(84) Gas Delivery Tetraethyl orthosilicate (TEOS), Boron trichloride (BCl3), Aluminum Chloride (AlCl3), Chlorine trifluoride (ClF3) and Dichlorosilane (DCS) are gases that condense or liquefy due to a phase shift at low temperatures. In semiconductor processes the condensation occurs in the gas line and puddles in the shower head before being injected into the vacuum chamber. A substantial number of wafer defects will occur if liquefied gases are injected into the vacuum chamber. Uniform heating of the lines will prevent condensation. TEOS lines are typically heated above 194°F (90°C) and BCl3 above 86°F (30°C), depending on pressure and flow rate. The optimum line temperature will vary ...
(32) In semiconductor processes condensation of many critical gases occurs due to a phase shift at low temperatures. Burning of the gases will occur if the delivery line is too hot. High or low temperature condition may result in undesirable particulates and cause costly device defects and tool maintenance. The Watlow STRETCH-TO-LENGTH® (S-T-L) gas line heater system was developed as an easy to assemble temperature solution with performance superior to heat tape. S-T-L's preformed construction gives engineers the ability to wrap it around the delivery line with consistent heater/gas line contact for improved temperature
uniformity. S-T-L's flexibility gives engineers the ability to compensate for the size of different components thus ...
