Integration Challenges for CMP of Copper

Bajaj, Rajeev; Zutshi, Ajoy; Surana, Rahul; Naik, Mehul; Pan, Tony

doi:10.1557/mrs2002.249

Cited by 16 publications

(8 citation statements)

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“…5 These problems can be mitigated by performing Cu and the barrier CMP at "low" pressures. 6,7 Because throughput cannot be sacrificed, this requires increasing the chemical activity of the CMP slurries so that soft surface films that can be easily removed at low polishing pressures are formed on the Cu film surface. A better understanding of the roles of various chemicals used in typical Cu CMP slurries along with the search for novel slurry additives is helpful to achieve this goal.…”

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confidence: 99%

Role of the Functional Groups of Complexing Agents in Copper Slurries

Patri

Aksu

Babu

2006

J. Electrochem. Soc.

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We investigate the role of -NH 2 and -COOH functional groups of complexing agents in H 2 O 2 -based slurries in controlling copper ͑Cu͒ removal rates. Slurries containing complexing agents with two of the same functional groups ͑succinic acid: HOOC-CH 2 CH 2 -COOH, ethylene diamine: H 2 N-CH 2 CH 2 -NH 2 ͒ and a complexing agent containing one each of the functional groups ͑␤-alanine: H 2 N-CH 2 CH 2 -COOH͒, all with the same carbon chain length, were investigated. Along with dissolution and disk polish experiments, potential-pH diagrams were constructed for these three systems in the presence of H 2 O. The dissolution and polish rates are consistent with the known activity of carboxylic acids ͑with -COOH groups͒ at acidic conditions and that of amines ͑with -NH 2 groups͒ in an alkaline environment. The observed trends in the removal rates with all these slurries are explained using potential-pH diagrams, UV/visible spectra, and electrochemical experiments. When compared to glycine ͑H 2 N-CH 2 -COOH͒, ␤-alanine ͑H 2 N-CH 2 CH 2 -COOH͒ produced higher removal rates at acidic pH values and lower removal rates at alkaline pH values. Finally, succinic acid and ␤-alanine-based slurries were found to result in lower dissolution rates and higher polish rates compared to glycine-based slurries at pH 4.Chemical mechanical planarization ͑CMP͒ is widely used to planarize metal and dielectric films during integrated circuit fabrication. 1,2 Damascene process 3 is currently used in conjunction with CMP in the fabrication of multilevel copper ͑Cu͒ interconnects for advanced logic and memory devices. In this fabrication scheme, trenches are first patterned in a dielectric material at each level. After the barrier, seed, and copper fill are sequentially deposited in the dielectric trenches, 4 CMP is used to remove excess copper and create a planar surface for subsequent fabrication of additional levels of metallization.Cu CMP involves removal of material by the combined action of chemical and mechanical means to achieve planarization. Chemicals aid in material removal by modifying the surface film while abrasion between the particles in the slurry, pad, and the modified film facilitates mechanical removal. Material removal solely involving chemicals usually leads to uniform etching of both elevated and recessed regions and does not level the topography. The synergistic interplay between chemical and mechanical components in the slurry facilitates effective planarization. An important requirement of any successful copper CMP slurry is a high polishing rate leading to short copper overburden polishing times while minimizing dishing and erosion and other surface defects.With the introduction of low-k dielectric materials, integration of Cu/low-k dielectrics has become a serious challenge. These low-k dielectric films are porous, poorly adhere to Cu/Ta, are mechanically weak, and hence are prone to damage during CMP. 5 These problems can be mitigated by performing Cu and the barrier CMP at "low" pressures. 6,7 Because throughput can...

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Role of the Functional Groups of Complexing Agents in Copper Slurries

Patri

Aksu

Babu

2006

J. Electrochem. Soc.

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“…Chemical mechanical polishing (CMP) is employed as a viable method for planarizing the surface globally [1][2][3]. In a typical CMP process, a rotating wafer is pressed against a rotating polishing pad in the presence of slurry in between.…”

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confidence: 99%

Application of Chemical Mechanical Polishing in the Infrared Focal Plane Arrays Manufacturing Process

Liu¹,

Liu

Zhao

et al. 2010

ECS Trans.

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Chemical mechanical polishing (CMP) is a powerful method for manufacturing the infrared focal plane arrays structure. In order to achieve planarizing surface and high polishing rate , the slurry prescription and polishing techniques for infrared focal plane arrays are studied, which is based on the low mechanical and high chemical polishing process, and the new point is put forward. The ingredient and prescription of slurry is found, in which the smaller size (ranging from 15 to 20 nm) silica sols is chosen as abrasive. The slurry with smaller abrasive and polishing technology effectively reduces the roughness and thickness of the damaged layer resulting from abrasion. After more research, the main ingredients, including oxidizer, complexing agent (organic-alkali hydroxide multi-amine) and surfactant are chosen preferentially.

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“…There is very little surface area between some of these high aspect ratio polymer mold features and the metal substrate, such that exposure to the etchant bath causes a loss of mold features and reduces the yield of usable MEMS components; wasting resources expended on x-ray lithography. Similar concerns regarding the adhesion of dielectric and barrier films arise in routine microelectronic fabrication procedures such as chemical-mechanical polishing 7,8 and packaging, [9][10][11][12] which involve exposure to wet environments and mechanical loading.…”

Section: Introductionmentioning

confidence: 99%

Effect of storage in aqueous environments on polymer–metal interfacial fracture

et al. 2004

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The effect of environmental exposure on the fracture characteristics of two polymer-metal interfaces was measured using a four-point bend delamination test. Films of high-molecular-weight polymethylmethacrylate (PMMA) resin were spin-cast on metal-coated silicon wafer substrates, for which the metal was either titanium or aluminum. Sandwich beam specimens were fabricated and stored in one of the following conditions prior to the bending tests: vacuum desiccator at 25°C, vacuum desiccator at 65°C, distilled water at 25°C, or distilled water at 65°C. Load-displacement behavior measured during bending revealed significant differences between the delamination characteristics of the two PMMA-metal interfaces after vacuum exposure which were eliminated after the degrading effects of water exposure. Three distinctive load-displacement behaviors were observed: plateau, fracture at a single load; R-curve, fracture at increasing load with crack extension; and stick-slip, cycles of gradual load increase and sudden load drop with crack extension. PMMA-Al samples stored in vacuum desiccator at 25°C exhibited R-curve fracture and the largest average crack driving force, G C , 12.2 (±0.5) J/m 2 , of all samples tested. After storage in 25°C water, these PMMA-Al samples exhibited stick-slip fracture and G C decreased to 7.1 (±2.6) J/m 2 ; storage in 65°C water further decreased G C to 2.1 (±0.7) J/m 2 . PMMA-Ti samples exhibited stick-slip fracture after storage in vacuum desiccator at 25°C, with an average G C of 8.0 (±2.6) J/m 2 ; storage in 65°C water resulted in a transition to plateau fracture and a decrease in G C to 1.6 (±0.3) J/m 2 . The initial difference and subsequent similarity are interpreted in terms of surface roughness and hydrolysis, respectively.

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Integration Challenges for CMP of Copper

Cited by 16 publications

References 0 publications

Role of the Functional Groups of Complexing Agents in Copper Slurries

Role of the Functional Groups of Complexing Agents in Copper Slurries

Application of Chemical Mechanical Polishing in the Infrared Focal Plane Arrays Manufacturing Process

Effect of storage in aqueous environments on polymer–metal interfacial fracture

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