An electrochemical investigation of additive effect in trench-filling of ULSI interconnects by electroless copper deposition

Madoka Hasegawa, Noriyuki Yamachika, Yutaka Okinaka, Yosi Shacham-Diamand, Tetsuya Osaka

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The filling of trenches in ULSI interconnect structure by electroless copper deposition was investigated for the effect of bath additives. The additive effect was found to depend strongly on the reducing agent used in the bath. Void-free trench-filling was achieved by using polyethylene glycol (PEG) as an inhibiting additive in the bath containing glyoxylic acid as the reducing agent, while the combined addition of 8-hydroxy-7-iodo-5-quinoline sulfonic acid (HIQSA) and PEG was necessary for achieving void-free filling in the bath containing formaldehyde as the reducing agent. The effect of PEG on trench filling in the former bath was studied in detail based on electrochemical measurements. It is suggested that the rinse water remaining in trenches before electroless deposition causes a decrease in PEG concentration at the trench bottom during copper filling. The addition of PEG was found to shift the deposition potential in the negative direction. A new potential measuring apparatus was devised and used in model experiments, which revealed that the deposition potential depends on the local concentration of PEG at the trench bottom, where it is expected to be low. The observed preferential growth of copper deposit at the trench bottom is thus attributed to the effects of the variation of PEG concentration within the trenches on the deposition rate and potential.

Original languageEnglish
Pages (from-to)349-358
Number of pages10
JournalElectrochemistry
Volume75
Issue number4
Publication statusPublished - 2007 Apr

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Polyethylene glycols
Copper
Reducing Agents
Reducing agents
Copper deposits
Sulfonic Acids
Acids
Electroless plating
Deposition rates
Formaldehyde
Water
Experiments

Keywords

  • Additive
  • Copper
  • Electroless deposition
  • ULSI interconnects

ASJC Scopus subject areas

  • Electrochemistry

Cite this

An electrochemical investigation of additive effect in trench-filling of ULSI interconnects by electroless copper deposition. / Hasegawa, Madoka; Yamachika, Noriyuki; Okinaka, Yutaka; Shacham-Diamand, Yosi; Osaka, Tetsuya.

In: Electrochemistry, Vol. 75, No. 4, 04.2007, p. 349-358.

Research output: Contribution to journalArticle

Hasegawa, Madoka ; Yamachika, Noriyuki ; Okinaka, Yutaka ; Shacham-Diamand, Yosi ; Osaka, Tetsuya. / An electrochemical investigation of additive effect in trench-filling of ULSI interconnects by electroless copper deposition. In: Electrochemistry. 2007 ; Vol. 75, No. 4. pp. 349-358.
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