Abstract: A method for automatically adjusting a concentration of a solution having a first component and a second component, used in a semiconductor manufacturing process, includes the steps of (a) providing target concentrations of the first component and the second component, (b) adjusting the concentration of the solution based on the first component by adding a first spiking amount of the first component during a first spiking time interval, and (c) adjusting the first spiking amount of the first component until a first deviation between an actual concentration of the first component and the target concentration of the first component is smaller than a first specific percentage.

Abstract: A method of LPCVD silicon nitride deposition for decreasing particles is disclosed. First, a silicon nitride layer is formed on a semiconductor substrate by LPCVD. Next, low gas flow rate purging step and cycle purging step are executed sequentially. Finally, the semiconductor substrate is taken out from the LPCVD tube. The key point of this invention is decreasing the gas flow rate of purging and cycle purging by inputting nitrogen gas slowly. Thereby the substrate surface contamination problem induced by conventional method can be avoided.