Multiscale optimization using hybrid PDE/kMC process systems with application to thin film growth

Amit Varshney, Antonios Armaou

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

The problem of optimal time-constant and time-varying operation for transport-reaction processes is considered, when the cost functional and/or equality constraints necessitate the consideration of phenomena that occur over disparate length scales. Multiscale process models are initially developed, linking continuum conservation laws with microscopic scale simulators. Subsequently, order reduction techniques for dissipative partial-differential equations are combined with adaptive tabulation of microscopic simulation data to reduce the computational requirements of the optimization problem, which is then solved using standard search algorithms. The method is applied to a conceptual thin film deposition process to compute optimal substrate-surface temperature profiles that simultaneously maximize film-deposition-rate uniformity (macroscale objective) and minimize surface roughness (microscale objective) across the film surface for a steady-state process operation. Subsequently, optimal time-varying policies of substrate temperature and precursor inlet concentrations are computed under the assumption of quasi-steady-state process operation.

Original languageEnglish (US)
Pages (from-to)6780-6794
Number of pages15
JournalChemical Engineering Science
Volume60
Issue number23
DOIs
StatePublished - Jan 1 2005

Fingerprint

Film growth
Thin films
Substrates
Deposition rates
Partial differential equations
Conservation
Simulators
Surface roughness
Temperature

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

Cite this

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abstract = "The problem of optimal time-constant and time-varying operation for transport-reaction processes is considered, when the cost functional and/or equality constraints necessitate the consideration of phenomena that occur over disparate length scales. Multiscale process models are initially developed, linking continuum conservation laws with microscopic scale simulators. Subsequently, order reduction techniques for dissipative partial-differential equations are combined with adaptive tabulation of microscopic simulation data to reduce the computational requirements of the optimization problem, which is then solved using standard search algorithms. The method is applied to a conceptual thin film deposition process to compute optimal substrate-surface temperature profiles that simultaneously maximize film-deposition-rate uniformity (macroscale objective) and minimize surface roughness (microscale objective) across the film surface for a steady-state process operation. Subsequently, optimal time-varying policies of substrate temperature and precursor inlet concentrations are computed under the assumption of quasi-steady-state process operation.",
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Multiscale optimization using hybrid PDE/kMC process systems with application to thin film growth. / Varshney, Amit; Armaou, Antonios.

In: Chemical Engineering Science, Vol. 60, No. 23, 01.01.2005, p. 6780-6794.

Research output: Contribution to journalArticle

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