Fabrication of DLC-Based Micro-Gear Patterns by Room-Temperature Curing Nanoimprint Lithography Using Glass-Like Carbon Molds

MRS Proceedings ◽

10.1557/opl.2013.21 ◽

2013 ◽

Vol 1511 ◽

Author(s):

Shuji Kiyohara ◽

Tomu Ikegaki ◽

Chigaya Ito ◽

Ippei Ishikawa ◽

Hideto Tanoue ◽

...

Keyword(s):

Diamond Film ◽

Nanoimprint Lithography ◽

Room Temperature ◽

High Accuracy ◽

Residual Layer ◽

Mold Material ◽

Etching Time ◽

Optimum Conditions ◽

Dlc Film ◽

Etching Selectivity

ABSTRACTThe fabrication of diamond-like carbon (DLC) micro-gear by room temperature curing nanoimprint lithography (RTC-NIL) using glass-like carbon (GC) molds as applications to the DLC-based medical MEMS (Micro Electronic Mechanical Systems) was investigated. The DLC film which has excellent properties similar to chemical vapor deposited (CVD) diamond films was used as the patterning material. We propose GC as mold material because GC has higher etching selectivity than a diamond film. The etching selectivity of polysiloxane film against a GC substrate is about 5 times as high as that of a diamond film. Therefore we fabricated the GC molds that have micro-gear patterns with 30 µm-tip diameter and 500 nm-tooth thickness. We carried out the RTC-NIL process using the GC micro-gear molds under the following optimum conditions. 1 min-time from spin-coating to imprint: t1, 0.5 MPa-imprinting pressure: P and 5 min-holding time: t2, and then the imprinted polysiloxane pattern on DLC film was processed with an electron cyclotron resonance (ECR) oxygen ion shower. However, we were not able to fabricate micro-gear patterns in high accuracy because of a remaining residual layer on the DLC film. Therefore we propose the removing process for the residual layer with trifluoromethane (CHF3) ion shower under the optimum conditions of 300 eV-ion energy and 4 min-etching time. As a result, we succeeded to fabricate concave DLC-based micro-gear patterns in high accuracy which has 30 µm-tip diameter and 1 µm-depth.

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Fabrication of Diamond Nanopit arrays by Room-temperature Curing Nanoimprint Lithography Using Glass-like Carbon Molds

MRS Proceedings ◽

10.1557/opl.2012.9 ◽

2012 ◽

Vol 1395 ◽

Author(s):

Shuji Kiyohara ◽

Chigaya Ito ◽

Ippei Ishikawa ◽

Hirofumi Takikawa ◽

Yoshio Taguchi ◽

...

Keyword(s):

Diamond Film ◽

Nanoimprint Lithography ◽

Room Temperature ◽

Electron Cyclotron Resonance ◽

Chemical Vapor ◽

Mold Material ◽

Oxygen Ion ◽

Mask Material ◽

Chemical Vapor Deposited ◽

Etching Selectivity

ABSTRACTWe have proposed the use of glass-like carbon (GC), as mold material because the 27-maximum etching selectivity of polysiloxane film against GC, which was approximately sixtimes larger than that of polysiloxane film against chemical vapor deposited (CVD) diamond film. We have investigated the fabrication of diamond nanopit arrays by room-temperature curing nanoimprint lithography (RTC-NIL) using GC mold, as applications to the emitter and the micro-gear. The polysiloxane has in the state of sticky liquid at room-temperature and negative-exposure characteristic. Therefore, the polysiloxane was used as RTC-imprint resist material, and also used as electron beam (EB) resist (oxide mask) material in EB lithography. We have fabricated the cylindrical GC nanodot mold with 500 nm-diameter, 600 nm-height and 2 μm-pitch. We carried out RTC-NIL using GC mold under the following optimum conditions: time from spin-coating to imprint of 1 min, imprinting pressure of 0.5 MPa and imprinting time of 5min. Then, we have processed the diamond film with an electron cyclotron resonance (ECR) oxygen ion shower. We have fabricated diamond nanopit array with 250 nm-depth and 500 nm-diameter. The diameter of diamond nanopit pattern was in good agreement with that of GC mold. Moreover, the depth of the diamond nanopit patterns fabricated by RTC-NIL using cylindrical GC mold was three times larger than that using conical diamond mold.

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Fabrication of Diamond-Like Carbon Emitter Patterns by Room-Temperature Curing Nanoimprint Lithography with PDMS Molds Using Polysiloxane

MRS Advances ◽

10.1557/adv.2016.49 ◽

2016 ◽

Vol 1 (16) ◽

pp. 1075-1080 ◽

Cited By ~ 2

Author(s):

Shuji Kiyohara ◽

Shogo Yoshida ◽

Ippei Ishikawa ◽

Toru Harigai ◽

Hirofumi Takikawa ◽

...

Keyword(s):

Nanoimprint Lithography ◽

Room Temperature ◽

Electron Cyclotron Resonance ◽

Mold Material ◽

Etching Time ◽

Diamond Like Carbon ◽

Curing Time ◽

Flat Panel Display ◽

Ion Energy ◽

Mask Material

ABSTRACTWe investigated the fabrication of diamond-like carbon (DLC) emitter patterns by room-temperature curing nanoimprint lithography (RTC-NIL) with polydimethylsiloxane (PDMS) molds using polysiloxane, as an application to the emitter for the next generation flat panel display.The DLC which has excellent properties similar to diamond properties was used as a pattern material. A PDMS was used as a mold material and fabricated by the following optimum conditions of the first curing time at RT for 36 h and the second curing time at the temperature of 150 °C for 15 mins. The polysiloxane is in the state of sticky liquid at RT and stable in air. Therefore, the polysiloxane was used the electron beam (EB) resist and oxide mask material in EB lithography, and also used as RT-imprint material.First, we fabricated the PDMS mold with pit array. Each dot is 5 µm-diameter and 400 nm-depth. We carried out the RTC-NIL process with PDMS molds using polysiloxane under the following optimum imprint conditions of 0.5 MPa-imprinting pressure, 1.5 min-the time between spin-coat and imprint, and 5 min-imprinting time. Next, the residual layer of imprinted polysiloxane pattern was 450 nm and then was removed with electron cyclotron resonance (ECR) trifluoromethane (CHF3) ion shower under the conditions of 300 eV-ion energy and 3 min-etching time. Then, we processed the imprinted polysiloxane patterns on the DLC film with an ECR oxygen (O2) ion shower under the conditions of 400 eV-ion energy and 12 min-etching time. As a result, we succeeded in fabricating convex DLC emitter patterns with high accuracy which has 5 µm-diameter and 500 nm-height.

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Nanofabrication of DLC-dot Arrays by Room-temperature Curing Imprint-liftoff Method

MRS Proceedings ◽

10.1557/opl.2013.15 ◽

2013 ◽

Vol 1511 ◽

Author(s):

Shuji Kiyohara ◽

Shohei Matta ◽

Ippei Ishikawa ◽

Hideto Tanoue ◽

Hirofumi Takikawa ◽

...

Keyword(s):

Room Temperature ◽

Polished Glass ◽

Aluminum Film ◽

Mold Material ◽

Ion Energy ◽

Dlc Film ◽

Oxygen Ion ◽

Mask Material ◽

Etching Selectivity ◽

20 Nm

ABSTRACTAs an application to the nanoemitter, we investigated the nanofabrication of diamond-like carbon (DLC)-dot arrays by room-temperature curing imprint-liftoff (RTCIL) method using aluminum mask. The DLC film which has excellent properties similar to diamond properties was used as the patterning material. A polished glass like carbon (GC) was used as a mold material. The polysiloxane in the state of sticky liquid at room temperature and stable in air exhibits a negative-exposure characteristics. Therefore, the polysiloxane was used as electron beam (EB) resist and oxide mask material in EB lithography, and also used as RTC-imprint resist material. An aluminum was used as oxide metal mask material of liftoff. We have fabricated the GC mold of dot arrays with 5 µm-square and 500 nm-height. We carried out the RTCIL process using the GC mold under the following optimum imprint conditions: 0.5 MPa-imprinting pressure and 5 min- holding time. Aluminum film on the imprinted polysiloxane was prepared by vacuum evaporation method and its thickness is 20 nm. Finally, the polysiloxane patterns were removed with acetone and aluminum mask patterns were fabricated. We found that the maximum etching selectivity of aluminum film against DLC film was as high as 35, which was obtained under an ion energy of 400 eV. Then we processed the patterned aluminum on DLC film with an ECR oxygen ion shower. We fabricated DLC-dot arrays with 5 µm-square and 400 nm-height with an aspect ratio of 0.08.

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Guiding Chart for Initial Layer Choice with Nanoimprint Lithography

Nanomaterials ◽

10.3390/nano11030710 ◽

2021 ◽

Vol 11 (3) ◽

pp. 710

Author(s):

Andre Mayer ◽

Hella-Christin Scheer

Keyword(s):

Nanoimprint Lithography ◽

Room Temperature ◽

Periodic Structures ◽

Residual Layer ◽

Graphical Form ◽

Initial Layer ◽

Lithography Process ◽

Cavity Filling ◽

Theoretical Results ◽

Relevant Factors

When nanoimprint serves as a lithography process, it is most attractive for the ability to overcome the typical residual layer remaining without the need for etching. Then, ‘partial cavity filling’ is an efficient strategy to provide a negligible residual layer. However, this strategy requires an adequate choice of the initial layer thickness to work without defects. To promote the application of this strategy we provide a ‘guiding chart’ for initial layer choice. Due to volume conservation of the imprint polymer this guiding chart has to consider the geometric parameters of the stamp, where the polymer fills the cavities only up to a certain height, building a meniscus at its top. Furthermore, defects that may develop during the imprint due to some instability of the polymer within the cavity have to be avoided; with nanoimprint, the main instabilities are caused by van der Waals forces, temperature gradients, and electrostatic fields. Moreover, practical aspects such as a minimum polymer height required for a subsequent etching of the substrate come into play. With periodic stamp structures the guiding chart provided will indicate a window for defect-free processing considering all these limitations. As some of the relevant factors are system-specific, the user has to construct his own guiding chart in praxis, tailor-made to his particular imprint situation. To facilitate this task, all theoretical results required are presented in a graphical form, so that the quantities required can simply be read from these graphs. By means of examples, the implications of the guiding chart with respect to the choice of the initial layer are discussed with typical imprint scenarios, nanoimprint at room temperature, at elevated temperature, and under electrostatic forces. With periodic structures, the guiding chart represents a powerful and straightforward tool to avoid defects in praxis, without in-depth knowledge of the underlying physics.

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Fabrication of Diamond-Like Carbon Microgears in Room-Temperature Curing Nanoimprint Lithography Using Ladder-Type Hydrogen Silsesquioxane

MRS Advances ◽

10.1557/adv.2016.126 ◽

2016 ◽

Vol 1 (16) ◽

pp. 1119-1124

Author(s):

Shuji Kiyohara ◽

Yuto Shimizu ◽

Ippei Ishikawa ◽

Toru Harigai ◽

Hirofumi Takikawa ◽

...

Keyword(s):

Nanoimprint Lithography ◽

Room Temperature ◽

Electron Cyclotron Resonance ◽

Sol Gel ◽

Etching Time ◽

Diamond Like Carbon ◽

Pdms Mold ◽

Hydrogen Silsesquioxane ◽

Ion Energy ◽

Mask Material

ABSTRACTWe investigated the fabrication of convex diamond-like carbon (DLC) based microgears in room-temperature curing nanoimprint lithography (RTC-NIL) using the ladder-type hydrogen silsesquioxane (HSQ), as an application for the medical micro electro mechanical system (MEMS). The HSQ which is an inorganic polymer of sol-gel system turns into a gel when exposed to air and has the siloxane bond. Therefore, the HSQ was used as RT-imprinting material, and also used as an oxide mask material in electron cyclotron resonance (ECR) oxygen (O2) ion shower etching. We fabricated the polydimethylsiloxane (PDMS) mold with concave microgear patterns which has 40, 50 and 60 μm-tip diameter and 300 nm-depth. We carried out the RTC-NIL process using the PDMS mold under the following optimum conditions of 0.10 MPa-imprinting pressure and 1.0 min-imprinting time. We found that the residual layer of imprinted HSQ microgear patterns was removed with ECR trifluoromethane (CHF3) ion shower under the following conditions of 300 eV-ion energy and 2.0 min-etching time, and then microgears of the HSQ on the DLC film were etched with ECR O2 ion shower under the following conditions of 400 eV-ion energy and 10 min-etching time. As a result, the convex DLC based microgears which have 40, 50 and 60 μm-tip diameter and 400 nm-height were fabricated with high accuracy in the new fabrication process of RTC-NIL.

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Challenges of residual layer minimisation in thermal nanoimprint lithography

10.1117/12.736926 ◽

2007 ◽

Cited By ~ 2

Author(s):

Nicolas Bogdanski ◽

Matthias Wissen ◽

Saskia Möllenbeck ◽

Hella-Christin Scheer

Keyword(s):

Nanoimprint Lithography ◽

Residual Layer

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Fabrication of Micro-OLEDs by Room-temperature Curing Nanocontact-print Lithography Using DLC Molds

MRS Proceedings ◽

10.1557/opl.2012.1711 ◽

2012 ◽

Vol 1511 ◽

Cited By ~ 1

Author(s):

Ippei Ishikawa ◽

Keisuke Sakurai ◽

Shuji Kiyohara ◽

Taisuke Okuno ◽

Hideto Tanoue ◽

...

Keyword(s):

Indium Tin Oxide ◽

Nanoimprint Lithography ◽

Room Temperature ◽

Hole Transport ◽

Transport Layer ◽

Electron Transport Layer ◽

Insulating Layer ◽

Light Emitting ◽

Light Emitting Devices ◽

Ito Glass

ABSTRACTThe microfabrication technologiesfor organic light-emitting devices (OLEDs) are essential to the fabrication of the next generation of light-emitting devices. The micro-OLEDs fabricated by room-temperature curing nanoimprint lithography (RTC-NIL) using diamond molds have been investigated. However, light emissions from 10 μm-square-dot OLEDs fabricated by the RTC-NIL method have not been uniform. Therefore, we proposed the fabrication of micro-OLEDs by room-temperature curing nanocontact-print lithography (RTC-NCL) using the diamond-like carbon (DLC) mold. The DLC molds used in RTC-NCL were fabricated by an electron cyclotron resonance (ECR) oxygen ion shower with polysiloxane oxide mask in electron beam (EB) lithography technology. The mold patterns are square and rectangle dots which has 10 µm-width, 10 µm-width and50 µm-length, respectively. The height of the patterns is 500 nm. The DLC molds were used to form the insulating layer of polysiloxane in RTC-NCL. We carried out the RTC-NCL process using the DLC mold under the following optimum conditions: 0.1 MPa-pressure for coating DLC mold with polysiloxane film, 2.1 MPa-pressure for transferring polysiloxane from DLC mold pattern to indium tin oxide (ITO) glass substrate. We deposited N, N'-Diphenyl -N, N'-di (m-tolyl)benzidine (TPD) [40 nm-thickness] as hole transport layer / Tris(8-quinolinolato)aluminum (Alq3) [40 nm-thickness] as electron transport layer / Al [200 nm-thickness] as cathode on ITO glass substrateas anode in this order. We succeeded in formation of the insulating layer with square and rectangle dots which has 10 µm-width,10 µm-width and 50 µm-length, and operation of micro-OLEDs by RTC-NIL using DLC molds.

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Room Temperature Planar Absolute Radiometer for High-Accuracy Optical Power Measurements

10.1364/cleo_at.2021.aw4m.4 ◽

2021 ◽

Author(s):

Anna K. Vaskuri ◽

Michelle S. Stephens ◽

Nathan A. Tomlin ◽

Matthew T. Spidell ◽

Christopher S. Yung ◽

...

Keyword(s):

Room Temperature ◽

Optical Power ◽

High Accuracy ◽

Power Measurements

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Effect of current density on the porous silicon preparation as gas sensors**

Journal of the Mechanical Behavior of Materials ◽

10.1515/jmbm-2021-0027 ◽

2021 ◽

Vol 30 (1) ◽

pp. 257-264

Author(s):

Muna H. Kareem ◽

Adi M. Abdul Hussein ◽

Haitham Talib Hussein

Keyword(s):

Porous Silicon ◽

Gas Sensors ◽

Current Density ◽

Room Temperature ◽

Low Cost ◽

High Surface ◽

Volume Ratio ◽

Etching Time ◽

Force Microscopy ◽

Materials Used

Abstract In this study, porous silicon (PSi) was used to manufacture gas sensors for acetone and ethanol. Samples of PSi were successfully prepared by photoelectrochemical etching and applied as an acetone and ethanol gas sensor at room temperature at various current densities J= 12, 24 and 30 mA/cm2 with an etching time of 10 min and hydrofluoric acid concentration of 40%. Well-ordered n-type PSi (100) was carefully studied for its chemical composition, surface structure and bond configuration of the surface via X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy and photoluminescence tests. Results showed that the best sensitivity of PSi was to acetone gas than to ethanol under the same conditions at an etching current density of 30 mA/cm2, reaching about 2.413 at a concentration of 500 parts per million. The PSi layers served as low-cost and high-quality acetone gas sensors. Thus, PSi can be used to replace expensive materials used in gas sensors that function at low temperatures, including room temperature. The material has an exceptionally high surface-to-volume ratio (increasing surface area) and demonstrates ease of fabrication and compatibility with manufacturing processes of silicon microelectronics.

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