IN-SITU OBSERVATION SYSTEM FOR SILICON-WAFER TRANSIENT DEFORMATION DURING INSERTION WITHDRAWAL INTO FROM HORIZONTAL FURNACES

An in situ observation system composed of a latticework, a mirror, and a video camera has been developed to quantitatively determine the tra nsient deformation of wafers when they are pushed into or pulled from a hot horizontal furnace. To observe a silicon wafer in the middle of many silicon wafers on a boat, those wafers that are located in front of the silicon wafer we want to observe are replaced by an equal numbe r of same-dimension transparent quartz wafers. An approximate relation for obtaining the actual amount of wafer distortion from the experime ntally observed image distortion is also derived. Using this observati on system, we examined in detail the effects of furnace temperature, b oat speed, wafer location, and wafer thickness on transient deformatio n. This system also provides more complete information on deformation distribution across a wafer, deformation speed, and recovery speed.