Abstract
A thin Al2O3 interlayer deposited between La2O3 layer and Si substrate was used to scavenge the interfacial layer (IL) by blocking the out-diffusion of substrate Si. Some advantages and disadvantages of this method were discussed in detail. Evident IL reduction corroborated by the transmission electron microscopy results suggested the feasibility of this method in IL scavenging. Significant improvements in oxygen vacancy and leakage current characteristics were achieved as the thickness of Al2O3 interlayer increase. Meanwhile, some disadvantages such as the degradations in interface trap and oxide trapped charge characteristics were also observed.
Highlights
INTRODUCTIONRare earth oxides (e.g., Y2O3, Gd2O3, La2O3) and their alloys have been extensively studied as alternative gate dielectric materials used in high-k/metal gate stacks, which has been applied to the sub-45-nm complementary metal oxide semiconductor (CMOS) technology to replace the conventional SiO2/poly-Si gate structures in order to scale in an equivalent oxide thickness (EOT).[1,2,3] Among the rare earth oxides and their alloys, because of its high k value (k∼27), large band gap (∼5.5 eV), and suitable conduction band offset with silicon (> 2 eV),[4,5] La2O3 is considered as one of the most promising alternative for HfO2 which has been used to replace SiO2 as the gate oxide by Intel in its 45 nm technology at a high technological cost of maintaining an interfacial SiOx layer, to achieve a more aggressive downscaling of the EOT.[1,6] the Al-incorporated La2O3, which is called lanthanum aluminate (LaxAl1−xOy, LAO), has a nearly high k value (k∼25–27) as La2O3 while providing an immunity against moisture absorption and much high thermal stability than that of pure La2O3 or HfO2.7
A thin Al2O3 interlayer deposited between La2O3 layer and Si substrate was used to scavenge the interfacial layer (IL) by blocking the out-diffusion of substrate Si
Rare earth oxides (e.g., Y2O3, Gd2O3, La2O3) and their alloys have been extensively studied as alternative gate dielectric materials used in high-k/metal gate stacks, which has been applied to the sub-45-nm complementary metal oxide semiconductor (CMOS) technology to replace the conventional SiO2/poly-Si gate structures in order to scale in an equivalent oxide thickness (EOT).[1,2,3]
Summary
Rare earth oxides (e.g., Y2O3, Gd2O3, La2O3) and their alloys have been extensively studied as alternative gate dielectric materials used in high-k/metal gate stacks, which has been applied to the sub-45-nm complementary metal oxide semiconductor (CMOS) technology to replace the conventional SiO2/poly-Si gate structures in order to scale in an equivalent oxide thickness (EOT).[1,2,3] Among the rare earth oxides and their alloys, because of its high k value (k∼27), large band gap (∼5.5 eV), and suitable conduction band offset with silicon (> 2 eV),[4,5] La2O3 is considered as one of the most promising alternative for HfO2 which has been used to replace SiO2 as the gate oxide by Intel in its 45 nm technology at a high technological cost of maintaining an interfacial SiOx layer, to achieve a more aggressive downscaling of the EOT.[1,6] the Al-incorporated La2O3, which is called lanthanum aluminate (LaxAl1−xOy, LAO), has a nearly high k value (k∼25–27) as La2O3 while providing an immunity against moisture absorption and much high thermal stability than that of pure La2O3 or HfO2.7. Capacitors using the ALD deposited nanolaminates with different thickness of Al2O3 interlayer as insulators
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