Patent ID: 7659212

Claim:
A method for controlling an etching amount and an etching solution in spin etching, comprising: (a) a first step of taking out one wafer from a loading cassette; (b) a second step of measuring the weight W 1 of the wafer before etching; (c) a third step of calculating an etching time T 0 with the following equation (1): T 0 =V 0 ÷R (1), wherein T 0 is an etching time (min), V 0 is a target etching amount (g), R is an initial value R 0 (g/min) of an etching rate of a starting etching solution to be used, an etching rate R 1 (g/min) of the etching solution after etching or an etching rate R 2 (g/min) of the etching solution into which an additional etching solution has been added; (d) a fourth step of etching the wafer for the calculated time T 0 ; (e) a fifth step of measuring weight W 2 of the wafer after etching; (f) a sixth step of calculating an etching rate R 1 of the etching solution after etching with the following equation (2): R 1 =( W 1 −W 2 )÷ T 0 (2), wherein R 1 is an etching rate of an etching solution after etching, W 1 is weight (g) of a wafer before etching, W 2 is weight (g) of a wafer after etching and T 0 is an etching time; (g) a seventh step of accommodating the etched wafer; and (h) an eighth step of determining whether or not an etching rate R 1 of the etching solution after etching falls within an allowable range, wherein when it is decided in the eighth step that an etching rate R 1 falls within the allowable range, the process from the first step to the seventh step is performed on a wafer to be processed in the next order, or when it is decided in the eighth step that an etching rate R 1 falls outside the allowable range, there is performed a ninth step of adding an additional etching solution into the etching solution to restore the etching rate R 1 to the etching rate R 2 in the vicinity of the initial value R 0 , and thereafter the process from the first step to the seventh step is performed on a wafer to be processed in the next order.