Efficient Oxidation Process for Ultrathin Gate Oxides
Staff -- Semiconductor International, 7/1/1998
Efficient Oxidation Process for Ultrathin Gate Oxides
The Inter-University Microelectronics Centre (IMEC, Leuven, Belgium) has developed a novel, high-efficiency, environmentally friendly oxidation process that allows the growth of ultrathin gate oxides in a conventional furnace using a standard CMOS processing environment. It has been designed to satisfy the increasing requirements for thinner gate oxides to meet the continuous downscaling of CMOS device dimensions. The good thickness control that is necessary for this process requires relatively mild oxidation conditions, using a low-temperature environment and a reduced oxygen concentration. This indicates the use of chlorine containing organic molecules to introduce chlorine in the furnace.
This IMEC technique for growing ultrathin gate oxides at relatively low temperatures (<700°C) involves the use of oxalyl chloride or a similar substance that is claimed to result in complete combustion using less oxygen. The technique can comprise two steps. First, an in situ clean is carried out in a gas phase ambient mixture with a very low oxygen concentration (<5%) to remove metal surface contaminants. Then, a thin silicon dioxide layer is grown using a gas phase mixture of oxygen and an organic compound containing chlorine, such as oxalyl chloride.
IMEC researchers say this technique enables a high-quality thin layer of silicon dioxide to be formed on a silicon substrate with a thickness of 1-8 nm or more.
