Enhancement of adhesion strength of Cu layer on single and multi-layer dielectric film stack in Cu/low k multi-level interconnects

Balakumar, S.; Wong, G.H.L.; Tsang, C.; Hara, Tohru; Yoo, Won Jong

doi:10.1016/j.mee.2004.05.003

Cited by 6 publications

(2 citation statements)

References 13 publications

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“…Resistance–capacitance (RC) delay could be reduced by the integration of Cu with low‐k dielectrics 3–5. Substitution of SiO 2 with low‐k materials can reduce the RC delay by up to 75% for materials with k values close to 1 6.…”

Section: Introductionmentioning

confidence: 99%

Removal of moisture contamination from porous polymeric low‐k dielectric films

et al. 2006

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Section: Introductionmentioning

confidence: 99%

Removal of moisture contamination from porous polymeric low‐k dielectric films

et al. 2006

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“…Many materials, including Ta, TaN, Ti, TiN, W, and WN X C Y , are being investigated for use as Cu diffusion barriers. [7][8][9][10][11][12][13][14][15][16] In the selection of a barrier material the ease of deposition, step coverage, adhesion to Cu, and adhesion to the dielectric must be considered. The demand for effective diffusion barriers with decreasing film thickness has increased along with the decrease in feature sizes.…”

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confidence: 99%

Corrosion and Inhibition of WN[sub X]C[sub Y] Barrier during Chemical Mechanical Planarization

Ernur

Terzieva

Schuhmacher

et al. 2005

J. Electrochem. Soc.

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We investigated the mechanism of chemical and galvanic corrosion of tungsten nitride carbide ͑WN X C Y ͒ barrier during Cu chemical mechanical planarization ͑CMP͒. Our results demonstrate that chemical corrosion is caused by the oxidation of tungsten ͑W͒ in the WN X C Y film by H 2 O 2 followed by the dissolution of a tungsten oxide complex, which leads to WN X C Y loss. WN X C Y loss is enhanced during CMP due to galvanic corrosion driven by the Cu/WN X C Y couple. A high loss rate occurs due to the strong potential difference between Cu and WN X C Y in H 2 O 2 -containing slurries. A model representing WN X C Y loss in Cu damascene lines during the CMP process is proposed. It supports WN X C Y loss in the top part of the trench sidewall at the interface with Cu. We demonstrate that the use of HNO 3 instead of H 2 O 2 as the oxidizer, in the formulation of the corrosion-inhibiting model slurries reduces chemical and galvanic corrosion of WN X C Y . Addition of monosaccharides or organic acids prevents excessive Cu loss. Wafer-level tests done with in-house corrosion-inhibiting model slurries show promising Cu and WN X C Y compatibility without significant WN X C Y loss.Copper ͑Cu͒ is selected as the interconnect material of choice for the fabrication of ultralarge scale integrated ͑ULSI͒ circuits due to its lower resistivity and improved electromigration resistance as compared to aluminum ͑Al͒. 1 The damascene process is successfully implemented in order to integrate Cu in ULSI. Unlike Al metallization, the damascene process relies on depositing Cu into the patterned dielectric by electrochemical deposition ͑ECD͒. Because Cu readily diffuses into the dielectric, a diffusion barrier is deposited prior to Cu deposition. Chemical mechanical planarization ͑CMP͒ is used to polish excess Cu overburden and barrier metal to provide surface planarity.In the manufacturing of microelectronic devices Cu is susceptible to corrosion in particular by reacting in oxidizing environments. Corrosion of Cu interconnects during integrated circuit ͑IC͒ manufacturing occurs mostly during the CMP process where Cu is in contact with the CMP slurry. Chemical, photo-, narrow-trench, and galvanic corrosion are reported to be the possible mechanisms. 2-4 Galvanic corrosion occurs when two dissimilar metals are in electrical and in ionic contact. Thus, during the CMP process, slurry acts as the electrolyte providing the ionic contact medium for the barrier metal and Cu, which are in electrical contact. Depending on the electrochemical potential difference, it is either Cu or the barrier that acts as the anode and suffers from enhanced material loss as shown schematically in Fig. 1. Galvanic corrosion has been reported 2,5,6 by several groups.Many materials, including Ta, TaN, Ti, TiN, W, and WN X C Y , are being investigated for use as Cu diffusion barriers. 7-16 In the selection of a barrier material the ease of deposition, step coverage, adhesion to Cu, and adhesion to the dielectric must be considered. The demand for effective diffusion b...

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