Silicon Dioxide LPCVD System

This LPCVD system is structured around a 213 cm (84") long quartz tube with a diameter of 208 mm. The temperature control is achieved by a solid state, three zone system with the sensitivity of +/- 0.1 degree Celsius. The vacuum is achieved by an Alcatel 2063 CP+ rotary vane vacuum pump using Fomblin fluid with a base pressure of 3 millitorr. The system is capable of processing 4" and 6" wafers, however, small pieces can also be processed by placing them on a sample holder.  The precursors are diethylsilane (a liquid, also known as Schumacher LTO-410) and oxygen.  Because the vapor pressure of diethylsilane is sufficiently high, it can be  introduced into the deposition environment without using a carrier gas. The standard process temperature and pressure are 410C and 640 mtorr respectively yielding an approximate deposition rate of 4 nm/min. The standard process yields an oxide thickness of 200 nm, however, depositions up to a maximum thickness of 800 nm have been successfully performed in the past.