Barrier and seed repair performance of thin RuTa films for Cu interconnects

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• 作者：H. Volders^a ; ^{Voldersh@imec.be} ; L. Carbonell^a ; N. Heylen^a ; K. Kellens^a ; C. Zhao^a ; K. Marrant^a ; G. Faelens^a ; T. Conard^a ; B. Parmentier^a ; J. Steenbergen^a ; M. Van de Peer^a ; C.J. Wilson^a ; E. Sleeckx^a ; G.P. Beyer^a ; Zs. Tő ; kei^a ; V. Gravey^b ; K. Shah^c ; A. Cockburn^b
• 关键词：RuTa ; Seed enhancement ; Narrow lines ; Barrier properties
• 刊名：Microelectronic Engineering
• 出版年：2011
• 出版时间：May 2011
• 年：2011
• 卷：88
• 期：5
• 页码：690-693
• 全文大小：802 K

文摘

Thin (<4 nm) Physical Vapor Deposited (PVD) Ru-10 at. % Ta films were evaluated as diffusion barriers and seed enhancement layers for Cu metallization in sub 25 nm trenches. The ratio of Ru/Ta on blanket wafers could be influenced by changing the process conditions. However, a difference in Ru/Ta ratio did not influence the thermal stability of the layers during High Temperature X-ray Diffraction (HT-XRD) measurements as all RuTa films exhibited good thermal properties since no Cu-silicide formation was observed for temperatures below 500 °C. The RuTa films also passed an 85 °C/85 % relative humidity (RH) test of one week of storage in order to test the H₂O barrier integrity of the films. Furthermore no difference was found when testing the O₂ barrier integrity during 300 s anneals at various temperatures between 250 °C and 500 °C. Good Cu fill of 20 nm trenches (AR 4:1) patterned in oxide was achieved when combining the RuTa films with PVD Cu seed layers with thicknesses ranging from 7 to 20 nm and Cu plating. When compared to a Ta(N)/Ta barrier, relatively high electrical yields (60–80 % ) were obtained for structures with CDs <30 nm when combining RuTa films with PVD Cu seed layers as thin as 7 nm (on field), hence evidencing the seed enhancement ability of these layers.