Some aspects on mechanisms responsible for contamination of optical components in DUV lithographic exposure tools

Fosshaug, Hans; Ekberg, Mats; Kylberg, Gunnar

doi:10.1117/12.600312

Cited by 8 publications

(5 citation statements)

References 31 publications

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“…Fosshaug et al [5] provides a detailed description of the multiple laser interactions occurring to initiate LIC. First, covering the interaction between the UV laser-light and the glass surface by pointing to experiments [6] showing that light-induced "prenucleation" occurs by photolysis of a molecular adlayer, forming radicals at the surface.…”

Section: Lic Initiation and Developmentmentioning

confidence: 99%

UV fatigue of laser optics: laser-induced contamination

Arnold¹,

Rashvand²,

Willis³

et al. 2022

Laser-Induced Damage in Optical Materials 2022

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Laser-induced contamination (LIC) can be a major concern of using UV laser systems. Surface contamination occurs via interactions between the UV laser and particulates, water vapor condensate, organics, and airborne molecular contaminates (AMC) from the environment or outgassing from system materials. A brief review of contamination of optics will lead into present results from long-term 355 nm quasi-CW laser transmission experiments at Edmund Optics. Time lapse microscopy was used to monitor nucleation and growth of surface contaminants. Laser burn boxes were constructed for use as a controlled UV LIC testbed; experimental results are presented on transmission losses for various material preparation methods.

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Section: Lic Initiation and Developmentmentioning

confidence: 99%

UV fatigue of laser optics: laser-induced contamination

Arnold¹,

Rashvand²,

Willis³

et al. 2022

Laser-Induced Damage in Optical Materials 2022

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show abstract

Section: Introductionmentioning

confidence: 99%

“…Because airborne molecular contamination during the lithographic process is the biggest problem causing lens contamination, 2 the sensitivity of the lithographic process to airborne molecular contamination is recognized as one of the most challenging issues affecting the next generation of submicron geometries. [3][4][5][6] During the early 2000s, an argon fluoride light source with a short wavelength of 193 nm and a high energy of 148 kcal∕mol was developed. 7 However, as the power of the light source was increased, more types of contaminants were activated.…”

Section: Introductionmentioning

confidence: 99%

Air shield system to reduce lens contamination in optical lithography based on turbulence simulation

Jung

Hong

Suk

et al. 2022

J. Micro/Nanopattern. Mats. Metro.

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The development of optical lithographic technology made important contributions to miniaturization. In optical lithography, it is critical to maintain high uniformity and high resolution of patterning on a silicon substrate by exposing the substrate to ultraviolet (UV) light. However, lens contamination limits the uniformity of the exposed UV light, and the effect of lens contamination on the critical dimension is increasing as electronic devices become smaller. Lens contamination can be generated by turbulence of clean air (CA) and it gradually accelerates over time. In this work, we suggest the extreme clean dry air (XCDA) shield system to reduce lens contamination in optical lithography. We have measured and analyzed the contaminants of a practical lithography lens through time-of-flight secondary mass spectrometry, and the expected contamination mechanism is also shown. Also, we simulated turbulence of CA in practical lithography based on the shield k-epsilon turbulence model. Turbulence simulations not only quantitatively showed the effects of XCDA and CA on lens contamination but also demonstrated that the lens could be directly purged with the XCDA shield system to prevent turbulence of CA. The XCDA shield system reduced the degree of contamination by 33% compared with the conventional level. We believe that the proposed system will provide high efficiency in the optical lithography industry.

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“…Therefore AMC limits within such lithography devices and its controlled environments have continuously been tightened. [11][12][13] The trend of AMC limits can easily been followed in the ITRS roadmap (International Technology Roadmap for Semiconductors).…”

Section: Introductionmentioning

confidence: 99%

Airborne molecular contamination: quality criterion for laser and optical components

Otto¹

2015

SPIE Proceedings

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Airborne molecular contaminations (AMCs) have been recognized as a major problem in semiconductor fabrication. Enormous technical and financial efforts are made to remove or at least reduce these contaminations in production environments to increase yield and process stability. It can be shown that AMCs from various sources in laser devices have a negative impact on quality and lifetime of lasers and optical systems. Outgassing of organic compounds, especially condensable compounds were identified as the main source for deterioration of optics. These compounds can lead to hazing on surfaces of optics, degradation of coating, reducing the signal transmission or the laser signal itself and can enhance the probability of laser failure and damage. Sources of organic outgassing can be molding materials, resins, seals, circuit boards, cable insulation, coatings, paints and others. Critical compounds are siloxanes, aromatic amines and high boiling aromatic hydrocarbons like phthalates which are used as softeners in plastic materials. Nowadays all sensitive assembly steps are performed in controlled cleanroom environments to reduce risks of contamination. We will demonstrate a high efficient air filter concept to remove AMCs for production environments with special AMC filters and methods for the qualification and monitoring of these environments. Additionally, we show modern techniques and examples for the pre-qualification of materials. For assembled components, we provide sampling concepts for a routine measurement for process, component and product qualification. A careful selection of previously tested and certified materials and components is essential to guarantee the quality of lasers and optical devices.

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Some aspects on mechanisms responsible for contamination of optical components in DUV lithographic exposure tools

Cited by 8 publications

References 31 publications

UV fatigue of laser optics: laser-induced contamination

UV fatigue of laser optics: laser-induced contamination

Air shield system to reduce lens contamination in optical lithography based on turbulence simulation

Airborne molecular contamination: quality criterion for laser and optical components

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