Accession Number : ADA259724


Title :   Process Toward a Comprehensive Control System for Molecular Beam Epitaxy


Descriptive Note : Interim rept. 1 Aug 1990-30 Jul 1992


Corporate Author : WRIGHT LAB WRIGHT-PATTERSON AFB OH


Personal Author(s) : Patterson, Oliver D ; Heyob, Jeffrey J ; Adams, Steven J ; Hunt, Victor ; Garrett, Patrick H


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a259724.pdf


Report Date : Aug 1992


Pagination or Media Count : 25


Abstract : A hierarchical control system for improving the manufacturing capability of the thin-film semiconductor growth process, Molecular Beam Epitaxy, is under development at the Air Force Materials Directorate. The focus of the first level is to improve the precision and tracking of the variables, flux and substrate temperature. The second level consists of an expert system that uses sensors to monitor the status of the product in order to generate a process plan in real time. The third level features a continuously evolving neural network model of the process which is used to recommend the recipe and command inputs to achieve a desired product goal. All three levels require models of the process which are updated using automatic process identification experiments. The three levels of the system are described and experimental data is used to illustrate the impact of select modules.... Molecular beam epitaxy, Thin-Film semiconductors, Gallium arsenide, Hierarchical control, Self-Directed control, Neural network, Real time.


Descriptors :   *CONTROL SYSTEMS , *THIN FILMS , *EPITAXIAL GROWTH , *MOLECULAR BEAMS , *SEMICONDUCTORS , INPUT , CONTROL , TEMPERATURE , MANUFACTURING , MODELS , REAL TIME , FLUX(RATE) , MONITORS , EXPERT SYSTEMS , GALLIUM , ARSENIDES , PRECISION , IDENTIFICATION , VARIABLES , SUBSTRATES , TRACKING , AUTOMATIC , HIERARCHIES , GALLIUM ARSENIDES , MATERIALS , NETWORKS , IMPACT , NEURAL NETS , AIR FORCE , EXPERIMENTAL DATA


Subject Categories : Inorganic Chemistry
      Electrical and Electronic Equipment
      Crystallography
      Atomic and Molecular Physics and Spectroscopy


Distribution Statement : APPROVED FOR PUBLIC RELEASE