Please use this identifier to cite or link to this item: https://scholarbank.nus.edu.sg/handle/10635/153883
Title: The Effects of Process Parameters on Electrical Properties of Phosphorus Implanted Polysilicon Deposited by LPCVD
Authors: AN TAO
Keywords: electrical properties
polysilicon
LPCVD
phosphorus implanted
process parameters
sheet resistance
temperature
pressure
mass flow rate
uniformity
Issue Date: 2008
Citation: AN TAO (2008). The Effects of Process Parameters on Electrical Properties of Phosphorus Implanted Polysilicon Deposited by LPCVD. ScholarBank@NUS Repository.
Abstract: Heavily doped polysilicon is widely used as material for gate electrode in metal-oxide-semiconductor field-effect transistor (MOSFET), in which application its electrical properties are of great importance. Such electrical properties are closely related with its microstructure, which is in turn affected by various process parameters, such as temperature, pressure and reactor gas mass flow rate during deposition. It was recognized in the company that low pressure chemical vapor deposited polysilicon film fabricated by certain reactor followed by phosphorus implantation had lower sheet resistance than those deposited by other reactors with the same process parameter settings, leading to deficiency for certain types of products. The root cause for such problem, however, is still unclear after two years of inspections. This work is aimed to find out the quantitative dependence of polysilicon film resistivity on these process parameters, so that appropriate modifications of the parameter settings can be made to shift product’s sheet resistance into the acceptable range. Polysilicon film with fixed thickness of 200nm was deposited on 8-inch silicon substrate with 105nm wet oxide on top under different parameter alternations including 5ºC decrease in temperature, 5-15sccm increases in reactor gas flow rate and 14% increase in total pressure. The samples were then phosphorus implanted to 3.5×1015cm-2 dose at 5keV and annealed. The polysilicon film deposited by the deficient reactor was found to have sheet resistance 2.25% below standard reference, while such difference can be offset by 15-sccm increment of mass flow rate of reactor gas, and same level of uniformity was maintained with such change.
URI: https://scholarbank.nus.edu.sg/handle/10635/153883
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