Holography Application to a Grating X-Ray Mask

Dumas, Remi Henri Marc (1985) Holography Application to a Grating X-Ray Mask. PhD thesis, University of Glasgow.

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This thesis reports the development of the holographic process towards the fabrication of a grating X-ray mask. A general study is proposed which determines the design characteristics of a grating X-ray mask: a thin pattern of gold lines on a silicon nitride membrane. Such a mask can be used in contact X-ray lithography systems at the carbon Ka line. The second part of the thesis deals with the theoretical aspects of the recording of holographic gratings in a layer of positive photoresist coating a silicon nitride/silicon substrate. A gaussian treatment of the holographic process is presented and shows that it is possible to dispense with the use of collimating lenses on the optical arrangement without noticeable contrast degradation. A computer simulation of the grating recording process on multilayer substrates has been developed and was used to determine the thickness of silicon nitride for which the photoresist grating presents an undercut line profile, an indispensable feature before metal lift-off can be carried out successfully. Finally the fabrication of gratings of various pitches was undertaken. 0.12 micron and 0.17 micron gratings were printed using the front prism technique with UV and blue light respectively. In some cases moire patterns were recorded and the gratings presented an overall patchy aspect and extended only over very small areas. 0.3 micron gratings were successfully fabricated and showed an undercut line profile as predicted by the computer simulation. A thin layer of gold or gold/palladium was evaporated under high vacuum and the grating pattern subsequently lifted-off by dissolution of the photoresist in acetone. In some cases the lift-off was successful and gold gratings were obtained over large areas, But occasionaly the evaporated metal thickness was too high and a tunnelling effect was observed. The fabrication of silicon nitride membranes was attempted but no reliable technique has yet been found of protecting the metal grating from the various etchants. A discussion on the encountered difficulties is presented, solutions to these problems are suggested and a line of progress for future experiments is proposed.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Electrical engineering
Date of Award: 1985
Depositing User: Enlighten Team
Unique ID: glathesis:1985-77689
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jan 2020 11:53
Last Modified: 14 Jan 2020 11:53
URI: https://theses.gla.ac.uk/id/eprint/77689

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