Current Model Model is 2D. FIDAP equates force and moment on the wafer surface and rotates the wafer into equilibrium.

Comparison with Experimental Results Model predictions compared with fluid film thickness and pitch angle results from Lu et al (2001) Results on same order Film thickness differs by constant of about 20 m - difference due to DELIF technique? Angle of attack is on same order as experimentally measured value Tufts University – Dept. of Mechanical Engineering – MS Thesis Defense –Oct 17, 2002 42

Adding Material Removal A method to determine removal rate must be determined. Possible models include: Modified Preston’s law Surface stress model Abrasive and chemical wear model Arbitrary user-defined model

RR Models A modified Preston model is probably best. Should provide flexibility for various problem types. Easiest way to obtain removal rate on global scale. Current research on Preston coefficients for CMP exists to some degree. Options could become limited depending on the method used in FIDAP to implement removal rate of the wafer.

Current Work – Computer Set-up Current version of FIDAP (8.7) is not compatible with the existing models created in the earlier version FIDAP (8.52), although it should be. Converting model databases and subroutines this month. Currently trying to working with FIDAP technical support to remedy FORTRAN compiler issues on new university UNIX server.

Project Priorities: Material Removal or Pad Deformation? Should we pursue pad deformation modeling in lieu of removal rate? If pad deformation – experimental envelope and simulations should be coordinated

Initial Strategies for Pad Deformation Model Two existing FIDAP approaches Model pad as a flexible thin film – elasticity…(vein wall example) – boundary condition to fluid problem Rigid body movement – full model of pad First approach is more compatible with previous modeling efforts Currently – running simpler test cases with standard FIDAP model while compiler problem is upgraded