Use of an Excimer Lamp for Photochemical Resistless Etching of Thermal Silicon Oxide Substrate

MRS Proceedings ◽

10.1557/proc-397-543 ◽

1995 ◽

Vol 397 ◽

Author(s):

N. Kamata ◽

M. Murahara

Keyword(s):

Excimer Laser ◽

Decomposition Method ◽

Silicon Oxide ◽

Etching Depth ◽

Excimer Lamp ◽

Oxide Substrate ◽

Arf Excimer Laser ◽

Krf Excimer Laser ◽

Decomposition Efficiency

ABSTRACTPhotochemical resistless etching was carried out by using a Xe2* excimer lamp and a KrF excimer laser. The decomposition method with Xe2* excimer lamp increases the decomposition efficiency by 100 times than that of using ArF excimer laser and etchant gas, CHClF2. Xe2* excimer lamp irradiation allowed decomposition of CHClF2 gas to produce CF2 radical with a small quantity of gas. The CF2 radical was polymerized to form fluorocarbon layer on the SiO2 substrate. Simultaneously, circuit patterned KrF excimer laser was vertically irradiated the fluorocarbon layer on the substrate for resistless etching. The etching depth was about 1,000Â.

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Improved Abruptness of Si/Sin Interface by ArF Excimer-Laser Pre-Annealing to Sin

MRS Proceedings ◽

10.1557/proc-345-105 ◽

1994 ◽

Vol 345 ◽

Author(s):

Yasutaka Uchida ◽

Masakiyo Matsumura

Keyword(s):

Laser Irradiation ◽

Excimer Laser ◽

Field Effect ◽

Field Effect Mobility ◽

Resolution Limit ◽

Laser Recrystallization ◽

Excimer Laser Irradiation ◽

Arf Excimer Laser ◽

Krf Excimer Laser ◽

Film Annealing

AbstractXPS measurement showed that undesirable SiNH component was reduced drastically from the low-temperature deposited SiN surface by intense ArF excimer-laser irradiation. Although the improved layer was as thin as 15nm, it was very effective to stop diffusion of N atoms from the bottom SiN layer to the top Si layer during the excimer-laser recrystallization step. N-diffused Si layer at the Si/SiN interface was less than the XPS resolution limit for the pre-annealed SiN structure, but about 5nm thick. As a result, the field-effect mobility of the poly-Si/SiN TFT was increased drastically by laser-irradiation to SiN film. Annealing characteristics are also presented for the various SiN film thicknesses and for both the ArF and KrF excimer-laser lights.

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Photochemical Pattern Etching of Single-Crystalline 3C-SiC

MRS Proceedings ◽

10.1557/proc-495-407 ◽

1997 ◽

Vol 495 ◽

Cited By ~ 1

Author(s):

T. Mori ◽

K. Hatao ◽

M. Murahara

Keyword(s):

Excimer Laser ◽

Surface Reaction ◽

Laser Light ◽

Sample Surface ◽

Etch Depth ◽

Reaction Cell ◽

Single Crystalline ◽

Excimer Lamp ◽

Krf Laser ◽

Krf Excimer Laser

ABSTRACTA single-crystalline 3C-SiC is very difficult to etch compared with a polycrystalline SiC. Thus, a photochemical pattern etching of the SiC was demonstrated by using Xe2* excimer lamp and ArF or KrF excimer laser. To promote the surface reaction, a Xe2* excimer lamp was employed to produce many radicals on the sample surface; simultaneously, ArF or KrF laser light irradiated the surface via a circuit pattern to dissociate the Si-C bonds. The Si and C reacted with the F and N radicals photo-dissociated from NF3 gas to form SiF4, CFn and CN, which diffused in the reaction cell. As a result, the single-crystalline 3C-SiC was photo-chemically etched effectively. With the NF3 gas of 200Torr, the Xe2* excimer lamp of 7mW/cm2, and the KrF excimer laser of 650mJ/cm2, 20Hz and 10,000shots, the etch depth of 700 Å was successfully achieved.

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ArF Excimer Laser Micromachining of MEMS Materials: Characterization and Applications

Journal of Micro and Nano-Manufacturing ◽

10.1115/1.4027121 ◽

2014 ◽

Vol 2 (2) ◽

Cited By ~ 1

Author(s):

Kewei Liu ◽

Yoontae Kim ◽

Hongseok (Moses) Noh

Keyword(s):

Laser Ablation ◽

Excimer Laser ◽

Laser Pulses ◽

Laser Micromachining ◽

Laser Frequency ◽

Excimer Laser Ablation ◽

Characterization Study ◽

Arf Excimer Laser ◽

Etch Rates ◽

Krf Excimer Laser

Excimer laser ablation is a versatile technique that can be used for a variety of different materials. Excimer laser ablation overcomes limitations of conventional two-dimensional (2D) microfabrication techniques and facilitates three-dimensional (3D) micromanufacturing. Previously, we have reported a characterization study on 248 nm KrF excimer laser micromachining. This paper extends the study to 193 nm ArF excimer laser micromachining on five representative micro-electro-mechanical systems (MEMS) materials (Si, soda-lime glass, SU-8, polydimethylsiloxane (PDMS), and polyimide). Relations between laser parameters (fluence, frequency and number of laser pulses) and etch performances (etch rates, aspect ratio, and surface quality) were investigated. Etch rate per shot was proportional to laser fluence but inversely proportional to number of laser pulses. Laser frequency did not show a notable impact on etch rates. Aspect ratio was also proportional to laser fluence and number of laser pulses but was not affected by laser frequency. Materials absorbance spectrum was found to have important influence on etch rates. Thermal modeling was conducted as well using numerical simulation to investigate how the photothermal ablation mechanism affects the etching results. Thermal properties of material, primarily thermal conductivity, were proved to have significant influence on etching results. Physical deformation in laser machined sites was also investigated using scanning electron microscopy (SEM) imaging. Element composition of redeposited materials around ablation site was analyzed using energy dispersive x-ray spectroscopy (EDXS) analysis. Combined with our previous report on KrF excimer laser micromachining, this comprehensive characterization study provides guidelines to identify optimized laser ablation parameters for desired microscale structures on MEMS materials. In order to demonstrate the 3D microfabrication capability of ArF excimer laser, cutting and local removal of insulation for a novel floating braided neural probe made of polyimide and nichrome was conducted successfully using the optimized laser ablation parameters obtained in the current study.

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Photo-Chemical Pattern Etching of Silicon-Carbide by Using Excimer Laser and Hydrogen Peroxide Solution

MRS Proceedings ◽

10.1557/proc-742-k5.15 ◽

2002 ◽

Vol 742 ◽

Author(s):

D. Sasaki ◽

M. Murahara

Keyword(s):

Silicon Carbide ◽

Laser Irradiation ◽

Excimer Laser ◽

Chemical Stability ◽

High Resistance ◽

Water Solution ◽

Mixed Solution ◽

Etching Depth ◽

Excimer Laser Irradiation ◽

Krf Excimer Laser

A circuit pattern etching of a Silicon-carbide (SiC) surface was conducted with KrF excimer laser irradiation in the presence of HF and H2O2 mixed solutions. SiC have excellent properties of a high hardness, high melting point, wide band gap, high resistance to radiation and chemical stability. This material has come to attract attention as an integrated circuit material for high resistance to environment. However, the material is very difficult in minute processing by the photo-lithography because of its chemical stability. Thus, we developed the new etching method in which a SiC surface was photo-oxidized with H2O or H2O2 by using excimer laser irradiation and was etched by HF water solution. In this experiment, the mixed solution was poured into the thin gap between an Al2O3 glass and the SiC surface with capillary phenomenon. A patterned excimer laser light was, then, irradiated on the SiC surface. The H2O or H2O2 in the reaction solution was photo-dissociated, and the photo-dissociated active oxygen reacted with the SiC. CO2 and SiO2 were formed only on the part exposed by the pattered light forcibly, and an oxidized layer was formed. In this chemical reaction, the CO2 evaporated, and the SiO2 remained on the sample surface. The SiO2 layer was then dissolved by the HF water solution. Thus, etching was conducted by the repetition of the forced oxidization of the SiC and the dissolving of the oxidized layer. In this experiment, the most effective conditions were 20% of H2O2 water solution, 15% HF water solution and 256mJ/cm2 of KrF excimer laser. The etching depth was 80 Å at the laser shot number of 10000. It significantly improved compared with that of using an ArF excimer laser (256mJ/cm2, 193nm), 50 Å.

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Patterned ZnS Thin-Film Growth using KrCl Excimer Lamp on the Zn Nuclei

MRS Proceedings ◽

10.1557/proc-585-147 ◽

1999 ◽

Vol 585 ◽

Author(s):

M. Toda ◽

H. Lizuka ◽

M. Murahara

Keyword(s):

Thin Film ◽

Excimer Laser ◽

Film Growth ◽

Thin Film Growth ◽

Single Shot ◽

Si Substrate ◽

Excimer Lamp ◽

Arf Excimer Laser

AbstractPatterned Zn nuclei were formed by exposure with a single shot of an ArF excimer laser through a patterned photo mask onto a Si substrate which adsorbed DMZ (dimethylezinc). A ZnS thin film was then grown only onto the patterned Zn nuclei by KrCl excimer lamp irradiation of the substrate which was sealed in the chamber along with DMZ and H2S.

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Arf Excimer Laser and Xe2· Excimer Lamp Induced Photochemical Fluorination of Polyimide Film

MRS Proceedings ◽

10.1557/proc-544-227 ◽

1998 ◽

Vol 544 ◽

Cited By ~ 10

Author(s):

T. Ikegame ◽

M. Murahara

Keyword(s):

Contact Angle ◽

Chemical Composition ◽

Excimer Laser ◽

Water Repellency ◽

Polyimide Film ◽

Dangling Bond ◽

Weak Point ◽

Excimer Lamp ◽

Chemically Modified ◽

Arf Excimer Laser

AbstractOnly one weak point of all aromatic group polyimide surface was changed to water repellency. Polyimide surface was photo-chemically modified to be fluorinate with ArF excimer laser and Xe2 · excimer lamp irradiation. To promote the photo- chemical reaction, Xe2· excimer lamp was employed to produce CFn. radical from CF4 gas. Simultaneously, ArF excimer laser was irradiated on the polyimide surface to dissociate C-H bond. Dangling bond of C was reacted with CF, radical and produced C-CF, on the polyimide surface. By this modification, polyimide surface was changed to water repellency. As a result, polyimide surface was photo-chemically modified to fluorinate with CF4 gas pressure of 100Torr, the Xe2 excimer lamp of 7mW/cm2, and the ArF excimer laser of 30mJ/cm2, 10Hz and 3000shots, the contact angle with water was 134 degrees. And chemical composition of the photo-modified polyimide surface was inspected by ATR-FTIR spectra measurement.

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Photochemical Micro-pattern Substitution of Functional Groups for Protein Attachment Control

MRS Proceedings ◽

10.1557/proc-0950-d06-04 ◽

2006 ◽

Vol 950 ◽

Cited By ~ 1

Author(s):

Masataka Murahara ◽

Yuji Sato

Keyword(s):

Absorption Coefficient ◽

Excimer Laser ◽

Area Ratio ◽

Water Contact ◽

Oh Groups ◽

Excimer Lamp ◽

Micro Pattern ◽

Pmma Surface ◽

Modified Surface ◽

Arf Excimer Laser

ABSTRACTHydrophilic and hydrophobic groups were selectively incorporated on the poly(methyl methacrylate) [PMMA] surface using a Xe2 excimer lamp and ArF excimer laser. With this new technique, a protein adsorption on the PMMA surface can be controlled.PMMA was firstly irradiated with a Xe2 excimer lamp in the presence of perfluoropolyether [PFPE] liquid layer to incorporate CF3 groups, and secondly, the PMMA surface was irradiated by an ArF excimer laser through a patterned reticle in the presence of water to incorporate OH groups or NH2 groups in an ammonia gas ambience. The area ratio of hydrophilic and hydrophobic of the modifying sample was made to 1:3, 1:1, and 3:1. The results showed that the fibrin absorption on the sample with hydrophilic and hydrophobic micro domains depended on the area ratio of the hydrophilic and hydrophobic. The absorption coefficient of the amide band remarkably decreased with increase in water contact angle. Furthermore, it was confirmed that the absorption coefficient of fibrin decreased as the interval of CF3 and OH or NH2 groups was narrowed from 250 to 20 μm, and the fibrin sticking on the modified surface with the 20 μm hydrophilic and hydrophobic micro domains was reduced to one-twenty of that on the untreated sample.

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High Resolution Displacement of Functional Groups onto Fluorocarbon Resin Surface by Using ArF Excimer Laser

MRS Proceedings ◽

10.1557/proc-451-521 ◽

1996 ◽

Vol 451 ◽

Cited By ~ 1

Author(s):

T. Shimizu ◽

M. Murahara

Keyword(s):

Contact Angle ◽

High Resolution ◽

Laser Beam ◽

Thin Layer ◽

Functional Groups ◽

Excimer Laser ◽

Laser Fluence ◽

Large Area ◽

Three Solutions ◽

Arf Excimer Laser

ABSTRACTA Fluorocarbon resin surface was selectively modified by irradiation with a ArF laser beam through a thin layer of NaAlO2, B(OH)3, or H2O solution to give a hydrophilic property. As a result, with low fluence, the surface was most effectively modified with the NaAlO2 solution among the three solutions. However, the contact angle in this case changed by 10 degrees as the fluence changed only 1mJ/cm2. When modifying a large area of the surface, high resolution displacement could not be achieved because the laser beam was not uniform in displacing functional groups. Thus, the laser fluence was successfully made uniform by homogenizing the laser beam; the functional groups were replaced on the fluorocarbon resin surface with high resolution, which was successfully modified to be hydrophilic by distributing the laser fluence uniformly.

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