingly, the blank mask according to an embodiment can reduce the number of the optical irregularities 52 and 53 caused by the residue 513, etc. The blank mask according to an embodiment can include the optical irregularities 52 and 53 in a number of less than 30/36 inch2.
Accordingly, a method of fabricating the blank mask according to an embodiment can implement the photoresist layer 50 having optical flatness overall. Accordingly, the photoresist layer 50 can precisely pattern the light-shielding film.
Accordingly, the blank mask according to an embodiment can provide a photomask having a precise pattern.
Accordingly, the apparatus for fabricating a blank mask according to an embodiment may minimize contamination of the produced blank mask due to the process by-products. In particular, the blank mask according to an embodiment may prevent the process byproducts from contaminating the sides and bottom of the optical substrate 10.
The apparatus for fabricating a blank mask according to an embodiment and a method thereof may provide a blank mask having improved performance.
Although the embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concepts of the present disclosure defined in the accompanying claims which are also within the scope of the present disclosure. Furthermore, the embodiments may be combined to form additional embodiments.
Resist coating was performed using FEP171 (manufactured by FUJIFILM Arch Co, Ltd) solution (solid content: 8.5 wt %). FEP171 is a positive electron beam resist, and a solvent for the solution was prepared by mixing propylene glycolmonomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME) in a ratio of 8 to 2.
A quartz substrate having a size of about 6 inches×about 6 inches was used, and the thickness of the quartz substrate was 0.25 inches. A MoSiON film was formed to a thickness of about 1000 Å on the quartz substrate by a sputtering process. Next, the quartz substrate where the MoSiON film had been formed was placed on a chuck.
Next, the inside of a nozzle was filled with the FEP171 solution, and the state where the FEP171 solution was filled up to the end of the nozzle was maintained for about 5 minutes. Next, the FEP171 solution in the nozzle was discharged and removed.
Next, the FEP171 solution was dropped onto the quartz substrate through the nozzle, and then a main rotation speed was changed stepwise in a range of about 100 rpm to about 3000 rpm at intervals of 250 rpm (5 conditions), and a main rotation time was changed stepwise in a range of 1 sec to 5 sec at 1-sec intervals (5 conditions). A dry rotation speed was fixed at 300 rpm, and dry rotation was performed for about 40 seconds.
As a result, an optical substrate where the photoresist layer had been formed was produced.
As shown in the following table, the holding time of the solution up to the end of the nozzle was adjusted. The remaining processes were referenced from Example 1.
In the optical substrates manufactured in the examples and comparative examples, the resist layer was irradiated with a laser having a wavelength of about 532 nm, and the reflected light was sensed to measure the sizes and number of the optical irregularities using optical surface inspection equipment (M6641S manufactured by LASERTEC).
In the resist layer, the number of optical irregularities detected by the surface inspection equipment was classified by pixel size as shown in Table 2 below.
As shown in Table 2, the photoresist layers according to the examples included a small number of optical irregularities.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0197825 | Dec 2023 | KR | national |
