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Title: Investigation of the interaction between nanoparticles and I-line radiation for nanolithography applications
Author: Lewis, Scott
ISNI:       0000 0004 2748 1414
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2009
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In 1965 Gordon E. Moore forecasted that the number of transistors on a chip would double every 18 months. This became known throughout the semiconductor industry as Moore's law. However, it was observed that this cannot be continued indefinitely but, it has been seen as a goal for the industry. Since the 1960s, semiconductor manufacturers have strived to scale down device features according to Moore's law. This has been achieved by photolithography, and has unquestionably been one of the major driving forces behind the progress made in the field of semiconductor technology. It is in this miniaturization of features that photolithography has made its contribution, and where the advancement of the fabrication techniques to produce a mask has played its role. In this thesis the focus was on investigating suitable technologies to economically maintain the trend of Moore's Law. The fabrication of next generation optical photomasks was studied that could produce the next generation ultra large scale integration (ULSI). Two methods were developed and contrasted these were both based on 'top down' photolithography using I-line radiation. However, two different approaches were adopted to fabricate these optical masks. The first was based on electron beam lithography by a fabricating a novel nanocomposite electron beam resist that incorporated nanoparticles into Polymethylmethacrylate (PMMA). The nanoparticles were used to attenuate the radiation propagating through the electron beam resist as the PMMA was found to be transparent at the wavelength of the incident radiation. When the nanocomposite resist was patterned by the electron beam, the pattern was transferred to a photoresist via contact printing using the conventional photolithography technique. The second approach exploited a novel photolithography technique using periodic hexagonally closely packed silver nanoparticle 2D arrays. A method to precisely control the spacing between nanoparticles by temperature has been demonstrated this was then used to transfer a nano - pattern into a photoresist. The high - density nanoparticle thin film was accomplished by self-assembling through the Langmuir - Schaefer (LS) technique on a water surface and transferring the nanoparticle monolayer to a temperature sensitive polymer membrane. A 30nm hexagonally packed silver nanoparticle 2D array pattern with a 50nm period has been successfully transferred into photoresist. The resultant feature sizes were 34nm with a period of 16nm, due to the surface plasmon resonance where the photoresist is approximately 11 times smaller than wavelength. This work demonstrated the suitability of these novel masks in certain applications where the complexity of fabrications and the associated costs varied considerably. 'Top down' techniques were often expensive and slow, but provided a direct route to achieving the desired features. The 'bottom up' techniques were often achieved at low cost but were limited in terms of control over geometry.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available