Chapter 3
Apertureless Scanning Near-Field
Optical Lithography
Ignacio Falcón Casas and Wolfgang Kautek
Abstract Optical nanolithography has experienced substantial advances in the last
decades. Lithography resolution by optical methods has been historically limited
by light diffraction. One potential approach to surpass this barrier is “apertureless
scanning near-field optical lithography”. In this method, a scanning probe microscope
tip is illuminated by a focused laser beam and the electromagnetic field is strongly
enhanced in the vicinity of the tip’s apex. This may generate nanomodifications
on a solid surface in close proximity with the tip. In this chapter, we review the
thermal effects that allow distinguishing the underlying physical mechanisms: nearfield optical enhancement and/or thermal surface modification.
3.1 Introduction
Since Synge proposed the first near-field microscope idea in 1928 [1], there have
been multiple attempts to overcome the diffraction limit of light. In 1984, Pohl et al.
[2] and Lewis et al. [3] independently developed the first scanning near-field optical
microscope (SNOM), a combination of a scanning probe microscope (SPM) with a
laser beam channeled into a tapered optical fibre, overcoming the diffraction limit
[4–9]. Soon it was pointed out that a similar scheme could be used for subwavelength
surface nanostructuring [10, 11]. The character of the evanescent near-field leads to a
strong spatial electromagnetic field decay both in lateral and vertical directions. This
near-field spatial confinement, combined with field enhancement are key elements for
near-field optical nanolithography. Several experimental setups have been proposed
and implemented during the last two decades, both for SNOM and scanning nearfield optical lithography (NFOL). In aperture schemes [12–28], light from a laser
source is delivered through an optical fibre with a nanometric hole (about 50–150
I. Falcón Casas · W. Kautek (B)
Department of Physical Chemistry, University of Vienna,
Währinger Strasse 42, 1090 Vienna, Austria
e-mail: wolfgang.kautek@univie.ac.at
I. Falcón Casas
e-mail: nacmenarg@gmail.com
© Springer Nature Switzerland AG 2020
A. Hu (ed.), Laser Micro-Nano-Manufacturing and 3D Microprinting, Springer Series
in Materials Science 309, https://doi.org/10.1007/978-3-030-59313-1_3
113
Apertureless Scanning Near-Field
Optical Lithography
Ignacio Falcón Casas and Wolfgang Kautek
Abstract Optical nanolithography has experienced substantial advances in the last
decades. Lithography resolution by optical methods has been historically limited
by light diffraction. One potential approach to surpass this barrier is “apertureless
scanning near-field optical lithography”. In this method, a scanning probe microscope
tip is illuminated by a focused laser beam and the electromagnetic field is strongly
enhanced in the vicinity of the tip’s apex. This may generate nanomodifications
on a solid surface in close proximity with the tip. In this chapter, we review the
thermal effects that allow distinguishing the underlying physical mechanisms: nearfield optical enhancement and/or thermal surface modification.
3.1 Introduction
Since Synge proposed the first near-field microscope idea in 1928 [1], there have
been multiple attempts to overcome the diffraction limit of light. In 1984, Pohl et al.
[2] and Lewis et al. [3] independently developed the first scanning near-field optical
microscope (SNOM), a combination of a scanning probe microscope (SPM) with a
laser beam channeled into a tapered optical fibre, overcoming the diffraction limit
[4–9]. Soon it was pointed out that a similar scheme could be used for subwavelength
surface nanostructuring [10, 11]. The character of the evanescent near-field leads to a
strong spatial electromagnetic field decay both in lateral and vertical directions. This
near-field spatial confinement, combined with field enhancement are key elements for
near-field optical nanolithography. Several experimental setups have been proposed
and implemented during the last two decades, both for SNOM and scanning nearfield optical lithography (NFOL). In aperture schemes [12–28], light from a laser
source is delivered through an optical fibre with a nanometric hole (about 50–150
I. Falcón Casas · W. Kautek (B)
Department of Physical Chemistry, University of Vienna,
Währinger Strasse 42, 1090 Vienna, Austria
e-mail: wolfgang.kautek@univie.ac.at
I. Falcón Casas
e-mail: nacmenarg@gmail.com
© Springer Nature Switzerland AG 2020
A. Hu (ed.), Laser Micro-Nano-Manufacturing and 3D Microprinting, Springer Series
in Materials Science 309, https://doi.org/10.1007/978-3-030-59313-1_3
113