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Mask inspection

About: Mask inspection is a research topic. Over the lifetime, 1072 publications have been published within this topic receiving 8696 citations.


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Patent
12 Nov 2010
TL;DR: In this paper, apparatuses, methods, and lithographic systems for holographic mask inspection are described, including an illumination source (330), a spatial filter (350), and an image sensor (380).
Abstract: Disclosed are apparatuses, methods, and lithographic systems for holographic mask inspection. A holographic mask inspection system (300, 600, 700) includes an illumination source (330), a spatial filter (350), and an image sensor (380). The illumination source being configured to illuminate a radiation beam (331) onto a target portion of a mask (310). The spatial filter (350) being arranged in a Fourier transform pupil plane of an optical system (390, 610, 710), where the spatial filter receives at least a portion of a reflected radiation beam (311) from the target portion of the mask. The optical system being arranged to combine (360, 660, 740) the portion of the reflected radiation beam (311) with a reference radiation beam (361, 331) to generate a combined radiation beam. Further, the image sensor (380) being configured to capture holographic image of the combined radiation beam. The image may contain one or more mask defects.

5 citations

Proceedings ArticleDOI
08 Oct 2018
TL;DR: In this article, a compact and accelerator-based light source with high brightness and stability for actinic mask inspection on EUV reticles is presented, which is based on the well-established components and design principles.
Abstract: One of the challenges of actinic metrology tools for EUV lithography is the availability of light sources with high brightness, stability, and availability. In particular, actinic patterned mask inspection on EUV reticles is considered an essential tool for the EUV lithography ecosystem and it requires an EUV source of high brightness. We present the design of a compact and accelerator-based light source producing EUV radiation with high-brightness for actinic metrology applications in the semiconductor industry. Our design is based on the well-established components and design principles. The specifications required for actinic mask inspection is achieved using a short period undulator and 430 MeV electron energy. The concentric design of storage and booster rings enables stable operation with a relatively small footprint. This study shows the commercial viability of a compact and high-brightness EUV source with high stability and reliability and demonstrates its feasibility for actinic metrology applications.

5 citations

Patent
28 Jul 1995
TL;DR: In this paper, a mask inspection equipment consisting of a first illuminator 2 for projecting the light vertically onto the surface of a mask, a second illuminators 3 for projecting light to the rear surface of the mask, and an optical sensor 6 for observing the mask 1, is presented.
Abstract: PURPOSE:To provide a mask inspection equipment in which the detection sensitivity can be equalized for a transparent defect and opaque defect. CONSTITUTION:The mask inspection equipment comprises a first illuminator 2 for projecting the light vertically onto the surface of a mask 1, a second illuminator 3 for projecting the light to the rear surface of the mask 1, an optical sensor 6 for observing the surface of the mask 1, means 5, 7, 15, 9, and 10 for attaining first or second image information from the output of the optical sensor 6, respectively, when only the first or second illuminator is operated, and means 11 for obtaining third image information by subjecting the first image information to correction of optical reflectance at the opaque part 17 of the mask 1. The mask inspection equipment further comprises means 12 for producing a fourth image signal by correcting the optical transmittance at the transparent part 16 of the mask 1 for the second image information, and means 13, 14 for producing the differential image information between the third and fourth image information.

5 citations

Proceedings ArticleDOI
05 Oct 2007
TL;DR: In this paper, a new captured image simulator based on RCWA was proposed to evaluate the sensitivity of the differential interference contrast (DIC) against bumps and divots with varying sizes.
Abstract: Recently, technologies of ArF laser exposure tools and alternating phase shifting masks (Alt-PSM) are expected to be used in actual production. To utilize such newly developed technologies, it is inevitable to develop a mask inspection technology to check them properly. But it is currently difficult to check them precisely because sufficient image contrast is hard to obtain with any conventional mask inspection tools. Among many observation methods, the differential interference contrast (DIC) is one of a few methods that can be used to observe a differentiated phase shift of transmitted light of an object with high resolution. To study precisely the performance of this optical configuration, we built a new captured image simulator in which Wollaston prisms were modeled as a kind of phase modulation plates. We built this simulator as an extension of the captured image simulator we reported formerly), which is based on Rigorous Coupled- Wave Analysis (RCWA) to calculate diffractions; this enables us to properly treat effects of polarization, high NA, and 3-dimensional mask structures. We applied this simulator to see sensitivities of DIC against bumps and divots with various sizes. We found that the image contrast for small phase defects 20 to 50 nm in sizes is much higher in DIC microscopes than in conventional optical setup with coherence factor less than 1. We also found the dependence of captured images on polarizations and optical axis directions. We expect our simulator to be a useful tool for studying, designing, and developing mask inspection tools.

5 citations

Patent
15 Dec 2000
TL;DR: In this paper, a projector for lithography includes a mask handling device, which can replace a mask between a load port module for receiving a mask and a mask holder, and an inspection module can detect the position of the mask.
Abstract: PROBLEM TO BE SOLVED: To get a mask handler, which brings about the rise of throughput of a board and the improvement of the maintenance cost of the device, by shortening the reticle replacement process very much SOLUTION: A projector for lithography includes a mask handling device, 10 for replacing a mask between a load port module for receiving a mask and a mask holder, and the mask handling device 10 has first and second robots 30 and 40 for executing the replacement The first robot 30 replaces a mask between a load port module 20 and the second robot 40, and the second robot 40 replaces a mask between the first robot 30 and a mask holder The first robot 30 can carry the mask to an internal mask library 50 or a mask inspection module This device replaces the mask between the first robot 30 and the second robot 40 or between the second robot 40 and the mask holder, a prealignment unit can detect the position of the mask

5 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202110
202016
201924
201819
201727
201632