Copper CMP evaluation: planarization issues

Fayolle, M.; Romagna, F.

doi:10.1016/s0167-9317(97)00104-4

Cited by 56 publications

(26 citation statements)

References 5 publications

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“…Among such oxidizing agents, hydrogen peroxide ͑H 2 O 2 ͒ is widely used for Cu CMP and its properties have been widely investigated. [4][5][6][7][8] Also, various organic additives were added into the slurry to maximize specific characteristics during the Cu CMP. To inhibit Cu corrosion, benzotriazole ͑BTA͒ or 5-aminotetrazole ͑ATRA͒ is commonly used.…”

mentioning

confidence: 99%

Effects of OH Radicals on Formation of Cu Oxide and Polishing Performance in Cu Chemical Mechanical Polishing

Kang

Nam²,

Won³

et al. 2008

Electrochem. Solid-State Lett.

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The amount of OH radicals generated varied according to the complexing agent or Cu ion, and the accelerating effect of OH radicals on the rate of Cu oxide formation was found in acidic pH. When Cu͑I͒ ions and oxalic acid were added to H 2 O 2 -based slurry, the decreases in etch and removal rates of Cu were observed because more generation of OH radicals resulted in the formation of thicker Cu oxide compared to additive-free slurry. Therefore, proper control of the formation and dissolution of Cu oxide led to an increase in etch and removal rates.Cu has been introduced as an interconnection material due to its low electrical resistance and high resistance to electromigration compared to W or Al. 1-3 The damascene process based on chemical mechanical polishing ͑CMP͒, which is used to remove the protruding part and planarize the whole wafer surface, makes it possible to use Cu as an interconnection material.During Cu CMP, the Cu surface is oxidized by an oxidizing agent through the oxidation of Cu to cuprous or cupric ions ͑Eq. 1͒. Among such oxidizing agents, hydrogen peroxide ͑H 2 O 2 ͒ is widely used for Cu CMP and its properties have been widely investigated. 4-8 Also, various organic additives were added into the slurry to maximize specific characteristics during the Cu CMP. To inhibit Cu corrosion, benzotriazole ͑BTA͒ or 5-aminotetrazole ͑ATRA͒ is commonly used. 9-11 An organic additive of the carboxylic group was added as a complexing agent to improve the removal rate of Cu. At present, citric acid, 12-14 oxalic acid, 15 and glycine 16-18 were introduced as the complexing agent and their properties and performance investigated. The complexing agents react with oxidized Cu and form complexes on the Cu surface. In an acidic pH, Cu cations, especially Cu͑I͒ ions, react with H 2 O 2 and then H 2 O 2 is converted into OH radicals and hydroxyl ions through the so-called Fenton reaction ͑Eq. 2͒. 19 The oxidation potential of the OH radical is higher than that of H 2 O 2 , which is well known to be one of the most powerful oxidizing agents Cu → Cu + + e or Cu 2+ + 2e ͓1͔It has been reported that OH radicals enhanced the removal rates of Cu in an H 2 O 2 -based slurry, including an amino acid at alkaline solution, 16 and that citric acid and oxalic acid improved the removal rate of Cu in the acidic solution. When using citric acid and oxalic acid as the complexing agent in weak acidic pH, the effect of OH radicals in the slurry on Cu CMP performance has not been reported. Therefore, the objective of this study is to understand the effect of OH radicals on Cu CMP. ExperimentalElectrochemical measurements.-For the electrochemical experiments, a 99.9% Cu rod with a surface area of 0.5 cm 2 was used. A Pt electrode and a saturated calomel electrode ͑SCE͒ were used as a counter and a reference electrode, respectively. Potentiodynamic studies were performed with an EG&G model 263 potentiostat/ galvanostat corrosion measurement system. The potentiodynamic polarization measurements were obtained with a scan rate of 10 mV/s a...

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confidence: 99%

Effects of OH Radicals on Formation of Cu Oxide and Polishing Performance in Cu Chemical Mechanical Polishing

Kang

Nam²,

Won³

et al. 2008

Electrochem. Solid-State Lett.

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“…In general case, most researchers are preferred to use H 2 O 2 as the oxidizer, benzotriazole (BTA) as the inhibitor (3,4), and various complexing agents such as organic polymer with amine functional group (5,6).…”

Section: Introductionmentioning

confidence: 99%

Effect of Organic Amine in Colloidal Silica Slurry on Polishing-rate Selectivity of Copper to Tantalum-nitride Film in Copper Chemical Mechanical Planarization

et al. 2008

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We investigated the effect of organic additives with amine functional group such as alanine and polyacrylamide (PAM) on the copper chemical mechanical planarization. We found that addition of alanine can significantly increase the copper polishing rate while slightly decrease the TaN polishing rate. We also concluded that small amount addition of PAM drastically suppress the TaN polishing rate. Both alanine and PAM can enhance the Cu-to-TaN removal selectivity. Finally, we also explained the interaction between organic additives and Cu/TaN film through the zetapotential.

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“…Most of the previous studies [1][2][3][4][5][6][7][8] have found that dishing is sensitive to the pattern density, feature size and overpolishing time. Further, the feature size has a stronger influence on dishing than the pattern density.…”

Section: Introductionmentioning

confidence: 99%

A dishing model for chemical mechanical polishing of metal interconnect structures

Chang

2005

Microelectronic Engineering

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Copper CMP evaluation: planarization issues

Cited by 56 publications

References 5 publications

Effects of OH Radicals on Formation of Cu Oxide and Polishing Performance in Cu Chemical Mechanical Polishing

Effects of OH Radicals on Formation of Cu Oxide and Polishing Performance in Cu Chemical Mechanical Polishing

Effect of Organic Amine in Colloidal Silica Slurry on Polishing-rate Selectivity of Copper to Tantalum-nitride Film in Copper Chemical Mechanical Planarization

A dishing model for chemical mechanical polishing of metal interconnect structures

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