Systems of manufacturing a photomask and a flat panel display

Abstract

A method for manufacturing a photomask includes the following steps: providing a photomask blank; detecting the photomask blank to determine the presence of one or more defects in the photomask blank, wherein the one or more defects include one or more photomask substrate defects; and compensating for the one or more photomask substrate defects by roughening one or more surface portions of the photomask substrate.

Description

Method for manufacturing a photomask and a flat panel display The present invention generally relates to the manufacture of photomasks and more particularly, to the manufacture of photomasks for flat panel display (FPD) and integrated circuit (IC) lithography. Photomasks are conventionally composed of an optically transparent substrate having an opaque light blocking region, which collectively selectively blocks or allows optical wavelengths to pass through to form a circuit pattern of interest for imaging by a lithographic projection system. These photomasks are commonly used in the lithography and production of integrated circuit (IC) and flat panel display (FPD) manufacturing, particularly by generating a pattern on a substrate (such as a silicon wafer in the case of IC manufacturing or a glass panel in the case of FPD manufacturing). The optically transparent substrate of a photomask is typically a highly polished sheet of fused silicate. For example, a chromium metal absorption film is deposited thereon and then patterned in the mask manufacturing process. Other films deposited on the substrate for patterning may include CrO for phase shift applications x 、CrO n and MoSi or SiN. Typical operating wavelengths of an optical photomask include but are not limited to 436 nm, 365 nm, 248 nm, and 193 nm. Photomasks greatly contribute to the ability and productivity of IC and FPD manufacturing. Photomasks are highly sensitive components in the manufacturing process because an image of the photomask appears in each exposure field during the IC or FPD pattern transfer process. Therefore, during the photolithography process, a single defect on a photomask can ruin a large number of IC and FPD devices. Defects can be generated in various ways, such as during the patterning of the mask, embedded in the film deposited on the mask, and from laminate contamination and / or defects embedded in the substrate material. Buried defects residing within the transparent substrate material of a photomask are commonly referred to as "inclusions". These inclusions can result from sources such as bubbles or impurities in the fused silicate material itself during the substrate manufacturing process. Inclusions can reside anywhere within the substrate, and since they are embedded in the hard fused silicate material once formed, they are extremely difficult to repair. For this reason, substrate manufacturers spend a lot of time and money to produce substrates that are substantially free of inclusions. There is a continuing need for improved techniques to minimize defects in photomask substrates. One object of the present invention is to minimize the influence and impact of buried defects (inclusions) residing within the transparent substrate material of a photomask. Another object of the present invention is to provide a method for treating a substrate to minimize the influence of inclusions to an acceptable level in lithographic imaging so as to have a positive effect on substrate manufacturing time, cost, and availability constraints. In an embodiment, surface treatment is performed to reduce the influence of inclusions and thus achieve a much lower cost and more widely available substrate material. According to an exemplary embodiment of the present invention, a method of manufacturing a photomask includes: (A) providing a photomask blank; (B) detecting the photomask blank to determine the presence of one or more defects in the photomask blank, wherein the one or more defects include one or more photomask substrate defects; and (C) compensating for the one or more photomask substrate defects by roughening one or more surface portions of the photomask substrate. In an exemplary embodiment, the compensating step includes roughening one or more surface portions of the photomask substrate by at least one of grinding or polishing. In an exemplary embodiment, the compensating step includes roughening one or more surface portions of the photomask substrate by an oxidation process. In an exemplary embodiment, the compensating step includes roughening one or more surface portions of the photomask substrate by a film coating process. In an exemplary embodiment, the compensating step includes roughening one or more surface portions of the photomask substrate by a particle coating process. In an exemplary embodiment, the compensating step includes roughening one or more surface portions of the photomask substrate by wet etching using an acid etchant. In an exemplary embodiment, the compensating step includes roughening one or more surface portions of the photomask substrate by ionization. In an exemplary embodiment, the compensating step includes roughening one or more surface portions of the photomask substrate by sputtering. In an exemplary embodiment, the photomask is used in a lithography process to manufacture a large photomask for a flat panel display (FPD). In an exemplary embodiment, a method of manufacturing a flat panel display includes irradiating light from an optical energy source through a large photomask and onto a glass plate substrate in a photolithography process such that at least one circuit pattern is transferred from the large photomask to the glass plate substrate, wherein the large photomask is manufactured according to a process that includes: (A) providing a photomask blank; (B) detecting the photomask blank to determine the presence of one or more defects in the photomask blank, wherein the one or more defects include one or more photomask substrate defects; and (C) compensating for the one or more photomask substrate defects by roughening one or more surface portions of the photomask substrate. In an exemplary embodiment, the flat panel display is a liquid crystal display, an active matrix liquid crystal display, an organic light emitting diode, a light emitting diode, a plasma display panel, or an active matrix organic light emitting diode. These and other features and advantages of the present invention will be presented in more detail in the following detailed description and in the accompanying drawings illustrated by the exemplary principles of the present invention. Flat panel displays (FPDs) are electronic viewing technologies used to display content (e.g., still images, moving images, text, or other visual materials) in a range of entertainment, consumer electronics, personal computers, and mobile devices, as well as many types of medical, transportation, and industrial equipment. For example, current FPD types include LCD (liquid crystal display), AM LCD (active matrix liquid crystal display), OLED (organic light emitting diode), LED (light emitting diode), PDP (plasma display panel), and AMOLED (active matrix OLED). During the manufacture of an FPD, an FPD lithography system shines light onto a mask that has an original thin film transistor (TFT) circuit pattern drawn thereon, and the light passes through a lens to expose the pattern onto a glass plate substrate. On a large glass plate, the exposure process is repeated several times to form the pattern over the entire plate. Figures 12A and 12B depict a typical mask configured for use in a photolithography process. As shown, the mask 2 (typically six inches by six inches in size and one-quarter inch thick) consists of a transparent substrate 4 (e.g., fused silicate) and a pattern layer of masking material 6 (e.g., chromium) that defines the desired image to be produced on the device. A pellicle frame 8 extends around the perimeter of the patterned masking material 6 and is attached to the substrate 4 via a deposition process well known in the art. A pellicle membrane 10 is stretched above the upper surface of the frame 8 and attached to the upper surface of the frame 8. As shown, the surface of the pellicle membrane 10 is generally parallel to the surface of the mask and covers the entire patterned area of the masking material 6. Thus, any contamination that would otherwise land on the mask instead lands on the pellicle membrane 10, which is located outside the focal plane of the exposure system. Another type of known mask is commonly referred to as a phase shift mask. Phase shift masks are generally preferred over binary masks in which the design to be transferred to the device contains smaller, tightly packed feature sizes that are below the resolution requirements of the optical equipment used. A phase shift mask is engineered to be 180 degrees out of phase with the light transmitted through the etched areas on the mask, such that the light transmitted through the openings in the mask is equal in amplitude. One type of known phase shift mask is commonly referred to as an embedded attenuated phase shift mask (“EAPSM”). The EAPSM (not shown) typically includes a substantially transparent material (such as fused silicate) commonly referred to as a mask substrate. The next layer is typically an embedded phase shift material (“PSM layer”), such as molybdenum silicon oxynitride (MoSiON), tantalum silicon nitride (TaSiN), titanium silicon nitride (TiSiN), or zirconium silicon oxide (ZrSiO) and other known phase materials. The next layer is typically an opaque material, such as chromium (Cr), which may optionally include an anti-reflection coating, such as chromium oxynitride (CrON). The top layer is a photosensitive photoresist material. As with binary masks, the desired pattern of opaque material to be produced on the EAPSM is scanned across the blank EAPSM in a raster or vector manner by an electron beam (E-beam) or a laser beam. As the electron beam or laser beam scans across the blank EAPSM, the exposure system directs the electron beam or laser beam to addressable locations on the EAPSM. In the case of a positive photosensitive photoresist material, the areas exposed to the electron beam or laser beam become soluble, while the unexposed portions remain insoluble. In the case of a negative photosensitive photoresist material, the unexposed areas become soluble, while the exposed portions remain insoluble. Another type of phase shift mask is an alternating aperture phase shift mask (“AAPSM”). As with binary masks, the AAPSM typically consists of an opaque material layer and a substantially transparent substrate that is etched on one side of the opaque features and not etched on the other side (i.e., the etching of the transparent substrate occurs at alternating positions in the substantially transparent substrate). More specifically, the AAPSM (not shown) includes a substantially transparent layer (e.g., fused silicate) and an opaque layer (e.g., chromium). The opaque layer is etched to form opaque regions and alternating substantially transparent regions. The substantially transparent regions are further etched such that the AAPSM has grooves in the substantially transparent layer. In other words, the AAPSM has substantially transparent regions (which are unetched) alternating with etched grooves between the opaque regions. The effect of this structure when placed in an exposure system is to produce light intensities with alternating polarities and 180 degrees out of phase. This alternating polarity forces the energy transmitted from the exposure system to become zero in the opaque regions, while maintaining the same transmission of light at the alternating transparent regions and grooves. Since the photoresist layer on the device substrate is insensitive to the phase of the exposed light, the positive and negative exposure regions appear the same, while the zero regions therebetween are clearly visible. Thus, a clearer contrast between the bright (e.g., transparent) and dark (e.g., opaque) regions in the resulting photoresist layer of a device is obtained, whereby a more accurate image can be etched onto the device substrate. In mask manufacturing, substrate defects or particles are key factors affecting yield and cost. Since FPD blanks are thicker and larger than IC masks and typically generate particles such as bubbles during the large glass melting process, this impact on yield and cost is particularly prominent in FPD product manufacturing. According to an exemplary embodiment of the present invention, a photomask substrate is subjected to a surface treatment to minimize inclusion defects. One purpose of this treatment is to scatter the light disrupted by inclusions during transmission through the substrate. That is, as the illumination beam of the photomask moves through the substrate, it is optically disrupted by inclusion defects. This disruption moves with the illumination beam to the imaging surface of the photomask, where it becomes a printable defect, resulting in a yield loss in the lithography process. However, in an embodiment, the disrupted transmitted light is effectively scattered at the imaging surface to average or erase the impact of this inclusion defect to minimize the effect of the inclusion to an acceptable level. Especially in the case of FPD lithography where the substrate is very large, this can have a profound effect on the cost structure and available capacity of the entire FPD manufacturing process. It should be understood that the systems and methods described herein are not limited to FPD masks, but can also be applied to IC masks. In an embodiment, imaging surface scattering can be achieved in various ways to provide an inclusion defect optical smoothing effect. The surface scattering property is preferably quite strong to eliminate the impact of inclusion defects and at least has the following properties: 1. A surface scattering effect sufficient to reduce or disrupt the directionality of the optical beam transmitted through the substrate. From the perspective of the imaging conditions of the lithography scanner imaging the photomask, the surface scattering is preferably nominally unstructured; and 2. Maintain a high transmittance of the optical wavelength through the scattering surface despite the beam directionality disruption effect. Although any surface modification technique that imparts the desired surface scattering effect to minimize the impact of substrate inclusions can be employed, in an embodiment, the following techniques can be used to affect this scattering-based inclusion smoothing function on the substrate surface: 1. Surface polishing, which leaves a fine-scale frosted glass type finish on the imaging surface of the substrate. This is preferably done before the deposition of the patterned film and mask manufacturing. 2. Sputtering or depositing a material or film method, which leaves a deposited film with sufficient scattering structure to produce a frosted glass effect on the transmitted beam through the mask substrate. 3. Methods based on surface oxidation or chemical etching to impart a scattering profile in the surface. 4. Patterned features, which are fine enough not to image in the lithography system but strong enough to disrupt the light field disrupted by inclusion defects on a scale. Figures 1A to 1E and Figure 2 show the types of defects that can be solved by embodiments of the present invention. Figures 1A to 1E show typical deposition defects that occur after the substrate has been constructed, polished, and is ready for coating. They may originate from defects in the deposited film or have evolved during the photomask manufacturing process. Specifically, Figure 1A shows a pinhole defect, Figure 1B shows a crescent defect, Figure 1C shows a deposition defect, Figure 1D shows a shadow defect, and Figure 1E shows a diffusion defect. Figure 2 shows examples of inclusion-type defects that are physically embedded in the substrate fused silicate or glass material during its manufacture. They are typically generated during the formation process of the fused silicate material in a furnace or during a glass melting process. In an embodiment, the latter type of inclusion defect can be optimally treated by surface scattering. Figures 3 and 4 illustrate how defects manifest in the mask and imaging processes. In Figure 3, no distinguishable defects are present on the mask, while in Figure 4, due to a hard spot in the middle of a line, the mask pattern is defective. Defects can affect the patterned area crucial for device imaging. Thus, in an embodiment, acceptable defect sizes and percentages of light intensity loss can be defined to determine defect severity. When the exposure light travels through the defined mask pattern on the thin film, the intensity or maximum intensity of the light will be reduced or perturbed due to a physical blocking or interference effect. There are many types, sizes, and positions of defects, and the critical ones will have a measurable impact on the quality of the imaged mask pattern on the substrate. Figures 5 and 6 simulate the correspondence between a pattern and a defect when forming an imaged intensity profile to be delivered to the substrate by a lithography scanner, which is required to resolve the pattern. As indicated by the dashed line in Figure 6, the intensity level is reduced due to the interference between the defect and the pattern. Thus, the intensity profile of the defective pattern will exhibit different pattern qualities compared to the defect-free pattern. If the defect size is large and / or highly opaque, it will have a more substantial impact on this image light intensity. The method according to an exemplary embodiment of the present invention reduces the effect of inclusion defects by roughening the surface of the mask on which the inclusion image will arrive. The optical intensity derived from the inclusion defect is disrupted and averaged, thereby producing a lower overall intensity of the light but a smoother and less defective transmission. Figure 7 shows a comparison of transmitted wavefronts, which depicts the change in optical transmission as the light field is transmitted through the scattering surface. Specifically, curve a in Figure 7 shows the wavefront originating from a defect on a glass substrate. The defective optical wavefront has a strong impact on patterning because the disrupted optical field is freely transmitted to the substrate via the lithography scanner. Curve b shows the wavefront originating from the same surface after surface roughening, and curve c shows the reduction in defect intensity or influence provided by the roughened surface. The scattering noise imparted to the transmitted wavefront generated from the rough glass surface weakens the optical perturbation of the defect. Thus, this scattering noise can reduce or remove the detrimental defect contrast difference. In an embodiment of the present invention, a rough surface is generated on a finely polished imaging surface to reduce the effect of defects in the mask (especially defects of the glass or fused silicate inclusion type). As explained, the rough surface gives a blurred defect image by reducing the interference effect and also reducing the difference in intensity levels between the pattern and the defect. A specific process or method in the manufacture of the FPD blank is defined as follows. It will be effective in terms of the dispersion defect image. In an exemplary embodiment, the roughened surface can be generated by a grinding and polishing process. Chemically and / or mechanically grinding and polishing the glass blank can be used to control the level of surface roughness. The mask blank can be ground on one or both sides of the glass. Optimal powder grains can be used to control the depth and / or roughness of the scratched surface. In an exemplary embodiment, an oxidation process can be used to generate substrate surface roughening. The quartz material is segmented from the quartz ingot by cutting. Then, the blank made of the quartz material can be ground or polished to produce a fine surface. After polishing, the glass surface can be scratched by chemical powder or any abrasive particles. Then, the blank can be subjected to oxidation by placing it in a furnace to improve the morphology on the surface. The scratched part of the surface usually has a higher oxidation rate or reaction rate. Then, another surface structure (such as (for example) a textured surface) can be formed on the roughened surface. In an exemplary embodiment, a film coating process can be used to generate substrate surface roughening. For example, a film material having properties similar to those of the substrate can be deposited. Examples of such materials include SiN x and SiO x , to give two examples. In an exemplary embodiment, a small particle coating can form the substrate roughness. For example, the size and other properties of the particles can be selected to achieve the desired roughness quality and / or scattering effect. In an exemplary embodiment, acid wet etching can be used to generate substrate surface roughening. In an exemplary embodiment, other techniques can be used to generate substrate surface roughening (such as (for example) ionization and sputtering) to add another film, to give two examples. In an exemplary embodiment, one or more of a variety of techniques can be used in combination to generate substrate surface roughening. FIG. 8 is a flowchart showing a process of manufacturing a photomask according to an exemplary embodiment of the present invention. In step S01 of the process, a mask blank is provided, and in step S03, the mask blank is subjected to defect detection. In this regard, photomask blank defect detection systems have been developed and are commercially available. For example, such systems include systems such as those available from KLA Instruments Corp. (Milpitas, California, USA) and Lasertec (Yokohama, Japan). In step S05, the detected defects (especially the detected defects in the substrate of the mask blank) are compensated by roughening one or more surface portions of the substrate. For example, such defects may include bubbles, scratches, pits, cracks, and the like. The roughening of the one or more surface portions can be achieved using, for example, grinding, polishing, oxidation, film coating, particle coating, wet etching, ionization, sputtering, and combinations thereof, and the like. FIG. 9 is a simplified block diagram of an embodiment of a flat panel display (FPD) manufacturing system 100 and an FPD manufacturing process associated therewith according to an exemplary embodiment of the present invention. The FPD manufacturing system 100 includes a plurality of entities that interact with each other in the design, development, and manufacturing cycles and / or services related to manufacturing an FPD device 160, such as a design house 120, a mask house 130, and an FPD manufacturer 150 (i.e., a wafer fab). The plurality of entities can be connected by a communication network, which can be a single network or multiple different networks, such as an intranet and the Internet, and can include wired and / or wireless communication channels. Each entity can interact with other entities and can provide services to and / or receive services from other entities. In an embodiment, one or more of the design house 120, the mask house 130, and the FPD manufacturer 150 can have a common owner and can even coexist in a common facility and use common resources. In various embodiments, a design company 120, which may include one or more design teams, generates an FPD design layout 122. The FPD design layout 122 may include various geometric patterns designed for the fabrication of the FPD device 160. By way of example, the geometric patterns may correspond to patterns of metal, oxide, or semiconductor layers of the various components that make up the FPD device 160 to be fabricated. The various layers are combined to form the various features of the FPD device 160, such as (for example) thin film transistors (TFTs). For example, the various portions of the FPD design layout 122 may include features such as an active region, a gate electrode, source and drain regions, metal lines or vias of a metal interconnect, openings for pads, and other features known in the art to be formed on an FPD glass substrate and on the various material layers disposed on the glass substrate. In an exemplary embodiment, the design company 120 implements a design process to form the FPD design layout 122. The design process may include logic design, physical design, and / or placement and routing. The FPD design layout 122 may be presented in one or more data files having information related to the geometric patterns to be used to fabricate the FPD device 160. In an embodiment, the FPD design layout 122 may be expressed in various formats, such as (for example) an Open Artwork System Interchange Standard (OASIS) file format, a GDSII file format, or a DFII file format, etc. In an embodiment, the design company 120 may transmit the FPD design layout 122 to the mask manufacturer 130, for example, via the network connection described above. The mask manufacturer 130 may then use the FPD design layout 122 to fabricate one or more masks for use in fabricating the various layers of the FPD device 160 in accordance with the FPD design layout 122. In various examples, the mask manufacturer 130 performs mask data preparation 132 in which the FPD design layout 122 is translated into a form that can be physically written by a mask writer, and mask fabrication 144 in which the design layout prepared by the mask data preparation 132 is modified to conform to a particular mask writer and / or mask manufacturer and then the mask for the design layout is fabricated. In the example of FIG. 9, the mask data preparation 132 and the mask fabrication 144 are depicted as separate elements; however, in some embodiments, the mask data preparation 132 and the mask fabrication 144 may be collectively referred to as mask data preparation. In an embodiment, mask data preparation 132 includes applying one or more resolution enhancement techniques (RET) to compensate for potential lithography errors, such as potential lithography errors that may result from diffraction, interference, or other process effects. In an embodiment, optical proximity correction (OPC) can be used to adjust line widths depending on the density of surrounding geometries, add "dogbone" end caps to the ends of lines to prevent line end shortening, correct electron beam (e-beam) proximity effects, or for other purposes. For example, OPC techniques can add sub-resolution assist features (SRAF), such as scattering bars, serifs, and / or hammerheads to the FPD design layout 122 according to an optical model or rules, such that after a lithography process, a final pattern on a glass substrate is improved with enhanced resolution and accuracy. Mask data preparation 132 may also include further RETs, such as off-axis illumination (OAI), phase shift masks (PSM), other suitable techniques, or combinations thereof. In an embodiment, mask data preparation 132 may include a mask process correction (MPC) for correcting errors introduced during the mask manufacturing process. For example, MPC can be used to correct the effects of the mask manufacturing process, such as fogging, development, and etch loading, as well as electron beam proximity effects. In an embodiment, the MPC process modifies a post-OPC design layout to compensate for limitations that may be encountered during mask fabrication 144. In an embodiment, mask data preparation 132 may include a lithography process check (LPC) that simulates the processes to be performed by the FPD manufacturer 150 to fabricate the FPD device 160. The LPC can simulate this process based on the FPD design layout 122 to create a simulated manufactured device, such as the FPD device 160. The process parameters in the LPC simulation can include parameters associated with various processes of the FPD manufacturing cycle, parameters associated with the tools used to manufacture the FPD, and / or other aspects of the manufacturing process. By way of example, the LPC can consider various factors, such as aerial image contrast, depth of focus (DOF), mask error enhancement factor (MEEF), other suitable factors, or combinations thereof. In an embodiment, after a simulated manufactured device has been created by the LPC, if the simulated device layout is not close enough in shape to meet the design rules, certain steps in the mask data preparation 132, such as OPC and MPC, can be repeated to further refine the IC design layout 122. It should be understood that the above description of mask data preparation 132 has been simplified for clarity purposes, and the data preparation can include additional features, such as a logic operation (LOP) for modifying the FPD design layout according to manufacturing rules. Additionally, the processes applied to the FPD design layout 122 during data preparation 132 can be performed in a variety of different orders. After mask data preparation 132 and during mask fabrication 144, a mask or a group of masks may be fabricated based on the modified FPD design layout. In an embodiment, an e-beam or a mechanism of multiple e-beams is used to form a pattern on a mask (reticle or reticle blank) based on the modified FPD design layout. In an embodiment, a mask pattern includes opaque regions and transparent regions. A radiation beam (such as an ultraviolet (UV) beam) for exposing a radiation-sensitive material layer (such as a photoresist) coated on a wafer is blocked by the opaque regions and transmitted through the transparent regions. In an embodiment, a binary mask includes a transparent substrate (such as fused quartz) and an opaque material (such as chromium) coated in the opaque regions of the mask. In an embodiment, a phase-shift technique is used to form the mask. In a phase-shift mask (PSM), various features in the pattern formed on the mask are configured to have a pre-configured phase difference to enhance image resolution and imaging quality. In an embodiment, the phase-shift mask may be an attenuated PSM or an alternating PSM. In an embodiment, the FPD manufacturer 150 may use the mask (or masks) fabricated by the mask manufacturer 130 to transfer one or more mask patterns onto a production glass substrate 152 and thus fabricate the FPD device 160 on the production glass substrate 152. The FPD manufacturer 150 may include an FPD fabrication facility, which may include a mass production facility for fabricating a variety of different FPD products. For example, the FPD manufacturer 150 may include a first manufacturing facility for front-end fabrication (i.e., front-end-of-line (FEOL) fabrication) of a plurality of FPD products, while a second manufacturing facility may provide back-end fabrication (i.e., back-end-of-line (BEOL) fabrication) for the interconnection and packaging of FPD products, and a third manufacturing facility may provide other services. In various embodiments, the production FPD 152 on which and / or within which the FPD device 160 is fabricated may include a glass substrate, where the glass type may be, for example, aluminosilicate glass, borosilicate glass, or fused silicate, etc. In an embodiment, a large reticle may be appropriately sized to accommodate photolithography for the glass plate substrate used to form the FPD. In an exemplary embodiment, mask data preparation may involve using a mask enhancer system. In this regard, FIG. 10 depicts a schematic diagram of an exemplary mask enhancer system 204 for enhancing a photomask layout in accordance with some embodiments. Some embodiments of mask enhancer system 204 include an OPC enhancer 222 that receives a design layout M generated by a design company 120 and generates an OPC (e.g., corrected) mask layout M'. As described, OPC is a lithography technique used to correct or enhance a mask layout M and produce an improved imaging effect to reproduce the original layout drawn by an FPD design company 120 on a glass substrate. For example, OPC can be used to compensate for imaging distortions due to optical diffraction. In some embodiments, mask layout M is a data file having information of geometric patterns to be generated on a substrate, and OPC enhancer 222 modifies the data file and generates a corrected data file representing a corrected mask layout M'. In an exemplary embodiment, a mask projector 230 may be applied to the corrected mask layout M to generate a projected mask layout 238 on a wafer. In some embodiments, the corrected mask layout M is a data file and mask projector 230 simulates the projection of corrected mask layout M' on a wafer and generates a simulated projected mask layout 238. A defect detector 232 of mask enhancer 204 detects the projected mask layout 238 and finds defective regions 236 of the projected mask layout 238. Although the corrected mask layout M' is subject to OPC, defective regions may be generated when the corrected mask layout M' is projected onto a substrate 208. In an embodiment, a defect corrector 234 of mask enhancer 204 may receive the defective regions 236 and the corrected mask layout M', and perform further correction (e.g., enhancement) on the corrected mask layout M', thereby generating an enhanced mask layout M''. In an embodiment, defect detector 232 may be incorporated into defect corrector 234, thereby producing a layout detection and correction system 233 that receives the projected mask layout 238 and the corrected mask layout M' and provides the enhanced mask layout M''. In an exemplary embodiment, mask enhancer system 204 may include specialized hardware components, software components, and / or a combination of both hardware and software components to perform various procedures related to the enhancement and correction of a photomask as part of an FPD manufacturing process. In this regard, FIG. 11 depicts an exemplary computer system related to a mask enhancer system in accordance with embodiments of the present invention. In some embodiments, the computer system includes a server 401, a display 402, one or more input interfaces 403, and one or more output interfaces 404 all conventionally coupled by one or more buses 405. For example, examples of suitable buses include PCI-Express®, AGP, PCI, ISA, and the like. A computer system can include any number of graphics processors. The graphics processors can reside on a motherboard, such as integrated with a motherboard chipset. One or more graphics processors can reside on an external board connected to the system through a bus (such as an ISA bus, a PCI bus, an AGP port, a PCI Express, or other system buses, etc.). The graphics processors can be on separate boards, each board connected to a bus (such as a PCI Express bus) to connect to each other and to the rest of the system. In addition, there can be a separate bus or connection (e.g., Nvidia SLI or ATI CrossFire connection, etc.) through which the graphics processors can communicate with each other. Instead of, or in addition to, the system bus, this separate bus or connection can also be used. Server 401 can include one or more CPUs 406, one or more GPUs 407, and one or more memory modules 412. Each CPU and GPU can be a single-core or multi-core unit. Examples of suitable CPUs include Intel Pentium®, Intel Core™ 2 Duo, AMD Athlon 64, AMD Opteron®, and the like. Examples of suitable GPUs include Nvidia GeForce®, ATI Radeon®, and the like. Input interface 403 can include a keyboard 408 and a mouse 409. Output interface 404 can include a printer 410. In an embodiment, communication interface 411 is a network interface that allows the computer system to communicate via a wireless or wired network. Communication interface 411 can be coupled to a transmission medium (not shown), such as a network transmission line, e.g., twisted pair, coaxial cable, fiber optic cable, and the like. In another embodiment, communication interface 411 provides a wireless interface, i.e., communication interface 411 uses a wireless transmission medium. Examples of other devices that can access the computer system via communication interface 411 include mobile phones, PDAs, personal computers, and the like (not shown). Memory module 412 can generally include different modalities, illustratively semiconductor memory, such as random access memory (RAM) and disk drives, etc. In various embodiments, memory module 412 stores an operating system 413, data structures 414, instructions 415, application programs 416, and processes 417. The storage device may include a large-capacity disk drive, floppy disk, magnetic disk, optical disk, magneto-optical disk, fixed disk, hard disk, CD-ROM, recordable CD, DVD, recordable DVD (e.g., DVD-R, DVD+R, DVD-RW, DVD+RW, HD-DVD or Blu-ray disc), flash memory and other non-volatile solid-state storage (e.g., USB flash drive), battery-backed volatile memory, tape storage, reader and other similar media, and combinations thereof. In various embodiments, the specific software instructions, data structures, and data for implementing the various embodiments of the present invention are generally incorporated into the server 401. Generally speaking, an embodiment of the present invention is tangibly embodied using a computer-readable medium (e.g., memory), and includes instructions, applications, and programs that, when executed by a processor, cause a computer system to utilize the present invention (e.g., collect and analyze data, pixelate structures, determine edge placement errors, move edge segments, optimize edge segment placement, and the like). The memory can store software instructions, data structures, and data for the operating system, data collection applications, data aggregation applications, data analysis procedures, and the like in semiconductor memory, disk memory, or a combination thereof. A computer-implemented or computer-executable version of the present invention can be embodied on, stored on, or associated with a computer-readable medium. A computer-readable medium can include any medium that participates in providing instructions to one or more processors for execution. Such a medium can take many forms, including but not limited to non-volatile, volatile, and transmission media. For example, non-volatile media includes flash memory or optical or magnetic disks. Volatile media includes static or dynamic memory, such as cache memory or RAM. Transmission media includes coaxial cables, copper wire, fiber optic lines, and conductors configured in a bus. Transmission media can also take the form of electromagnetic waves, radio frequencies, sound waves, or light waves (such as those generated during radio and infrared data communications). For example, the binary, machine-executable version of the software of the present invention can be stored or resident in RAM or cache memory or on a large-capacity storage device. The source code of the software of the present invention can also be stored or resident on a large-capacity storage device (e.g., hard disk, magnetic disk, magnetic tape, or CD-ROM). As a further example, the code of the present invention can be transmitted via wire, radio wave, or over a network (such as the Internet). The operating system can be implemented by any conventional operating system including the following: Windows® (a registered trademark of Microsoft Corporation), Unix® (a registered trademark of The Open Group in the United States and other countries), Mac OS® (a registered trademark of Apple Computer, Inc.), Linux® (a registered trademark of Linus Torvalds), and other operating systems not specifically listed herein. In various embodiments, the present invention can be implemented as a method, system, or article of manufacture for using standard programming or engineering techniques or both to produce software, firmware, hardware, or any combination thereof. As used in this application, the term "article of manufacture" (or alternatively, "computer program product") is intended to encompass a computer program that can be accessed from any computer-readable device, carrier, or medium. Additionally, the software in which the various embodiments are implemented can be accessed via a transmission medium (e.g., from a server via a network). The article of manufacture in which the code is implemented also encompasses transmission media such as network transmission lines and wireless transmission media. Thus, the article of manufacture also includes the medium in which the code is embedded. Those skilled in the art will recognize that many modifications can be made to this configuration without departing from the scope of the present invention. The computer system illustrated in FIG. 11 is not intended to limit the present invention. Other alternative hardware and / or software environments can be used without departing from the scope of the present invention. Although a detailed description of a particular embodiment of the present invention has been set forth in the foregoing specification, it should be understood that many of the details given herein can be significantly varied by those skilled in the art without departing from the spirit and scope of the present invention. 4: Transparent substrate 6: Masking material 8: Film frame 10: Film diaphragm 100: Flat panel display (FPD) manufacturing system 120: Design company 122: Flat panel display (FPD) design layout 130: Mask manufacturing factory 132: Mask data preparation 144: Mask production 150: Flat panel display (FPD) manufacturer 152: Produce glass substrate 160: Flat panel display (FPD) device 204: Mask enhancer system 222: Optical proximity correction (OPC) enhancer 230: Mask projector 232: Defect detector 233: Layout detection and correction system 234: Defect corrector 236: Defective area 238: Projected mask layout 401: Server 402: Display 403: Input interface 404: Output interface 405: Bus 406: CPU 407: GPU 408: Keyboard 409: Mouse 410: Printer / Contact opening 411: Communication interface 412: Memory module 413: Operating system 414: Data structure 415: Instruction 416: Application program 417: Procedure a: Curve b: Curve c: Curve M: Design layout M’: Corrected mask layout M’’: Enhanced mask layout S01: Step S03: Step S05: Step Exemplary embodiments of the present invention will be described in detail with reference to the following figures, wherein: Figures 1A to 1E are micrographs showing the types of defects that can be solved by exemplary embodiments of the present invention; Figure 2 is a micrograph showing one of the types of defects that can be solved by exemplary embodiments of the present invention; Figure 3 is a micrograph showing a portion of a defect-free photomask; Figure 4 is a micrograph showing the same portion of the photomask in Figure 3 with a defect; Figure 5 is a diagram showing the position of a defect in a photomask; Figure 6 is a diagram showing the effect of the defect shown in Figure 5 on the intensity profile; Figure 7 shows a transmitted wavefront comparison according to an exemplary embodiment of the present invention, which depicts the change in optical transmission as the light field is transmitted through the scattering surface; Figure 8 is a flowchart of a procedure for compensating for photomask defects according to an exemplary embodiment of the present invention; Figure 9 is a simplified block diagram of an embodiment of a flat panel display (FPD) manufacturing system and an FPD manufacturing process associated therewith according to an exemplary embodiment of the present invention; Figure 10 illustrates a schematic diagram of an exemplary mask enhancer system; FIG. 11 depicts an exemplary computer system associated with a mask enhancer system in accordance with embodiments of the present invention; and FIGS. 12A and 12B depict a top view and a side view of a typical photomask configured for use in a photolithography process. S01: Step S03: Step S05: Step

Claims

1. A system for manufacturing a photomask, comprising: One or more processors, and a non-transitory computer-readable memory operatively connected to the one or more processors, the non-transitory computer-readable memory having machine-readable instructions stored thereon, which, when executed by the one or more processors, cause the one or more processors to perform the following steps: (A) detecting a photomask blank comprising a glass substrate to determine the presence of one or more defects in the glass substrate; and (B) compensating for the one or more defects by roughening one or more surface portions of the glass substrate, wherein the roughened one or more surface portions of the glass substrate disrupt the directionality of an optical beam transmitted through the glass substrate.

2. The system of claim 1, wherein step (B) includes roughening one or more surface portions of the glass substrate by at least one of grinding or polishing.

3. The system of claim 1, wherein step (B) includes roughening one or more surface portions of the glass substrate by means of an oxidation process.

4. The system of claim 1, wherein step (B) includes roughening one or more surface portions of the glass substrate by means of a film coating process.

5. The system of claim 1, wherein step (B) includes roughening one or more surface portions of the glass substrate by means of a particle coating process.

6. The system of claim 1, wherein step (B) includes roughening one or more surface portions of the glass substrate by wet etching using an acid etchant.

7. The system of claim 1, wherein step (B) includes roughening one or more surface portions of the glass substrate by ionization.

8. The system of claim 1, wherein step (B) includes roughening one or more surface portions of the glass substrate by sputtering.

9. The system of claim 1, wherein the photomask is used in a lithography process to manufacture a large photomask for a flat panel display (FPD).

10. The system as described in claim 1 further includes: A flat panel display (FPD) manufacturer is operatively connected to one or more processors, wherein the one or more processors are further configured to perform the steps of processing the photomask blank by the FPD manufacturer.

11. The system of claim 10, wherein the processing steps performed by the FPD manufacturer include etching the photomask blank by the FPD manufacturer or exposing the photomask blank to at least one of an electron beam or laser energy.

12. A system for manufacturing a flat panel display, further comprising an optical energy source operatively connected to one or more processors, wherein the one or more processors are further configured to perform, in a photolithography process, a step of irradiating light from the optical energy source through a large photomask manufactured according to the system of claim 10 onto a glass substrate, such that at least one circuit pattern is transferred from the large photomask to the glass substrate.

13. The system of claim 12, wherein the flat panel display is a liquid crystal display, an active matrix liquid crystal display, an organic light-emitting diode, a light-emitting diode, a plasma display panel, or an active matrix organic light-emitting diode.

Images