A verification sample and verification method for a half-tone mask HTM repair process

Abstract

This invention discloses a verification sample and verification method for halftone mask HTM repair process, relating to the field of flat panel display mask manufacturing technology. The verification sample includes a substrate, on which are integrated dimensional accuracy testing structures, edge straightness testing structures, seam straightness testing structures, and ZAP repair straightness testing structures. The ZAP repair straightness testing structure comprises two opposing HTM patterns, forming an overlapping area. After being removed by ZAP laser scanning, a third seam is formed for evaluating the repair effect. The halftone layer of the verification sample has a light transmittance of 35%-45%. The verification method includes five steps: dimensional accuracy verification, edge straightness verification, seam straightness verification, ZAP repair effect verification, and transmittance consistency verification. This invention, through the integrated design of four types of testing structures, achieves systematic quantitative verification of the dimensional accuracy, multi-directional straightness, ZAP repair straightness, and optical transmittance of the HTM repair process.

Description

Technical Field

[0001] This invention relates to the field of flat panel display mask manufacturing technology, specifically to a verification sample and verification method for a halftone mask HTM repair process. Background Technology

[0002] In the field of flat panel display (FPD) manufacturing, halftone masks (HTMs) are key components for achieving grayscale exposure. They precisely control light transmittance through a semi-transparent layer and are widely used in photolithography processes for array substrates and color filter substrates. During the manufacturing and use of HTMs, various defects can easily occur in the semi-transparent layer pattern. The industry commonly uses repair processes such as laser ablation (ZAP) and chemical vapor deposition (CVD) to restore the pattern accuracy and optical performance. The development of repair processes, parameter calibration, and yield control in mass production all highly depend on the accurate verification and quantitative evaluation of the repair effect.

[0003] However, the existing verification methods mentioned above have obvious shortcomings:

[0004] First, there is a lack of unified and standardized verification carriers. The verification of key indicators such as dimensional accuracy, straightness of repaired edges, and quality of seams in different directions is fragmented. Multiple different samples need to be made separately, resulting in a highly fragmented verification process, poor data comparability, and low efficiency.

[0005] Secondly, the evaluation of ZAP laser repair effect has long been limited to the qualitative judgment of whether defects can be eliminated. There is a lack of test structures that can directly quantify and evaluate the microscopic quality such as the straightness of the repaired edge, the presence of burrs, over-etching, or under-etching, which makes it difficult to achieve fine parameter optimization of the repair process.

[0006] Third, existing verification focuses solely on restoring the geometric dimensions of the pattern, neglecting the optical transmittance upon which HTM grayscale exposure depends, and especially failing to consider the impact of the post-repair cleaning process on transmittance consistency. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the shortcomings of existing technologies, this invention provides a verification sample and verification method for the half-color mask HTM repair process, thus solving the problems mentioned in the background section.

[0009] (II) Technical Solution

[0010] To achieve the above objectives, the present invention provides the following technical solution: a verification sample for a half-color mask HTM repair process, comprising a substrate, wherein the substrate integrates:

[0011] The dimensional accuracy test structure includes two specifications of spot patterns, used to verify the dimensional accuracy of CVD deposition repair.

[0012] A line edge straightness test structure includes a test pattern, which is set on the right side of a sample line edge and forms a first line seam perpendicular to the line edge.

[0013] A seam straightness test structure includes a test pattern, which is positioned above a sample line edge and forms a second seam parallel to the line edge.

[0014] The ZAP repair straightness test structure includes two HTM patterns arranged opposite each other, with an overlapping area between the two HTM patterns. The overlapping area is configured to be removed by ZAP laser scanning with a specific spot, forming a third suture for evaluating the repair effect.

[0015] Furthermore, the light spot pattern specifications in the dimensional accuracy testing structure are 20×20μm and 20×15μm.

[0016] Furthermore, both HTM patterns in the ZAP repair straightness test structure are 20×20μm rectangles.

[0017] Furthermore, the halftone layer of the verification sample has a light transmittance of 35%-45%.

[0018] Furthermore, the halftone layer has a light transmittance of 40%, and the dimensional accuracy test structure, edge straightness test structure, seam straightness test structure, and ZAP repair straightness test structure on the substrate are all used to perform measurements before and after the cleaning process to verify the transmittance stability.

[0019] A verification method for the HTM repair process applied to the above-mentioned verification sample includes the following steps:

[0020] Dimensional accuracy verification steps: Perform key dimension measurements on the dimensional accuracy test structure and compare the difference between the CVD deposition pattern size and the design value;

[0021] Line edge straightness verification steps: Perform multi-point width measurements on the first seam in the line edge straightness test structure, and calculate the maximum and minimum range of its value;

[0022] Seam straightness verification steps: Perform multi-point width measurements on the second seam in the seam straightness test structure and calculate the maximum and minimum range of its values;

[0023] ZAP repair effect verification steps: After performing ZAP laser scanning repair on the overlapping area, the width of the formed third seam is measured at multiple points, and its range is calculated to quantitatively evaluate the straightness of the ZAP repair.

[0024] Transmittance consistency verification steps: Perform the HTM cleaning procedure on the verification sample and measure the light transmittance of each test structure area before and after cleaning to verify the deviation from the target transmittance.

[0025] Furthermore, in the transmittance consistency verification step, the target transmittance is 40%, and the difference in transmittance before and after cleaning is recorded.

[0026] (III) Beneficial Effects

[0027] (1) This invention integrates four types of test structures—dimensional accuracy, line edge straightness, line seam straightness, and ZAP repair straightness—onto the same substrate to form a one-stop multi-functional integrated verification sample. One verification can cover the quantitative evaluation of CVD deposition repair, multi-directional line edge and line seam quality, and ZAP laser repair effect. This completely changes the fragmented mode of traditional methods that require the separate production of multiple different samples and repeated testing, and greatly improves the standardization and efficiency of the verification process.

[0028] (2) The present invention has innovatively designed a ZAP repair straightness test structure. The overlapping area formed by two HTM patterns is removed by ZAP laser scanning to form a third seam, which enables precise and intuitive quantitative detection of micro-defects such as ZAP repair edge straightness, burrs, over-cutting or under-cutting that have been difficult to quantify in the industry for a long time. This breaks through the limitation that the traditional repair effect can only be qualitatively judged and cannot be quantitatively analyzed, and greatly improves the detection accuracy and refinement of HTM repair precision.

[0029] (3) This invention links geometric dimension accuracy with optical transmittance performance for verification. It sets a target transmittance of 35%-45% for the halftone layer and forces verification of the consistency of transmittance before and after cleaning. This breaks through the one-sidedness of traditional mask verification that only focuses on geometric dimension recovery. It returns to the core functional requirements of grayscale exposure of HTM mask, ensuring that the repaired mask not only meets the graphic size standard, but also meets the strict requirements of FPD lithography process, effectively avoiding panel display problems caused by transmittance deviation. Attached Figure Description

[0030] Figure 1 These are schematic diagrams illustrating the design schemes of the four samples in this invention;

[0031] Figure 2 This is a schematic diagram showing the transmittance and size difference measured after cleaning samples one and two in this invention.

[0032] Figure 3 This is a schematic diagram showing the transmittance and seam range measured after cleaning samples three and four in this invention.

[0033] Figure 4This is a flowchart illustrating the verification method in this invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see Figures 1 to 4 As shown, the embodiments of the present invention provide the following technical solutions:

[0036] A verification sample for a half-color mask HTM repair process includes a substrate, which can be a quartz or soda-lime glass substrate. Four types of test structures are integrated on the substrate: a dimensional accuracy test structure, a line edge straightness test structure, a seam straightness test structure, and a ZAP repair straightness test structure. These four test structures are integrated on the same substrate, forming a one-stop, multi-functional integrated verification sample. A single verification can cover the quantitative evaluation of CVD deposition repair, multi-directional line edge and seam quality, and ZAP laser repair effects, completely solving the problem of fragmented verification in existing technologies.

[0037] It should be noted that the test pattern and HTM pattern mentioned in this embodiment can be one or a combination of the following: a light-shielding area formed by a chromium layer, a semi-transparent area formed by a halftone layer, or a light-transmitting area formed by a region without a chromium layer. Similarly, the line edge refers to the existing pattern boundary on the sample, such as the straight edge of a long strip-shaped light-shielding pattern.

[0038] Specifically, the four types of test structures are described in detail below:

[0039] The dimensional accuracy test structure includes two sizes of light spot patterns to verify the dimensional accuracy of CVD deposition repair. Specifically, the light spot patterns in the dimensional accuracy test structure are 20×20μm and 20×15μm in size, designed as transparent areas penetrating the light-shielding layer and halftone layer to simulate the defects to be repaired. When performing CVD deposition repair, repair material is filled into these transparent areas to restore the pattern. By measuring the critical dimension (CD) of the filled pattern, the dimensional control capability of the repair process can be accurately evaluated.

[0040] The line edge straightness test structure includes a test pattern, which is positioned on the right side of a sample line edge, forming a first seam perpendicular to the line edge. Specifically, the test pattern is, for example, a 20×20μm light-shielding pattern, positioned on the right side of a reference line edge. The gap between the two constitutes the first seam, and the uniformity of the width of this first seam directly reflects the straightness of the repair process in the direction perpendicular to the line edge.

[0041] A seam straightness test structure includes a test pattern positioned above a sample line edge, forming a second seam parallel to the line edge. Specifically, unlike the line edge straightness test structure, this test pattern is located above a reference line edge, and the direction of the formed second seam is parallel to the reference line edge, used to independently evaluate the repair straightness in the parallel direction.

[0042] The ZAP repair straightness test structure includes two opposing Hidden Markings (HTMs), each a 20×20μm rectangle. An overlay is formed between the two HTMs, which can be a light-blocking or semi-transparent area with a specific shape. This overlay is removed by a ZAP laser scan with a specific spot size, forming a third seam for evaluating the repair effect. Specifically, the overlay is the target of the ZAP laser: during ZAP repair verification, a ZAP laser beam with a spot size of, for example, 2μm is used to scan and completely remove the overlay along a preset path. After the overlay is ablated, the two originally connected semi-transparent HTM rectangles are separated, forming a very fine third seam between their opposing edges. Ideally, the third seam should have straight edges, be burr-free, and have no material residue. Its actual shape directly and accurately reflects the straightness quality of the ZAP laser repair process, enabling the quantification of defects such as edge straightness, burrs, over-cutting, or under-cutting in ZAP repairs, which have long been difficult to quantify in the industry.

[0043] In this embodiment, the halftone layer of the verification sample has a light transmittance of 35%-45%; preferably, the halftone layer has a light transmittance of 40%, which is a typical target value for grayscale exposure of HTM masks in the FPD industry. The dimensional accuracy test structure, edge straightness test structure, seam straightness test structure, and ZAP repair straightness test structure on the substrate are all used to perform measurements before and after the cleaning process to verify the transmittance stability of the HTM repair process and ensure that the repaired mask can still meet the grayscale exposure requirements under multiple cleaning conditions on the production line. This design breaks the limitation of traditional mask verification samples that only focus on geometric dimensions, and verifies geometric accuracy and optical performance in a linked manner, returning to the core function of HTM masks.

[0044] This embodiment also provides a verification method for the HTM repair process applied to the above-mentioned verification samples. Please refer to [link to relevant documentation]. Figure 4 This includes the following steps:

[0045] Dimensional accuracy verification steps: Perform key dimension measurements on the dimensional accuracy test structure and compare the difference between the CVD deposition pattern size and the design value; this difference value is the dimensional deviation index of the CVD repair process, and the smaller the deviation, the higher the dimensional control accuracy of the repair process.

[0046] Line edge straightness verification steps: Measure the width of the first seam in the line edge straightness test structure at multiple points and calculate its maximum / min range. Specifically, along the length of the first seam, select at least 5 equidistant or unequally spaced measurement points. Using a high-powered optical microscope, measure the seam width at each point sequentially, and record it as... , ... Calculate the maximum value among all measurements. and minimum value The difference between the two is the range that characterizes the straightness of the seam. The closer the range is to zero, the straighter the edge of the line formed by the repair process in the direction perpendicular to the line edge is.

[0047] Seam straightness verification step: Perform multi-point width measurements on the second seam in the seam straightness test structure and calculate its maximum / min range. The specific measurement and calculation methods are the same as the steps above. This step is used to independently evaluate the straightness of the repair process in the direction parallel to the seam edge.

[0048] ZAP Repair Effect Verification Steps: After performing ZAP laser scanning repair on the overlapping area, the width of the formed third seam is measured at multiple points, and its range is calculated to quantitatively evaluate the straightness of the ZAP repair. The measurement method is consistent with the aforementioned steps. This range value quantitatively reflects the straightness of the edge after laser repair, and can accurately capture microscopic defects such as burrs, over-cutting, or under-cutting that cannot be identified by traditional qualitative judgment methods, thus achieving a quantitative evaluation of the ZAP repair effect.

[0049] Transmittance consistency verification steps: Perform the HTM cleaning procedure on the verification sample, and use a spectrophotometer or a dedicated transmittance tester to measure the light transmittance of each test structure area before and after cleaning at 400nm or a specific exposure wavelength to verify the deviation from the target transmittance; wherein, the transmittance is 40%, and the difference in transmittance before and after cleaning is recorded.

[0050] Specifically, the initial transmittance is measured first. After cleaning, the transmittance of the same area was measured again. ,verify and Whether all fall within the target range of 35%-45%, and preferably, and Deviation from the target transmittance of 40%, and Compared to The absolute difference should be less than the preset tolerance deviation. If the transmittance drifts significantly after cleaning, it indicates that the repair material or repair area is not resistant to the cleaning process and there is a process risk. This step incorporates optical performance into the repair verification system to ensure that the repaired HTM mask not only meets the pattern size requirements, but also meets the core grayscale exposure requirements of the FPD lithography process.

[0051] Overall workflow:

[0052] The overall workflow of the present invention will be fully described below in conjunction with the above structure and steps.

[0053] When it is necessary to develop, calibrate, or control the yield of a certain HTM repair process in mass production, the operator can use a standardized verification sample provided by this invention, which integrates four types of test structures. This sample can cover all core verification dimensions at once, completely changing the fragmented mode of the traditional method that requires the separate production of multiple different samples and repeated testing, and greatly improving the standardization and efficiency of the verification process.

[0054] In the first step, the operator used the CVD deposition process to be verified to fill and repair the 20×20μm and 20×15μm spot patterns in the dimensional accuracy test structure. At the same time, the operator used the ZAP laser repair process to be verified to scan and remove the overlapping area in the ZAP repair straightness test structure according to the preset 2μm spot and scanning path. At this point, all the test structures on the sample were ready.

[0055] The second step is to verify the dimensional accuracy. The CD (cathode diametrical) measurement of the CVD-repaired spot pattern is performed, and the difference between the CD measurement and the design value is compared. This step directly quantifies the material filling accuracy of the CVD deposition process, providing objective data support for optimizing deposition parameters and improving the dimensional consistency of the repaired pattern.

[0056] The third step involves multi-mode straightness verification. The width of the first seam (perpendicular to the line edge), the second seam (parallel to the line edge), and the third seam (after ZAP repair) are measured at multiple points, and the range is calculated. Through quantitative analysis of the seam ranges in different directions, not only can the straightness of the repair process in each direction be comprehensively evaluated, but more importantly, thanks to a unique ZAP repair straightness testing structure, a quantitative evaluation of the ZAP laser repair effect is achieved for the first time. This structure can accurately and intuitively detect microscopic defects such as straightness, burrs, over-cutting, or under-cutting at the edges after laser repair, solving the technical problem in the industry of the inability to quantitatively evaluate the straightness of ZAP repairs.

[0057] The fourth step is to perform transmittance consistency verification. The repaired verification sample undergoes a standard cleaning procedure, and the light transmittance of each test structural area is measured before and after cleaning to verify whether it stably maintains a value close to the target of 40%. This step is another core innovation of this invention. It breaks through the one-sidedness of traditional mask verification, which only focuses on geometric dimension restoration, and links geometric dimension accuracy with optical transmittance performance for verification, returning to the core functional requirement of HTM mask grayscale exposure. By forcibly verifying the transmittance consistency before and after cleaning, the risk of performance degradation in the repaired area under multiple cleaning conditions on the production line can be effectively predicted, ensuring that the repaired mask truly meets the stringent requirements of the FPD lithography process.

[0058] Through the complete verification process described above, process engineers can obtain a set of multi-dimensional quantitative data covering dimensional accuracy, edge straightness, seam straightness, ZAP repair straightness, and optical transmittance stability. Based on the comprehensive evaluation conclusions formed by this data, engineers can quickly and accurately locate the defects in existing repair processes and optimize CVD deposition parameters or ZAP laser repair parameters accordingly. This effectively improves the stability and production yield of the HTM repair process and reduces the process risks and production costs of FPD panels.

[0059] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0060] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A verification sample for a half-color mask HTM repair process, characterized in that, Includes a substrate, on which: The dimensional accuracy test structure includes two specifications of spot patterns, used to verify the dimensional accuracy of CVD deposition repair. A line edge straightness test structure includes a test pattern, which is set on the right side of a sample line edge and forms a first line seam perpendicular to the line edge. A seam straightness test structure includes a test pattern, which is positioned above a sample line edge and forms a second seam parallel to the line edge. The ZAP repair straightness test structure includes two HTM patterns arranged opposite each other, with an overlapping area between the two HTM patterns. The overlapping area is configured to be removed by ZAP laser scanning with a specific spot, forming a third suture for evaluating the repair effect.

2. A verification sample for the half-color mask HTM repair process according to claim 1, characterized in that: The light spot pattern specifications in the dimensional accuracy testing structure are 20×20μm and 20×15μm.

3. A verification sample for the half-color mask HTM repair process according to claim 1, characterized in that: Both HTM patterns in the ZAP repair straightness test structure are 20×20μm rectangles.

4. A verification sample for the half-color mask HTM repair process according to claim 1, characterized in that: The halftone layer of the verification sample has a light transmittance of 35%-45%.

5. A verification sample for a half-color mask HTM repair process according to claim 4, characterized in that: The halftone layer has a light transmittance of 40%. The dimensional accuracy test structure, edge straightness test structure, seam straightness test structure, and ZAP repair straightness test structure on the substrate are all used to perform measurements before and after the cleaning process to verify the transmittance stability.

6. A verification method for applying the HTM repair process of the verification sample according to any one of claims 1-5, characterized in that, Includes the following steps: Dimensional accuracy verification steps: Perform key dimension measurements on the dimensional accuracy test structure and compare the difference between the CVD deposition pattern size and the design value; Line edge straightness verification steps: Perform multi-point width measurements on the first seam in the line edge straightness test structure, and calculate the maximum and minimum range of its value; Seam straightness verification steps: Perform multi-point width measurements on the second seam in the seam straightness test structure and calculate the maximum and minimum range of its values; ZAP repair effect verification steps: After performing ZAP laser scanning repair on the overlapping area, the width of the formed third seam is measured at multiple points, and its range is calculated to quantitatively evaluate the straightness of the ZAP repair. Transmittance consistency verification steps: Perform the HTM cleaning procedure on the verification sample and measure the light transmittance of each test structure area before and after cleaning to verify the deviation from the target transmittance.

7. The verification method according to claim 6, characterized in that: In the transmittance consistency verification step, the transmittance is 40%, and the difference in transmittance before and after cleaning is recorded.

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