Accession Number : ADA332640

Title :   Application of Modern Signal Processing to Semiconductor Manufacturing and Phase Mask Design

Descriptive Note : Final technical rept. 31 Dec 96-1 Sep 97

Corporate Author : STANFORD UNIV CA DEPT OF ELECTRICAL ENGINEERING

Personal Author(s) : Kailath, Thomas

PDF Url : ADA332640

Report Date : 17 JAN 1997

Pagination or Media Count : 9

Abstract : The semiconductor manufacturing industry faces the need for tighter control of thermal budget and process variations as circuit feature sizes decrease. Strategies to meet this need include supervisory control, run-to-run control, and real-time feedback control. Typically, the level of control chosen depends upon the actuation and sensing available. Rapid Thermal (RTP) is one step of the manufacturing cycle requiring precise temperature control and hence real-time feedback control. At the outset of this research, the primary ingredient lacking from in-situ RTP temperature control was suitable sensor. This research looks at an alternative to the traditional approach of pyrometry, which is limited by the unknown and possibly time-varying wafer emissivity. the technique is based upon the temperature dependence of the propagation time of an acoustic wave in the wafer. The aim of this thesis is to demonstrate that ultrasonic sensors are a viable sensor for control in RTP. To do this, an experimental implementation was developed at the Center for Integrated Systems. Because of the difficulty in applying a known temperature standard in an RTP environment, calibration to absolute temperature is nontrivial Given reference propagation delays, multivariable model-based feedback control is applied to the system. The modelling and implementation details are described. The control techniques have been applied to a number of research processes including rapid thermal annealing and rapid thermal crystallization of thin silicon films on quartz/glass substrates.

Descriptors :   *SIGNAL PROCESSING, *MANUFACTURING, *SEMICONDUCTORS, THERMAL PROPERTIES, CONTROL, PROPAGATION, ANNEALING, INTEGRATED SYSTEMS, DETECTORS, REAL TIME, ACOUSTIC WAVES, THIN FILMS, THESES, SUBSTRATES, CRYSTALLIZATION, GLASS, CYCLES, VARIATIONS, QUARTZ, ULTRASONICS, FEEDBACK, SILICON, VIABILITY, PRECISION, DELAY, TEMPERATURE CONTROL, CALIBRATION, CIRCUITS, WAFERS, MASKS, THERMAL RADIATION, EMISSIVITY, PYROMETERS.

Subject Categories : Electrical and Electronic Equipment
      Mfg & Industrial Eng & Control of Product Sys

Distribution Statement : APPROVED FOR PUBLIC RELEASE