Purpose - This paper aims to clarify adequate control characteristics for using a control chart on the basis of a case study of the low-pressure chemical vapor deposition (LPCVD) process, which is one of the semiconductor manufacturing processes. Design/methodology/approach - The paper opted for a simulation study using the data generated by EWMA model and the real data obtained from the LPCVD process. Findings - The paper provides adequate control characteristics for control charts. It suggests that it is desirable to employ both the quality characteristic and the process rate for monitoring when the process was modeled by the EWMA model. Furthermore, if only one control characteristic is employed, then the process rate is the most adequate characteristic. Originality/value - This paper newly proposes the process rate as a control characteristic for control charts.