(Invited) Study on Chemical Bonding States of High-k Gate Stacks for Advanced CMOS

Abstract

The paper reviews the non-destructive depth profiling of the composition and the chemical structure of high-κ/Si using angleresolved photoelectron spectroscopy. Analyses of Si 2s spectra show that the reactivity between ScOx or CeOx and Si substrate is lower than that between LaOx and Si substrate. Analyses of Ce 3d 5/2 and O 1s spectra show that a oxidation state of Ce changes from Ce 4+ to Ce 3+ by PDA in N 2 at and above 400°C and changes from Ce 3+ to Ce 4+ by PDA in O 2 at 300°C. This implies that a oxidation state of Ce can be controlled by changing the condition of PDA. The hard X-ray(hν = 8 keV) excited ARXPS study on high-κ/Si structure show that the existence of La-silicate accelerates the formation of La-silicate by PDA.

Silicate Reaction Control at Lanthanum Oxide and Silicon Interface for Equivalent Oxide Thickness of 0.5 nm: Adjustment of Amount of Residual Oxygen Atoms in Metal Layer

“…On the other hand, the increase in the number of La-O-Si bonds with the thickness of the W film indicates that silicate reaction could be controlled by changing the thickness of the W film. 23,24) The windows of the hysteresis in the C-V curves for TiN (40 nm)/W (6 or 12 nm)/ La 2 O 3 (3.5 nm)/n-Si and W (60 nm)/La 2 O 3 (3.5 nm)/n-Si gate stack capacitors annealed for 2 s are summarized in Fig. 7.…”

Suppression of Oxide and Interface Charge Density in Radio Frequency Sputtered Ta2O5 Thin Films

“…[5] To overcome the scaling restriction of microelectronic device size, Si-based conventional dielectric materials such as SiO 2 need to be replaced with advanced high permittivity (high-k) materials. [6][7][8][9] Various high-k materials, such as barium strontium titanate (BaSrTiO 3 ), titanium oxide (TiO 2 ), zirconium oxide (ZrO 2 ), aluminum oxide (Al 2 O 3 ), tantalum oxide (Ta 2 O 5 ), hafnium oxide (HfO 2 ), and silicon nitride (Si 3 N 4 ) are being investigated to meet the requirement. [10][11][12][13][14][15][16] Among these metal oxides, Ta 2 O 5 is the most promising gate insulator and an appropriate candidate for memory dielectrics in storage capacitors in place of SiO 2 .…”

Electrical Characteristics of La2O3 Gated MOS Capacitors with Different Wafer Orientation

“…To achieve an EOT of 0.5 nm, which is the ultimate specification reported in ITRS roadmap, high-k should be in directly contact with Si substrate without any SiO 2 based interfacial layer. It has been reported that rare earth oxides can achieve a direct contact structure by forming silicates at Si interface [3] and an EOT of 0.5 nm has already been demonstrated [4]. In this paper, we will focus on the interface properties of La-silicate/Si interface through fabrication of MOS capacitors on Si wafers with different orientations.…”