Nanosize fabrication using etching of phase-change recording films

Shintani, Toshimichi; Anzai, Yumiko; Minemura, Hiroyuki; Miyamoto, Hiroyuki; Ushiyama, Junko

doi:10.1063/1.1775889

Cited by 55 publications

(47 citation statements)

References 6 publications

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“…Laser thermal lithography [1] has recently attracted substantial attention as a new lithography technique for nanostructure fabrication because of its potential application in low-cost manufacturing of high-density ROM disk mastering [2,3], small-lot microelectromechanical systems [4], nanophotonic devices [5], and light-emitting diodes [6]. In thermal lithography, when a laser beam is irradiated directly onto the thermal lithography film, changes in the physical and chemical properties of the film take place because of the photo-induced thermal change effect, e.g., amorphouscrystalline state transformation, resulting in a difference in the etching rate between the two states.…”

Section: Introductionmentioning

confidence: 99%

“…Compared with organic resist materials, inorganic resist materials generally exhibit a high resolution and a clear, regular, and steep edge profile at the boundary after etching due to their light molecular weight and narrow temperature change transition region [7,8]. In recent years, several inorganic resist materials, which include phase-change films, such as Ge-Sb-Te, Te-O, ZnS-SiO 2 or Ge-Sb-Sn-O, and metal oxide films, such as W-O or Mo-O, have been developed [2,3,[9][10][11]. Clear pattern profile and regular pits or dots on the Te-O and ZnS-SiO 2 phase-change films are obtained.…”

Section: Introductionmentioning

confidence: 99%

“…Dots of 40 nm in size can be observed on the Ge 2 Sb 2 Te 5 phase-change film, nearly 1/10 of the spot size. However, some issues remain for the Ge-Sb-Te films that limit their practical application, such as slow etching rate of 27 nm/h [12], small etching selectivity of 5 [12], larger surface roughness of 14 nm [13], and irregular dot shape [2]. To address these problems, discovering new laser lithography materials with superior performance is necessary.…”

Section: Introductionmentioning

confidence: 99%

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Selective etching characteristics of the AgInSbTe phase-change film in laser thermal lithography

Geng

2012

Appl. Phys. A

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In the current work, the etching selectivity of the AgInSbTe phase-change film in laser thermal lithography is reported for the first time. Film phase change induced by laser irradiation and etching selectivity to crystalline and amorphous states in different etchants, including hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, sodium hydroxide, sodium sulfide, ammonium sulfide and ammonium hydroxide, are investigated. The results indicated that ammonium sulfide solvent (2.5 mol/L) had excellent etching selectivity to crystalline and amorphous states of the AgInSbTe film, and the etching characteristics were strongly influenced by the laser power density and laser irradiation time. The etching rate of the crystalline state of the AgInS- bTe film was 40.4 nm/min, 20 times higher than that of the amorphous state under optimized irradiation conditions (power density: 6.63 mW/μm 2 and irradiation time: 330 ns), with ammonium sulfide solvent (2.5 mol/L) as etchant. The step profile produced in the selective etching was clear, and smooth surfaces remained both on the step-up and stepdown with a roughness of less than 4 nm (10 × 10 μm). The excellent performance of the AgInSbTe phase-change film in selective etching is significant for fabrication of nanostructures with super-resolution in laser thermal lithography.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Selective etching characteristics of the AgInSbTe phase-change film in laser thermal lithography

Geng

2012

Appl. Phys. A

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“…Phasechange materials as a promising inorganic photoresist have recently attracted much attention because of their high resolution [6][7][8]. Based on the thermal-mode lithography, phasechange lithography (PC lithography) that uses a chemical or physical reaction of phase-change resist by temperature rise caused by light absorption, is not limited by diffraction limit,and is not influenced by the history of irradiation because of thermal diffusion [6]. In addition, the facilities required are relatively simple [9].…”

Section: Introductionmentioning

confidence: 99%

“…Using the difference of reflectivity or resistance between the two states, optical data storage and random access memory (RAM) can be carried out, respectively [4,5]. Phasechange materials as a promising inorganic photoresist have recently attracted much attention because of their high resolution [6][7][8]. Based on the thermal-mode lithography, phasechange lithography (PC lithography) that uses a chemical or physical reaction of phase-change resist by temperature rise caused by light absorption, is not limited by diffraction limit,and is not influenced by the history of irradiation because of thermal diffusion [6].…”

Section: Introductionmentioning

confidence: 99%

Selective wet etching of Ge2Sb2Te5 phase-change thin films in thermal lithography with tetramethylammonium

Deng

Geng

2011

Appl. Phys. A

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In this paper, we study Ge 2 Sb 2 Te 5 phase-change film as a promising inorganic photoresist using organic alkaline: tetramethylammonium hydroxide (TMAH) solution, instead of inorganic alkali or acid as etchant. The basic etching properties are investigated by prior and posterior annealing Ge 2 Sb 2 Te 5 films. Selectivity is found to be dependent on concentration of TMAH. There is a good selectivity in the 25% TMAH solution, in which the amorphous state is etched away, whereas the crystalline state remains. The etching rate decreases when the concentration of TMAH is diluted; and an opposite selectivity, compared with 25% TMAH solution, is observed in the 0.125% TMAH solution. Selective etching with laser crystallization in different power levels is also studied, and an excellent wet selectivity in the 25% TMAH solution is obtained. The remaining crystalline lines are observed by atomic force microscopy. The surface roughness after etching is at a good level. The selective wet-etching mechanism is also discussed.

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Laser precision engineering: from microfabrication to nanoprocessing

Chong

Hong

Shi

2010

Laser & Photonics Reviews

197

105

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Laser precision engineering is being extensively applied in industries for device microfabrication due to its unique advantages of being a dry and noncontact process, coupled with the availability of reliable light sources and affordable system cost. To further reduce the feature size to the nanometer scale, the optical diffraction limit has to be overcome. With the combination of advanced processing tools such as SPM, NSOM, transparent and metallic particles, feature sizes as small as 20 nm have been achieved by near-field laser irradiation, which has extended the application scope of laser precision engineering significantly. Meanwhile, parallel laser processing has been actively pursued to realize large-area and high-throughput nanofabrication by the use of microlens arrays (MLA). Laser thermal lithography using a DVD optical storage process has also been developed to achieve low-cost and high-speed nanofabrication. Laser interference lithography, another large area nanofabrication technique, is also capable of fabricating sub-100 nm periodic structures. To further reduce the feature size to the atomic scale, atomic lithography using laser cooling to localize atoms is being developed, bringing laser-processing technology to a new era of atomic engineering. 20-nm nanoline fabricated by 400-nm/100-fs laser irradiation through a near-field scanning microscope.

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Nanosize fabrication using etching of phase-change recording films

Cited by 55 publications

References 6 publications

Selective etching characteristics of the AgInSbTe phase-change film in laser thermal lithography

Selective etching characteristics of the AgInSbTe phase-change film in laser thermal lithography

Selective wet etching of Ge2Sb2Te5 phase-change thin films in thermal lithography with tetramethylammonium

Laser precision engineering: from microfabrication to nanoprocessing

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