Maximizing performance for higher K gate dielectrics

Abstract

Further scaling of complementary metal oxide semiconductor gate stacks will require gate dielectrics with a higher dielectric constant (K) than HfO2. We point out that this will require strategies to minimize the overall effective oxide thickness of the gate stack, and not just maximizing the dielectric constant, so that the channel mobility is not impaired and there is still control of the flatband voltages. This may require retention of a SiO2-based interfacial layer, and attention should be paid to the flatband voltages of lanthanide oxides. Phase control of HfO2 and ZrO2 by addition of group IV elements offers simpler advances.

O 3 -based atomic layer deposition of hexagonal La2O3 films on Si(100) and Ge(100) substrates

“…3 Over the last few years, rare earth oxides have received extensive attention as potential gate insulators for sub-45 nm CMOS technology nodes for which an equivalent oxide thickness ͑EOT͒ below 1 nm has been envisaged. 4,5 In particular, La 2 O 3 has been identified as a promising candidate to achieve the above EOT target mainly due to its high k value ͑k ϳ 27͒, 6,7 which is achieved when the material is entirely crystallized into the hexagonal ͑h-͒ P6 3 / mmc phase, and wide band gap ͑ϳ5.3 eV͒. 8 However, hygroscopicity 9 associated to the socalled "lanthanide contraction" phenomenon 4 impedes the acquisition of a stable h-La 2 O 3 phase as this quickly relaxes upon air exposure to a h-La͑OH͒ 3 phase 7,10 with a concomitant k value degradation.…”

High‐density remote plasma sputtering of high‐dielectric‐constant amorphous hafnium oxide films

“…In particular, the high value of k (typically $25) allows the thickness of the gate insulator to be increased whilst maintaining the same gate capacitance, resulting in a reduction in the gate leakage current due to electron tunnelling [3][4][5]. The industrial relevance of HfO 2 is evident by Intel Corporation's milestone of incorporating high-k hafnium-based dielectric material into their 45-nm CMOS process technology [6,7].…”

Calculated and experimental electron energy-loss spectra of La2O3, La(OH)3, and LaOF nanophases in high permittivity lanthanum-based oxide layers

“…1 In the same time, rare earth oxides received attention as candidates for sub-45 nm CMOS technology nodes. 2,3 Crystalline La 2 O 3 is particularly of concern due to its high value ͑ϳ27͒ which is achieved when stabilized with the hexagonal P63/ mmc structure. 4,5 However, this oxide is the most reactive of the lanthanide series because hygroscopicity 6 associated with the lanthanide contraction phenomenon 2 impedes the formation of a stable hexagonal La 2 O 3 phase as this quickly relaxes upon air exposure to monoclinic LaO͑OH͒ and hexagonal La͑OH͒ 3 .…”

“…Calculated and experimental electron energy-loss spectra of La 2 Using first principles methods, the O K energy-loss near-edge structure of cubic and hexagonal La 2 O 3 , La͑OH͒ 3 , and LaOF phases have been calculated. These calculations support the identification of nanocrystalline phases evidenced experimentally by electron energy-loss spectroscopy ͑EELS͒ performed in a transmission electron microscope.…”