IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 Taking on the Multiscale Challenge Even Small-Scale Victories are Good Len Borucki Digital DNA Lab Motorola, Inc. Phoenix, AZ

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 Why do multiscale modeling? - Perspective from semiconductor manufacturing. Typically, tool “knobs” control tool physics on the ~0.1-1 meter scale 0.2 m However, the goal is to control an outcome at the micron scale or below over a wide area of the wafer. 0.1  m Deposited Filmwafer Tools are expensive, so optimizing their use is important. T Merchant

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 Several spatial scales may be involved. Equipment or Wafer Scale Die (Chip) Scale Feature Scale ~1 cm Differences in feature packing densities within a die or across a wafer may affect local feature scale uniformity due to depletion of reactants or other effects related to feature density.

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000

Starting at the atomic level, the goal of modeling may be to predict structure and properties at much larger length and time scales. There are huge gaps. ~ m and ~ sec Film precursors. Gas phase and surface chemistry. A. Korkin, N. Tanpipat Film nucleation, growth, grain structure and transport properties. ~ ~10 -5 m and ~10 2 sec Void Nucleation C-L Liu D. Richards Metal Lifetime ~ ~10 -3 m and ~ ~10 8 sec Electronic properties Film thickness ~ ~10 -8 m

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 Challenge: Film Nucleation, Growth Source: J. Zhang, J. Adams, Arizona State University See Facet growth during physical vapor deposition with surface diffusion. KLMC. Activation energies for diffusion along and between facets. Embedded atom method. Grain Nucleation (FCC nuclei with {100}, {111} or {110} facets, randomly rotated and cut) Grain growth for an isotropic or unidirectional source. String algorithm, not a level set method. Isotropic Source

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 Challenge: Calculation of properties of polycrystalline structures.

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 Calculating transport properties of large polycrystalline structures - an example. D A j x  Tilt Angle W=Line Width  = Grain Boundary Width This very simple model produces a fairly convincing statistical failure time distribution.

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 Joule Heating in a Snake

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 A Different Reacting Flow Multiscale Problem: Chemical-Mechanical Polishing A chemically reactive slurry containing ~0.1  m particles is sprayed on a rotating polyurethane pad in front of a rotating wafer. The slurry attacks the surface layer on the wafer, allowing the particles to more easily abrade and smooth the layer.

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 The polyurethane pad contains numerous voids averaging ~30 microns in diameter. Voids exposed at the surface fill with slurry. The slurry layer is very thin in highly compressed areas between the voids. Slurry particles probably contact the wafer in these compressed regions. Chemical-Mechanical Polishing

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 Somehow, this surface structure plays a role in the details of the development of suction fluid pressure under the wafer. The suction pressure may in turn affect the uniformity of the removal rate on the wafer scale. Shan, Georgia Tech Chemical-Mechanical Polishing Question: How to describe the pad surface and utilize the information in a model with a longer length scale; eg. the Reynolds equation?

IMA Workshop on Multiscale Models for Surface Evolution and Reacting Flows June 5-9, 2000 Summary Multiscale models either Start at equipment scale and connect with the feature scale. Start at the atomic level and progress toward longer length and time scales. Very significant gaps exist, for example, Modeling of nucleation and growth of polycrystalline films, particularly in 3D and with topography. Prediction of properties of polycrystalline materials. Better mathematical and numerical methods.