Optical induce tungsten plug corrosion in CMP process

To reduce the reset current for developing reliable high-density phase change random access memory, small bottom electrode contact (BEC) size formation is a critical process. One of the failure modes for the process is the corrosion of the tungsten (W) plug, which is caused by the W chemical mechanical polisher (CMP) process. An ultrasmooth surface of BEC nanoscale W plug structure was successfully fabricated by the CMP process, which reduced the W/phase change material (Ge 2 Sb 2 Te 5 , GST) contact resistance, and gained more homogeneous resistance distribution. Thus, the stability of the device was improved greatly by the acidic buff CMP process compared with that of the device with alkali buff owing to the reduction of W/GST connect resistance fluctuation.

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“…Whereas in an alkali environment, it forms a non‐protective oxide film

{normalWO}_{4}^{2 -}

that creates a corrosive environment in water. A similar explanation was reported by Chiu et al [6].…”

Section: Resultssupporting

confidence: 89%

Switching operation improvement of phase change memory with nanoscale W plug structure by CMP process

Zhang

Liu

et al. 2013

Electron. lett.

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“…The known mechanism of tungsten void defect cannot explain why it has strong brush lifetime dependency. 11,12,14,15 This paper suggests that brush friction force contributed a lot to the formation of tungsten void defect, which can explain brush lifetime effect at CMP in-situ cleaner module.…”

Section: Resultsmentioning

confidence: 79%

“…1 For tungsten CMP, tungsten voids are one of the most important defects in the RMG/MOL integration scheme. 2,[7][8][9][10][11][12] The scanning electron microscope (SEM) images of tungsten voids are shown in Figure 1. The tungsten contact width is approximately ∼25nm.…”

mentioning

confidence: 99%

“…The source of tungsten void defect and its formation mechanism has been reported several times. 11,12,14,15 Chiu et al suggests optical energy induced voltage difference at P+/N-well as tungsten plug corrosion mechanism. 12 They also proposed q-time effect on electrochemical reaction of tungsten plug.…”

mentioning

confidence: 99%

“…11,12,14,15 Chiu et al suggests optical energy induced voltage difference at P+/N-well as tungsten plug corrosion mechanism. 12 They also proposed q-time effect on electrochemical reaction of tungsten plug. Hwang et al reported effect of contact pattern density and post CMP clean chemical on the tungsten plug corrosion.…”

mentioning

confidence: 99%

See 2 more Smart Citations

A New Approach to the Formation Mechanism of Tungsten Void Defect in Chemical Mechanical Polishing

Kim¹,

Egan²,

Shi³

et al. 2018

ECS J. Solid State Sci. Technol.

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The advanced node semiconductor device fabrication needs tungsten chemical mechanical polishing as a critical process to enable transistor formation as well as metal interconnection. Accordingly, CMP induced defect concerns have drawn attention to the process integration. Tungsten voids by CMP are one of the major defects to detract device yield. Their formation mechanism has been known as electrochemical corrosion or an optical induced corrosion phenomenon associated with polishing slurry chemistry. However, this paper proposes a new mechanism of tungsten void formation. Different from known corrosion mechanisms, it is observed that tungsten void frequency has strong correlation with CMP in-situ cleaner brush lifetime. At early brush life, tungsten void forms more frequently. Moreover, this paper reveals that CMP brush cleaning play a critical role in the formation of tungsten voids. Tungsten etch rate dependence on brush condition, tungsten void defect density correlation to brush life, and surface chemical analysis of tungsten blanket wafers show that tungsten voids are induced by combined effect of friction force and oxidation in brush cleaner module, which is a new approach to the formation mechanism of tungsten void defect.

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Brush cleaning effect on tugnsten voids defect in chemical mechanical polishing: CFM: Contamination free manufacturing

Kim

Egan

Solan

et al. 2018

2018 29th Annual SEMI Advanced Semiconductor Manufacturing Conference (ASMC)

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Optical induce tungsten plug corrosion in CMP process

Cited by 5 publications

References 6 publications

Switching operation improvement of phase change memory with nanoscale W plug structure by CMP process

Switching operation improvement of phase change memory with nanoscale W plug structure by CMP process

A New Approach to the Formation Mechanism of Tungsten Void Defect in Chemical Mechanical Polishing

Brush cleaning effect on tugnsten voids defect in chemical mechanical polishing: CFM: Contamination free manufacturing

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