Light enhanced tungsten via corrosion

Westergard, L.; Belisle, C.; Florence, D.; Haskett, Thomas

doi:10.1109/irws.2002.1194257

Cited by 3 publications

(2 citation statements)

References 5 publications

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“…The post via etch clean uses a solvent-based HDA chemistry in a batch process Semitool Spray Solvent Tool (SST). Two previous instances of corrosion of tungsten plugs had been seen in the same production fab; the first was attributed to light enhanced corrosion, and the second was due to a residual HDA reaction with the tungsten to form a tungsten stringer and an electrical bridge to short metal lines (8,9). Based on the previous failure occurrence caused by a reaction from residual HDA, known to be worse with sit time following the clean step, a correlation to sit-time following clean for the more recent failures was done.…”

Section: Sit-time Correlationmentioning

confidence: 94%

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Via Failures in a Plug Process Due to Incomplete Via Clean Chemistry Removal

Florence¹,

Burtosky²,

Cioffi³

et al. 2007

ECS Trans.

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Reliable via formation requires complete polymer removal in vias prior to barrier deposition to obtain low electrical resistance contacts between metal conductor layers. A failure mechanism of high resistance and open vias was observed due to aluminum polymer in the via either partially or fully blocking barrier deposition onto the metal layer at the via bottom. This failure mechanism involved a breach of the titanium-nitride (TiN) anti-reflective coating (ARC) layer over the aluminum in the underlying conductor metal layer, allowing via clean chemistry to react with the aluminum. An aluminum polymer is formed, partially or fully blocking barrier deposition. Experimental data show that open via occurrences worsened with increased sit-time between via clean and the via barrier deposition step. In this paper we will discuss the mechanism causing high resistance or open via failures due to incomplete hydroxylamine (HDA) chemistry removal.

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Section: Sit-time Correlationmentioning

confidence: 94%

“…Rate of corrosion is dependant on the amount of charging and solvent pH. Metal charging is normally induced during an etch or ash process, or by a light source (6,8). Examination of via etch and ash process steps was begun to look for a charging source to trigger the aluminum corrosion during clean.…”

Section: Aluminum Corrosion Mechanismsmentioning

confidence: 99%

Via Failures in a Plug Process Due to Incomplete Via Clean Chemistry Removal

Florence¹,

Burtosky²,

Cioffi³

et al. 2007

ECS Trans.

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New Failure Analysis of Tungsten Plug Corrosion in Via Process

Kim

Ho²,

Kim

et al. 2006

13th International Symposium on the Physical and Failure Analysis of Integrated Circuits

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bit failure as shown in Fig. 1(b) which shows failure bit map In this paper, systematic pair bit failure is analyzed in failure of center die. bit map of deep-submicron CMOS technology. Tungsten plug corrosion in contacts of stacked contact/metal/via structure is observed from careful analysis of failure bit. Then, some experiments have been carried out to identify and g X resolve this corrosion failure. This corrosion reaction occurred through the void space, which is formed by excess via over-etch along the sidewall of underlying metal in contact-metal-via stack structure and by the plasma charging and electrochemical reaction during via etch and post cleaning. This failure can be practically avoided by optimizing via over-etch time and underlying metal profile | and it is confirmed by product yield and failure bit map data.

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