AbstractA statistical experimental design has been succesfully used to evaluate the integration of CVD tungsten plugs into a PVD-Ti/TiN/AlSiCu metallization. Optimum titanium (Ti) and titanium nitride (TiN) layer thicknesses for tungsten filled contacts with aspect ratios of up to 1.8 have been dete...
AbstractA statistical experimental design has been succesfully used to evaluate the integration of CVD tungsten plugs into a PVD-Ti/TiN/AlSiCu metallization. Optimum titanium (Ti) and titanium nitride (TiN) layer thicknesses for tungsten filled contacts with aspect ratios of up to 1.8 have been determined with respect to contact resistance and leakage current data in both n+ and p+ contacts. Ti thickness (10–50 nm), TiN thickness (50–150 nm) and contact depth (1050–1500 nm) were each varied in three levels and the corresponding responses were investigated for contacts with different diameter.The investigations show that for given contact dimensions, contact resistance is only determined by the Ti thickness. In order to achieve lowest contact resistances even in the contacts with highest aspect ratios, the nominal Ti thickness should at least be 40 nm. A deficiency in Ti, which causes higher contact resistivities, cannot be compensated by an increase of TiN thickness. These results are independent of contact doping.TiN thickness is the most relevant parameter with respect to barrier integrity. However, CVD tungsten filled contacts with a TiN barrier of nominally only 50 nm thickness exhibited lowest leakage currents and also did pass an electrical stress test (1000 h, 150°C, 1.9 × 106 A/cm2), even if the aspect ratio was 1.8 TEM investigations are in agreement with these electrical data although they reveal that the effective barrier thickness is only approximately 10% of the nominal value in contacts with aspect ratio 1.4. Based on these results it is concluded that contact filling with CVD tungsten will be a viable and reliable metallization for sub-0.5-μm technology, especially if improved Ti- and TiN-deposition methods (like, e.g., collimated PVD or conformal CVD) are available.
AbstractA statistical experimental design has been succesfully used to evaluate the integration of CVD tungsten plugs into a PVD-Ti/TiN/AlSiCu metallization. Optimum titanium (Ti) and titanium nitride (TiN) layer thicknesses for tungsten filled contacts with aspect ratios of up to 1.8 have been determined with respect to contact resistance and leakage current data in both n+ and p+ contacts. Ti thickness (10–50 nm), TiN thickness (50–150 nm) and contact depth (1050–1500 nm) were each varied in three levels and the corresponding responses were investigated for contacts with different diameter.The investigations show that for given contact dimensions, contact resistance is only determined by the Ti thickness. In order to achieve lowest contact resistances even in the contacts with highest aspect ratios, the nominal Ti thickness should at least be 40 nm. A deficiency in Ti, which causes higher contact resistivities, cannot be compensated by an increase of TiN thickness. These results are independent of contact doping.TiN thickness is the most relevant parameter with respect to barrier integrity. However, CVD tungsten filled contacts with a TiN barrier of nominally only 50 nm thickness exhibited lowest leakage currents and also did pass an electrical stress test (1000 h, 150°C, 1.9 × 106 A/cm2), even if the aspect ratio was 1.8 TEM investigations are in agreement with these electrical data although they reveal that the effective barrier thickness is only approximately 10% of the nominal value in contacts with aspect ratio 1.4. Based on these results it is concluded that contact filling with CVD tungsten will be a viable and reliable metallization for sub-0.5-μm technology, especially if improved Ti- and TiN-deposition methods (like, e.g., collimated PVD or conformal CVD) are available.
참고문헌 (5)
J. Electrochem. Soc. Riley 138 3008 1991 10.1149/1.2085356
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