Characterization of deep UV photoresist properties by infrared near-field scanning optical microscopy and related methods [Elektronische Ressource] / vorgelegt von Jan Preußer
127 pages
English

Characterization of deep UV photoresist properties by infrared near-field scanning optical microscopy and related methods [Elektronische Ressource] / vorgelegt von Jan Preußer

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127 pages
English
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Characterization of deep UV photoresist propertiesby infrared near- eld scanning optical microscopyand related methodsD i s s e r t a t i o nzur Erlangung des Grades eines Doktorsder Naturwissenschaftenvorgelegt vonJan Preu eraus Otterndorfgenehmigt von derMathematisch-Naturwissenschaftlichen Fakult atder Technischen Universit at ClausthalTag der mundlic hen Prufung7. Juli 2003Vorsitzender der Prufungsk ommission..........................Prof. Dr. D. MayerHauptberichterstatter ........................................ Prof. Dr. W. SchadeBerichterstatter .................................................. Prof. Dr. D. KipDie vorliegende Arbeit wurde im Zeitraum vom November 1998 bis Juni 2003 am Institutfur Physik und Physikalische Technologien der Technischen Universit at Clausthal sowieam JILA, University of Colorado in Boulder, USA angefertigt.Contents1 Introduction 12 Fundamentals of lithography 52.1 Introduction to optical lithography in semiconductor device manufacturing 52.2 Chemically ampli ed photoresists . . . . . . . . . . . . . . . . . . . . . . . . 72.2.1 Nonlinear chemistry in latent image formation . . . . . . . . . . . . 72.2.2 Poly(t-butoxyoxycarbonylstyrene) (PTBOCST) . . . . . . . . . . . . 72.2.3 Poly(t-butylmethacrylate) (PTBMA) . . . . . . . . . . . . . . . . . . 102.3 Di usion in polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 Image formation in optical microscopy 153.

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Publié par
Publié le 01 janvier 2004
Nombre de lectures 34
Langue English
Poids de l'ouvrage 5 Mo

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Characterization of deep UV photoresist properties by infrared nearfield scanning optical microscopy and related methods
D i s s e r t a t i o n zur Erlangung des Grades eines Doktors der Naturwissenschaften
vorgelegt von Jan Preußer aus Otterndorf
genehmigt von der MathematischNaturwissenschaftlichen Fakultät der Technischen Universität Clausthal
Tag der mündlichen Prüfung 7. Juli 2003
Vorsitzender der Prüfungskommission . . . . . . . . . . . . . . . . . . . . . . . . . . Prof. Dr. D. Mayer
Hauptberichterstatter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Prof. Dr. W. Schade
Berichterstatter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Prof. Dr. D. Kip
Die vorliegende Arbeit wurde im Zeitraum vom November 1998 bis Juni 2003 am Institut für Physik und Physikalische Technologien der Technischen Universität Clausthal sowie am JILA, University of Colorado in Boulder, USA angefertigt.
3.2
2.3
5
1
Multiple multipole approximation (MMP) . . . . . . . . . . . . . . . 22
Dipole induced dipole interaction . . . . . . . . . . . . . . . . . . . . 24
. . . . . . . . . . . . . . . . . . . 24
Chemically amplified photoresists . . . . . . . . . . . . . . . . . . . . . . . .
Poly(tbutoxyoxycarbonylstyrene) (PTBOCST) . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . 26
7
7
7
Introduction to optical lithography in semiconductor device manufacturing
Nonlinear chemistry in latent image formation
3.3
Artifact reduced optical imaging
3.3.1
Apertureless nearfield optical microscopy
3.3.2
Fundamentals of lithography
Introduction
2
1
Contents
2.2.1
2.2
2.2.2
2.1
3.4.2
3.4
3.4.1
2.2.3
Theory of Bethe and Bouwkamp . . . . . . . . . . . . . . . . . . . . 19
3.1
3
Image formation in optical microscopy
Resolution limit in conventional microscopy . . . . . . . . . . . . . . . . . . 15
. . . . . . . . . . . .
I
15
Diffusion in polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Overcoming the resolution limit . . . . . . . . . . . . . . . . . . . . . . . . . 17
Theoretical approximations for nearfield imaging . . . . . . . . . . . . . . . 19
5
Poly(tbutylmethacrylate) (PTBMA) . . . . . . . . . . . . . . . . . . 10
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
29
29
. . . . . . . . . . . . . . . . . . . . . . . . .
5.3
5.2.6
4
4.1
II
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Sapphire
Fiber taper preparation by melting/pulling
5.2.5.1
5.2.5.2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fiber tip preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47
46
48
8
8.1.1
8.1
7
47
48
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Color center laser (FCL) . . . . . . . . . . . . . . . . . . . . . . . . .
Twotaper pulling of nearfield optical probes . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
5.1
5.2
Infrared nearfield optical imaging
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4
Chalcogenide
40
35
. . . . . . . . . . . . . . . . . . . . . . . . .
35
. . . . . . . . . . . . . . . . . . . . . . . . . .
40
Fiber taper preparation by etching . . . . . . . . . . . . . . . . . . .
44
55
61
61
51
. . . . . . . . . . . . . . . . . . . . . . .
61
40
. . . . . . . . . . . . . .
42
45
49
44
44
Waveguide materials for the infrared wavelength range . . . . . . . .
Structuring by mask
Lithographic sample preparation
Infrared nearfield optical microscopy
Setup . . . . . . . . . . . . . .
Photoresist polymer structures
Apertureless nearfield optical microscopy
General remarks
6
Zirconium aluminum fluoride . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
40
. . . . . . . . . .
4.2
Detectors
5.3.3
Incoherent light sources
Fourier Transform Infrared Spectroscopy (FTIR)
5.3.2
Diode laser (PbS)
31
Structuring by interferometric lithography . . . . . . . . . . . . . . . . . . .
CONTENTS
Overview
5.2.2
5.2.3
5.2.4
5.2.5
5.3.1
Light sources
5.2.5.3
5.2.1
Aperture formation by deposition of metal coating
CONTENTS
9
8.2
8.1.2
8.1.3
8.1.4
Contrast mechanisms in polymer films . . . . . . . . . . . . . . . . .
Absorption contrast for on and offresonance imaging . . . . . . . .
Diffractioninduced artifacts in latent image formation . . . . . . . .
Diffusion properties of chemically amplified photoresists
8.2.1
8.2.2
8.2.3
. . . . . . . . . . .
UV response for poly(tbutoxycarbonyloxystyrene) . . . . . . . . . .
Acid distribution after UV exposure
. . . . . . . . . . . . . . . . . .
Latent image spreading under the influence of bake time and UV intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Imaging with apertureless nearfield optical microscopy
9.1
9.2
9.3
Gold islands on glass surface
. . . . . . . . . . . . . . . . . . . . . . . . . .
Diblock copolymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Photoresist polymer structures imaged by ANSOM . . . . . . . . . . . . . .
10 Conclusions
Bibliography
Acknowledgements
Eidesstattliche Erklärung
III
62
66
69
71
71
75
76
83
83
90
95
99
101
113
115
IV
CONTENTS
1
Introduction
With advancing needs for higher packaging densities in chip technology, smaller and smaller feature sizes have to be realized in substrate materials used for microchip fabrication. It was proposed that the development in decreasing structure size follows an exponential behavior, also termed ”Moore’s Law” [1].
Today probably the most limiting factor is given by the photolithographic process, which is used to transfer an image of the designed structure onto the semiconductor. Polymeric photoresists are the key component in industry for patterning semiconductors, flat panel displays and data storage device components. An important step towards even smaller features was taken by Ito and coworkers [2, 3] by developing chemically amplified photoresists, which allow for an optical lithography process beyond Rayleigh’s resolution limit. While the smallest dimensions possible scaled directly with the wavelength of light used in the lithographic process, the new resists open a range of possibilities due to their nonlinear response to UV irradiation.
With the introduction of acidcatalyzed chemically amplified photoresist chemistry, a microscopic understanding of dynamics in the photopolymers is needed. Latent image metrology provides the means to study the evolution of resist profiles at different steps of the pattern formation: after exposure, postexposure bake and development. Image spreading and surface roughness are only two examples of parameters that have to be understood and controlled on a nanometer length scale.
While optical microscopy utilizes fluorescent tracers to track diffusion properties and feature broadening at a microscopic level, other work employs atomic force microscopy to perform topographic profiling and examine local shrinkage, which is related to the acidcatalyzed process. Fourier transform infrared spectroscopy (FTIR) is used to deliver macroscopic information on bulk samples but none of the techniques above allow to gain unperturbed insitu information on the dynamics in patterned photolithographic polymers.
Nearfield scanning optical microscopy (NSOM) offers the possibility to obtain images at lateral resolutions far beyond the diffraction limit impinged on conventional microscopy. This is achieved by illuminating the sample through a subwavelength aperture in
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