Galvanic Corrosion of Stacked Metal Gate Electrodes During Cleaning in HF Solutions

摘要

This work demonstrates that future metal gate electrodes can form a galvanic cell in dilute HF solutions and can result in an increased corrosion of the less noble material. In the worst case, it could lead to fully removal of small gate electrodes during wet processing. Depending on the gate stack and the integration scheme, the galvanic corrosion at the gate could be a major problem. In this case, dissolved oxygen and flow rate of the HF mixture during cleaning offer opportunities to minimize the galvanic corrosion impact.