X-Ray Lithography: A Complementary Technique to Electron Beam Lithography

Smith, Henry I.; Spears, D. L.; Bernacki, S. E.

doi:10.1116/1.1318514

Cited by 66 publications

(14 citation statements)

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“…Deep uv lithography 2 started with proximity printing. Same is <1-nm x-ray 14,3 . E-beam also took advantage of proximity printing 15,16 .…”

Section: The Proximity Printing Leg Of the Horsesmentioning

confidence: 98%

Marching of the microlithography horses: electron, ion, and photon: past, present, and future

Lin

2007

SPIE Proceedings

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Microlithography patterning employs one of three media; electron, ion, and photon. They are in a way like horses, racing towards the mainstream. Some horses such as electrons run fast but repel each other. Ion beams behave like electron beams but are less developed. The photon beam is the undisputed workhorse, taking microlithography from the 5-µm minimum feature size to 32-nm half pitch. This paper examines the history of microlithography in pattern generation, proximity printing, and projection printing, then identifies the strong and weak points of each technology. In addition to ion-beam and e-beam lithography, the coverage of optical lithography spans the wavelength from 436 to 13.5 nm. Our learning from history helps us prevent mistakes in the future. In almost all cases, making or using the mask presents one of the limiting problems, no matter the type of beams or the replication method. Only the maskless method relieves us from mask-related problems. A way to overcome the low throughput handicap of maskless systems is to use multiple e-beam direct writing, whose imaging lens can be economically and compactly fabricated using MEMS techniques.In a way, the history of microlithography parallels that of aviation. Proximity printing is like the Wright-Brothers' plane; 1X projection printing, single-engine propeller plane with unitized body; reduction step-and-repeat projection printing, multi-engine commercial airliner; scanners, jet airliners. Optical lithography has improved in many ways than just increasing NA and reducing wavelength just as the commercial airliners improving in many other areas than just the speed. The SST increased the speed of airliners by more than a factor of two just as optical resolution doubled with double exposures. EUV lithography with the wavelength reduced by an order of magnitude is similar to the space shuttle increasing its speed to more than 10 times that of the SST. Multiple-beam direct write systems are like helicopters. They do not need airports(masks) but we need a lot of beams to carry the same payload.Keywords: Microlithography, e-beam lithography, ion-beam lithography, optical lithography, x-ray lithography, EUV lithography, microlithography history, microlithography outlook IntroductionMicrolithography, a specific technology used to pattern IC circuits as early as 1958, is coming to its 50 th anniversary. Initially, it was as straightforward as ancient-day lithographers replicating patterns carved in stone masks. However, as circuit dimensions continued to shrink, more care had to be taken for microlithography. Very early on, people recognized that there was a limit to photon-based patterning techniques, higher energy particles or shorter wavelengths such as electrons and ions were proposed as the patterning carrier. "Optical techniques for fabricating devices are generally limited to > 5 µm linewidths in practical production by the diffraction effects", according to Herriot 1 in 1975. He must have in mind proximity printing at a large mask-to-wafer gap using near-uv...

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“…Deep uv lithography 2 started with proximity printing. Same is <1-nm x-ray 14,3 . E-beam also took advantage of proximity printing 15,16 .…”

Section: The Proximity Printing Leg Of the Horsesmentioning

confidence: 98%

Marching of the microlithography horses: electron, ion, and photon: past, present, and future

Lin

2007

SPIE Proceedings

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“…As the base substrate, a polished graphite sheet with a thickness of 2000 µm was spin-coated four times using a liquid-type PMMA C9 before bonding with the PMMA. The graphite sheet exhibits a high adhesion ability with PMMA as well as a low back-scattering effect during X-ray exposure [20]. With these advantages, the graphite was adhered to the PMMA photoresist using methyl methacrylate (MMA; Sigma Aldrich, St. Louis, MO, USA).…”

Section: Hard X-ray Lithography Processmentioning

confidence: 99%

Microfabrication of Ni-Fe Mold Insert via Hard X-ray Lithography and Electroforming Process

Park

Shin

et al. 2020

Metals

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In this research, a Ni-Fe mold insert for the efficient replication of high aspect-ratio microstructure arrays was fabricated via hard X-ray lithography and an electroforming process. For the X-ray exposure on a photoresist, a gold-based X-ray mask was prepared with conventional UV photolithography. The gold thickness was designed to be over 15 μm to prevent development underneath the absorber and to enhance the adhesion strength between the photoresist and substrate. By using the X-ray mask, a positive-type photoresist was selectively exposed to X-ray under an exposure energy of 4 kJ/cm3. Thereafter, the exposed region was developed in a downward direction to effectively remove the residual photoresist from the substrate. During the evaporation process, deionized water mixed with a surface additive prevented the bending and clustering of the photoresist microstructure arrays by lowering the capillary force, resulting in a defect-free mother structure for electroforming. Lastly, the mother structure was uniformly Ni-Fe electroformed on a conductive substrate without the formation of any pores or detachment from the substrate. Based on the proposed microfabrication process, a Ni-Fe mold insert with a 183 μm pattern size, 68 μm gap size, 550 μm height, 2116 microcavities and a hardness of 585 Hv was precisely manufactured. It can be utilized for the mass production of high aspect ratio metal and ceramic microstructure arrays in micro molding technologies.

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“…The first devices made using x-ray lithography were surface acoustic wave devices, 22 and this was soon followed by bipolar 23 and metal-oxide semiconductor ͑MOS͒ transistors. 24 The first sub-100 nm Si transistors were made using x-ray lithography, 25 and velocity overshoot was observed as well as intrinsic transconductances greater than 1 S/mm.…”

Section: Device Research Using X-ray Lithographymentioning

confidence: 99%

100 years of x rays: Impact on micro- and nanofabrication

Smith

1995

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Hard x-ray phase zone plate fabricated by lithographic techniquesIn November of 1895 Wilhelm C. Röntgen observed fluorescence caused by invisible rays emanating from a discharge tube. This discovery of x rays was not a mere happenstance; Röntgen was a highly skilled experimentalist, well prepared to launch a series of clever experiments and startle the world with the announcement of ''a new kind of ray.'' The practice of medicine was transformed, and the era of modern physics inaugurated. X rays have proven essential to the probing of atomic, molecular, and solid-state structures. X-ray astronomy has revealed some of the most exotic and violent phenomena in the universe, including the black holes. X-ray microscopy provides information complementary to what is obtainable from optical and electron microscopies. In microand nanolithography x rays provide high quality aerial images and simple processing, in part because of an absence of spurious scattering, something that Röntgen himself observed. However, application in ultralarge scale integrated ͑ULSI͒ manufacturing is still uncertain for a variety of reasons, primarily because ultraviolet optical-projection lithography continues to satisfy commercial needs. X-ray lithography may find application in areas outside the ULSI industry, for example in optoelectronics, flat-panel displays, and magnetic data storage. It has the intrinsic resolution to reach the practical limits of the lithographic process, around 20 nm. However, to approach this limit diffraction blurring must be avoided by reducing the mask-sample gap below 5 m, which may not be acceptable in manufacturing. In this event, and in order to retain the lithographic qualities of 1 nm wavelength radiation, projection with Fresnel zone plate arrays could be employed.

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X-Ray Lithography: A Complementary Technique to Electron Beam Lithography

Cited by 66 publications

References 0 publications

Marching of the microlithography horses: electron, ion, and photon: past, present, and future

Marching of the microlithography horses: electron, ion, and photon: past, present, and future

Microfabrication of Ni-Fe Mold Insert via Hard X-ray Lithography and Electroforming Process

100 years of x rays: Impact on micro- and nanofabrication

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