Campus Units

Aerospace Engineering, Mechanical Engineering

Document Type

Article

Publication Version

Submitted Manuscript

Publication Date

2016

Journal or Book Title

International Journal of Machine Tools and Manufacture

First Page

49

Last Page

57

DOI

10.1016/j.ijmachtools.2016.07.003

Abstract

Paired polishing process (PPP) is a variant of the chemical mechanical polishing process which facilitates defect mitigation via minimization of maximum force as well as effective planarization via profile driven determination of force gradient. The present embodiment of PPP machine employs two polishing wheels, radially spanning the wafer surface on a counter-gimbaled base. The PPP machine is deployed to experimentally investigate the role of the process parameters on the surface roughness evolution, and the effective material removal rate. Two sets of copper and aluminum blanket layers were polished under a range of applied down force, polishing wheel speed and transverse feed rate to examine the scalability of the process parameters for different material constants. The experimental measurements along with the topological details of the polishing pad have been utilized to develop a mechanistic model of the process. The model employs the soft wheel-workpiece macroscopic contact, the polishing wheel roughness and its amplification to the local contact pressure, the kinematics of abrasive grits at the local scale, and the collective contribution of these individual micro-events to induce an effective material removal rate at the macroscale. The model shows the dependence of the material removal on the ratio of wheel rotational to feed speed for the PPP process, in a form of an asymptote that is scaled by the surface hardness of each material. The PPP machine exploits this insight and utilizes an oblique grinding technique that obviates the traditional trade-off between MRR and planarization efficiency.

Comments

This is a manuscript of an article from International Journal of Machine Tools and Manufacture (2016). The final publication is available via: http://dx.doi.org/10.1016/j.ijmachtools.2016.07.003.

Copyright Owner

Elsevier Ltd.

Language

en

File Format

application/pdf