Systems and methods for improving performance of a non-volatile memory by utilizing one or more tier select gate transistors between different portions of a NAND string are described. A first memory string tier may comprise a first set of memory cell transistors that may be programmed to store a first set of data and a second memory string tier may comprise a second set of memory cell transistors that are arranged above the first set of transistors and that may be programmed to store a second set of data. Between the first set of memory cell transistors and the second set of memory cell transistors may comprise a tier select gate transistor in series with the first set of memory cell transistors and the second set of memory cell transistors. The tier select gate transistor may comprise a programmable transistor or a non-programmable transistor.