Influence of plasma-based in-situ surface cleaning procedures on HfO2/In0.53Ga0.47As gate stack properties

Abstract

We report on the influence of variations in the process parameters of an in-situ surface cleaning procedure, consisting of alternating cycles of nitrogen plasma and trimethylaluminum dosing, on the interface trap density of highly scaled HfO2 gate dielectrics deposited on n-In0.53Ga0.47As by atomic layer deposition. We discuss the interface chemistry of stacks resulting from the pre-deposition exposure to nitrogen plasma/trimethylaluminum cycles. Measurements of interface trap densities, interface chemistry, and surface morphology show that variations in the cleaning process have a large effect on nucleation and surface coverage, which in turn are crucial for achieving low interface state densities.

Electrical properties of GaAs metal–oxide–semiconductor structure comprising Al2O3 gate oxide and AlN passivation layer fabricated in situ using a metal–organic vapor deposition/atomic layer deposition hybrid system

“…47 As substrate. 29,30,26 This observation suggested that nitrogen simply eliminated the defect states. In this work, the same nitrogen passivation mechanism is expected to occur toward suppressing the interface states at the AlO x N y /GaAs interface.…”

“…This mechanism was experimentally confirmed in the case of In 0.53 Ga 0.47 As. 29,30 Inserting a AlN (or AlO x N y ) layer improved the electrical properties of the dielectric/In 0.53 Ga 0. 47 As interface though X-ray photoemission spectroscopy detected little influence of such layers on the chemical states of the In 0.53 Ga 0.…”

“…[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Forming an AlN or AlO x N y layer is advantageous because of its relatively wide band gap and high dielectric constant. 33 Various techniques have been used to form such layers on III-V semiconductors at low processing temperatures, including radio frequency sputtering, [22][23][24][25] thermal- 26 and plasma-enhanced [27][28][29] ALD, cyclic exposure of nitrogen plasma and trimethylaluminum (TMA), [30][31][32] and metal-organic vapor deposition (MOCVD). [33][34][35][36][37] Recently, we reported the use of MOCVD, as a high throughput and cost-effective process, to achieve AlN passivation in situ prior to ALD-based Al 2 O 3 gate oxide formation.…”

Scaled ZrO2 dielectrics for In0.53Ga0.47As gate stacks with low interface trap densities

“…13,14 In contrast, high-quality stacks show only a small "D it hump," and they exhibit deep depletion as the Fermi level moves into the lower half of the band gap in capacitance-voltage measurements. 5,13 In this work, we show that a cyclic, in-situ nitrogen plasma/trimethylaluminum (TMA) pre-cleaning procedure allows for ZrO 2 dielectrics on n-In 0.53 Ga 0.47 As with low D it and low EOT. We characterize the interface chemistry, which, in conjunction with the electrical results, allows for insights into the passivation of such interfaces.…”

“…We have recently reported on in-situ, plasma-based surface treatments 3 prior to atomic layer deposition (ALD) of HfO 2 gate dielectrics on In 0.53 Ga 0.47 As. 4,5 This process allowed for low D it and scaling of the accumulation capacitance densities to $3 lF/cm 2 (EOT of less than 1 nm) on n-type doped In 0.53 Ga 0.47 As channels, as well as high-performance MOSFETs. 6 We note that the accumulation capacitance density of metal-oxide capacitors (MOSCAPs) on n-In 0.53 Ga 0.47 As is not equivalent to the oxide capacitance, due to the low conduction band density of states of the In 0.53 Ga 0.47 As.…”