Behaviour of a Well-Designed Megasonic Cleaning System

Lippert, Alexander R.; Engesser, P.; Ferrell, Garry; Klitzke, J.; Köffler, Martin; Kumnig, Franz; Leberzammer, Jörg; Obweger, Rainer; Pfeuffer, Alexander; Okorn‐Schmidt, Harald; Sax, Harry C.

doi:10.4028/www.scientific.net/ssp.103-104.155

Cited by 10 publications

(8 citation statements)

References 1 publication

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“…However, for smaller device structures, megasonics may cause significant device damage to obtain high particle-removal efficiency. 20 Also, megasonics is typically accompanied by a nonuniform areal power density that causes local regions of dense cavitation events 21 and prevents high particle-removal efficiencies without feature damage. 22 Nonuniform collapse of a megasonic-generated cavitation bubble initiates a high-velocity jet directed at the wafer surface, 23 a fundamental problem that probably cannot be resolved through improved hardware or process optimization.…”

mentioning

confidence: 99%

Silicon-Wafer Cleaning with Aqueous Surfactant-Stabilized Gas/Solids Suspensions

Андреев

Freer

Larios

et al. 2011

J. Electrochem. Soc.

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As feature sizes in the microelectronics industry diminish, cleanliness becomes an ever more important requirement. In response to these challenges, a novel wet-cleaning technology was developed at Lam Research Corporation to remove strongly adhered contaminants. An alkaline, foamed aqueous dispersion of insoluble platelet solids flows in linear shear past a particle-contaminated surface. Contaminant removal increases with solids concentration, foam quality, process time, and shear rate and can approach 100%. Particle-removal experiments indicate that dispersed solids are necessary for contaminant removal. Exponential decline of adhered particles with number of immersion/withdrawal events and a linear increase in the rate of particle removal with solids concentration indicate that the removal mechanism is binary collision between the insoluble fatty-acid platelets and Si 3 N 4 contaminant particles. Foam or surfactant solution alone is not effective in particle removal. A binary-collision rate model is derived to relate particle detachment to contact time. The binary-collision rate law agrees well with experimental removal data and provides a powerful design tool to assess the role of cleaning parameters, including process time, shear rate, dispensing flow rate, system geometry, solids concentration, and foam quality.Conventional metal-oxide-semiconductor manufacture of microelectronic devices can require over 100 process steps entailing deposition, removal, and alteration of material. For each step, processing, handling, and transport of the silicon wafers generates or transfers particulate contamination that can adversely affect device performance. The impact of particulate contamination can be drastic, significantly diminishing device yield; the trend toward smaller etch features exacerbates the problem as a single Ͻ100-nm contaminant particle can render a chip inoperative. In addition to efficient contaminant removal, cleaning processes must not damage features on the wafer and must not lose native material from the surface ͑film loss͒. Accordingly, an entire subindustry, primarily focused on wet cleaning, has emerged to remove particulate contamination. 1,2 Contaminant removal relies on the relative magnitudes of adhesion and detachment forces. Hence, successful detachment depends not only on particle-substrate chemistry but also on contaminant morphology and size. 3-7 All alternatives for cleaning wafers, including those few utilizing nonaqueous fluids, 1,8 require some means of supplying the energy necessary to remove a particle from a siliconwafer surface, 6 in addition to chemical action of the cleaning solution. 9 Standard methods of providing mechanical energy include undercutting, 10 brush scrubbing, 7,11,12 megasonics, 3,5,13,14 cryogenic aerosols, 15,16 and fluid jets. 17 Chemical undercutting of the particulate contamination by etching connecting bridges between the particle and substrate ͑in the case of chemical bonding͒ significantly improves particle-removal efficiencies ͑PREs͒ compared to simpl...

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mentioning

confidence: 99%

Silicon-Wafer Cleaning with Aqueous Surfactant-Stabilized Gas/Solids Suspensions

Андреев

Freer

Larios

et al. 2011

J. Electrochem. Soc.

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“…A quite accurate measure for separating hard from soft cavitation is the sonoluminescence signal. 16 Acoustic streaming.-Acoustic streaming, i.e. the generation of directed flow by a sound field, is a known phenomenon to disturb boundary layers.…”

Section: Acoustics Based Cleaning Of Particlesmentioning

confidence: 99%

Particle Cleaning Technologies to Meet Advanced Semiconductor Device Process Requirements

Okorn‐Schmidt

Holsteyns

Lippert

et al. 2013

ECS J. Solid State Sci. Technol.

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Dealing with nanometer-sized particulate contamination is still one of the major challenges during the manufacturing of yielding semiconductor devices. This is especially true for the increasing number of critical processing steps, where residues of particulate matter need to be removed without mechanically damaging sensitive device patterns and, at the same time, achieve the lowest possible substrate loss. If higher substrate loss would be permitted, a more or less pure chemical mechanism could be employed (e.g. particle undercut by substrate etching and lift-off). However, being only allowed to have statistically seen sub-Angstrom material loss, physical forces need to be integrated jointly with the appropriate chemical support. In this paper we describe particle cleaning techniques, which are based on monodisperse droplet impact, controlled bubble cavitation (acoustic and laser induced), moving contact lines as well as normal-directed extensional flow to meet present and future industry requirements.

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“…An example of an acoustically driven bubble, cleaning a substrate, is shown in Figure 11. A measure to separate the hard from the soft cavitation is the sonoluminescence signal (14).…”

Section: Soft Bubblesmentioning

confidence: 99%

(Invited) Particle Cleaning Technologies to Meet Advanced Semiconductor Device Process Requirements

et al. 2013

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Dealing with nanometer-sized particulate contamination is still one of the major challenges during the manufacturing of yielding semiconductor devices. This is especially true for the increasing number of critical processing steps, where residues of particulate matter need to be removed without mechanically damaging sensitive device patterns and, at the same time, achieve the lowest possible substrate loss. If higher substrate loss would be permitted, pure chemical mechanism could be employed (e.g. particle undercut and lift-off). However, being only permitted to have statistical sub-Angstrom material loss, physical forces need to be integrated jointly with the appropriate chemical support. This paper provides an overview of prospective techniques being currently investigated to meet present and future industry requirements.

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Behaviour of a Well-Designed Megasonic Cleaning System

Cited by 10 publications

References 1 publication

Silicon-Wafer Cleaning with Aqueous Surfactant-Stabilized Gas/Solids Suspensions

Silicon-Wafer Cleaning with Aqueous Surfactant-Stabilized Gas/Solids Suspensions

Particle Cleaning Technologies to Meet Advanced Semiconductor Device Process Requirements

(Invited) Particle Cleaning Technologies to Meet Advanced Semiconductor Device Process Requirements

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