Abstract
This invention relates to a plasma manufacturing method with plasma density feedback control and its system. In this invention, by using heterodyne millimeter wave interferometer as the sensor, the plasma density inside the process chamber measured by the sensor and the expected plasma density required for the plasma process are provided in real time for the digital controller to perform the numerical operation in order to drive a radio frequency (RF) power generator and change RF output power such that the plasma density in the plasma process is made to close to the expected plasma density. In the conventional technique, the operation parameter method is adopted such as the controls of pressure, RF power, gas flow rate, temperature, and so on, in which the most direct plasma parameter that affects the process is not under control. Therefore, it can not assure that different batches of wafers are operated under similar state of plasma process in the fabrication process of wafers. The present invention provides a plasma source of process that can be directly controlled and is stable, so as to obtain a plasma process with stable quality.