Method and solution for preparing SEM samples for low-K materials

Abstract

A method and a solution for preparing SEM samples comprising low-K dielectric materials. The process begins by providing a SEM sample comprising low-K dielectric material and silicon oxide material. A solution is formed for preparing (staining and etching) the SEM sample by adding NH4F (s) to a solution comprising CH3COOH having a concentration of about 98% at a ratio of about 1 g NH4F (s):20 ml CH3COOH, then stirring until the NH4F (s) is thoroughly dissolved. Alternatively, the NH4F (s) can be added to a solution comprising HNO3 having a concentration of about 70% and CH3COOH having a concentration of about 98%, with a volume ratio of about 15 ml HNO3:20 ml CH3COOH. The NH4F (s) is added at a ratio of about 1 g NH4F (s):35 ml CH3COOH and HNO3, and stirred until the NH4F (s) is thoroughly dissolved. The SEM sample is then etched in this solution for about 3 seconds, whereby the low-K dielectric material and silicon oxide material have similar etch rates with good selectivity to metals.

Dependencies are inferred from the claim text.