Ru Passivated and Ru Doped e-TaN surfaces as Combined Barrier and Liner Material for Copper Interconnects: A First Principles Study

2018 ◽  
Author(s):  
Suresh Natarajan ◽  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
First Principles ◽  
Film Growth ◽  
Early Stage ◽  
Copper Interconnects ◽  
Liner Material ◽  
Critical Dimensions ◽  
Industry Standard ◽  
Cu Film ◽  
Improved Performance ◽  
And Diffusion

<div>As the critical dimensions of transistors continue to be scaled down to facilitate improved performance and device speeds, new ultrathin materials that combine diffusion barrier and seed/liner properties are needed for copper interconnects at these length scales. Ideally, to facilitate coating of high aspect ratio structures, this alternative barrier+liner material should only consist of one or as few layers as possible. We studied TaN, the current industry standard for Cu diffusion barriers, and Ru, which is a</div><div>suitable liner material for Cu electroplating, to explore how combining these two materials in a barrier+liner material influences the adsorption of Cu atoms in the early stage of Cu film growth. To this end, we carried out first-principles simulations of the adsorption and diffusion of Cu adatoms at Ru-passivated and Ru-doped e-TaN(1 1 0) surfaces. For comparison, we also studied the behaviour of Cu and Ru adatoms at the low index surfaces of e-TaN, as well as the interaction of Cu adatoms with the (0 0 1) surface of hexagonal Ru. Our results confirm the barrier and liner properties of TaN and Ru, respectively while also highlighting the weaknesses of both materials. Ru passivated TaN was found to have improved binding with Cu adatoms as compared to the bare TaN and Ru surfaces.</div><div>On the other hand, the energetic barrier for Cu diffusion at Ru passivated TaN surface was lower than at the bare TaN surface which can promote Cu agglomeration. For Ru-doped TaN however, a decrease in Cu binding energy was found in addition to favourable migration of the Cu adatoms toward the doped Ru atom and unfavourable migration away from it or into the bulk. This suggests that Ru doping sites in the TaN surface can act as nucleation points for Cu growth with high migration barrier preventing agglomeration and allow electroplating of Cu. Therefore Ru-doped TaN is proposed as a candidate for a combined barrier+liner material with reduced thickness.</div>

Ru Passivated and Ru Doped e-TaN surfaces as Combined Barrier and Liner Material for Copper Interconnects: A First Principles Study

2018 ◽  
Author(s):  
Suresh Natarajan ◽  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
First Principles ◽  
Film Growth ◽  
Early Stage ◽  
Copper Interconnects ◽  
Liner Material ◽  
Critical Dimensions ◽  
Industry Standard ◽  
Cu Film ◽  
Improved Performance ◽  
And Diffusion

<div>As the critical dimensions of transistors continue to be scaled down to facilitate improved performance and device speeds, new ultrathin materials that combine diffusion barrier and seed/liner properties are needed for copper interconnects at these length scales. Ideally, to facilitate coating of high aspect ratio structures, this alternative barrier+liner material should only consist of one or as few layers as possible. We studied TaN, the current industry standard for Cu diffusion barriers, and Ru, which is a</div><div>suitable liner material for Cu electroplating, to explore how combining these two materials in a barrier+liner material influences the adsorption of Cu atoms in the early stage of Cu film growth. To this end, we carried out first-principles simulations of the adsorption and diffusion of Cu adatoms at Ru-passivated and Ru-doped e-TaN(1 1 0) surfaces. For comparison, we also studied the behaviour of Cu and Ru adatoms at the low index surfaces of e-TaN, as well as the interaction of Cu adatoms with the (0 0 1) surface of hexagonal Ru. Our results confirm the barrier and liner properties of TaN and Ru, respectively while also highlighting the weaknesses of both materials. Ru passivated TaN was found to have improved binding with Cu adatoms as compared to the bare TaN and Ru surfaces.</div><div>On the other hand, the energetic barrier for Cu diffusion at Ru passivated TaN surface was lower than at the bare TaN surface which can promote Cu agglomeration. For Ru-doped TaN however, a decrease in Cu binding energy was found in addition to favourable migration of the Cu adatoms toward the doped Ru atom and unfavourable migration away from it or into the bulk. This suggests that Ru doping sites in the TaN surface can act as nucleation points for Cu growth with high migration barrier preventing agglomeration and allow electroplating of Cu. Therefore Ru-doped TaN is proposed as a candidate for a combined barrier+liner material with reduced thickness.</div>

FIRST-PRINCIPLES STUDY OF THE ADSORPTION AND DIFFUSION OF O2 ON A Si(001) SURFACE

2011 ◽  
Vol 18 (06) ◽  
pp. 315-321
Author(s):  
CHUN YANG ◽  
CHONG YANG ◽  
PING HUANG ◽  
XIAO QIN LIANG
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Early Stage ◽  
Physical Adsorption ◽  
Stable State ◽  
Surface Oxidation ◽  
Chemical Adsorption ◽  
Bridge Structure ◽  
Oxygen Bridge ◽  
And Diffusion

We apply a first-principles molecular-dynamics method based on the density functional theory to calculate several initial configurations of an O2 molecule adsorbed on a Si(001) surface. The bonding processing, adsorption energy, dynamic track, and diffusion coefficient are investigated. The results indicate that the adsorption process may be divided into four stages: physical adsorption, chemical adsorption early stage, chemical adsorption late stage, and the superficial stable state. The Si=O structure, the Si–O–Si surface oxygen-bridge structure, and the Si–O–Si oxygen-bridge structure where oxygen atoms are inserted into the backbonds between the surface and the second layer of silicon atoms in the stable adsorption structures, are beneficial to the formation of the silica tetrahedral structure. We conclude that the remarkable difference between the diffusion coefficients during the physical adsorption stage leads to different diffusion paths, which results in the formation of two concomitant stable structures in the early process of silicon surface oxidation.

scholarly journals Ru passivated and Ru doped ε-TaN surfaces as a combined barrier and liner material for copper interconnects: a first principles study

2019 ◽  
Vol 7 (26) ◽  
pp. 7959-7973 ◽  
Author(s):  
Suresh Kondati Natarajan ◽  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
Potential Barrier ◽  
First Principles ◽  
Copper Interconnects ◽  
Liner Material ◽  
First Principles Study

A study of Cu adatoms on Ru passivated and Ru doped ε-TaN to highlight their potential barrier and liner properties for copper interconnects.

scholarly journals The Role of Ru Passivation and Doping on the Barrier and Seed Layer Properties of Ru-Modified TaN for Copper Interconnects

2020 ◽  
Author(s):  
Suresh Natarajan ◽  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
Seed Layer ◽  
Surface Interactions ◽  
Copper Interconnects ◽  
Liner Material ◽  
Electro Deposition ◽  
Surface Stability ◽  
Cu Film ◽  
Major Bottleneck ◽  
Ru Doping

<div>Size reduction of the barrier and liner stack for copper interconnects is a major bottleneck in further down-scaling of transistor devices. The role of the barrier is to prevent diffusion of Cu atoms into the surrounding dielectric, while the liner (also referred to as a seed layer) ensures that a smooth Cu film can be electroplated. Therefore, a combined barrier+liner material that restricts the diffusion of Cu into the dielectric and allows for copper electro-deposition is needed. In this paper, we have explored barrier+liner materials composed of 1 and 2 monolayers (MLs) of Ru-passivated epsilon-TaN and Ru doped epsilon-TaN and focus on their interactions with Cu through the adsorption of small Cu clusters with 1-4 atoms. Moreover, different doping patterns for Ru doping in TaN are investigated to understand how selective doping of the epsilon-TaN surface influences surface stability. We found that an increased concentration of Ru atoms in the outermost Ta layer improves the adhesion of Cu. The strongest binding of the Cu atoms was found on the 100% Ru doped surface followed by 1 ML Ru passivated surface. These two surfaces are recommended for the combined barrier+liner for Cu interconnects. The closely packed arrangements of Cu were found to exhibit weak Cu-slab and strong Cu-Cu interactions, whereas the sparse arrangements of Cu exhibit strong Cu-slab and weak Cu-Cu interactions. The Cu atoms seem to bind more favourably when they are buried in the doped or passivated surface layer due to the increase in their coordination number. This is facilitated by the surface distortion arising from the ionic radius mismatch between Ta and Ru. We also show that the strong Cu-Cu interaction alone cannot predict the association of Cu atoms as a few 2D Cu clusters showed stronger Cu-Cu interaction than the 3D clusters, highlighting the importance of Cu-surface interactions</div>

scholarly journals The Role of Ru Passivation and Doping on the Barrier and Seed Layer Properties of Ru-Modified TaN for Copper Interconnects

2020 ◽  
Author(s):  
Suresh Natarajan ◽  
Cara-Lena Nies ◽  
Michael Nolan
Keyword(s):  
Seed Layer ◽  
Surface Interactions ◽  
Copper Interconnects ◽  
Liner Material ◽  
Electro Deposition ◽  
Surface Stability ◽  
Cu Film ◽  
Major Bottleneck ◽  
Ru Doping

<div>Size reduction of the barrier and liner stack for copper interconnects is a major bottleneck in further down-scaling of transistor devices. The role of the barrier is to prevent diffusion of Cu atoms into the surrounding dielectric, while the liner (also referred to as a seed layer) ensures that a smooth Cu film can be electroplated. Therefore, a combined barrier+liner material that restricts the diffusion of Cu into the dielectric and allows for copper electro-deposition is needed. In this paper, we have explored barrier+liner materials composed of 1 and 2 monolayers (MLs) of Ru-passivated epsilon-TaN and Ru doped epsilon-TaN and focus on their interactions with Cu through the adsorption of small Cu clusters with 1-4 atoms. Moreover, different doping patterns for Ru doping in TaN are investigated to understand how selective doping of the epsilon-TaN surface influences surface stability. We found that an increased concentration of Ru atoms in the outermost Ta layer improves the adhesion of Cu. The strongest binding of the Cu atoms was found on the 100% Ru doped surface followed by 1 ML Ru passivated surface. These two surfaces are recommended for the combined barrier+liner for Cu interconnects. The closely packed arrangements of Cu were found to exhibit weak Cu-slab and strong Cu-Cu interactions, whereas the sparse arrangements of Cu exhibit strong Cu-slab and weak Cu-Cu interactions. The Cu atoms seem to bind more favourably when they are buried in the doped or passivated surface layer due to the increase in their coordination number. This is facilitated by the surface distortion arising from the ionic radius mismatch between Ta and Ru. We also show that the strong Cu-Cu interaction alone cannot predict the association of Cu atoms as a few 2D Cu clusters showed stronger Cu-Cu interaction than the 3D clusters, highlighting the importance of Cu-surface interactions</div>

Area-selective Cu Film Growth on TiN and SiO2 by Supercritical Fluid Deposition

2020 ◽  
Vol 140 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Naoto Usami ◽  
Etsuko Ota ◽  
Akio Higo ◽  
Takeshi Momose ◽  
Yoshio Mita
Keyword(s):  
Supercritical Fluid ◽  
Film Growth ◽  
Cu Film

scholarly journals When band convergence is not beneficial for thermoelectrics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Junsoo Park ◽  
Maxwell Dylla ◽  
Yi Xia ◽  
Max Wood ◽  
G. Jeffrey Snyder ◽  
...  
Keyword(s):  
Charge Carrier ◽  
First Principles ◽  
Design Principle ◽  
Phonon Scattering ◽  
Charge Carrier Concentration ◽  
Deformation Potential ◽  
Interband Scattering ◽  
Improved Performance ◽  
Full Heusler ◽  
Electron Phonon Scattering

AbstractBand convergence is considered a clear benefit to thermoelectric performance because it increases the charge carrier concentration for a given Fermi level, which typically enhances charge conductivity while preserving the Seebeck coefficient. However, this advantage hinges on the assumption that interband scattering of carriers is weak or insignificant. With first-principles treatment of electron-phonon scattering in the CaMg2Sb2-CaZn2Sb2 Zintl system and full Heusler Sr2SbAu, we demonstrate that the benefit of band convergence can be intrinsically negated by interband scattering depending on the manner in which bands converge. In the Zintl alloy, band convergence does not improve weighted mobility or the density-of-states effective mass. We trace the underlying reason to the fact that the bands converge at a one k-point, which induces strong interband scattering of both the deformation-potential and the polar-optical kinds. The case contrasts with band convergence at distant k-points (as in the full Heusler), which better preserves the single-band scattering behavior thereby successfully leading to improved performance. Therefore, we suggest that band convergence as thermoelectric design principle is best suited to cases in which it occurs at distant k-points.

Direct Nucleation of Crystalline SiGe on Substrates by Reactive Thermal CVD with Si2H6 and GeF4

1997 ◽  
Vol 467 ◽  
Author(s):  
Fumio Yoshizawa ◽  
Kunihiro Shiota ◽  
Daisuke Inoue ◽  
Jun-ichi Hanna
Keyword(s):  
Growth Rate ◽  
Gas Phase ◽  
Heterogeneous Nucleation ◽  
Homogeneous Nucleation ◽  
Film Growth ◽  
Early Stage ◽  
Gaseous Mixture ◽  
The Other ◽  
Thermal Cvd ◽  
Initial Deposition

ABSTRACTPolycrystalline SiGe (poly-SiGe) film growth by reactive thermal CVD with a gaseous mixture of Si2H6 and GeF4 was investigated on various substrates such as Al,Cr, Pt, Si, ITO, ZnO and thermally grown SiO2.In Ge-rich film growth, SEM observation in the early stage of the film growth revealed that direct nucleation of crystallites took place on the substrates. The nucleation was governed by two different mechanisms: one was a heterogeneous nucleation on the surface and the other was a homogeneous nucleation in the gas phase. In the former case, the selective nucleation was observed at temperatures lower than 400°C on metal substrates and Si, where the activation of adsorbed GeF4 on the surface played a major role for the nuclei formation, leading to the selective film growth.On the other hand, the direct nucleation did not always take place in Si-rich film growth irrespective of the substrates and depended on the growth rate. In a growth rate of 3.6nm/min, the high crystallinity of poly-Si0.95Ge0.05in a 220nm-thick film was achieved at 450°C due to the no initial deposition of amorphous tissue on SiO2 substrates.

Doped graphenes as anodes with large capacity for lithium-ion batteries

2016 ◽  
Vol 4 (35) ◽  
pp. 13407-13413 ◽  
Author(s):  
Liujiang Zhou ◽  
Z. F. Hou ◽  
Bo Gao ◽  
Thomas Frauenheim
Keyword(s):  
Lithium Ion Batteries ◽  
First Principles ◽  
Lithium Ion ◽  
Doping Effect ◽  
Chemical Doping ◽  
First Principles Calculations ◽  
Large Capacity ◽  
And Diffusion ◽  
Li Storage

To understand the chemical doping effect on the lithium (Li) storage of graphene, we have performed first-principles calculations to study the adsorption and diffusion of Li adatoms on boron (B)- and nitrogen (N)-doped graphenes, which include individual and paired B (and N) dopants in graphene.

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