Mechanism of Resist Pattern Collapse

Tanaka, Toshihiko; Morigami, Mitsuaki; Atoda, Nobufumi

doi:10.1149/1.2220782

Cited by 48 publications

(46 citation statements)

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“…For most current resist technologies with feature aspect ratios above four, development or rinsing with liquid solvents can lead to pattern collapse caused by the force of surface tension of the liquid/air interface acting on the image sidewalls. [18] This inward force causes features of high aspect ratio to topple onto one another, thereby rendering the pattern useless. Supercritical fluids avoid this problem because the fluid is entirely one phase, and therefore there is no liquid/air interface.…”

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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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confidence: 99%

High‐Resolution Patterning of Molecular Glasses Using Supercritical Carbon Dioxide

2006

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“…Here, a mechanism of the forming the concave structure is considered by referring to a collapsing model of resist pillars which upstanding on Si wafer [19,20]. The collapsing of the pillars is caused by the Laplace pressure acting as the cohesive force between pillars at the drying with a rinse liquid.…”

Section: Resultsmentioning

confidence: 99%

“…A mechanism about the formation was discussed with a collapsing model of resist patterns at the drying [19,20].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Concave and Convex Structure Array Consisted of Epoxy Long-Nanowires by Light and Heavy Ion Beams Lithography

Takano

Sugimoto

Asano

et al. 2012

Trans. Mat. Res. Soc. Japan

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New microprocessing method with a combination of Proton Beam Writing (PBW) and Single Particle Nanofabrication Technique (SPNT) was demonstrated to control a location and a shape on cohering epoxy nanowires. The feature of this method is to utilize a flame structure which is able to rectify the solvent flow at the development and drying. At first, flame array with a rectification for solvent flows were fabricated by the PBW using SU-8 photoresist films. And next, long nanowires with the length over 50 µm were obliquely formed on these flames by heavy beam with the energy of hundreds MeV. In the case of the overwriting on the passage-type flame, concave structures which consist of the nanowires were formed with matrix array. On the other hand, convex structures were formed among the each cavity-type flame. It was shown that the polymer nanowires were can be controlled the cohering shape and the fixing at designed locations by the flames to rectify the solvent flow.

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“…PDMS has proven to be an outstanding material for micro-and high-aspect ratio [87][88][89]. In structures fabricated by microcontact printing or replica molding, which can possess residual physical stresses from the molding procedure, collapse of structures begins to occur at an aspect ratio of -2 [80,89].…”

Section: Fabrication Processmentioning

confidence: 99%

Hypersonic phononic crystals

Gorishnyy¹,

Ullal²,

Maldovan³

et al. 2006

The Journal of the Acoustical Society of America

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Manipulation of the distribution of phonons ini a solid is important for both basic science and applications ranging from heat management to reduction of noise in electronic circuits and creating materials with superior acoustic and acousto-optical properties. This thesis explores hypersonic phononic crystals as means to achieve control over high frequency acoustic phonons. An integrated approach to fabrication, measurement and analysis of hypersonic phononic crystals with band gaps in the GHz range is presented.First, the phonon dispersion relation for one dimensional polymeric phononic crystals fabricated by coextrusion of a large number of poly(methylmethacrylate)/poly(carbonate) and poly(methylmethacrylate)/poly(ethylene terephthalate) bilayer pairs is investigated as a function of a lattice constant and composition using Brillouin light scattering and numerical simulations. This set of relatively simple multilayer structures represents an excellent platform to gain a basic understanding of phononic band gap phenomena. In addition, their in-plane phonon dispersion is used to extract information about the elastic constants and glass transition temperatures of individual nanolayers in a periodic multilayer arrangement. Next, two dimensional epoxy/air phononic crystals fabricated in a photoresist using interference lithography are studied. These structures are 2D single crystalline, enabling direction-resolved measurements of their phonon dispersion relation. with performance characteristics that can be adjusted dynamically during operation. The investigations described in this thesis demonstrate both theoretically and experimentally that 1D, 2D and 3D periodic submicron structures have complex phonon dispersion relations at GHz frequencies. As a result, these crystals can be used to manipulate the flow of random thermal phonons as well as externally generated acoustic waves resulting in novel acoustic and thermal properties.

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Mechanism of Resist Pattern Collapse

Cited by 48 publications

References 0 publications

High‐Resolution Patterning of Molecular Glasses Using Supercritical Carbon Dioxide

High‐Resolution Patterning of Molecular Glasses Using Supercritical Carbon Dioxide

Fabrication of Concave and Convex Structure Array Consisted of Epoxy Long-Nanowires by Light and Heavy Ion Beams Lithography

Hypersonic phononic crystals

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