Exemplary embodiments of the present invention relate to a method of repairing a polymer mask. More particularly, exemplary embodiments of the present invention relate to a method of repairing fabrication defects to a polymer mask such as spots and voids using a laser.
A polymer mask is a type of photolithography mask used for a contact exposure or a near-field imaging. The polymer mask may include non-transparent patterns on a transparent and flexible polymer substrate. The polymer mask may be fabricated by forming a non-transparent layer on an entire area of a flexible substrate, and then patterning the non-transparent layer by a conventional photolithography process. The polymer mask may be a quick and economical solution for a large-area lithography having moderate resolution. For example, the polymer mask is a good solution for achieving a high-density printed circuit board (PCB), which requires quick and economical means to expose a large area. A conventional example of the polymer mask may include a patterned UV curing ink on a polyethylene terephthalate (PET) substrate. To fabricate this, the UV curing ink is spray-coated on a large PET substrate, and then the substrate is exposed to a UV light by a photolithography process to selectively cure the ink, thereby forming patterns.
Due to a developing process followed by the lithography exposure of the large area, the PTE mask is hard to be fabricated without generating defects. Defects may usually include voids on ink-patterned area resulted from an improper exposure, and ink spots on a transparent area resulted from an improper developing. Sizes of these defects may be in a range of a few micrometers to a few millimeters. The defects may be repaired before using the polymer mask for performing the lithography. However, repairing these defects is difficult and time-consuming. Especially, a manual touch-up for repairing the voids in micron-scale may be challenging. Removing the spot defect by using mechanical methods such as a polishing and a grinding may not be practical solutions either. Further, a selective ink removal by a laser ablation may be difficult due to a small difference in absorption between the polymer-based ink and the polymer substrate. What is needed therefore is an effective method of repairing the defects to the polymer mask.
Exemplary embodiments of the present invention provide a method of readily repairing defects to a polymer mask.
In a method of repairing a patterned polymer substrate in accordance with a first aspect of the present invention, a transparent polymer substrate having first and second surfaces, and a patterned layer on the first surface of the polymer substrate is provided. Defects to the patterned layer and the first surface of the polymer substrate are then detected. Here, the defects include a spot defect and a void defect. A laser irradiation removes the spot defect. The void defect is then touched up.
In a method of repairing a patterned polymer mask for performing a photolithography process in accordance with a second aspect of the present invention, a transparent polymer substrate having first and second surfaces, and a non-transparent patterned layer on the first surface of the polymer substrate are provided. Defects to the patterned layer and the first surface of the polymer substrate are then detected. Here, the defects include a spot defect and a void defect. The spot defect is removed by a laser irradiation. Here, the laser irradiation maintains transparency of the polymer substrate. The void defect is then restored by a laser-assisted touch-up.
In a method of repairing a defect to a patterned polymer mask for performing a photolithography process in accordance with a third aspect of the present invention, a transparent polymer substrate having first and second surfaces and a non-transparent patterned layer on the first surface of the polymer substrate are provided. A spot defect to the first surface of the polymer substrate is then detected. The spot defect is removed by a laser irradiation. Here, the laser irradiation is sufficiently provided to induce an effective ablation for substantially maintaining transparency of the first surface of the polymer substrate.
According to one exemplary embodiment, the laser irradiation for the effective ablation may be performed using a pulsed laser having an irradiance in a range of about 106 W/cm2 to 1015 W/cm2. Alternatively, the laser irradiation may be performed using a pulsed UV laser having a wavelength in a range of about 150 nm to about 400 nm. Further, the laser irradiation may be performed using a near-field imaging that uses a mask for forming a beam spot shape incident on the spot defect. Furthermore, the laser irradiation may be performed using a far-field imaging that has a beam profile having a TEM00 mode in the Gaussian distribution.
According to another exemplary embodiment, the laser irradiation may form a crater having a depth of about 0.1 μm to 50 μm. Further, the crater may have a concave shape crater. Furthermore, the crater may be covered by a polymer emulsion having a refractive index substantially similar to that of the polymer substrate.
In a method of repairing a patterned polymer mask for a photolithography process in accordance with a fourth aspect of the present invention, a transparent polymer substrate having first and second surfaces and a non-transparent patterned layer on the first surface of the polymer substrate are provided. A void defect to the patterned layer is then detected. A laser is irradiated to the void defect to form a blind hole. The blind hole is then filled with a non-transparent filler-ink.
According to an exemplary embodiment, the method may further include removing an excessive amount of the filler-ink around the blind hole to fill the blind hole with the ink.
According to another exemplary embodiment, the laser irradiation may be performed using a pulsed laser having an irradiance in a range of about 106 W/cm2 to 1015 W/cm2. Alternatively, the laser irradiation may be performed using a pulsed UV laser having a wavelength in a range of about 150 nm to about 400 nm. Further, the laser irradiation may be performed using a near-field imaging that uses a mask for forming a beam spot shape incident on the spot defect. Furthermore, the laser irradiation may be performed using a far-field imaging that has a beam profile having a TEM00 mode in the Gaussian distribution.
According to still another exemplary embodiment, the blind hole may have a depth in a range of about 1 μm to 50 μm.
According to yet still another exemplary embodiment, filling the blind hole with the filler-ink may be performed using an injection nozzle. Further, the injection nozzle may include an inkjet nozzle cartridge for delivering droplets of the filler-ink to the blind hole, and a needle-type dot marker for delivering dots of the filler-ink through a needle tube adjacent to the blind hole.
In a method of repairing a patterned polymer mask for a photolithography process in accordance with a fifth aspect of the present invention, a transparent polymer substrate having first and second surfaces, and a non-transparent patterned layer on the first surface of the polymer substrate are provided. A void defect on the patterned layer is then detected. A first laser is irradiated to the void defect to expose the first surface of the polymer substrate. A second laser is then irradiated to the exposed first surface to form a diffractive structure for trapping an incident light.
According to one exemplary embodiment, the first laser irradiation may be performed using a pulsed laser with an irradiance in a range of about 106 W/cm2 to 1015 W/cm2. Alternatively, the first laser irradiation and the second laser irradiations may be performed using a pulsed UV laser having a wavelength in a range of about 150 nm to about 400 nm. Furthermore, the first laser irradiation may be performed using an ArF excimer laser at 193 nm with a laser energy density in a range of about 0.1 J/cm2 to about 100 J/cm2. The second laser irradiation may be performed using an ArF excimer laser at 193 nm with a laser energy density in a range of about 0.01 J/cm2 to about 0.5 J/cm2.
According to another exemplary embodiment, the first laser irradiation and the second laser irradiation may be performed using a near-field imaging that uses a mask for forming a beam spot shape incident on the spot defect. Alternatively, the first laser irradiation and the second laser irradiation may be performed using a far-field imaging that has a beam profile with a TEM00 mode in the Gaussian distribution.
According to still another exemplary embodiment, the diffractive structure may have a plurality of micro-scaled cones.
In a method of repairing a patterned polymer mask for a photolithography process in accordance with a sixth aspect of the present invention, a transparent polymer substrate having first and second surfaces, and a non-transparent patterned layer on the first surface of the polymer substrate are provided. A void defect on the patterned layer is then detected. A transparent photosensitive layer including at least one kind of photosensitive particles is formed over the void defect. A laser is irradiated to the photosensitive layer to photochemically change a color of the photosensitive layer.
According to one exemplary embodiment, the photosensitive layer may include a mixture of titanium dioxide particles in a polymer emulsion. Further, the titanium dioxide particles may have an average size of about 1 nanometer to 1,000 nanometers.
According to still another exemplary embodiment, the laser irradiation may be performed using a pulsed laser with an irradiance in a range of about 106 W/cm2 to 1015 W/cm2. Alternatively, the laser irradiation may be performed using a pulsed UV laser with a wavelength in a range of about 150 nm to about 400 nm. Further, the laser irradiation may be performed using a near-field imaging that uses a mask for forming a beam spot shape incident on the photosensitive layer. Furthermore, the laser irradiation may be performed using a far-field imaging that has a beam profile with a TEM00 mode in the Gaussian distribution.
In a method of repairing a patterned polymer mask for a photolithography process in accordance with a seventh aspect of the present invention, a transparent polymer substrate having first and second surfaces, and a non-transparent patterned layer on the first surface of the polymer substrate are provided. A void defect to the patterned layer is then detected. A transparent photo-reactive layer including at least one kind of photo-reactive particles is formed over the void defect. A laser is then irradiated to the photo-reactive layer to react the photo-reactive particles with the laser, thereby creating carbonization debris.
According to one exemplary embodiment, the photo-reactive layer may include a mixture of polyimide particles in a polymer emulsion.
According to another exemplary embodiment, the laser irradiation may be performed using a pulsed laser having an irradiance in a range of about 106 W/cm2 to 1015 W/cm2. Alternatively, the laser irradiation may be performed using a pulsed UV laser with a wavelength in a range of about 150 nm to about 400 nm. Further, the laser irradiation may be performed using a near-field imaging that uses a mask for forming a beam spot shape incident on the photo-reactive layer. Furthermore, the laser irradiation may be performed using a far-field imaging that has a beam profile with a TEM00 mode in the Gaussian distribution.
In a method of repairing a patterned polymer mask for a photolithography process in accordance with an eighth aspect of the present invention, a transparent polymer substrate having first and second surfaces, and a non-transparent patterned layer on the first surface of the polymer substrate are provided. A void defect on the patterned layer is then detected. A non-transparent ink for preventing transmission of UV light is applied to the void defect. A laser is irradiated to the non-transparent ink to trim an overflow of the non-transparent ink beyond the patterned area on the first surface of the polymer substrate.
According to one exemplary embodiment, applying the non-transparent ink may be performed using an injection nozzle. The nozzle may include an inkjet nozzle cartridge for delivering droplets of the non-transparent ink to the void defect, and a needle-type dot marker for delivering dots of the non-transparent ink through a needle tube upon a contact on the void defect.
According to another exemplary embodiment, the non-transparent ink may include a mixture of at least one colorant in a polymer emulsion. Further, the non-transparent ink may include a UV curing ink that is cured by an exposure to UV light including a UV lamp and a pulsed UV laser before the laser irradiation.
According to still another exemplary embodiment, the laser irradiation may be performed using a pulsed laser with an irradiance in a range of about 106 W/cm2 to 1015 W/cm2. Alternatively, the laser irradiation may be performed using a pulsed UV laser having a wavelength in a range of about 150 nm to about 400 nm. Further, the laser irradiation may be performed using a near-field imaging that uses a mask for forming a beam spot shape incident on the overflowed non-transparent ink. Furthermore, the laser irradiation may be performed using a far-field imaging that has a beam profile with a TEM00 mode in the Gaussian distribution.
In a method of repairing a patterned polymer mask for a photolithography process in accordance with a ninth aspect of the present invention, a transparent polymer substrate having first and second surfaces, and a non-transparent patterned layer on the first surface of the polymer substrate are provided. A void defect to the patterned layer is then detected. A UV curing ink is applied to the void defect. A UV laser is partially irradiated to the UV curing ink to convert a region of the UV curing ink irradiated by the UV laser into an insoluble state. A region of the UV curing ink non-irradiated by the UV laser is then removed.
According to one exemplary embodiment, applying the non-transparent ink may be performed using an injection nozzle. The nozzle may include an inkjet nozzle cartridge for delivering droplets of the non-transparent ink to the void defect, and a needle-type dot marker for delivering dots of the non-transparent ink through a needle tube upon a contact on the void defect.
According to another exemplary embodiment, the UV laser irradiation may be performed using a pulsed laser with a wavelength in a range of about 150 nm to about 400 nm. Alternatively, the UV laser irradiation may be performed using a near-field imaging that uses a mask for forming a beam spot shape incident on the UV curing ink. Further, the UV laser irradiation may be performed using a far-field imaging that has a beam profile with a TEM00 mode in the Gaussian distribution. Furthermore, the UV laser irradiation may be performed using a pulsed UV laser with a laser energy density in a range of about 0.001 J/cm2 to about 0.05 J/cm2.
In a method of repairing a patterned polymer mask for a photolithography process in accordance with a tenth aspect of the present invention, a transparent polymer substrate having first and second surfaces, and a non-transparent patterned layer on the first surface of the polymer substrate are provided. A transparent overlay having first and second surfaces, and an ink layer formed on the second surface of the transparent overlay to form an interface between the transparent overlay and the ink layer are then provided. A void defect on the patterned layer is detected. The transparent overlay is overlapped with the patterned layer of the polymer substrate to contact the ink layer to the void defect. A localized laser, which is substantially transmitted through the transparent overlay and substantially absorbed in the interface, is irradiated to the first surface of the transparent overlay to separate the ink layer from the second surface of the transparent overlay. The ink layer is then transcribed from the transparent overlay to the void defect.
According to one exemplary embodiment, the ink layer may include a mixture of at least one colorant in a polymer emulsion. Further, the ink layer may include a colored photoresist.
According to another exemplary embodiment, the laser irradiation may be performed using a pulsed UV laser with a wavelength in a range of about 150 nm to about 400 nm. Alternatively, the laser irradiation may be performed using a near-field imaging that uses a mask for forming a beam spot shape incident on the interface. Further, the laser irradiation may be performed using a far-field imaging that has a beam profile with a TEM00 mode in the Gaussian distribution. Furthermore, the laser irradiation may be performed using a pulsed UV laser with a laser energy density in a range of about 0.001 J/cm2 to about 0.05 J/cm2.
According to the present invention, the defects such as the spot defect, the void defect, etc., in the transparent polymer mask may be readily removed. Further, the methods of the present invention may easily repair the micro-sizes of voids. Therefore, the defects to the polymer mask for the photolithography process may be readily and effectively repaired.
The above and other features and advantages of the invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:
The present invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the present invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity.
It will be understood that when an element or layer is referred to as being “on”—or “connected to” another element or layer, it can be directly on or connected 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” or “directly connected to” another element or layer, there are no intervening elements or layers present. Like reference numerals refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
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 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 “lower,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) 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 or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at 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 present 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.
Exemplary embodiments of the present invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the present invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, exemplary embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. 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.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
This detailed description describes exemplary embodiments of processes consistent with the present disclosure, which addresses the problem associated with a polymer mask. Applications of the invention are not limited to the following exemplary embodiments. Although some exemplary embodiments refer to non-transparent inks on the PET substrate repaired by the ArF excimer laser at 193 nm, other types of non-UV-transparent layers and polymer substrates may be used with other types of lasers which are known to those skilled in the art.
A polymer mask for a photolithography exposure consists of an ink pattern on a transparent polymer substrate, distinctively dividing the mask into a patterned area and a transparent area (or alternatively a non-transparent and a transparent area). During a photolithography exposure, usually by a UV lamp or a UV laser, the patterned area blocks incident light and the rest of the transparent area transmit the light.
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Ablation of a polymer by a laser beam depends on absorption properties of, the polymer and characteristics of the laser beam. The absorption property of a polymer may be denoted by the absorption coefficient (cm−1), and determined by a depth of absorbed photons in the polymer material. The absorbed photons are reacted with atoms and molecules of the polymer to thereby lead the polymer material to excited states for instantaneous vaporization. A polymer with strong absorption property may have a higher absorption coefficient.
The characteristics of laser beam depend mainly on two properties, wavelength and pulse duration. This relationship may be expressed by I=E/(A·t), where I is irradiance [J/(cm2 sec)], E is pulse energy of laser (Joule), A is an area of the laser beam (cm2) and t is pulse duration (sec). When the pulse duration is determined by a type of laser, the relationship may be expressed by D=E/A, where D is laser energy density (J/cm2). The pulse energy E may be described by Plank's equation of photonic energy, E=h·(c/λ), where h is the Plank's constant (6.62618×10−34 J·sec), c is the speed of light (m/sec), and λ is wavelength (nm). Based on these relationships, the short pulse duration results in higher irradiance, and reduces heat transfer by quick absorption. The shorter wavelength increases the photonic energy, contributing to the improved optical absorption, and reduces absorption depth. When the pulse duration is fixed, a highly focused laser beam, resulting in a smaller area of the laser beam, significantly increases the laser energy density. However, the overflow of the laser energy density causes the excessive energy transformed into heat, resulting in thermal damages to a target. In general, an efficient ablation benefits from smaller laser wavelength and shorter pulse duration for both optical and thermal reasons. That is, when properties of a properly selected laser such as short pulse duration and high photonic energy are coupled with properties of a polymer material such as small absorption depth and low thermal conductivity, the excessive heat transfer is minimized by the efficient ablation resulting in cleaner material removal from a small heat-affected zone.
For example, a polymethyl methacrylate (PMMA) has a low absorption coefficient values around a few hundreds cm−1 at 248 nm laser beam, which makes a long penetration depth. The absorption of the PMMA of about 248 nm laser irradiation is poor, thereby making the PMMA hard to have efficient ablation. In contrast, a polyimide (PI) has a much higher absorption coefficient values over 105 cm−1 at 248 nm laser beam. The penetration depth at the wavelength is relatively short, making the PI a good absorber to the incident laser beam. With an optimum laser energy density, a clean and efficient ablation is possible for the PI at 248 nm wavelength.
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In contrast, when a repaired site 22b has a sharp and distinctive edge 24b as illustrated in
Thus, when the repaired site 22b has the edge 24b, this edge shadow may be reduced by forming a transparent layer 28 on the repaired site 22b as shown in
As mentioned above, when the laser irradiation for the efficient ablation is performed using a pulsed laser with an irradiance below about 106 W/cm2, the efficient ablation of the spot defect 16 may not be readily carried out. In contrast, when the laser irradiation for the efficient ablation is performed using a pulsed laser with an irradiance above about 1015 W/cm2, the efficient ablation of the spot defect 16 may cause damages to the substrate 14. Therefore, the laser irradiation for the efficient ablation may be performed using a pulsed laser with an irradiance of about 106 W/cm2 to about 1015 W/cm2.
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As mentioned above, when the laser irradiation for repairing the void defect 18 is performed using a pulsed laser with an irradiance below about 106 W/cm2, the repair of the void defect 18 may not be readily carried out. In contrast, when the laser irradiation for the efficient ablation is performed using a pulsed laser with an irradiance above about 1015 W/cm2, the repair of the void defect 18 may cause damages to the substrate 14. Therefore, the laser irradiation for the efficient ablation may be performed using a pulsed laser with an irradiance of about 106 W/cm2 to about 1015 W/cm2.
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For example, the photosensitive layer 50 may be a mixture of titanium dioxide (TiO2) particle in a polymer emulsion. The particle size of the titanium dioxide is preferably small, particularly a nano-powder, which has an average particulate size of a few nanometers to hundreds of nanometers. The nano-sized particles in the emulsion transmit incident light, during a photolithography exposure, better than large particles. The emulsion preferably has a matching refractive index to the transparent polymer substrate 14. A volume percentage of the nano-titanium dioxide in the emulsion may vary from 1% to 50%, and a thickness of the mixed emulsion applied over the polymer mask 10 may range between 1 μm and 500 μm. The volume percent of the titanium dioxide may depend on a thickness of the applied emulsion. Generally, a thicker emulsion layer may require less volume percentage of the titanium dioxide. It is well known to those skilled in the art that the titanium dioxide photochemically changes color from colorless to black, when it is exposed to a pulsed UV laser.
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Here, when the laser irradiation is performed using a pulsed laser with an irradiance below about 106 W/cm2, the trimming may not be readily carried out. In contrast, when the laser irradiation is performed using a pulsed laser with an irradiance above about 1015 W/cm2, the trimming may cause damages of the substrate 14. Therefore, the laser irradiation may be performed using a pulsed laser with an irradiance of about 106 W/cm2 to about 1015 W/cm2.
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However, when the selective removal is not practical due to slight differences in absorption coefficient between the cured ink 70a and the polymer surface 72, the laser irradiation 20 may ablate through the polymer surface 72 up to a certain depth less than 100 μm by the aforementioned efficient ablation.
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According to the present invention, the defects such as the spot defect, the void defect, etc., in the transparent polymer mask may be readily removed using the laser. Therefore, since the above-mentioned defects may be rapidly and accurately repaired, the methods of the present invention may be effectively available for repairing the polymer mask.
Although this disclosure describes this invention in terms of exemplary embodiments, the invention is not limited to those embodiments. Rather, a person skilled in the art will construe the appended claims broadly, to include other variants and embodiments of the invention, which those skilled in the art may make or use without departing from the scope and range of equivalents of the invention.
Number | Date | Country | Kind |
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10-2006-0044589 | May 2006 | KR | national |
10-2007-0029396 | Mar 2007 | KR | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/KR07/02333 | 5/11/2007 | WO | 00 | 9/12/2008 |