Comparison of lifetime improvements in electromigration between Ti barrier metal and chemical vapor deposition Co capping

Yumi Kakuhara, Shinji Yokogawa, Kazuyoshi Ueno

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

As promising technologies for fabrication of highly reliable Cu interconnects, using Ti barrier metal (Cu/Ti) and chemical vapor deposition (CVD) Co capping (Co/Cu/Ta/TaN) were compared. Both Cu interconnects similarly showed longer electromigration (EM) lifetime and larger activation energy of lifetime than conventional Cu interconnects fabricated using Ta/TaN barrier metal without capping metal (Cu/Ta/TaN). The residual resistance of Cu lines was measured cryogenically. Cu/Ti showed a higher residual resistance than Co/Cu/Ta/TaN and Cu/Ta/TaN, which indicates the presence of more impurities and a higher density of grain boundaries in Cu/Ti. Energy dispersive X-ray spectroscopy (EDX) analysis showed that a large amount of Ti doped into the Cu line segregated mostly at the grain boundaries on the Cu surface. It is suggested that Ti doped into a Cu line suppresses Cu diffusion through only the grain boundaries on the Cu surface. On the other hand, Co capping suppresses Cu diffusion through the entire Cu surface. As Cu/Ti improved EM lifetime significantly, the grain boundaries on the Cu surface are proposed to be a predominant diffusion path in EM. Since the density of grain boundaries probably increases on the Cu surface as interconnects shrink, suppressing the grain boundary diffusion on the Cu surface is highly effective to strengthen EM reliability.

Original languageEnglish
Article number04DB08
JournalJapanese Journal of Applied Physics
Volume49
Issue number4 PART 2
DOIs
Publication statusPublished - 2010 Apr

Fingerprint

metal vapors
Electromigration
electromigration
Chemical vapor deposition
Grain boundaries
grain boundaries
vapor deposition
life (durability)
Metals
metals
Activation energy
Impurities
activation energy
Fabrication
impurities
fabrication
spectroscopy
x rays

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Comparison of lifetime improvements in electromigration between Ti barrier metal and chemical vapor deposition Co capping. / Kakuhara, Yumi; Yokogawa, Shinji; Ueno, Kazuyoshi.

In: Japanese Journal of Applied Physics, Vol. 49, No. 4 PART 2, 04DB08, 04.2010.

Research output: Contribution to journalArticle

@article{e9cc0d0a1ec142a389373e74656b826c,
title = "Comparison of lifetime improvements in electromigration between Ti barrier metal and chemical vapor deposition Co capping",
abstract = "As promising technologies for fabrication of highly reliable Cu interconnects, using Ti barrier metal (Cu/Ti) and chemical vapor deposition (CVD) Co capping (Co/Cu/Ta/TaN) were compared. Both Cu interconnects similarly showed longer electromigration (EM) lifetime and larger activation energy of lifetime than conventional Cu interconnects fabricated using Ta/TaN barrier metal without capping metal (Cu/Ta/TaN). The residual resistance of Cu lines was measured cryogenically. Cu/Ti showed a higher residual resistance than Co/Cu/Ta/TaN and Cu/Ta/TaN, which indicates the presence of more impurities and a higher density of grain boundaries in Cu/Ti. Energy dispersive X-ray spectroscopy (EDX) analysis showed that a large amount of Ti doped into the Cu line segregated mostly at the grain boundaries on the Cu surface. It is suggested that Ti doped into a Cu line suppresses Cu diffusion through only the grain boundaries on the Cu surface. On the other hand, Co capping suppresses Cu diffusion through the entire Cu surface. As Cu/Ti improved EM lifetime significantly, the grain boundaries on the Cu surface are proposed to be a predominant diffusion path in EM. Since the density of grain boundaries probably increases on the Cu surface as interconnects shrink, suppressing the grain boundary diffusion on the Cu surface is highly effective to strengthen EM reliability.",
author = "Yumi Kakuhara and Shinji Yokogawa and Kazuyoshi Ueno",
year = "2010",
month = "4",
doi = "10.1143/JJAP.49.04DB08",
language = "English",
volume = "49",
journal = "Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes",
issn = "0021-4922",
publisher = "Japan Society of Applied Physics",
number = "4 PART 2",

}

TY - JOUR

T1 - Comparison of lifetime improvements in electromigration between Ti barrier metal and chemical vapor deposition Co capping

AU - Kakuhara, Yumi

AU - Yokogawa, Shinji

AU - Ueno, Kazuyoshi

PY - 2010/4

Y1 - 2010/4

N2 - As promising technologies for fabrication of highly reliable Cu interconnects, using Ti barrier metal (Cu/Ti) and chemical vapor deposition (CVD) Co capping (Co/Cu/Ta/TaN) were compared. Both Cu interconnects similarly showed longer electromigration (EM) lifetime and larger activation energy of lifetime than conventional Cu interconnects fabricated using Ta/TaN barrier metal without capping metal (Cu/Ta/TaN). The residual resistance of Cu lines was measured cryogenically. Cu/Ti showed a higher residual resistance than Co/Cu/Ta/TaN and Cu/Ta/TaN, which indicates the presence of more impurities and a higher density of grain boundaries in Cu/Ti. Energy dispersive X-ray spectroscopy (EDX) analysis showed that a large amount of Ti doped into the Cu line segregated mostly at the grain boundaries on the Cu surface. It is suggested that Ti doped into a Cu line suppresses Cu diffusion through only the grain boundaries on the Cu surface. On the other hand, Co capping suppresses Cu diffusion through the entire Cu surface. As Cu/Ti improved EM lifetime significantly, the grain boundaries on the Cu surface are proposed to be a predominant diffusion path in EM. Since the density of grain boundaries probably increases on the Cu surface as interconnects shrink, suppressing the grain boundary diffusion on the Cu surface is highly effective to strengthen EM reliability.

AB - As promising technologies for fabrication of highly reliable Cu interconnects, using Ti barrier metal (Cu/Ti) and chemical vapor deposition (CVD) Co capping (Co/Cu/Ta/TaN) were compared. Both Cu interconnects similarly showed longer electromigration (EM) lifetime and larger activation energy of lifetime than conventional Cu interconnects fabricated using Ta/TaN barrier metal without capping metal (Cu/Ta/TaN). The residual resistance of Cu lines was measured cryogenically. Cu/Ti showed a higher residual resistance than Co/Cu/Ta/TaN and Cu/Ta/TaN, which indicates the presence of more impurities and a higher density of grain boundaries in Cu/Ti. Energy dispersive X-ray spectroscopy (EDX) analysis showed that a large amount of Ti doped into the Cu line segregated mostly at the grain boundaries on the Cu surface. It is suggested that Ti doped into a Cu line suppresses Cu diffusion through only the grain boundaries on the Cu surface. On the other hand, Co capping suppresses Cu diffusion through the entire Cu surface. As Cu/Ti improved EM lifetime significantly, the grain boundaries on the Cu surface are proposed to be a predominant diffusion path in EM. Since the density of grain boundaries probably increases on the Cu surface as interconnects shrink, suppressing the grain boundary diffusion on the Cu surface is highly effective to strengthen EM reliability.

UR - http://www.scopus.com/inward/record.url?scp=77952730729&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77952730729&partnerID=8YFLogxK

U2 - 10.1143/JJAP.49.04DB08

DO - 10.1143/JJAP.49.04DB08

M3 - Article

AN - SCOPUS:77952730729

VL - 49

JO - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes

JF - Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes

SN - 0021-4922

IS - 4 PART 2

M1 - 04DB08

ER -