Accession Number : ADA313683

Title :   Instrumentation for Advanced Feedback Control of a Metalorganic Chemical Vapor Deposition Facility.

Descriptive Note : Final rept. 23 Jan 95-22 Jan 96,

Corporate Author : CALIFORNIA UNIV SANTA BARBARA

Personal Author(s) : Smith, R. S. ; DenBaars, S. P. ; Gaffney, M. S.

PDF Url : ADA313683

Report Date : 17 JUN 1996

Pagination or Media Count : 80

Abstract : This report describes the purchase of equipment for instrumentation and feedback control of chemical vapor deposition reactors for III-V compound semiconductor device manufacturing. A combination of ultrasonic and optical sensors are used to measure component gas concentrations and the growth rate at the sample surface. Mass flow controllers, at various locations in the reactor gas delivery system, are used to control the pure component flow. Two optical sensing systems are being developed with funds from this grant. The first is an ultraviolet light absorption monitor, which uses the absorption at a particular ultraviolet frequency to measure the gas partial pressure, and thereby infer the concentration above the growing surface. The second is a reflective difference spectroscopy system which determines the growing layer thickness in real-time, from the polarization of a reflected light beam. Digital computers are used to implement the data acquisition and feedback control systems. The report contains an overview of the metalorganic chemical vapor deposition system. The sensing, actuation, and control approaches are described in detail. A complete description of the components is also provided. The research is ongoing and the publications related to the funded development work are attached.

Descriptors :   *METALS, *CONTROL SYSTEMS, *CHEMICAL VAPOR DEPOSITION, *FEEDBACK, FREQUENCY, MEASUREMENT, OPTICAL EQUIPMENT, POLARIZATION, ULTRAVIOLET RADIATION, MONITORING, SPECTROSCOPY, LAYERS, LIGHT, REFLECTION, GASES, CHEMICAL REACTORS, PURITY, MASS FLOW, ULTRASONICS, REACTOR SYSTEM COMPONENTS, ORGANIC COMPOUNDS, DATA ACQUISITION, ABSORPTION, OPTICAL DETECTORS, DIGITAL COMPUTERS, PARTIAL PRESSURE.

Subject Categories : Industrial Chemistry and Chemical Processing
      Inorganic Chemistry
      Physical Chemistry
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE