Wafer bonding : mechanics-based models and experiments

Direct wafer bonding has emerged as an important technology in the manufacture of silicon-on-insulator substrates (SOI), microelectromechanical systems (MEMS), and three-dimensional integrated circuits (3D IC's). While the process is currently employed in applications such as these, a lack of knowledge of the basic mechanics of the process has made developing robust processes and preventing process failures extremely challenging. The current work addresses this problem through the development and validation of mechanics-based models that connect the wafer geometry, etch pattern, clamping configuration, and work of adhesion to bonding failure. An energy-based bonding criterion, which allows the effect of flatness variations and etch patterns to be quantified, is presented and employed to develop analytical and numerical models. Analytical models, based on plate theory, are developed to examine the role of wafer-scale shape variations, etch patterns, and the clamping configuration. Finite element models are developed to verify the analytical models and to evaluate the bonding criterion for wafers with anisotropic elastic properties and arbitrary geometries. Experiments in which silicon substrates with wafer-scale shape variations and etch patterns were bonded demonstrate that the shape and size of the bonded area and the shape of the bonded pair can be predicted using the models developed. The effect of mid-spatial wavelength height variations (nanotopography) on bonding is examined through a combination of modeling and experiments. The experiments and analysis provide a route for characterizing nanotopography and assessing its impact on bonding. The accuracy of the wafer bonded double cantilever beam, which

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2004

Author dc:creator

• Turner, Kevin Thomas, 1977-

Advisor dc:contributor.advisor

• S. Mark Spearing.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/16675

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/16675