Adhesion and Removal of Silica and Ceria Particles on the Wafer Surfaces in STI and Poly Si CMP

Hong, Yi Koan; Kang, Young Jae; Park, Jin Goo; Han, Sang Yeob; Yun, Seong Kyu; Yoon, Bo Un; Hong, Chang Ki

doi:10.4028/www.scientific.net/ssp.134.159

Cited by 10 publications

(10 citation statements)

References 1 publication

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“…It was reported by Hong et al that the adhesion force of irregular ceria particles is much higher on SiN x than on SiO x surface at pH 3, 7, and 11, based on theoretical calculation and AFM adhesion tests. 1 Consequently, relative to SiO x , more ceria particles will stick to SiN x surface, and a stronger force, chemical or mechanical, is needed to clean the ceria particles off.…”

Section: Resultsmentioning

confidence: 99%

“…1 Consequently, relative to SiO x , more ceria particles will stick to SiN x surface, and a stronger force, chemical or mechanical, is needed to clean the ceria particles off.…”

Section: Ecs Journal Of Solidmentioning

confidence: 99%

“…However, atomic force microscope (AFM) measurement suggests that the adhesion force of irregular ceria is much lower than that of spherical silica on the surface of TEOS oxide, SiN x , and poly-Si in both acidic and basic pH regimes. 1 Unlike silica, ceria exhibit redox reactions on SiO x surface, which should be taken into account when selecting the chemicals for pCMP cleaning. Meanwhile, besides silica and ceria abrasive particles, a robust FEOL pCMP clean process need to remove organic additives from slurry itself; by-products or polish residues (PR) such as SiO x , SiN x , and poly-Si from the wafer; and debris from CMP consumables such as pad (PU, polyurethane), carrier (stainless steel), retaining ring (e.g., polyether ether ketone, PEEK), and roller brush (polyvinyl alcohol, PVA).…”

mentioning

confidence: 99%

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Post Cleaning for FEOL CMP with Silica and Ceria Slurries

Tseng

McCormack

et al. 2017

ECS J. Solid State Sci. Technol.

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Post cleaning experiments for front end of the line (FEOL) CMP with silica and ceria slurries are carried out on commercial polishers with 300 mm oxide, nitride, and integrated shallow trench isolation (STI) wafers. Considering the charge attraction or repulsion between particles and wafer surface, both acidic and basic clean chemicals are applied at different stages in the post CMP process sequence. Diluted hydrogen peroxide in a non-contact megasonic cleaner is used to remove ceria abrasive particles and polish residues with high efficiency. On-platen buff clean with or without pad conditioning can make an impact on the post CMP cleaning performance. Post CMP cleaning splits are executed in order to evaluate the effectiveness of each of the process steps and their roles in the overall cleaning performance. Silica-based slurries are usually adopted for bulk oxide polish while ceria-based slurries are more suited for the final "buff" polish where high selectivity is required. The ever stringent requirements for scratch reduction lead to the trend of adopting nano-sized (< 60 nm) abrasive particles in all types of CMP slurries. However, the higher surface charges per area of these nanoparticles and the resulting stronger adhesion force between them and wafer surface necessitates the modification of the chemistry and optimization of post CMP (pCMP) cleaning process to meet the low defect requirement.Between silica and ceria abrasive particles, the latter are heavier in weight and irregular in shape (as opposed to circular like silica), and hence may present more challenges for pCMP cleaning from weight and geometry point of view. However, atomic force microscope (AFM) measurement suggests that the adhesion force of irregular ceria is much lower than that of spherical silica on the surface of TEOS oxide, SiN x , and poly-Si in both acidic and basic pH regimes.1 Unlike silica, ceria exhibit redox reactions on SiO x surface, which should be taken into account when selecting the chemicals for pCMP cleaning. Meanwhile, besides silica and ceria abrasive particles, a robust FEOL pCMP clean process need to remove organic additives from slurry itself; by-products or polish residues (PR) such as SiO x , SiN x , and poly-Si from the wafer; and debris from CMP consumables such as pad (PU, polyurethane), carrier (stainless steel), retaining ring (e.g., polyether ether ketone, PEEK), and roller brush (polyvinyl alcohol, PVA).The selection of proper chemicals is often the first step toward pCMP cleaning. However, design of cleaning sequence, exploitation of the tool hardware, and optimization of process parameters are equally critical to achieve maximum cleaning efficiency.2 During the final ("buff") polish step, for example, the use of hard vs. soft pads, in-situ vs. ex-situ conditioning, and pad rinse with DIW vs. clean chemical can all modulate defect generation to various degrees, and hence affect the overall post cleaning performance. In the post CMP clean module, cleaning with or without mechanical contact, brush or "penci...

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Section: Resultsmentioning

confidence: 99%

“…1 Consequently, relative to SiO x , more ceria particles will stick to SiN x surface, and a stronger force, chemical or mechanical, is needed to clean the ceria particles off.…”

Section: Ecs Journal Of Solidmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Post Cleaning for FEOL CMP with Silica and Ceria Slurries

Tseng

McCormack

et al. 2017

ECS J. Solid State Sci. Technol.

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“…The poly-Si surface is more chemically active and has less abrasive contamination than oxide CMP. 137 The poly-Si surface is susceptible to temperature. 138 Hence, elevation in temperature has significant impact on the RR, pits, voids, and topography removal.…”

Section: Application-based Post-cmp Cleaningmentioning

confidence: 99%

Review—Post-Chemical Mechanical Planarization Cleaning Technology

Hazarika,

Gupta,

Rajaraman

2023

ECS J. Solid State Sci. Technol.

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Chemical mechanical planarization (CMP), a commonly employed process for attaining local and global planarization in integrated circuits fabrication, leaves contaminants and defects on the surface polished. Due to the miniaturization of devices, new materials/ processes for the fabrication of IC circuits are considered, introducing new post-CMP issues. As such, understanding of post-CMP cleaning process is critical to choose an appropriate method for the given material. Here, the types of contaminants and defects generated during the post-CMP process and the issues related to it are discussed. The different physical and chemical cleaning methods employed in the post-CMP cleaning process to eradicate these defects are elucidated.In particular, the PVA brushing method, which is currently preferred, is elaborated upon in detail. The various chemistries, including the newly suggested ones in recent years for cleaning different substrates, are summarized. The post-CMP cleaning methods for various materials such as Cu, Al, W, Co, Ru, InGaAs, Ge, and SiO2 are mainly addressed here. This review also provides the direction of progress for the post-CMP cleaning process in terms of evolution of new techniques and chemistries for the next generation of materials.

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“…[1][2][3] However, to optimize the CMP performance, several parameters have to be monitored such as pad, conditioner, and slurry. [1][2][3] However, to optimize the CMP performance, several parameters have to be monitored such as pad, conditioner, and slurry.…”

mentioning

confidence: 99%

Generation of Pad Debris during Oxide CMP Process and Its Role in Scratch Formation

Prasad¹,

Kwon²,

Kim³

et al. 2011

J. Electrochem. Soc.

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The generation of pad debris during the chemical mechanical planarization (CMP) process was studied. A fresh pad was conditioned with deionized water alone without polishing any wafer in order to characterize the pad debris exclusively. It was found that the pad debris presented in several size ranges with irregular shapes, mostly in agglomerated form. Polishing experiments were performed continuously without conditioning the pad, and the byproducts were gathered several times during the process. No pad debris was found in the gathered slurry during this process, but dispersion of some agglomerated silica particles was observed. The slurry was gathered during CMP processes conducted under both in situ and ex situ pad conditions. The generation of pad debris during polishing was observed with in situ conditioning but not observed with ex situ conditioning. The effect of the presence of pad debris on scratch formation was also studied, and it was found that the occurrence of pad debris seriously increased the number of scratches. An increase in the number of diamonds per unit area of a conditioner could ultimately avoid the generation of pad debris, eventually reducing the scratch formation by sustaining the same removal rate and nonuniformity after the CMP process.

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Adhesion and Removal of Silica and Ceria Particles on the Wafer Surfaces in STI and Poly Si CMP

Cited by 10 publications

References 1 publication

Post Cleaning for FEOL CMP with Silica and Ceria Slurries

Post Cleaning for FEOL CMP with Silica and Ceria Slurries

Review—Post-Chemical Mechanical Planarization Cleaning Technology

Generation of Pad Debris during Oxide CMP Process and Its Role in Scratch Formation

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