Ym. Cho et T. Kailath, IMPROVEMENT OF PYROMETRIC SENSING IN RAPID THERMAL-PROCESSING VIA ADAPTIVE CANCELLATION OF LAMPLIGHT INTERFERENCE, Control engineering practice, 3(5), 1995, pp. 643-649
Citations number
5
Categorie Soggetti
Controlo Theory & Cybernetics","Robotics & Automatic Control
Rapid thermal processing (RTP) is an emerging and promising technology
in semiconductor manufacturing that provides numerous advantages over
traditional batch processing. A central problem in RTP technology is
the precise control of wafer temperature. However, the inability to ac
curately measure wafer temperatures during processing has thus far pro
ved a major obstacle to the effectiveness of temperature control strat
egies. Pyrometry, the most commonly encountered temperature-sensing te
chnique used in RTP, suffers from large bias due to uncertainty in the
emissivity of silicon wafers. Texas Instruments has recently proposed
an innovative technique that overcomes the problem of emissivity unce
rtainty. However, the new technique suffers from interference of lampl
ight that is the heating source in RTP. This paper proposes a system-t
heoretic approach to greatly mitigate the lamplight interference. An o
n-line adaptive cancellation technique is adopted to estimate time-var
ying gains. Experimental results of the proposed method are described.