UVM Theses and Dissertations
Format:
Print
Author:
Burns, Dylan
Dept./Program:
Mechanical Engineering
Year:
2006
Degree:
MS
Abstract:
This research addresses the aeroelastic mechanics of thin film membrane masks during proximity (X-ray) lithography. This ultra-high precision manufacturing process uses an X-ray source to expose resist on silicon substrates in patterns carried by a thin membrane mask that is held near to the substrate. The mask is positioned relative to the substrate wafer with a stepper tool. Positioning and alignment maneuvers cause aerodynamic loads that may give rise to unwanted deformations in the mask. The deformations in the mask feedback to alter the aerodynamic loads to produce aeroelastic effects.
Testing was done both experimentally and theoretically. The experimental testing was performed using a custom built aeroelasticity test rig, which allowed for various means of positioning and moving of the mask relative to a fixed flat surface in a manner tha mimics many of the positioning maneuvers used in a production stepper. These tests were also simulated in FEMLAB using a theoretical model based on principles of hydodynamic lubrication coupled with membrane mechanics. The models predicted the aeroelastic behavior of the thin film membranes for various gas, wedge angles, and velocities. The experimental results agree favorably with the numerical models in both qualitative and quantitative aspects.
These situations simulated the stepping process that occurs during the proximity (X-ray) lithography. In the application of proximity lithrography, it would be greatly beneficial to be able to model these experiments in FEMLAB first before actually performing them. This would allow for the ideal settings to be determined for the manufacturing process, so as to optimize production rates by stepping at gap, and to examine the efficacy control devices and mesa mask geometries.
Testing was done both experimentally and theoretically. The experimental testing was performed using a custom built aeroelasticity test rig, which allowed for various means of positioning and moving of the mask relative to a fixed flat surface in a manner tha mimics many of the positioning maneuvers used in a production stepper. These tests were also simulated in FEMLAB using a theoretical model based on principles of hydodynamic lubrication coupled with membrane mechanics. The models predicted the aeroelastic behavior of the thin film membranes for various gas, wedge angles, and velocities. The experimental results agree favorably with the numerical models in both qualitative and quantitative aspects.
These situations simulated the stepping process that occurs during the proximity (X-ray) lithography. In the application of proximity lithrography, it would be greatly beneficial to be able to model these experiments in FEMLAB first before actually performing them. This would allow for the ideal settings to be determined for the manufacturing process, so as to optimize production rates by stepping at gap, and to examine the efficacy control devices and mesa mask geometries.