Monitoring of HF/H₂O treated silicon surfaces using non-contact surface charge measurements

In this work, a new commercial system allowing non-contact measurement of the surface charge is used to monitor the condition of the silicon surface following HF/water etch. Results obtained demonstrate that by monitoring changes of surface charge using this system, a truly non-invasive, instant and easy to carry out characterization of Si surfaces after HF/water etch can be accomplished. The results show that HF/water exposure adds positive charge to the silicon surface. Change in the surface charge, considered to be indicative of the change in the electro-chemical condition of the surface, appears to precede initiation of the oxide etching process, and is proposed to be a factor in initiating etching reactions that involve mainly negatively charged species.