Striking a balance: Role of supramolecular assemblies on the modulation of the chemical and mechanical contributions during Post-STI CMP cleaning

Graverson, Carolyn F.; Wortman-Otto, Katherine M.; Linhart, Abigail N.; Sampurno, Yasa; Philipossian, Ara; Keleher, Jason J.

doi:10.1016/j.matchemphys.2020.124170

Cited by 8 publications

(7 citation statements)

References 25 publications

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“…In all of our experiments, we used the Araca, Inc. PCC-300 ® single-sided PVA brush scrubber and tribometer. 1,2 The main body of the cleaning module is a fully-automated robotic assembly consisting of a wafer carrier component (mainly based on a modified Struers LaboPol-30 system 3 ) and a brush cleaner component. The wafer carrier holds and acts as a rotating platform for a 300-mm blanket or patterned wafer.…”

Section: Experimental Apparatus and Conditionsmentioning

confidence: 99%

Communication—An Analysis of Shear Forces in Post-CMP PVA Brush Scrubbing for Stationary and Rotating Wafers

Sampurno

Linhart

Wortman-Otto

et al. 2021

ECS J. Solid State Sci. Technol.

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After defining certain sign conventions for sliding velocity and shear force for a PVA brush scrubbing process, a simple kinematics model is used to calculate net sliding velocities in the brush-wafer contact region. Next, a series of experiments are performed where brush velocity is gradually increased while the wafer is kept stationery, and repeated again with the wafer rotating at a certain velocity. For a stationary wafer, with increasing brush velocity, partial lubrication takes effect which results in less brush asperity contact (i.e. a reduction in SF). For a rotating wafer, SF decreases significantly. We attribute this to the net negative sliding velocity across the wafer that partially offsets the positive SF values. However, SF rises with brush velocity which is likely due to fluid distribution effects and increased brush asperity-wafer contact.

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Section: Experimental Apparatus and Conditionsmentioning

confidence: 99%

Communication—An Analysis of Shear Forces in Post-CMP PVA Brush Scrubbing for Stationary and Rotating Wafers

Sampurno

Linhart

Wortman-Otto

et al. 2021

ECS J. Solid State Sci. Technol.

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“…Previous work has shown that the shape and charge of the supramolecular structure play a crucial role in effective CeO 2 nanoparticle removal. 19 − 21 More specifically, upon delivery to the wafer surface, micelles recover at a slower rate than polyelectrolytes. Though these additives do reduce the overall shear force and help to minimize defectivity induced during the cleaning process, it is not perfect and can cause p-CMP defects from the contact modality.…”

Section: Introductionmentioning

confidence: 99%

“…While this has shown to be an effective mode of particle removal, there is an increase in the process shear force (mechanical component), which results in secondary defect formation (i.e., increased scratching/surface roughness). , More recently attention has shifted to developing p-CMP cleaning formulations that employ encapsulation of the CeO 2 nanoparticle using supramolecular chemistries (i.e., surfactants, polyelectrolytes, liposomes, etc.). Previous work has shown that the shape and charge of the supramolecular structure play a crucial role in effective CeO 2 nanoparticle removal. − More specifically, upon delivery to the wafer surface, micelles recover at a slower rate than polyelectrolytes. Though these additives do reduce the overall shear force and help to minimize defectivity induced during the cleaning process, it is not perfect and can cause p-CMP defects from the contact modality.…”

Section: Introductionmentioning

confidence: 99%

Coupling Supramolecular Assemblies and Reactive Oxygen Species (ROS) with Megasonic Action for Applications in Shallow Trench Isolation (STI) Post-Chemical Mechanical Planarization (p-CMP) Cleaning

Wortman-Otto

Watson²,

Dussault³

et al. 2022

ACS Omega

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Due to the continued miniaturization of semiconductor devices, slurry formulations utilized in the chemical mechanical planarization (CMP) process have become increasingly complex to meet stringent manufacturing specifications. Traditionally, in shallow trench isolation (STI), CMP, a contact cleaning method involving a poly(vinyl alcohol) (PVA) brush, is used to effectively transfer cleaning chemistry to the oxide substrate. This PVA brush can cause nonuniform cleaning chemistry transport, increased interfacial shear force, and cleaning-induced defectivity from brush loading. Previous work with traditional cleaning processes has shown that using “soft” supramolecular cleaning chemistries has dramatically improved cleaning efficacy while also minimizing the number of induced p-CMP defects. To minimize these effects, noncontact cleaning via the implementation of megasonic action has gained attention. This work employs “soft” cleaning chemistries with Cu 2+ –amino acid complexes, which can catalyze the formation of critical reactive oxygen species (ROS), and evaluates the p-CMP performance under megasonic action. Results from a second-order kinetic model indicate that megasonic conditions (i.e., time and power), “soft” cleaning chemistry structure (i.e., shape and charge), and the generation of ROS all play a critical role in cleaning efficacy under low shear stress conditions.

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“…25 The "soft" cleaning chemistries strike a delicate balance between the need for charge-flipping and the control of aggregates formed at the brush-wafer interface, clearly reducing wafer-level defects, and controlling the surface passivation mechanisms. 26 The specific driving force behind our study.-What precipitated this fundamental study was our access to a series of marathon runs performed at IBM's 14-nm node manufacturing line where a total of 2,600 specially-prepared 300-mm particle monitor wafers having 2,000 Angstroms of PETEOS-based silicon dioxide film deposited on them were polished and cleaned in HVM copper CMP and postcleaning processes, and their surfaces analyzed to determine the net number of added wafer-level defects (NADD).…”

mentioning

confidence: 99%

“…1, and described in detail elsewhere. 27,28 The main body of the cleaning module is a fully automated robotic assembly consisting of a wafer carrier component (mainly based on a modified Struers Labopol-30 system) 29 and a brush cleaner component. The wafer carrier holds and acts as a rotating platform for a 300-mm blanket or patterned wafer.…”

mentioning

confidence: 99%

Understanding the Reasons Behind Defect Levels in Post-Copper-CMP Cleaning Processes with Different Chemistries and PVA Brushes

Sampurno

Philipossian

Linhart

et al. 2021

ECS J. Solid State Sci. Technol.

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Results from a series of post-CMP PVA scrubbing marathon runs performed in a high-volume manufacturing fab are scientifically explained via a series of controlled laboratory tests. The major differences in the ingredients within the cleaning solutions, and some of the key physical properties of the brushes are identified and their effects on various critical factors are studied. These include the magnitude of shear forces present in the brush-solution-wafer interface, the water uptake and porosity of the brushes, the diffusivity of a given cleaning solution through the micro-pores and macro-pores of each type of brush, the open-circuit potential in a dynamic process, and the availability of the cleaning fluid between the brush nodules and the wafer surface. Results show a strong inverse correlation between wafer-level defects and shear force. The latter is shown to decrease with solution availability at the brush-wafer interface which in turn is shown to depend on brush porosity and the diffusion rate of the solution through the pores. Our understanding is further strengthened by dynamic electrochemical analysis data where we see a greater interfacial chemical activity (i.e., an increase in corrosion current) as solution availability is increased.

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Striking a balance: Role of supramolecular assemblies on the modulation of the chemical and mechanical contributions during Post-STI CMP cleaning

Cited by 8 publications

References 25 publications

Communication—An Analysis of Shear Forces in Post-CMP PVA Brush Scrubbing for Stationary and Rotating Wafers

Communication—An Analysis of Shear Forces in Post-CMP PVA Brush Scrubbing for Stationary and Rotating Wafers

Coupling Supramolecular Assemblies and Reactive Oxygen Species (ROS) with Megasonic Action for Applications in Shallow Trench Isolation (STI) Post-Chemical Mechanical Planarization (p-CMP) Cleaning

Understanding the Reasons Behind Defect Levels in Post-Copper-CMP Cleaning Processes with Different Chemistries and PVA Brushes

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