Interfacial reactions and electrical properties of hafnium-based thin films in Cu/barrier/n+-p junction diodes

Keng Liang Ou, Ming Hung Tsai, Haw Ming Huang, Shi Yung Chiou, Che Tong Lin, Sheng Yang Lee

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

In this study, the barrier properties of Hf and nitrogen incorporated Hf films were investigated by Cu/Hf-N/Si structure. Hafnium and hafnium nitride films were prepared by reactive rf-magnetron sputtering on blank silicon wafers. The barrier properties were evaluated by sheet resistance, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The as-deposited Hf film has a hexagonal close packed structure and a low resistivity of 100.98 μΩ-cm. With increasing nitrogen concentration of Hf-N film, phase transformations are identified as hcp-Hf → fcc-HfN. The thermal stability of Cu/Hf/Si and Cu/HfN 0.47/Si contact system is evaluated by thermal stressing at various annealing temperatures. Nitrogen incorporated Hf films possess better barrier performance than sputtered Hf films. For the Cu/Hf/Si contact system, the interfacial reaction between the Hf barrier layer and the Cu layer is observed after annealing at 550 °C for 30 min, and copper-hafnium compounds form. Highly resistive copper silicide forms after annealing at 600 °C for 30 min. The Hf barrier fails due to the reaction of Cu and the Hf barrier, in which Cu atoms penetrate into the Si substrate after annealing at high temperature. The Cu/HfN0.47/Si is fairly stable up to annealing at 650 °C for 30 min. In addition, no copper-hafnium and copper silicide compounds are found. Diffusion resistance of nitrogen-incorporated Hf barrier is more effective. The thermal stabilities of Cu/HfN0.47/n+-p junction diodes are enhanced by nitrogen incorporation. The Cu/Hf/n+-p junction diodes result in large reverse-biased junction leakage currents after annealing at 500 °C for 30 min. On the other hand, Nitrogen incorporated Hf diffusion barriers retained the integrity of junction diodes up to 550 °C with lower reverse current densities. Phase transformation of hafnium-based barrier films with nitrogen incorporation are believed to impede Cu diffusion into the Si substrate and hence improve the barrier performance. Nitrogen incorporated hafnium diffusion barrier can suppress the formation of copper-hafnium compounds and copper penetration, and thus improve the thermal stability of barrier layer.

Original languageEnglish
Pages (from-to)184-192
Number of pages9
JournalMicroelectronic Engineering
Volume77
Issue number2
DOIs
Publication statusPublished - Feb 2005

Fingerprint

Hafnium
junction diodes
hafnium
Surface chemistry
p-n junctions
Diodes
Electric properties
Nitrogen
electrical properties
Thin films
Copper
Annealing
nitrogen
thin films
Hafnium compounds
annealing
hafnium compounds
copper
Thermodynamic stability
Diffusion barriers

Keywords

  • Copper
  • Hafnium
  • Junction diodes
  • Nitrides
  • Sputtering

ASJC Scopus subject areas

  • Hardware and Architecture
  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Atomic and Molecular Physics, and Optics

Cite this

Interfacial reactions and electrical properties of hafnium-based thin films in Cu/barrier/n+-p junction diodes. / Ou, Keng Liang; Tsai, Ming Hung; Huang, Haw Ming; Chiou, Shi Yung; Lin, Che Tong; Lee, Sheng Yang.

In: Microelectronic Engineering, Vol. 77, No. 2, 02.2005, p. 184-192.

Research output: Contribution to journalArticle

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abstract = "In this study, the barrier properties of Hf and nitrogen incorporated Hf films were investigated by Cu/Hf-N/Si structure. Hafnium and hafnium nitride films were prepared by reactive rf-magnetron sputtering on blank silicon wafers. The barrier properties were evaluated by sheet resistance, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The as-deposited Hf film has a hexagonal close packed structure and a low resistivity of 100.98 μΩ-cm. With increasing nitrogen concentration of Hf-N film, phase transformations are identified as hcp-Hf → fcc-HfN. The thermal stability of Cu/Hf/Si and Cu/HfN 0.47/Si contact system is evaluated by thermal stressing at various annealing temperatures. Nitrogen incorporated Hf films possess better barrier performance than sputtered Hf films. For the Cu/Hf/Si contact system, the interfacial reaction between the Hf barrier layer and the Cu layer is observed after annealing at 550 °C for 30 min, and copper-hafnium compounds form. Highly resistive copper silicide forms after annealing at 600 °C for 30 min. The Hf barrier fails due to the reaction of Cu and the Hf barrier, in which Cu atoms penetrate into the Si substrate after annealing at high temperature. The Cu/HfN0.47/Si is fairly stable up to annealing at 650 °C for 30 min. In addition, no copper-hafnium and copper silicide compounds are found. Diffusion resistance of nitrogen-incorporated Hf barrier is more effective. The thermal stabilities of Cu/HfN0.47/n+-p junction diodes are enhanced by nitrogen incorporation. The Cu/Hf/n+-p junction diodes result in large reverse-biased junction leakage currents after annealing at 500 °C for 30 min. On the other hand, Nitrogen incorporated Hf diffusion barriers retained the integrity of junction diodes up to 550 °C with lower reverse current densities. Phase transformation of hafnium-based barrier films with nitrogen incorporation are believed to impede Cu diffusion into the Si substrate and hence improve the barrier performance. Nitrogen incorporated hafnium diffusion barrier can suppress the formation of copper-hafnium compounds and copper penetration, and thus improve the thermal stability of barrier layer.",
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AU - Ou, Keng Liang

AU - Tsai, Ming Hung

AU - Huang, Haw Ming

AU - Chiou, Shi Yung

AU - Lin, Che Tong

AU - Lee, Sheng Yang

PY - 2005/2

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N2 - In this study, the barrier properties of Hf and nitrogen incorporated Hf films were investigated by Cu/Hf-N/Si structure. Hafnium and hafnium nitride films were prepared by reactive rf-magnetron sputtering on blank silicon wafers. The barrier properties were evaluated by sheet resistance, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The as-deposited Hf film has a hexagonal close packed structure and a low resistivity of 100.98 μΩ-cm. With increasing nitrogen concentration of Hf-N film, phase transformations are identified as hcp-Hf → fcc-HfN. The thermal stability of Cu/Hf/Si and Cu/HfN 0.47/Si contact system is evaluated by thermal stressing at various annealing temperatures. Nitrogen incorporated Hf films possess better barrier performance than sputtered Hf films. For the Cu/Hf/Si contact system, the interfacial reaction between the Hf barrier layer and the Cu layer is observed after annealing at 550 °C for 30 min, and copper-hafnium compounds form. Highly resistive copper silicide forms after annealing at 600 °C for 30 min. The Hf barrier fails due to the reaction of Cu and the Hf barrier, in which Cu atoms penetrate into the Si substrate after annealing at high temperature. The Cu/HfN0.47/Si is fairly stable up to annealing at 650 °C for 30 min. In addition, no copper-hafnium and copper silicide compounds are found. Diffusion resistance of nitrogen-incorporated Hf barrier is more effective. The thermal stabilities of Cu/HfN0.47/n+-p junction diodes are enhanced by nitrogen incorporation. The Cu/Hf/n+-p junction diodes result in large reverse-biased junction leakage currents after annealing at 500 °C for 30 min. On the other hand, Nitrogen incorporated Hf diffusion barriers retained the integrity of junction diodes up to 550 °C with lower reverse current densities. Phase transformation of hafnium-based barrier films with nitrogen incorporation are believed to impede Cu diffusion into the Si substrate and hence improve the barrier performance. Nitrogen incorporated hafnium diffusion barrier can suppress the formation of copper-hafnium compounds and copper penetration, and thus improve the thermal stability of barrier layer.

AB - In this study, the barrier properties of Hf and nitrogen incorporated Hf films were investigated by Cu/Hf-N/Si structure. Hafnium and hafnium nitride films were prepared by reactive rf-magnetron sputtering on blank silicon wafers. The barrier properties were evaluated by sheet resistance, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The as-deposited Hf film has a hexagonal close packed structure and a low resistivity of 100.98 μΩ-cm. With increasing nitrogen concentration of Hf-N film, phase transformations are identified as hcp-Hf → fcc-HfN. The thermal stability of Cu/Hf/Si and Cu/HfN 0.47/Si contact system is evaluated by thermal stressing at various annealing temperatures. Nitrogen incorporated Hf films possess better barrier performance than sputtered Hf films. For the Cu/Hf/Si contact system, the interfacial reaction between the Hf barrier layer and the Cu layer is observed after annealing at 550 °C for 30 min, and copper-hafnium compounds form. Highly resistive copper silicide forms after annealing at 600 °C for 30 min. The Hf barrier fails due to the reaction of Cu and the Hf barrier, in which Cu atoms penetrate into the Si substrate after annealing at high temperature. The Cu/HfN0.47/Si is fairly stable up to annealing at 650 °C for 30 min. In addition, no copper-hafnium and copper silicide compounds are found. Diffusion resistance of nitrogen-incorporated Hf barrier is more effective. The thermal stabilities of Cu/HfN0.47/n+-p junction diodes are enhanced by nitrogen incorporation. The Cu/Hf/n+-p junction diodes result in large reverse-biased junction leakage currents after annealing at 500 °C for 30 min. On the other hand, Nitrogen incorporated Hf diffusion barriers retained the integrity of junction diodes up to 550 °C with lower reverse current densities. Phase transformation of hafnium-based barrier films with nitrogen incorporation are believed to impede Cu diffusion into the Si substrate and hence improve the barrier performance. Nitrogen incorporated hafnium diffusion barrier can suppress the formation of copper-hafnium compounds and copper penetration, and thus improve the thermal stability of barrier layer.

KW - Copper

KW - Hafnium

KW - Junction diodes

KW - Nitrides

KW - Sputtering

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