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... etch rate of the buffered oxide etchant can be determined through the following calculation: where rmin is the minimum possible etch rate of the buffered oxide etchant and rnominal is the minimum possible etch rate of the buffered oxide etchant. Therefore, rnominal = 750 A min-1. Using the conversion factors 1 A = 10-10 m and 1 um = 10-6 m, rnominal can be converted to um min-1 in the following manner: with significant figures applied As was demonstrated above, this percentage value can alternatively be expressed as a decimal. Therefore, 85% can be expressed as 0.85. Using this decimal format, the above formula can be rewritten in the following manner: Substituting our previously determined value for rnominal into the above formula yields: with significant figures applied I have completed this question with the assumption that the etching process is perfect, with no overetching or underetching. This implies that the time required to complete the etching ...