Effect of moisture on electrical properties and reliability of low dielectric constant materials

• Porous low-k dielectrics absorb more moisture than dense low-k dielectrics.
• The chemically-adsorbed moisture degrades the electrical and reliability performance of the low-k dielectrics.
• A higher temperature anneals at 400 °C can decompose physically-adsorbed water and restore reliability performance.
• The absorbed water in the low-k dielectrics affects electromigration performance of the Cu interconnects.

The effect of absorbed moisture on the electrical characteristics and reliability of low dielectric constant materials (low-k) was investigated in this study. The experimental results reveal that porous low-k dielectrics absorb more moisture than dense low-k dielectrics. This absorbed moisture degrades the electrical performance and reliability of both classes of low-k dielectrics. Annealing at a higher temperature of 400 °C is required to decompose the physically-adsorbed moisture and thereby restore reliability performance. However, the chemically-adsorbed moisture seems to be difficult to remove by annealing at 400 °C, causing a degraded TDDB performance.

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