ToF-SIMS profiles of a Ni(45 nm)/Hf(55 nm)/SiO2 sample as deposited and after 1 h of anneal in vacuum at 300 °C, 500 °C, and 700 °C.
ToF-SIMS profiles of a Ni(60 nm)/Hf (40 nm)/Ni(10 nm)/SiO2 sample as deposited and after 1 h of anneal in vacuum at 300 °C, 400 °C, and 450 °C.
Cross-section TEM micrograph of multilayer samples after thermal treatment. The nominal Ni concentrations of the samples are (a) 20 at. % Ni, (b) 50 at. % Ni, and (c) 80 at. % Ni.
(a) EDS line profile of Ni for the samples shown in Fig. 3. (b) The average EDS counts of Ni in the HfNix layer vs. the nominal Ni concentration.
C-V measurement before and after a heat treatment of 400 °C of a Ni/Hf(35 nm)/Ni(35 nm)/SiO2 sample.
Cross-section TEM micrograph of a Ni/Hf(20 nm)/Ni(50 nm)/SiO2 capacitor after a 400 °C heat treatment.
Cross-section TEM micrographs of an in situ heating experiment done on a Ni(91 nm)/Hf(28 nm)/SiO2 stack. (a) Before heating. (b) At 490 °C, the voids immediately appear. (c) and (d) are 12 and 77 min after (b).
EFTEM elemental map of Ni L2,3-edge of the Ni(91 nm)/Hf(28 nm)/SiO2 stack before heating and at 490 °C after 30 min.
CAcc of Ni/Hf(20 nm)/Ni(50 nm)/HfO2 samples after heat treatment vs. CAcc of the same samples before heat treatment.
(a) Cross-section TEM micrograph from a Ni/Hf(10 nm)/Ni(10 nm)/SiO2 capacitor after a heat treatment of 400 °C. 2 EDS line profiles were performed incident to: (b) Voids. (c) Area between voids.
1/Cacc of Ni(10 nm)/Hf(90 nm)/HfO2 samples after heat treatment vs. 1/Cacc of the same samples before heat treatment.
Effective work-function vs. Hf thickness ratio for “Hf-under” and “Ni-under” capacitors.
Flatband voltage vs. EOT plots of several HfNix/HfO2 samples.
Effective work-function compositional dependence of HfNix/SiO2 and HfNix/HfO2 and the vacuum work-function compositional dependence on HfNix as measured by KP. The experimental data points are connected with a straight line in order to guide the eye.
Effective work-function values of HfNix/SiO2 and HfNix/HfO2 systems vs. vacuum work-function values.
An example of a symmetric 6.4 × 6.4 × 22.8 Å3, (100)-oriented Hf2Ni slab model with Hf terminating planes, consisting of two repeating structural units along the -direction with a total thickness of 12.8 Å and a vacuum region having 10 Å thickness. Ni atoms are marked in green, and Hf atoms are marked in aqua.
AHT/AAD of capacitors with different initial Hf/Ni thicknesses on SiO2 and HfO2.
and values calculated using DFT.
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