Mask Repair Research Articles

Progressive mask‐oriented unsupervised fabric defect detection under background repair

AbstractDetection of defects is an essential quality control method in fabric production. Unsupervised deep learning‐based reconstruction algorithms have recently been deeply concerned owing to scarce fabric defect samples, high annotation cost, and deficient prior knowledge. Most unsupervised reconstruction models are prone to overfitting and poor generalisation performance, resulting in blurred images, residual defects, and uneven textures in the reconstruction results. On this account, an unsupervised fabric surface defect detection method using the Progressive Mask Repair Model (PMRM) has been developed. Specifically, PMRM with transformer architecture gathers detailed feature information. In order to pay closer attention to the textural properties of fabrics, the model incorporates structural similarity as a constraint in the training stage. In the detection stage, we designate the non‐defective area of the fabric image as the background and the defective area as the foreground. Next, a progressive mask is applied to repair the background of the defective area, which avoids defect false detection resulting from the poor reconstruction effect of the traditional reconstruction model in the non‐defective area. Finally, image processing methods such as image difference, frequency‐tuned salient detection, and threshold binarisation are used to segment the defects. Relative to the other six unsupervised defect detection methods, the proposed scheme increases the F1 score and intersection over union (IoU) by at least 9.34% and 8.49%, respectively. According to the earlier results, PMRM is effective and exhibits superiority.

Nanoscale Ruthenium-Containing Deposits from Ru(CO)4I2 via Simultaneous Focused Electron Beam-Induced Deposition and Etching in Ultrahigh Vacuum: Mask Repair in Extreme Ultraviolet Lithography and Beyond

Nanoscale Ruthenium-Containing Deposits from Ru(CO)₄I₂ via Simultaneous Focused Electron Beam-Induced Deposition and Etching in Ultrahigh Vacuum: Mask Repair in Extreme Ultraviolet Lithography and Beyond

Pushing the limits of EUV mask repair: addressing sub-10 nm defects with the next generation e-beam-based mask repair tool

Mask repair is an essential step in the manufacturing process of extreme ultraviolet (EUV) masks. Its key challenge is to continuously improve resolution and control to enable the repair of the ever-shrinking feature sizes on mask along the EUV roadmap. The state-of-the-art mask repair method is gas-assisted electron-beam (e-beam) lithography also referred to as focused electron-beam induced processing (FEBIP). We discuss the principles of the FEBIP repair process, along with the criteria to evaluate the repairs, and identify the major contributions determining the achievable resolution. As key results, we present several high-end repairs on EUV masks including a sub-10-nm extrusion achieved with the latest generation of e-beam-based mask repair tools, the MeRiT® LE. Furthermore, we demonstrate the corresponding repair verification using at-wavelength (actinic) measurements.

Advanced photolithographic mask repair using electron beams

Mask repair plays an important role in yielding advanced masks that support the lithography roadmap. It is also one of the more challenging parts of mask fabrication. Electron beam induced deposition and etching have shown great potential for mask repair applications. Our work has demonstrated that e-beam mask repair provides the superior resolution and damage-free process that is needed to support mask generations for the 32nm technology node and beyond. This article describes an installed e-beam mask repair tool at Intel Mask Operation and discusses the capabilities of this enabling technology based on results obtained from repairing masks with “defects” intentionally inserted into the design (programmed defect masks). Specifically, results are presented for quartz etch repair of alternating phase shift masks and TaBN absorber etch of extreme ultraviolet masks, two of the most difficult types of mask to repair using conventional methods.

Laser Mask Repair System for the Recent Semiconductor and LCD Manufacturing

Laser mask repair system is a machine to repair defects of photomasks by laser zapping and laser CVD (Chemical Vapor Deposition). Laser zapping and laser CVD are briefly explained. Our laser mask repair systems LM700A, LM710A and LM500A/B are explained. LM700A/LM710A has been developed to repair defects of reticles used for 130/100 nm node semiconductor devices and LM500A/B has been designed for large scale photomasks used for the LCD manufacturing.

UV Laser Deposition of Thin Films at 248 NM for Phase Shifting Mask Repair

AbstractLaser-induced deposition of controlled quality silicon dioxide and thin metallic films was investigated at 248 nm for phase shifting mask (PSM) repair. SiOx (x-1.5-2) films were deposited from single precursors, such as triethoxyvinylsilane (TEVS), tetraallyloxysilane (TAOS), di-t-butoxy-diacetooxysilane (TBSA) with no oxidizing coreactant. A deposition rate of 0.25 A/pulse was possible at room temperature, with excellent optical properties (n-1.47, k-0.05). Metallic films were deposited from tungsten, gold, molybdenum and chromium compounds. The results showed that the optical transmission and phase-shifting properties of the deposits can be matched well to the films commonly used in phase shifting masks.

Diagonal Phase Errors Affecting Optical Intensity in Phase Defect Repair Elements

The phase shift method (PSM) improves practical resolution in optical lithography, but phase defects in masks significantly degrade image integrity. Mask repair reduces the effects of these defects by satisfying both phase step and diagonal phase conditions. Repair methods optimized for phase defects of π/2 and π are discussed. Analysis of diagonal phases in the vicinity of defects has been used to determine the approprinate conditions for restoring optical intensity. Repair elements are produced using a simple focused ion beam (FIB) milling process. The location and phase of each repair element are optimized to reduce the required number of repair elements. Effectiveness of the repair technique is verified using an i-line resist process.

Materials Issues In X-Ray Mask Repair by Focused Ion Beams

AbstractIn x-ray mask repair high Z absorber features, such as gold or tungsten, must be removed or added. The main challenges are the small lateral dimensions (0.25 μm and below) and the thickness of the absorbers (˜ 0.5 μm) The focused ion beam appears to be the best tool developed to meet this challenge. Unwanted features are removed by ion milling while missing absorber is reconstructed using ion induced deposition from a locally piped-in precursor gas. The high aspect ratio of the features complicates both of these processes. Milling away 0.5 μm thick absorber can lead to redeposition of the sputtered material on neighboring features. The crystal grains of the absorber mill at different rates depending on orientation which results in nonuniform features. A possible alternative which only works with W absorber is to use ion assisted etching. In ion induced deposition a precursor gas such as dimethylgold hexafluoro acetylacetonate is provided by a capillary tube aimed at the region scanned by the ion beam. The incident Ga+ ions, usually at energies in the 25–100 keV range, dissociate the adsorbed precursor molecules leaving a deposit of gold mixed with carbon. The carbon content can approach 50 atomic % resulting in an x-ray attenuation which is about one half of that of pure gold. A number of unexplored materials science issues are associated with mask repair including: the reduction of the carbon content, redeposition both from milling and from induced deposition, milling as a function of crystal orientation and energy, and deposition of high aspect features. The technology is well enough developed so that mask repair of 0.25 μm features can be considered. However, a better understanding of the materials science aspects of x-ray mask repair will help to advance the state-of-the-art.

Focused Ion Beam Assisted Etching of Quartz in XeF2 without Transmittance Reduction for Phase Shifting Mask Repair

Focused ion beam (FIB) assisted etching of quartz by a Ga FIB and XeF2 gas was studied for the purpose of avoiding the transmittance reduction by a Ga FIB. Transmittance was above 99% with the existence of XeF2 to the extent that the etching yield was more than 1.7 times larger than that of sputtering. It was also found that postetching above 15 nm by a Ga FIB and XeF2 gas after the Ga ion implantation recovered the transmittance. These techniques will be applied to repairing phase shifting masks without transmittance reduction.

Direct patterning using metallo‐organics and its application to mask repair

AbstractAu patterns are formed by photographical patterning of polymeric Au mercaptoterpenes (Au resinate), followed by bakeout of the Au resinate patterns to remove carbonaceous materials. Since commercially available Au resinate is not sensitive to 436 nm (g‐line) light and cannot be photographically patterned, we mixed azide (photocrosslinker) with Au resinate to give photosensitivity to the g‐line. The mixture of Au resinate and azide was spun on an Si substrate, and then exposed with 436 nm (g‐line) light by a standard contact printing technique. Upon exposure, Au resinate was crosslinked by the reaction with azide, and became insoluble. Au resinate patterns were generated by development with monochlorobenzene. On baking out the Au resinate patterns to remove carbonaceous materials, we obtained 2 μm line and space Au patterns. The conductivity of the Au patterns obtained was 1/4 that of bulk Au. For a mask repair application, we mixed Cr resinate with a mixture of Au resinate and azide to improve the adhesion of the resulting metal patterns onto the quartz plate. The transmittance and the adhesion were found to depend on the bakeout condition and the mixing ratios of the Cr resinate. Bakeout in vacuum with 0.1 torr oxygen gave far better adhesion and opaqueness than bakeout in air, because of residual carbon in the resultant metal. Mask repair was carried out at the optimized condition by using a spot exposure system. The clear defect was repaired with the transmittance < 1% and good adhesion.

Simulation of X-Ray Mask Repair by Means of FIB-Technology

The angular dependence of the sputter yield of a 100 keV gallium FIB (focused ion beam) on gold was determined by evaluating the sufficient ion dose for complete removal of a 0.8 µm thick electroplated gold layer. For two angles of incidence (0°, 45°), the redeposition characteristics of sputtered gold particles were measured. They can be approximated by a cos2 function. With these data included, simulations of FIB-processes were carried out, both concerning the structuring of III-V compounds and the repair of opaque defects in X-ray masks. By parameter variation in the simulations, the sticking coefficient of sputtered gold particles was found to be µ=0.5±0.1.

X-ray mask repair by electron beam induced metal deposition

The electron beam induced metal deposition is a powerful technique to repair clear X-ray mask defects in the sub-μm range. The initial growth rate of dots deposited at 10 keV e-beam energy and 3 nA/μm 2 current density was 10 nm/sec. Dots of different heights were exposed to synchroton radiation. Dot growth times of 150 sec gave sufficient X-ray contrast for pattern transfer into HPR 204 resist. Mask repair is demonstrated on a test structure by closing clear defects and adding lines. The spatial resolution of deposited structures is ⩽ 500 nm with aspect ratios up to 6.

Mask Repair Using Focused Ion Beam Technology

Mask Repair Using Focused Ion Beam Technology

Mask and circuit repair applications of focused ion beam deposition

Mask and circuit repair applications of focused ion beam deposition