Systems, methods, and program products for photomask surface treatment

Abstract

1. A method of manufacturing a photomask, the method comprising: providing a photomask blank; inspecting the photomask blank to determine the presence of one or more defects in the photomask blank, the one or more defects including 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

[Technical field]

[0001] Related Applications This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 323,705, entitled “SYSTEM, METHOD AND PROGRAM PRODUCT FOR PHOTOMASK SURFACE TREATMENT,” filed March 25, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates generally to the manufacture of photomasks, and more particularly to the manufacture of photomasks used in flat panel display (FPD) and integrated circuit (IC) lithography. [Background technology]

[0003] Photomasks traditionally consist of an optically transparent substrate with opaque light blocking regions that combine to selectively block or pass light wavelengths to form the circuit pattern of the object imaged by the lithographic projection system. These photomasks are commonly used in photolithography and production for integrated circuit (IC) and flat panel display (FPD) manufacturing, among others, by generating patterns on substrates such as silicon wafers for IC manufacturing, or on glass panels for FPD manufacturing. The optically transparent substrate of a photomask is typically a highly polished slab of fused silica, on which, for example, a chromium metal absorbing film is deposited and subsequently patterned in a mask making process. Other films deposited on the substrate for patterning can include CrOx, CrOn, and MoSi or SiN for phase shifting applications. Typical operating wavelengths for optical photomasks include, but are not limited to, 436 nm, 365 nm, 248 nm, and 193 nm. Photomasks contribute significantly to the capacity and productivity of IC and FPD manufacturing.

[0004] The photomask is a very sensitive component in the manufacturing process since the image of the photomask appears in every exposed area in the IC or FPD pattern transfer process. Therefore, a single defect in the photomask can waste many IC and FPD devices during the photolithography process. Defects can arise in various ways, for example, they arise during the patterning of the mask, are embedded in the film deposited on the mask, arise from added contaminants, and / or are embedded in the substrate material. Embedded defects present in the transparent substrate material of the photomask are commonly referred to as "inclusions." These inclusions can arise during the substrate manufacturing process from sources such as air bubbles or impurities in the fused silica material itself. Inclusions can be present anywhere in the substrate and are very difficult to repair once formed because they are embedded in the hard fused silica material. For this reason, substrate manufacturers spend a lot of time and money to manufacture substrates that are substantially free of inclusions.

[0005] There is a continuing need for improved techniques for minimizing defects in photomask substrates. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present invention to minimize the effect and impact of embedded defects (inclusions) present within the transparent substrate material of a photomask. [Means for solving the problem]

[0007] Another object of the present invention is to provide a method of processing a substrate to minimize the effect of inclusions on lithographic imaging to an acceptable level, to have a positive effect on the constraints of substrate manufacturing time, cost, and availability. In some embodiments, surface treatments are performed to reduce the effect of inclusions on imaging, thereby enabling much lower cost and more widely available substrate materials.

[0008] According to an exemplary embodiment of the present invention, a method of manufacturing a photomask includes the steps of: (A) providing a photomask blank; (B) inspecting the photomask blank to determine the presence of one or more defects in the photomask blank, where 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.

[0009] In some exemplary embodiments, the compensating step includes roughening one or more surface portions of the photomask substrate by at least one of grinding or polishing.

[0010] In some exemplary embodiments, the compensating step includes roughening one or more surface portions of the photomask substrate by an oxidation process.

[0011] In some exemplary embodiments, the compensating step includes roughening one or more surface portions of the photomask substrate by a film coating process.

[0012] In some exemplary embodiments, the compensating step includes roughening one or more surface portions of the photomask substrate with a particulate coating process.

[0013] In some exemplary embodiments, the compensating step includes roughening one or more surface portions of the photomask substrate by wet etching with an acid etchant.

[0014] In some exemplary embodiments, the compensating step includes roughening one or more surface portions of the photomask substrate by ionization.

[0015] In some exemplary embodiments, the compensating step includes roughening one or more surface portions of the photomask substrate by sputtering.

[0016] In some exemplary embodiments, the photomask is a large photomask for use in lithography processes to manufacture flat panel displays (FPDs).

[0017] In some exemplary embodiments, a method for forming a flat panel display includes irradiating light from an optical energy source onto a glass plate substrate through a large photomask in a photolithography process, where at least one circuit pattern is transferred from the large photomask to the glass plate substrate, and the large photomask is formed according to a process including: A) providing a photomask blank; (B) inspecting the photomask blank to determine the presence of one or more defects in the photomask blank, where 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.

[0018] In some exemplary embodiments, 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.

[0019] These and other features and advantages of the present invention will be presented in more detail in the following detailed description and the accompanying drawings, which illustrate, by way of example, the principles of the invention.

[0020] Various exemplary embodiments of the present invention will be described in detail with reference to the following figures. [Brief description of the drawings]

[0021] [Figure 1]FIG. 1A is a micrograph showing one type of defect that may be addressed by an exemplary embodiment of the present invention; FIG. 1B is a micrograph showing another type of defect that may be addressed by an exemplary embodiment of the present invention; FIG. 1C is a micrograph showing another type of defect that may be addressed by an exemplary embodiment of the present invention; FIG. 1D is a micrograph showing another type of defect that may be addressed by an exemplary embodiment of the present invention; and FIG. 1E is a micrograph showing another type of defect that may be addressed by an exemplary embodiment of the present invention. [Diagram 2] 1A-1C are micrographs illustrating the types of defects that can be addressed by exemplary embodiments of the present invention. [Diagram 3] FIG. 1 is a photomicrograph showing a portion of a photomask without defects. [Figure 4] FIG. 4 is a micrograph showing the same portion of the photomask of FIG. 3 with a defect. [Diagram 5] 1 is a graph showing the location of defects on a photomask. [Figure 6] 6 is a graph illustrating the effect of the defect shown in FIG. 5 on the intensity profile. [Figure 7] 1A-1C are diagrams illustrating a comparison of transmitted wavefronts illustrating the change in light transmission as a light field transmits through a scattering surface, in accordance with an exemplary embodiment of the present invention. [Figure 8] 4 is a flow diagram of a process for compensating for defects in a photomask in accordance with an exemplary embodiment of the present invention. [Figure 9] FIG. 1 is a simplified block diagram of one embodiment of a flat panel display (FPD) manufacturing system and associated FPD manufacturing flow, in accordance with an exemplary embodiment of the present invention. [Figure 10] FIG. 1 is a schematic diagram of an exemplary mask enhancer system. [Figure 11] FIG. 2 illustrates an exemplary computer system associated with a mask enhancer system in accordance with various embodiments of the present invention. [Figure 12A]FIG. 1 is a top view of a typical photomask configured for use in a photolithography process. [Figure 12B] FIG. 1 is a side view of a typical photomask configured for use in a photolithography process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] A flat panel display (FPD) is an electronic viewing technology used to display content (e.g., still images, video, text, or other visual material) in a variety of entertainment, consumer electronics, personal computers, and mobile devices, as well as many types of medical, transportation, and industrial equipment. Current types of FPD include, for example, LCD (liquid crystal display), AMLCD (active matrix liquid crystal display), OLED (organic light emitting diode), LED (light emitting diode), PDP (plasma display panel), and AMOLED (active matrix OLED).

[0023] During FPD manufacturing, the FPD lithography system shines light onto a photomask that contains the original thin-film transistor (TFT) circuit pattern, and the light passes through a lens to expose the pattern onto a glass plate substrate. For large glass plates, the exposure process is repeated several times to form the pattern across the entire plate.

[0024] 12A and 12B show top and side views of a typical photomask configured for use in a photolithography process. As shown, the photomask 2 (typically 6" x 6" in size and ¼" thick) is comprised of a transparent substrate 4 (e.g., fused silica) and a patterned layer of masking material 6 (e.g., chrome) that defines the desired image to be generated in the device. A pellicle frame 8 extends around the periphery of the patterned masking material 6 and is attached to the substrate 4 by a deposition process well known in the art. A pellicle film 10 is stretched and secured to the top surface of the frame 8. As shown, the surface of the pellicle film 10 is generally parallel to the surface of the photomask and covers the entire patterned area of ​​the masking material 6. Thus, any contamination that would normally land on the photomask will instead fall onto the pellicle film 10, which is outside the focal plane of the exposure system.

[0025] Another type of known photomask is commonly referred to as a phase-shift photomask. Phase-shift photomasks are generally preferred over binary photomasks when the design to be transferred to a device contains smaller dense feature sizes that are below the resolution requirements of the optics being used. Phase-shift photomasks are designed such that the light transmitted through the etched areas of the photomask is 180 degrees out of phase with the light transmitted through the openings in the photomask is equal in amplitude.

[0026] One type of known phase shift photomask 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 silica) commonly referred to as a photomask substrate. The next layer is typically an embedded phase shift material ("PSM layer") such as molybdenum silicide oxynitride (MoSiON), tantalum silicon nitride (TaSiN), titanium silicon nitride (TiSiN), or zirconium silicon oxide (ZrSiO), and other known phase shift materials. The next layer is typically an opaque material such as chromium (Cr), which may optionally include an anti-reflective coating such as chromium oxynitride (CrON). The top layer is a photosensitive resist material. As with a binary photomask, the desired pattern of opaque material to be generated on the EAPSM is scanned in a raster or vector fashion across the blank EAPSM by an electron beam (E-beam) or laser beam. As the E-beam or laser beam is scanned across the blank EAPSM, the exposure system directs the E-beam or laser beam to addressable locations on the EAPSM. For positive-tone photosensitive resist materials, the areas exposed to the E-beam or laser beam become soluble and the unexposed areas remain insoluble. For negative-tone photosensitive resist materials, the unexposed areas become soluble and the exposed areas remain insoluble.

[0027] Another type of phase shift mask is the alternating aperture phase shift mask ("AAPSM"). Similar to a binary photomask, an AAPSM is typically composed of a layer of opaque material and a substantially transparent substrate, where the substrate is etched on one side of the opaque features and not etched on the other side (i.e., etching of the transparent substrate occurs at alternating locations in the substantially transparent substrate). More specifically, an AAPSM (not shown) includes a substantially transparent layer (e.g., fused silica) and an opaque layer (e.g., chrome). 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 recesses in the substantially transparent layer. In other words, the AAPSM has etched recesses and alternating substantially transparent regions (not etched) between each opaque region.

[0028] The effect of this structure when placed in an exposure system is to produce light intensities of alternating polarity and 180 degrees out of phase. This alternating polarity forces the energy transmitted from the exposure system to zero in the opaque areas while maintaining the same light transmission in the alternating transparent areas and recesses. Because the photoresist layer on the device substrate is insensitive to the phase of the exposed light, the positive and negative exposed areas appear the same, but the zero areas between them are clearly demarcated. Thus, there is a sharper contrast between the light (e.g., transparent) and dark (e.g., opaque) areas in the resulting device photoresist layer, thereby allowing a more precise image to be etched into the device substrate.

[0029] In mask manufacturing, defects or particles on the substrate are important factors affecting yield and cost. This impact on yield and cost is emphasized in the manufacturing of FPD products, because FPD blanks are thicker and larger than IC masks, and particles such as air bubbles are often generated during the large-scale glass melting process.

[0030] According to an exemplary embodiment of the present invention, the photomask substrate is subjected to a surface treatment to minimize inclusion defects. The purpose of this treatment is to scatter the light that is blocked by the inclusions during transmission through the substrate. That is, the photomask illumination beam is optically disrupted by the inclusion defects as it passes through the substrate. This disruption travels with the illumination beam to the image plane of the photomask where it becomes a printable defect, leading to yield loss in the lithography process. However, in some embodiments, the disrupted transmitted light is effectively scattered at the image plane, averaging or smearing the effect of this inclusion defect, minimizing the effect of the inclusions to an acceptable level. Especially for FPD lithography where the substrates are very large, this can have a significant impact on the cost structure and available capacity of the entire FPD manufacturing process.

[0031] It should be understood that the systems and methods described herein are not limited to FPD masks, but may also be applied to IC masks.

[0032] In some embodiments, the image plane scattering can be achieved in various ways to provide an optical smoothing effect of inclusion defects. The surface scattering properties are preferably quite strong to mitigate the effects of inclusion defects and have at least the following properties:

[0033] 1. Surface scattering effects sufficient to degrade or scramble the directionality of the light beam transmitted through the substrate. The surface scattering is preferably nominally structureless in terms of the imaging conditions of the lithography scanner imaging the photomask.

[0034] 2. Maintains high transmission of light wavelengths through the scattering surface despite beam directivity scrambling effects.

[0035] While any surface modification technique can be employed that provides the necessary surface scattering effect to minimize the effects of substrate inclusions, in some embodiments the following techniques can be used to affect this scattering-based inclusion smoothing function at the substrate surface.

[0036] 1. Surface grinding that leaves a fine-scale ground-glass type finish on the substrate imaging surface. This is preferably done prior to patterned film deposition and mask fabrication.

[0037] 2. A sputtering or additive deposited material or film method that leaves the deposited film with a scattering structure sufficient to produce a ground glass-like effect in the beam transmitted through the mask substrate.

[0038] 3. Surface oxidation or chemical etching based methods to impart a scattering profile to the surface.

[0039] 4. Patterned features that are too fine in scale to be imaged by lithography systems, but strong enough to scramble the optical field disrupted by inclusion defects.

[0040] 1(A)-1(E) and 2 show types of defects that can be addressed by embodiments of the present invention. 1(A)-1(E) show typical additive defects that arise after a substrate is built, polished, and ready for coating. These can be due to defects in the deposited film or can be generated during the photomask manufacturing process. In particular, 1(A) shows a pinhole defect, 1(B) shows a crescent defect, 1(C) shows an additive defect, 1(D) shows a shading defect, and 1(E) shows a diffuse defect. 2 shows an example of an inclusion type defect that is physically embedded in the fused silica or glass material of the substrate during its manufacture. These defects are typically generated when the fused silica material is in the forming process in a furnace or during the glass melting process. In some embodiments, this latter type of inclusion defect can be best handled by surface scattering.

[0041] Figures 3 and 4 show how defects manifest themselves in the mask and imaging process. In Figure 3, there is no discernible defect on the mask, and in Figure 4, the mask pattern is defective due to a hard spot in the middle of a line. This defect may affect a patterned area that is important for imaging of the device. Thus, in some embodiments, an acceptable defect size and a percentage of light intensity loss can be defined to determine the criticality of the defect. When the exposure light passes through the mask pattern defined in the thin film, the intensity or maximum intensity of the light is reduced or disturbed by the defect due to physical blocking or interference effects. There are many types, sizes, and locations of defects, and critical defects have a measurable impact on the quality of the mask pattern imaged onto the substrate.

[0042] Figures 5 and 6 simulate the correspondence between a pattern and a defect in forming an imaged intensity profile to be transferred to a substrate by a lithography scanner, which is required to resolve the pattern. The interference between the defect and the pattern reduces the intensity level, as shown by the dashed line in Figure 6. As a result, the intensity profile of a defective pattern shows a different pattern quality compared to a defect-free pattern. If the defect size is large and / or very opaque, it has a larger impact on the light intensity of the image.

[0043] A 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 arrives. The light intensity originating from the inclusion defects is scrambled and averaged, producing a light transmission that is lower overall in intensity, but smoother and less defective. Figure 7 shows a comparison of transmitted wavefronts illustrating the change in light transmission as the light field transmits through a scattering surface. In particular, curve a in Figure 7 shows a wavefront resulting from a defect in a glass substrate. The defective light wavefront has a strong effect on pattern formation, since the lithography scanner can transmit a destroyed light field to the substrate. Curve b shows the wavefront resulting from the same surface after roughening the surface, and curve c shows the reduction in defect intensity or effect provided by the roughened surface. The scattering noise imparted to the transmitted wavefront generated from the rough glass surface weakens the optical disturbance of the defect. This scattering noise can therefore reduce or eliminate the harmful defect contrast difference.

[0044] In some embodiments of the present invention, a rough surface on the finely polished imaging surface is generated to mitigate the effect of mask defects, especially glass or fused silica inclusion type defects. As explained, the rough surface reduces the interference effect and also reduces the difference in intensity level between the pattern and the defect, thereby giving a blurred defect image. The specific process or method in FPD blank manufacturing is defined as follows. This is effective for distributed defect images.

[0045] In some exemplary embodiments, the roughened surface can be produced by a grinding and polishing process. Chemical and / or mechanical grinding and polishing of the glass blank can be used to control the level of surface roughness. Mask blanks may be ground on one or both sides of the glass. The depth and / or roughness of the scratched surface can be controlled using optimal powder grains.

[0046] In some exemplary embodiments, an oxidation process can be used to generate roughening of the substrate surface. Quartz material is split from a quartz ingot by cutting. A blank made of the quartz material can then be ground or polished to form a fine surface. After polishing, the glass surface can be scratched by chemical powder or any abrasive grain. The blank can then be placed in a furnace to undergo oxidation to improve the surface morphology. The scratched portion of the surface typically has a higher oxidation or reaction rate. Another surface structure, such as an embossed surface, can then be formed on the roughened surface.

[0047] In some exemplary embodiments, a film coating process can be used to create a roughened surface of a substrate. For example, a film material can be deposited that has properties similar to those of the substrate. Examples of such materials include SiNx and SiOx, to name two.

[0048] In some exemplary embodiments, a coating of small particles can form the surface roughness. For example, the size and other characteristics of the particles may be selected to achieve a desired roughness quality and / or scattering effect.

[0049] In some exemplary embodiments, an acid wet etch may be used to create a roughened surface of the substrate.

[0050] In some exemplary embodiments, other techniques can be used to create a roughened surface of the substrate, such as ionization and sputtering to add another film, to name just two.

[0051] In some exemplary embodiments, one or more of a variety of techniques may be used in combination to generate roughening of the substrate surface.

[0052] FIG. 8 is a flow chart showing a process of making 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, defect detection is performed on the mask blank. In this regard, photomask blank defect detection systems have been developed and are commercially available. Such systems include, for example, systems available from KLA Instruments Corp. (Milpitas, Calif., USA) and Lasertec (Yokohama, Japan). In step S05, the detected defects, particularly defects of the substrate of the photomask blank, are compensated for by roughening one or more surface portions of the substrate. Such defects include, for example, bubbles, scratches, dents, and cracks, to name a few. The roughening of one or more surface portions can be achieved using, for example, grinding, polishing, oxidation, film coating, particulate coating, wet etching, ionization, sputtering, and combinations thereof, to name a few.

[0053] 9 is a simplified block diagram of one embodiment of a flat panel display (FPD) manufacturing system 100 and associated FPD manufacturing flow, according to an exemplary embodiment of the present invention. The FPD manufacturing system 100 includes multiple entities, such as a design house 120, a mask house 130, and an FPD manufacturer 150 (i.e., a factory), that interact with each other in the design, development, and manufacturing cycle and / or services related to the production of an FPD device 160. The multiple entities may be connected by a communications network, which may be a single network or a variety of different networks, such as an intranet or the Internet, and may include wired and / or wireless communication channels. Each entity may interact with the other entities and may provide services to and / or receive services from the other entities. In some embodiments, one or more of the design house 120, mask house 130, and FPD manufacturer 150 may have a common owner, may coexist in a common facility, and may even use common resources.

[0054] In various embodiments, design house 120, which may include one or more design teams, generates FPD design layout 122. FPD design layout 122 may include various geometric patterns designed for the manufacture of FPD device 160. By way of example, the geometric patterns may correspond to patterns of metal, oxide, or semiconductor layers that make up various components of FPD device 160 to be manufactured. The various layers combine to form various features of FPD device 160, such as thin film transistors (TFTs). For example, various portions of FPD design layout 122 may include features such as active areas, gate electrodes, source and drain regions, metal lines or vias for metal interconnects, openings for bond pads, and other features known in the art to be formed in an FPD glass substrate and various material layers disposed on the glass substrate. In an exemplary embodiment, design house 120 implements a design procedure to form FPD design layout 122. The design procedure may include logical design, physical design, and / or place and route. FPD design layout 122 may be represented in one or more data files that contain information related to the geometric patterns to be used to fabricate FPD device 160. In some embodiments, FPD design layout 122 may be represented in a variety of formats, such as the Open Artwork System Interchange Standard (OASIS) file format, the GDSII file format, or the DFII file format, to name a few.

[0055] In some embodiments, the design house 120 can transmit the FPD design layout 122 to the mask house 130, for example via a network connection as described above. The mask house 130 can then use the FPD design layout 122 to manufacture one or more masks to be used in fabricating various layers of the FPD device 160 according to the FPD design layout 122. In various examples, the mask house 130 performs mask data preparation 132, in which the FPD design layout 122 is converted into a form that can be physically written by a mask writer, and further performs mask fabrication 144, in which the design layout prepared by the mask data preparation 132 is modified to suit a particular mask writer and / or mask manufacturer and then fabricated. In the example of FIG. 9, the mask data preparation 132 and the mask fabrication 144 are shown 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.

[0056] In some embodiments, mask data preparation 132 includes application of one or more resolution enhancement techniques (RET) to compensate for potential lithography errors, such as those that may result from diffraction, interference, or other process effects. In some embodiments, optical proximity correction (OPC) may be used to adjust line widths depending on the density of surrounding geometric features, add "dog-bone" end caps to the ends of lines to prevent shortening of the line ends, correct for electron beam (e-beam) proximity effects, or achieve other purposes. For example, OPC techniques may add sub-resolution assist features (SRAFs), which may include, for example, adding scattering bars, serifs, and / or hammerheads to the FPD design layout 122 according to an optical model or rule, thereby refining the final pattern on the glass substrate after the lithography process to improve resolution and accuracy. Mask data preparation 132 may also include additional RET, such as off-axis illumination (OAI), phase shift masks (PSM), other suitable techniques, or combinations thereof.

[0057] In some embodiments, mask data preparation 132 may include mask process correction (MPC) that is used to correct errors introduced during the mask making process. For example, MPC can be used to correct for effects of the mask making process, such as fogging, development and etch loads, and e-beam proximity effects. In some embodiments, the MPC process modifies the post-OPC design layout to compensate for limitations that may occur during mask fabrication 144.

[0058] In some embodiments, mask data preparation 132 may include a lithography process check (LPC) that simulates the processing performed by FPD manufacturer 150 to create FPD device 160. The LPC may simulate this processing based on FPD design layout 122 to produce a simulated manufactured device, such as FPD device 160. The processing parameters in the LPC simulation may include parameters associated with various processes in the FPD manufacturing cycle, parameters associated with tools used to manufacture the FPD, and / or other aspects of the manufacturing process. By way of example, the LPC may take into account various factors, such as aerial image contrast, depth of focus (DOF), mask error emphasis factor (MEEF), other suitable factors, or a combination thereof.

[0059] In some embodiments, after the simulated manufactured device is created by LPC, if the simulated device layout is not close enough to the geometry to meet the design rules, certain steps of mask data preparation 132, such as OPC and MPC, may be repeated to further refine the IC design layout 122.

[0060] It should be understood that the above description of mask data preparation 132 has been simplified for purposes of clarity and that data preparation may also include additional functions such as logic operations (LOPs) to modify the FPD design layout in accordance with manufacturing rules. Additionally, the processes applied to the FPD design layout 122 during data preparation 132 may be performed in a variety of different orders.

[0061] After mask data preparation 132, during mask fabrication 144, a mask or group of masks can be fabricated based on the modified FPD design layout. In some embodiments, an electron beam (e-beam) or multiple e-beams mechanism is used to form a pattern on a mask (photomask or reticle) based on the modified FPD design layout. In some embodiments, the mask pattern includes opaque and transparent regions. A radiation beam, such as an ultraviolet (UV) beam used to expose a radiation sensitive material layer (e.g., photoresist) coated on the wafer, is blocked by the opaque regions and transmitted through the transparent regions. In some embodiments, a binary mask includes a transparent substrate (e.g., fused quartz) and an opaque material (e.g., chrome) coated on the opaque regions of the mask. In some embodiments, the mask is formed using phase shifting techniques. In a phase shift mask (PSM), various features of a pattern formed on the mask are configured to have a pre-set phase difference to enhance image resolution and imaging quality. In some embodiments, the phase shift mask can be an attenuated PSM or an alternating PSM.

[0062] In some embodiments, FPD manufacturer 150 can use a mask (or masks) produced by mask house 130 to transfer one or more mask patterns to product glass substrate 152, thus producing FPD devices 160 on product glass substrate 152. FPD manufacturer 150 can include an FPD manufacturing facility, which can include multiple manufacturing facilities for producing a variety of different FPD products. For example, FPD manufacturer 150 can include a first manufacturing facility for front-end fabrication (i.e., front-end-of-line (FEOL) fabrication) of multiple FPD products, a second manufacturing facility can provide back-end fabrication (i.e., back-end-of-line (BEOL) fabrication) for interconnection and packaging of FPD products, and a third manufacturing facility can provide other services. In various embodiments, product FPD 152 in and / or on which FPD devices 160 are produced can include a glass substrate, where the type of glass can be, for example, aluminosilicate glass, borosilicate glass, or fused silica, to name a few. In some embodiments, the large photomask may be appropriately sized to accommodate the photolithographic processing of the glass plate substrate used to form the FPD.

[0063] In some exemplary embodiments, mask data preparation may include the use of a mask enhancer system. In this regard, FIG. 10 illustrates a schematic diagram of an exemplary mask enhancer system 204 for enhancing a photomask layout in accordance with some embodiments. Some embodiments of the mask enhancer system 204 include an OPC enhancer 222 that receives the mask layout M generated by the design house 120 and generates an OPC-processed (e.g., corrected) mask layout M. As described above, OPC is a lithography technique used to correct or enhance the mask layout M and create improved imaging effects to reproduce the original layout drawn by the FPD design house 120 on a glass substrate. For example, OPC can be used to compensate for imaging distortions due to optical diffraction. In some embodiments, the mask layout M is a data file that includes information of a geometric pattern to be generated on a substrate, and the OPC enhancer 222 modifies the data file and generates a corrected data file representing the corrected mask layout M′.

[0064] In some exemplary embodiments, the mask projection apparatus 230 may be applied to the corrected mask layout M to generate a projected mask layout 238 onto the wafer. In some embodiments, the corrected mask layout M is a data file, and the mask projection apparatus 230 simulates the projection of the corrected mask layout M′ onto the wafer to generate a simulated projected mask layout 238. The defect detector 232 of the mask enhancer 204 inspects the projected mask layout 238 and finds defect regions 236 in the projected mask layout 238. Although the corrected mask layout M′ is OPC processed, defect regions may be generated when the corrected mask layout M′ is projected onto the substrate 208.

[0065] In some embodiments, the defect corrector 234 of the mask enhancer 204 may receive the defect regions 236 and the corrected mask layout M' and perform further corrections, e.g., enhancements, on the corrected mask layout M', thereby generating an enhanced mask layout M". In some embodiments, the defect detector 232 may be coupled to the defect corrector 234 to produce a layout detection and correction system 233 that receives the projected mask layout 238 and the corrected mask layout M' and provides an enhanced mask layout M".

[0066] In some exemplary embodiments, the mask enhancer system 204 includes specialized hardware components, software components, and / or a combination of both hardware and software components to perform various procedures related to photomask enhancement and correction as part of the FPD manufacturing process. In this regard, FIG. 11 illustrates an exemplary computer system associated with a mask enhancer system according to various 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 of which are conventionally coupled by one or more buses 405. Examples of suitable buses include, for example, PCI-Express, AGP, PCI, ISA, etc., to name a few.

[0067] A computer system may include any number of graphics processors. The graphics processor may reside on a motherboard, such as integrated with a motherboard chipset. One or more graphics processors may reside on external boards connected to the system via a bus, such as an ISA bus, a PCI bus, an AGP port, a PCI Express, or other system bus, to name a few. The graphics processors may be on separate boards, each connected to a bus, such as a PCI Express bus, connected to each other, and connected to the rest of the system. Additionally, there may be separate buses or connections (e.g., Nvidia SLI® or ATI CrossFire® connections, to name two) over which the graphics processors can communicate with each other. This separate bus or connection may be used in addition to or instead of the system bus.

[0068] The server 401 may include one or more CPUs 406, one or more GPUs 407, and one or more memory modules 412. Each CPU and GPU may be a single-core or multi-core unit. Examples of suitable CPUs include Intel Pentium®, Intel Core™ 2 Duo, AMD Athlon® 64, AMD Opteron®, to name a few. Examples of suitable GPUs include Nvidia GeForce®, ATI Radeon®, to name a few. The input interface 403 may include a keyboard 408 and a mouse 409. The output interface 404 may include a printer 410.

[0069] In some embodiments, communication interface 411 is a network interface that allows the computer system to communicate over a wireless or wired network. Communication interface 411 may be coupled to a network transmission line, a transmission medium (not shown), such as twisted pair, coaxial cable, fiber optic cable, to name a few. 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 be used to access the computer system via communication interface 411 include mobile phones, PDAs, personal computers, to name a few (not shown).

[0070] The memory module 412 may generally include different modalities, such as semiconductor memory, such as random access memory (RAM), disk drives, etc. In various embodiments, the memory module 412 stores an operating system 413, data structures 414, instructions 415, applications 416, and procedures 417.

[0071] Storage devices include high capacity disk drives, floppy disks, magnetic disks, optical disks, magneto-optical disks, fixed disks, hard disks, CD-ROMs, recordable CDs, DVDs, recordable DVDs (e.g., DVD-R, DVD+R, DVD-RW, DVD+RW, HD-DVD, or Blu-ray Discs), flash and other non-volatile solid state storage (e.g., USB flash drives), battery backed volatile memory, tape storage, readers, and other similar media, and combinations thereof.

[0072] In various embodiments, the specific software instructions, data structures, and data implementing various embodiments of the invention are typically embodied in server 401. In general, an embodiment of the invention is tangibly embodied using a computer readable medium, e.g., a memory, and includes instructions, applications, and procedures that, when executed by a processor, cause a computer system to utilize the invention, e.g., collect and analyze data, pixelate structures, determine edge placement error, move edge fragments, optimize edge fragment placement, etc. The memory can store software instructions, data structures, and data for any of the operating systems, data collection applications, data aggregation applications, data analysis procedures, etc., in semiconductor memory, disk memory, or a combination thereof.

[0073] A computer-implemented or computer-executable version of the invention may be embodied using, stored on, or associated with a computer-readable medium. A computer-readable medium may include any medium that participates in providing instructions to one or more processors for execution. Such media may take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, flash memory, or optical or magnetic disks. Volatile media include static or dynamic memory, such as cache memory or RAM. Transmission media include coaxial cables, copper wire, fiber optic lines, and wires arranged in a bus. Transmission media may also take the form of electromagnetic, radio frequency, acoustic, or light waves, such as those generated during radio wave or infrared data communications.

[0074] For example, a binary, machine-executable version of the software of the present invention may be stored or reside in RAM or cache memory or a mass storage device. The source code of the software of the present invention may also be stored or reside in a mass storage device (e.g., a hard disk, magnetic disk, tape, or CD-ROM). As a further example, the code of the present invention may be transmitted over wires, radio waves, or a network such as the Internet.

[0075] The operating system may be implemented by any conventional operating system, including 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 expressly enumerated herein.

[0076] In various embodiments, the invention may be implemented as a method, system, or article of manufacture using standard programming or engineering techniques, or both, to generate software, firmware, hardware, or any combination thereof. The term "article of manufacture" (or alternatively "computer program product") as used in this application is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. Furthermore, the software in which the various embodiments are implemented may be accessible via a transmission medium, for example, over a network from a server. The article of manufacture in which the code is implemented also includes 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 invention.

[0077] The computer system illustrated in Figure 11 is not intended to be limiting of the present invention, as other alternative hardware and / or software environments may be used without departing from the scope of the present invention.

[0078] Although the foregoing specification provides a detailed description of particular embodiments of the invention, it should be understood that many of the details described herein may be significantly modified by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. 1. A method for manufacturing a photomask, comprising: (A) providing a photomask blank comprising a glass substrate; (B) inspecting the photomask blank to determine the presence of one or more defects in the glass substrate; (C) compensating for the one or more defects by roughening one or more surface portions of the glass substrate; The method includes:

2. The method of claim 1 , wherein the compensating step comprises roughening one or more surface portions of the glass substrate by at least one of grinding or polishing.

3. The method of claim 1 , wherein the compensating step comprises roughening one or more surface portions of the glass substrate by an oxidation process.

4. The method of claim 1 , wherein the compensating step comprises roughening one or more surface portions of the glass substrate by a film coating process.

5. The method of claim 1 , wherein the compensating step comprises roughening one or more surface portions of the glass substrate with a particulate coating process.

6. The method of claim 1 , wherein the compensating step comprises roughening one or more surface portions of the glass substrate by wet etching with an acid etchant.

7. The method of claim 1 , wherein the compensating step comprises roughening one or more surface portions of the glass substrate by ionization.

8. The method of claim 1 , wherein the compensating step comprises roughening one or more surface portions of the glass substrate by sputtering.

9. 10. The method of claim 1, wherein the photomask is a large photomask for use in a lithography process to manufacture flat panel displays (FPDs).

10. The method of claim 1 , further comprising the step of treating the photomask blank.

11. 10. The method of claim 1, wherein the processing step comprises at least one of etching the photomask blank or exposing the photomask blank to electron beam or laser energy.

12. 13. A method for forming a flat panel display, comprising the steps of irradiating a glass plate substrate with light from an optical energy source through a large photomask formed according to the method of claim 10 in a photolithography process, wherein at least one circuit pattern is transferred from the large photomask to the glass plate substrate.

13. 13. The method 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.

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