We investigated corrosion at AlSiCu/TiN interconnection lines in VLSI devices. This type of corrosion appeared during the deionized water rinse treatment after the dry etching and ashing treatment (with O2+CF4 gas mixture). The corrosion shape was “pitlike”. When added the vacuum heating treatment before the deionized water rinse, the corrosion number was decreased. However, the ashing treatment had a contrary effect for this type of corrosion suppression. We investigated this type of corrosion mechanism by ion-chromatography analysis. In this analysis, residual Cl concentration decreased when the ashing time was prolonged, but the corrosion number was increased significantly. We measured residual F concentration at the same time, and detected a high concentration of F- ions. We consider that these F- ions contribute to this type of corrosion.
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Ishida et al. (1992) studied this question.
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