Recent progress in electron-beam resists for advanced mask-making

Medeiros, David R.; Aviram, Ari; Guarnieri, C. R.; Huang, Wu‐Song; Kwong, Ranee W.; Magg, Christopher; Mahorowala, Arpan P.; Moreau, Wayne M.; Petrillo, Karen; Angelopoulos, Marie

doi:10.1147/rd.455.0639

Cited by 45 publications

(19 citation statements)

References 15 publications

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“…Although it represents a different type of exposure energy, e-beam lithography can still be used successfully to image chemically amplified resists of this type. [17] However, e-beam doses are difficult to correlate due to their strong dependence on feature density and size. These patterned films were developed in scCO 2 at a temperature of 35°C and pressure of 34 MPa for 3 min.…”

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confidence: 99%

High‐Resolution Patterning of Molecular Glasses Using Supercritical Carbon Dioxide

2006

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Continuous advances in the semiconductor and microfabrication industries are based on formation of increasingly smallscale devices. Photolithography, the process by which small features are patterned into a thin organic film (photoresist) by UV or electron-beam (e-beam) irradiation, is the principle process by which small features are formed. To produce the planned sub-50 nm features required for next-generation devices remains a challenge due to the increased importance of pattern perfection and elimination of problems such as pattern collapse in small, high-aspect-ratio features. At these very small dimensions, conventional development in an aqueous base can cause small, dense lines to collapse inward due to high surface tension. These and other problems will remain significant challenges unless new approaches to lithography are pursued. Supercritical carbon dioxide (scCO 2 ), which is known for its properties of high diffusivity and zero surface tension, is an ideal alternative to aqueous bases as an advanced development solvent and can help to realize the potential of sub-50 nm patterning.Supercritical CO 2 development is a powerful alternative process to aqueous-base or organic-solvent development for high-resolution patterning from both an environmental and practical point of view. In practice, scCO 2 is a single-phase fluid that exists above the critical temperature and pressure of CO 2 (T = 31°C, P = 7.4 MPa). Supercritical CO 2 as a solvent can provide environmental benefits, which result from a reduction in solvent and water waste, and it may also serve as a platform where harmful solutes are easily separated from the solvent in question (via depressurization). scCO 2 has been shown to be an ideal solvent for processing structures on the nanoscale. [1,2] In terms of performance, scCO 2 is a solvent with zero surface tension and high diffusivity. This leads to better development characteristics compared to liquid solvents for dense, high-aspect-ratio features. However, scCO 2 tends to be a very poor solvent for polymers, such as those that current photoresists are comprised of; though certain fluoropolymers and silicones have been shown to be soluble at moderate supercritical conditions. [3,4] This would necessitate the incorporation of groups, such as fluorinated side chains, into photoresist materials to effect scCO 2 solubility. Despite the advantages of scCO 2 development, there are several reasons that make the incorporation of fluorine in scCO 2 developable resists undesirable. Usually the large quantities of fluorine present in scCO 2 -soluble polymers degrade plasma-etch resistance and are undesirably expensive. Also, due to their persistent nature, fluorinated compounds are coming under increased scrutiny [5] and their use needs to be phased out. Finally, although scCO 2 -soluble polymeric resists based on fluoropolymer platforms have been studied in recent years, [6,7] no features smaller than 100 nm have been demonstrated. Regardless of exposure method, these materials have not shown sufficien...

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High‐Resolution Patterning of Molecular Glasses Using Supercritical Carbon Dioxide

2006

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“…As shown in Figure 1, the contrast for P5 and ZEP are very similar, however P1 and P2 are much more sensitive requiring nearly two orders of magnitude less dose to develop. 5 Although the contrast for P1 for the investigated conditions is poor, subsequent work was able to demonstrate good contrast. P2 displays higher contrast than P5 and ZEP.…”

Section: Contrast Curvesmentioning

confidence: 83%

Fluorinated polymethacrylates as highly sensitive nonchemically amplified e-beam resists

Strahan

Adams

Jen

et al. 2009

J. Micro/Nanolith. MEMS MOEMS

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In an effort to improve upon the sensitivity of commercial non-chemically amplified e-beam resists, four polyacrylates functionalized with α-CF 3 and/or CH 2 CF 3 alkoxy substituents were studied. The α-CF 3 substituent is known to increase backbone-scission efficiency while simultaneously eliminating acidic out-gassing and cross-linking known to occur in α-halogen substituted polyacrylates. Contrast curves for the polymeric α-CF 3 acrylates, generated through e-beam exposure, showed the resists required an order of magnitude less dose than the current industry-standards, PMMA and ZEP. The fundamental sensitivity of these materials to backbone scissioning was determined via 60 Co γ-ray irradiation. The chain scissioning, G(s), and cross-linking, G(x), values calculated from the resulting change in molecular weight demonstrated that all fluorinated resists possess higher G(s) values than either PMMA or ZEP and have no detectable G(x) values. Utilizing e-beam and EUV interference lithographies, the photospeed of PMTFMA was found to be 2.8x and 4.0x faster, respectively, than PMMA.

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“…[7f, 28] The practical resolution of this technique is mainly determined by the spot size of the beam, and several other factors such as scattering effects and the generation of secondary electrons. Poly(methyl methacrylate) (PMMA) remains a classical resist for e-beam lithography, and much work continues to be done with this polymer despite extensive technological advances and development in e-beam lithography, and the large number of resist formulations that have been developed.…”

Section: Writing With a Beam Of Photons Or Other Energetic Particlesmentioning

confidence: 99%

Patterning: Principles and Some New Developments

Geißler

Xia²

2004

Advanced Materials

608

463

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This article provides an overview of various patterning methodologies, and it is organized into three major sections: generation of patterns, replication of patterns, and three‐dimensional patterning. Generation of patterns from scratch is usually accomplished by serial techniques that are able to provide arbitrary features. The writing process can be carried out in many different ways. It can be achieved using a rigid stylus; or a focused beam of photons, electrons, and other energetic particles. It can also be accomplished using an electrical or magnetic field; or through localized add‐on of materials such as a liquid‐like ink from an external source. In addition, some ordered but relatively simple patterns can be formed by means of self‐assembly. In replication of patterns, structural information from a mask, master, or stamp is transferred to multiple copies with the use of an appropriate material. The patterned features on a mask are mainly used to direct a flux of radiation or physical matter from a source onto a substrate, whereas a master/stamp serves as the original for replication based on embossing, molding, or printing. The last section of this article deals with three‐dimensional patterning, where both vertical and lateral dimensions of a structure need to be precisely controlled to generate well‐defined shapes and profiles. The article is illustrated with various examples derived from recent developments in this field.

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Recent progress in electron-beam resists for advanced mask-making

Cited by 45 publications

References 15 publications

High‐Resolution Patterning of Molecular Glasses Using Supercritical Carbon Dioxide

High‐Resolution Patterning of Molecular Glasses Using Supercritical Carbon Dioxide

Fluorinated polymethacrylates as highly sensitive nonchemically amplified e-beam resists

Patterning: Principles and Some New Developments

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