Advanced PECVD SiCOH low-k films with low dielectric constant and/or high Young’s modulus

• A PECVD based low-k film with k as low as 1.82 was obtained.
• A PECVD based low-k film with E as high as 5.3GPa and k as low as 2.02 was obtained.
• Good resistance against HF wet etching was obtained.
• The HF wet etching was characterized and a simple etch model proposed.

In the quest for materials with a lower dielectric constant and/or a higher Young’s modulus, new results on advanced low-k films are reported. These films are fabricated using a sequence of three process steps: a PECVD co-deposition of matrix skeleton and porogen, a remote plasma to remove the porogen and a UV cure to strengthen the film. In this study, most emphasis was put on the optimization of the remote plasma and of the UV cure step. In this way it was possible to obtain a film with dielectric constant as low as 1.82 and another with a dielectric constant of 2.02 combined with a Young’s modulus higher than 5 GPa. Besides, this series of films showed also a very good resistance against 0.5% HF etching. FTIR analyses indicated that during this HF etching a C–F bond is formed. A model for the HF etching of this porous low-k material is proposed.

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