Electron-beam direct write for lithography is a slow process. If lithography with a small linewidth is carried out by the electron-beam direct write and the remaining pattern uses optical lithography, the throughput of masking can be increased. Electron-beam and optical lithography mix-and-match can be realized in a number of ways. In this article, we report a resist hardening process that uses low power fluorocarbon plasma. It is a simple and low-temperature process. An analysis of the process variables will be discussed. The critical dimension of the optical masking does not change significantly in our process. This method can be used to improve the electron-beam lithography throughput as well.