With the further development of the semiconductor-integrated process for advanced technology nodes, the requirements for process control are demanding. Spin-on-carbon (SOC) hard masks have been widely implemented in the advanced lithography process for good gap filling properties and planarization performance. For process integration, SOC needs to be further planarized by the plasma etching process to cover the shrinkage in process window. The uniformity is always a concern not only because of the SOC coating process itself but also because the plasma etching process is hard to be controlled precisely. In this paper, a method for precise uniformity control in the SOC dry etching process is proposed. The method relies on the HYDRA function within LAM FXE etch tool as the SOC etching process is sensitive to the temperature during reaction. In this paper, the advanced-process-control (APC) system combined with HYDRA function is applied in the SOC etching process, and the standard deviation of SOC height within wafer or wafer-to-wafer can be improved by 59% and 68%, respectively, which further improve the height control of the metal gate or spacer for the related process integration afterwards shown in Figure 1. Thus, the application of this study can effectively reduce process variations in mass production.