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Title:Mediated Patterning of Sol -Gel Thin Layers: Shrinkage, Decohesion, and Lift-Off
Author(s):Mikalsen, Erik Arthur
Doctoral Committee Chair(s):Payne, David A.
Department / Program:Materials Science and Engineering
Discipline:Materials Science and Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Engineering, Materials Science
Abstract:The shrinkage and densification of sol-gel layers were determined by in-situ and ex-situ measurements, where a ∼30% decrease in thickness (t) was typical during drying of sol-gel layers (T < 300°C). Constrained shrinkage, resulting from adhesion to the supporting silicon substrate, led to a coherent (crack-free) film with biaxial stresses of ∼200 MPa (t ∼ 50 nm). For ODTS-mediated sol-gel films, however, precise in-situ wafer curvature measurements determined that film stresses never exceeded 75 MPa. Additionally, interfacial adhesive strength between the substrate and the sol-gel film were evaluated for the first time using a unique pulsed-laser stress-wave technique. An adhesive strength threshold of 15 MPa was determined for sol-gel films on ODTS-functionalized silicon, whereas, the threshold strength of films deposited on unmodified silicon was determined as >25 MPa and greater than the fracture strength of silicon. In this work, hydrophobic surface regions, facilitated by directed mu-CP of a molecular film, affected adhesion so as to reduce the substrate constraint and promote de-cohesion of the sol-gel film on the sub-micron scale. That is, selective de-cohesion and lift-off were enabled by the control of local mechanical interfacial constraints.
Issue Date:2003
Description:231 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2003.
Other Identifier(s):(MiAaPQ)AAI3086141
Date Available in IDEALS:2015-09-25
Date Deposited:2003

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