Fast and blister-free irradiation conditions for cross-linking of PMMA induced by 2 MeV protons

Somrit Unai; Nitipon Puttaraksa; Nirut Pussadee; Kanda Singkarat; Michael W. Rhodes; Harry J. Whitlow; Somsorn Singkarat

doi:10.1016/j.mee.2012.05.010

Fast and blister-free irradiation conditions for cross-linking of PMMA induced by 2 MeV protons

Somrit Unai, Nitipon Puttaraksa, Nirut Pussadee, Kanda Singkarat, Michael W. Rhodes, Harry J. Whitlow, Somsorn Singkarat

Research output: Contribution to journal › Article › peer-review

6 Citations (Scopus)

Abstract

For soft lithography, the conventional negative tone resists, such as SU-8, that are used to create the mold have a number of drawbacks. PMMA, which is normally used as a positive tone resist, can be used as a negative resist by using high-fluence irradiation conditions. In this report, we outline optimization of the irradiation conditions for PMMA thin films using 2 MeV H ⁺ ions to exploit their ability to work as a negative tone resist at ion fluences above 1.0 × 10 ¹⁵ ions cm ^-2. The main aim was to induce cross-linking while maintaining the exposed regions free of blisters and maintaining short irradiation times. We found that by using a two-step process with a low-flux irradiation, followed by a high-flux irradiation, the exposure time could be shortened by ∼50%. We also found that ion fluences greater than 5.0 × 10 ¹⁵ ions cm ^-2 minimized the distortion in stitched regions.

Original language	English
Pages (from-to)	18-21
Number of pages	4
Journal	Microelectronic Engineering
Volume	102
DOIs	https://doi.org/10.1016/j.mee.2012.05.010
Publication status	Published - 2013 Feb
Externally published	Yes

Keywords

Blisters
Contraction
Cross-linking
H ion irradiation
Negative resists
PMMA

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Atomic and Molecular Physics, and Optics
Condensed Matter Physics
Surfaces, Coatings and Films
Electrical and Electronic Engineering

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10.1016/j.mee.2012.05.010

Cite this

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title = "Fast and blister-free irradiation conditions for cross-linking of PMMA induced by 2 MeV protons",

abstract = "For soft lithography, the conventional negative tone resists, such as SU-8, that are used to create the mold have a number of drawbacks. PMMA, which is normally used as a positive tone resist, can be used as a negative resist by using high-fluence irradiation conditions. In this report, we outline optimization of the irradiation conditions for PMMA thin films using 2 MeV H + ions to exploit their ability to work as a negative tone resist at ion fluences above 1.0 × 10 15 ions cm -2. The main aim was to induce cross-linking while maintaining the exposed regions free of blisters and maintaining short irradiation times. We found that by using a two-step process with a low-flux irradiation, followed by a high-flux irradiation, the exposure time could be shortened by ∼50%. We also found that ion fluences greater than 5.0 × 10 15 ions cm -2 minimized the distortion in stitched regions.",

keywords = "Blisters, Contraction, Cross-linking, H ion irradiation, Negative resists, PMMA",

author = "Somrit Unai and Nitipon Puttaraksa and Nirut Pussadee and Kanda Singkarat and Rhodes, {Michael W.} and Whitlow, {Harry J.} and Somsorn Singkarat",

note = "Funding Information: This work was partly supported by the CoE Program of Chiang Mai University and the International Atomic Energy Agency (IAEA, Vienna). SU gratefully acknowledges the ThEP Center for his scholarship. NP (N. Puttaraksa) gratefully acknowledges financial support by the Royal Golden Jubilee Scholarship from the Thailand Research Fund . HJW and NP{\textquoteright}s work was carried out under the Academy of Finland Centre of Excellence in Nuclear and Accelerator Based Physics (Ref. 213503). HJW is grateful for a Senior Researcher grant from the Academy of Finland (Ref. 129999). The authors would also like to thank Mr. Chome Thongleurm and Mr. Witoon Ginamoon for their technical support.",

year = "2013",

month = feb,

doi = "10.1016/j.mee.2012.05.010",

language = "English",

volume = "102",

pages = "18--21",

journal = "Microelectronic Engineering",

issn = "0167-9317",

publisher = "Elsevier",

}

TY - JOUR

T1 - Fast and blister-free irradiation conditions for cross-linking of PMMA induced by 2 MeV protons

AU - Unai, Somrit

AU - Puttaraksa, Nitipon

AU - Pussadee, Nirut

AU - Singkarat, Kanda

AU - Rhodes, Michael W.

AU - Whitlow, Harry J.

AU - Singkarat, Somsorn

N1 - Funding Information: This work was partly supported by the CoE Program of Chiang Mai University and the International Atomic Energy Agency (IAEA, Vienna). SU gratefully acknowledges the ThEP Center for his scholarship. NP (N. Puttaraksa) gratefully acknowledges financial support by the Royal Golden Jubilee Scholarship from the Thailand Research Fund . HJW and NP’s work was carried out under the Academy of Finland Centre of Excellence in Nuclear and Accelerator Based Physics (Ref. 213503). HJW is grateful for a Senior Researcher grant from the Academy of Finland (Ref. 129999). The authors would also like to thank Mr. Chome Thongleurm and Mr. Witoon Ginamoon for their technical support.

PY - 2013/2

Y1 - 2013/2

N2 - For soft lithography, the conventional negative tone resists, such as SU-8, that are used to create the mold have a number of drawbacks. PMMA, which is normally used as a positive tone resist, can be used as a negative resist by using high-fluence irradiation conditions. In this report, we outline optimization of the irradiation conditions for PMMA thin films using 2 MeV H + ions to exploit their ability to work as a negative tone resist at ion fluences above 1.0 × 10 15 ions cm -2. The main aim was to induce cross-linking while maintaining the exposed regions free of blisters and maintaining short irradiation times. We found that by using a two-step process with a low-flux irradiation, followed by a high-flux irradiation, the exposure time could be shortened by ∼50%. We also found that ion fluences greater than 5.0 × 10 15 ions cm -2 minimized the distortion in stitched regions.

AB - For soft lithography, the conventional negative tone resists, such as SU-8, that are used to create the mold have a number of drawbacks. PMMA, which is normally used as a positive tone resist, can be used as a negative resist by using high-fluence irradiation conditions. In this report, we outline optimization of the irradiation conditions for PMMA thin films using 2 MeV H + ions to exploit their ability to work as a negative tone resist at ion fluences above 1.0 × 10 15 ions cm -2. The main aim was to induce cross-linking while maintaining the exposed regions free of blisters and maintaining short irradiation times. We found that by using a two-step process with a low-flux irradiation, followed by a high-flux irradiation, the exposure time could be shortened by ∼50%. We also found that ion fluences greater than 5.0 × 10 15 ions cm -2 minimized the distortion in stitched regions.

KW - Blisters

KW - Contraction

KW - Cross-linking

KW - H ion irradiation

KW - Negative resists

KW - PMMA

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JO - Microelectronic Engineering

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ER -

Fast and blister-free irradiation conditions for cross-linking of PMMA induced by 2 MeV protons

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Keywords

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