4.1. Nanomachining with Scanning Probes 1831 4.2. Soft Lithography 1832 4.3. Embossing with Rigid Masters 1835 4.4. Near-Field Phase-Shifting Photolithography 1835 4.5. Topographically Directed Photolithography 1837 4.6. Topographically Directed Etching 1837 4.7. Lithography with Neutral Metastable Atoms 1838 4.8. Approaches to Size Reduction 1839 5. Techniques for Making Regular or Simple Patterns 1839

https://www.engr.colostate.edu/ECE581/fall07/xia%20chem%20rev%2099.pdf

Unconventional Methods for Fabricating and Patterning Nanostructures.

An projection exposure apparatus and method for illuminating a transfer pattern and forming an image upon a mask for exposure from the illumination light and transfer exposing the image of the pattern of the mask under the illumination light Switching is performed between a normal illumination condition and a modified illumination condition based upon the numerical aperture of the illumination light; wherein the normal illumination condition occurs when the light quantity distribution at the illumination pupil plane is in a first region, including the optical-axis; and the modified illumination condition occurs when the light quantity distribution at the illumination pupil plane is in a second region, not including the optical-axis and wherein the pupil plane is an optical Fourier conversion surface of a pattern surface of the mask in an illumination system

Exposure apparatus and method

Optical Projection System and Method for Photolithography. A lithographic immersion projection system and method for projecting an image at high resolution over a wide field of view. The projection system and method include a final lens which decreases the marginal ray angle of the optical path before light passes into the immersion liquid to impinge on the image plane.

Projection optical system and method for photolithography and exposure apparatus and method using same

A lithographic apparatus configured to project a patterned beam of radiation onto a target portion of a substrate is disclosed. The apparatus includes a first radiation dose detector and a second radiation dose detector, each detector comprising a secondary electron emission surface configured to receive a radiation flux and to emit secondary electrons due to the receipt of the radiation flux, the first radiation dose detector located upstream with respect to the second radiation dose detector viewed with respect to a direction of radiation transmission, and a meter, connected to each detector, to detect a current or voltage resulting from the secondary electron emission from the respective electron emission surface.

Lithographic apparatus, and device manufacturing method

A projection exposure apparatus includes an illuminating device for illuminating a pattern of an original, a holder for holding a substrate, and a projection system for projecting an image of the pattern of the original onto the substrate. The projection system includes a projection optical system and a plane optical element spaced from the projection optical system and disposed opposite to the surface of the substrate. Also provided is a casing having a filled interspace formed between the optical element and the substrate, with the optical element providing an upper cover of the casing.

Immersion type projection exposure apparatus

Optical projection lithography using lenses with numerical apertures greater than unity

We report on transport measurements in grid‐gate lateral‐surface‐superlattice (LSSL) field‐effect transistors on a modulation‐doped GaAs/AlGaAs heterostructure. The LSSL is created by a 0.2 μm period Ti/Au grid on top of the AlGaAs layer, which presents a tunable, two‐dimensional periodic potential modulation to the electrons traveling from source to drain. Current measurements at 4.2 K as a function of gate bias exhibit negative transconductance at a fixed drain bias below 15 mV, providing evidence of a superlattice effect (i.e., coherent back‐diffraction). In addition, negative differential resistance is observed at a fixed gate bias and a drain bias around 100 mV, which could be a manifestation of sequential resonant tunneling.

Negative transconductance and negative differential resistance in a grid‐gate modulation‐doped field‐effect transistor

For the fabrication of large-area, spatially coherent gratings with periods of 100 nm or less, a grating interferometer is preferred over a conventional holographic configuration because of the limited coherence of available sources. Using a configuration that employs two matched fused silica phase gratings and an ArF excimer laser, we obtain high-quality 100-nm gratings in polymethyl methacrylate. We analyze the conditions for achieving high-contrast fringes with such an achromatic holographic configuration and show that the depth of focus depends only on the spatial coherence of the source. We also describe a highly accurate method for calculating the diffraction efficiency of the phase gratings as a function of polarization, incidence angle, and grating structure.

Achromatic holographic configuration for 100-nm-period lithography

We have studied the characteristics and limitations of optical projection lithography using high numerical-aperture (NA) optical microscopy lenses. With oil-immersion, NA's as large as 1.4 were realized, and linewidths asfine as 140 nm were achieved in 70 nm-thick commercial photoresist films using illumination of wavelength λ = 453 nm. Previous researchers have also obtained deep-submicron linewidths using high NA lenses. The new elements in our work are: (1) use of a photoresist-compatible oil to achieve NA = 1.4; (2) use of modern antireflection coatings (ARC) and tri-level processing to circumvent the problem of substrate back-reflection; (3) use of NA > 1 optical-projection to make masks for x-ray lithography, and the x-ray replication of such masks. Our motivation in pursuing this work was to explore the limits of high-NA optical projection, and to develop a simple, quick-turn-around method of making sub-quarter-micron-linewidth x-ray masks. Using the formula for minimum feature width W m i n = kλ/NA, we find that with an ARC and careful focusing one can work at k ∼ 0.43. Focusing and alignment are done by projecting the reticle image onto the resist with yellow light, which does not expose the resist. For exposure, the yellow filter is removed and a narrow-band blue filter (λ = 453 nm) inserted.

An antireflection coating (ARC) for use with poly(methyl methacrylate) (PMMA) resist for ArF excimer laser lithography (193 nm) was formulated. It consists of PMMA and a bis-azide, 4.4-prime-diazidodiphenyl sulfone (DDS) which crosslinks the film after deep UV (260 nm) irradiation and subsequent annealing. The reacted DDS then serves as the absorber for the 193 nm radiation and also prevents mixing of the ARC and PMMA during PMMA spin-coating and development. The effectiveness of the ARC was demonstrated by exposing, in PMMA, using achromatic holographic lithography, gratings of 100 nm period (about 50 nm linewidth) that are almost entirely free of an orthogonal standing wave.

A. Yen

Papers

Optical projection lithography using lenses with numerical apertures greater than unity

Negative transconductance and negative differential resistance in a grid‐gate modulation‐doped field‐effect transistor

Achromatic holographic configuration for 100-nm-period lithography

Optical projection lithography using lenses with numerical apertures greater than unity

An Anti‐Reflection Coating for Use with PMMA at 193 nm