Microstructural and compositional characterization of TiW/Al(0.8%Si)/TiW/PtSi/(100)Si

Ashkenazi, A.; Komen, Y.; Lerner, I.

doi:10.1016/0169-4332(93)90749-2

Cited by 3 publications

(4 citation statements)

References 4 publications

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“…For example, even studies on pure W diffusion barriers, [68][69][70][71] or on a TiW barrier with a relatively low Ti concentration (4.9 at.%) [72] do not report any mobility of W. However, some studies observe W diffusion from a W or TiW barrier within thin film stacks at temperatures below 600°C, although no details are given on a possible reason as to why this occurs. [73][74][75] Based on the present results, it is hypothesised that the Ti concentration of the TiW film dictates the overall stability the diffusion barrier. If it is too low (i.e., in the 5Ti sample), a small amount of W becomes mobile and is free to migrate through the Cu overlayer alongside Ti and accumulate at the surface.…”

Section: Tungstenmentioning

confidence: 66%

“…For example, even studies on pure W diffusion barriers, [ 68–71 ] or on a TiW barrier with a relatively low Ti concentration (4.9 at.%) [ 72 ] do not report any mobility of W. However, some studies observe W diffusion from a W or TiW barrier within thin film stacks at temperatures below 600°C, although no details are given on a possible reason as to why this occurs. [ 73–75 ]…”

Section: Resultsmentioning

confidence: 99%

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Capturing the Dynamics of Ti Diffusion Across Ti_xW_1−x/Cu Heterostructures using X‐Ray Photoelectron Spectroscopy

Kalha

Thakur

Lee

et al. 2023

Advanced Physics Research

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Interdiffusion phenomena between adjacent materials are highly prevalent in semiconductor device architectures and can present a major reliability challenge for the industry. To fully capture these phenomena, experimental approaches must go beyond static and post‐mortem studies to include in situ and in‐operando setups. Here, soft and hard X‐ray photoelectron spectroscopy (SXPS and HAXPES) is used to monitor diffusion in real‐time across a proxy device. The device consists of a Si/SiO2/TixW1−x(300 nm)/Cu(25 nm) thin film material stack, with the TixW1−x film (x = 0.054, 0.115, 0.148) acting as a diffusion barrier between Si and Cu. The interdiffusion is monitored through the continuous collection of spectra whilst in situ annealing to 673 K. Ti within the TiW is found to be highly mobile during annealing, diffusing out of the barrier and accumulating at the Cu surface. Increasing the Ti concentration within the TixW1−x film increases the quantity of accumulated Ti, and Ti is first detected at the Cu surface at temperatures as low as 550 K. Surprisingly, at low Ti concentrations (x = 0.054), W is also mobile and diffuses alongside Ti. By monitoring the Ti 1s core level with HAXPES, the surface‐accumulated Ti was observed to undergo oxidation even under ultra‐high vacuum conditions, highlighting the reactivity of Ti in this system. These results provide crucial evidence for the importance of diffusion barrier composition on their efficacy during device application, delivering insights into the mechanisms underlying their effectiveness and limitations.

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Section: Tungstenmentioning

confidence: 66%

Section: Resultsmentioning

confidence: 99%

Capturing the Dynamics of Ti Diffusion Across Ti_xW_1−x/Cu Heterostructures using X‐Ray Photoelectron Spectroscopy

Kalha

Thakur

Lee

et al. 2023

Advanced Physics Research

View full text Add to dashboard Cite

show abstract

“…For example, even studies on pure W diffusion barriers, [69][70][71][72] or on a TiW barrier with a relatively low Ti concentration (4.9 at.%) [73] do not report any mobility of W. However, some studies observe W diffusion from a W or TiW barrier within thin film stacks at temperatures below 600 • C, although no details are given on a possible reason as to why this occurs. [74][75][76] Based on the present results, it is hypothesised that the Ti concentration of the TiW film dictates the overall stability of the diffusion barrier. If it is too low (i.e.…”

Section: Tungstenmentioning

confidence: 82%

Capturing the dynamics of Ti diffusion across Ti$_x$W$_{1-x}$/Cu heterostructures using X-ray photoelectron spectroscopy

Kalha¹,

Thakur²,

Lee³

et al. 2023

Preprint

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Interdiffusion phenomena between adjacent materials are highly prevalent in semiconductor device architectures and can present a major reliability challenge for the industry. To fully capture these phenomena, experimental approaches must go beyond static and post-mortem studies to include in-situ and in-operando setups. Here, soft and hard X-ray photoelectron spectroscopy (SXPS and HAXPES) is used to monitor diffusion in real-time across a proxy device. The device consists of a Si/SiO2/TixW1−x(300 nm)/Cu(25 nm) thin film material stack, with the TixW1−x film acting as a diffusion barrier between Si and Cu. The diffusion is monitored through the continuous collection of spectra whilst in-situ annealing to 673 K. Ti within the TiW is found to be highly mobile during annealing, diffusing out of the barrier and accumulating at the Cu surface. Increasing the Ti concentration within the TixW1−x film increases the quantity of accumulated Ti, and Ti is first detected at the Cu surface at temperatures as low as 550 K. Surprisingly, at low Ti concentrations (x = 0.054), W is also mobile and diffuses alongside Ti. These results provide crucial evidence for the importance of diffusion barrier composition on their efficacy during device application, delivering insights into the mechanisms underlying their effectiveness and limitations.

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“…11,12 Since the introduction of TiW and its associated benefits, TiW has been applied between various metal contacts and metallization layers, all with moderate to good success. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] However, these studies predominately focus on determining the conditions that are required for the barrier to fail (i.e., temperature and duration), with less emphasis on defining the mechanism that promotes the failure or studying the chemical states across the critical diffusion barrier/metallization interface.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the thermal stability of TiW/Cu heterojunctions using a combined SXPS and HAXPES approach

Kalha

Reisinger

Thakur

et al. 2022

Journal of Applied Physics

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Power semiconductor device architectures require the inclusion of a diffusion barrier to suppress or at best prevent the interdiffusion between the copper metallization interconnects and the surrounding silicon substructure. The binary pseudo-alloy of titanium–tungsten (TiW), with >70 at. % W, is a well-established copper diffusion barrier but is prone to degradation via the out-diffusion of titanium when exposed to high temperatures ([Formula: see text]400 [Formula: see text]C). Here, the thermal stability of physical vapor deposited TiW/Cu bilayer thin films in Si/SiO[Formula: see text](50 nm)/TiW(300 nm)/Cu(25 nm) stacks were characterized in response to annealing at 400 [Formula: see text]C for 0.5 h and 5 h, using a combination of soft and hard x-ray photoelectron spectroscopy and transmission electron microscopy. Results show that annealing promoted the segregation of titanium out of the TiW and interdiffusion into the copper metallization. Titanium was shown to be driven toward the free copper surface, accumulating there and forming a titanium oxide overlayer upon exposure to air. Annealing for longer timescales promoted a greater out-diffusion of titanium and a thicker oxide layer to grow on the copper surface. However, interface measurements suggest that the diffusion is not significant enough to compromise the barrier integrity, and the TiW/Cu interface remains stable even after 5 h of annealing.

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Microstructural and compositional characterization of TiW/Al(0.8%Si)/TiW/PtSi/(100)Si

Cited by 3 publications

References 4 publications

Capturing the Dynamics of Ti Diffusion Across Ti_xW_1−x/Cu Heterostructures using X‐Ray Photoelectron Spectroscopy

Capturing the Dynamics of Ti Diffusion Across Ti_xW_1−x/Cu Heterostructures using X‐Ray Photoelectron Spectroscopy

Capturing the dynamics of Ti diffusion across Ti$_x$W$_{1-x}$/Cu heterostructures using X-ray photoelectron spectroscopy

Evaluation of the thermal stability of TiW/Cu heterojunctions using a combined SXPS and HAXPES approach

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Microstructural and compositional characterization of TiW/Al(0.8%Si)/TiW/PtSi/(100)Si

Cited by 3 publications

References 4 publications

Capturing the Dynamics of Ti Diffusion Across TixW1−x/Cu Heterostructures using X‐Ray Photoelectron Spectroscopy

Capturing the Dynamics of Ti Diffusion Across TixW1−x/Cu Heterostructures using X‐Ray Photoelectron Spectroscopy

Capturing the dynamics of Ti diffusion across Ti$_x$W$_{1-x}$/Cu heterostructures using X-ray photoelectron spectroscopy

Evaluation of the thermal stability of TiW/Cu heterojunctions using a combined SXPS and HAXPES approach

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Capturing the Dynamics of Ti Diffusion Across Ti_xW_1−x/Cu Heterostructures using X‐Ray Photoelectron Spectroscopy

Capturing the Dynamics of Ti Diffusion Across Ti_xW_1−x/Cu Heterostructures using X‐Ray Photoelectron Spectroscopy