Optical Science and Engineering ETDs

Publication Date

Fall 11-23-2021

Abstract

In this dissertation interferometric lithography is approached in two different ways to address two important constraints of nanopatterning. One approach solves the problem of scaling up interferometric lithography to wafer scale (4 inch or larger) area. Through the second approach we have developed a nanopatterning technique based on interferometric lithography by using an inexpensive (~$100) diode laser as source, making interferometric lithography a very cost-effective technique.

Wafer-scale large-area nanopatterning was developed using an amplitude grating mask as a grating beam splitter along with spatial averaging of laser intensity by wobbling. The longitudinal and transverse coherence issues both are eased by using grating beam splitters in the place of the Lloyd’s mirror or partially reflecting beam splitters. An inexpensive 1D amplitude mask is used as a grating splitter. Scanning or wobbling of the laser source helps in attaining uniform pattern through averaging effect in spite of Gaussian profile of the light source. 4-inch silicon wafers were successfully nanopatterned with a pitch close to 880 nm. The unique configuration of optical setup makes it really compact and in the future this setup is scalable to pattern 6-inch wafers or larger by changing the size of the optics.

We have also demonstrated an oblique-incidence interferometric nanopatterning using a low-cost multi-longitudinal-mode diode laser as source and a spin-on-glass (SOG) based diffraction-phase-mask grating beam splitter. The phase mask is engineered to have only two, equal intensity orders (0th and -1st), dramatically simplifying the optical arrangement and decreasing the propagation distance between the beam splitter and the sample. The low-cost, high power (150 mW) TEM00 405-nm diode laser operates with a large number of longitudinal modes, resulting in an impractical mask-to-sample-gap proximity requirement with a single grating beam splitter. A dual-grating-mask, achromatic interferometric scheme is introduced to extend this gap dimension to easily accessible scales. Uniform nanopatterns with a periodicity of 600 nm were fabricated over a 1 cm diameter area using this multimode diode laser. This technique is scalable and has the potential for large area nanopatterning applications.

Degree Name

Optical Science and Engineering

Level of Degree

Doctoral

Department Name

Optical Science and Engineering

First Committee Member (Chair)

Dr. Steven R J Brueck

Second Committee Member

Dr. Sang Eon Han

Third Committee Member

Dr. Sang M Han

Fourth Committee Member

Dr. Jean Claude Diels

Keywords

nanopatterning, nanolithography, large area nanopatterning, diode laser nanolithography, nanofabrication, optical engineering

Sponsors

NSF, Nascent

Document Type

Dissertation

Language

English

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