In a flash memory, error management units which store information on a physical occurrence position of an error which occurred during data reading are prepared by as much as the number of bits which can be corrected by an error correction code, in a redundant portion of a physical page. In one example, a controller is programmed with a sequence of steps and parameters required to carry out a bioreactor process. A carrier material including a dopant is formed at least on the sides of the stems in the undercut portions of the trenches.