Patent ID: 8266080

Claim:
A method of predicting a deposition thickness of amorphous silicon being deposited on a substrate, the method comprising: during a process of depositing the amorphous silicon to the substrate, predicting the deposition thickness by using a prediction model expressing a relationship between the deposition thickness and a plurality of process factors that are correlated with the deposition thickness of the amorphous silicon; and after measuring the deposition thickness, and comparing the predicted deposition thickness with the measured deposition thickness, adapting the prediction model to compensate the relationship between the deposition thickness and the plurality of process factors according to the comparison difference, wherein the adapted prediction model is used to predict a deposition thickness during a subsequent process of depositing amorphous silicon, wherein adapting the prediction model uses exponentially weighted moving averages (EWMA) in order to include a moving average of deviations that have occurred in the prediction model, wherein the plurality of process factors include a radio frequency power (RF power) of a deposition apparatus in a process of depositing the amorphous silicon and manufacturing the substrate, a TUNE that is an impedance control factor of a power source that supplies power to the deposition apparatus during the deposition process, and a process time (PT) of the deposition process, and wherein the prediction model is modified by using the exponentially weighted moving averages (EWMA), such that y k =THK k +c k|k−1 +e k where, THK k =PT k [β 0 +β 1 (Vpp)+β 2 (TUNE)] denotes the estimated deposition thickness of a kth substrate; β 0 , β 1 , and β 2 denote values that reflect a variation in the process factors over time, c k|k−1 denotes a deviation of the estimated deposition thickness of the k-th substrate based on deviations of the estimated deposition thickness, and a measured deposited thickness of a (k−1)-th substrate and the measured deposited thickness; e k denotes a theoretical error term of the equation; and y k denotes the modified estimated deposition thickness of the k-th substrate.