Abstract: As the critical dimension (CD) of transistor scaling down to 14nm and below, contact etch has encountered big challenges due to the balance of CD shrink and contact open. Polymer richer etch process has to be used for much larger CD shrink gap from litho. to etch and higher selectivity requirement. However, this heavier polymer process will easily lead to metal void or block the metal formation in subsequent metal deposition step. In-situ post etch treatment (PET) is therefore widely used after contact etch process to help remove the polymer residues. PET can effectively enlarge the process window. This paper focuses on the N2/H2 PET process optimization with uniform design DOE for N2/H2 ratio, and aims to find the most efficient polymer removal N2/H2 PET. XPS and FTIR are adopted to characterize the C-based polymer on wafer surface. C atom% measured by XPS is then utilized as the polymer amount index. With this method, we can quantitatively analyze the polymer removal efficiency. It is found that N2/H2 ratio has huge effects on the polymer removal efficiency, N2/H2 =1.07 is the predicted as the most efficient polymer removal ratio. The DOE model is validated by inline DVC (dark voltage contrast) count data. Our DOE results can act as a guideline for the PET optimization.

Key words: Post etch treatment, contact etch, N2/H2, DOE.

Cite: Jian Chen, Sheng Wang, Yan Wang, Zhidong Wang, Wutao Tu, Haiyang, Zhang, "Post Etch Treatment Optimization for Contact Etch," International Journal of Materials Science and Engineering, Vol. 10, No. 1, pp. 1-9, March 2022. doi: 10.17706/ijmse.2022.10.1.10-17
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