Bistable behavior of silicon wafer in rapid thermal processing setup

The bistable behavior of a silicon wafer in the thermal reactor of the rapid thermal processing (RTP) setup has been theoretically predicted and for the first time detected experimentally. It is shown that the effect of the temperature and optical bistability depends on a doping degree of the wafer. It has been found experimentally that the lightly doped silicon wafer with resistivity 12 Ω cm has the bistable behavior being heated by the radiation of tungsten–halogen quartz lamps, in argon atmosphere, with 0.2 mm between the wafer and the water-cooled pedestal. At the same heating conditions, the heavily doped silicon wafer with resistivity 0.01 Ω cm has not exhibited the bistable behavior. As a part of the study, an analytical expression is proposed to approximate the temperature dependence of the spectral emissivity of the lightly doped silicon wafer.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The heat exchange mode between Si-wafer and the elements of the thermal reactor depends on the gas gap width b. ► The theoretical simulations predict the temperature bistability in the Si-wafer for low values of the gas gap. ► The bistability is observed for the gas gap width b = 0.2 mm.