SK hynix H25FTD0 238L 512 Gb TLC 3D NAND Internal Waveform Analysis

The SK hynix 238L 512 Gb TLC 3D NAND flash memory device (die markings: H25FTD0) was found on the SK hynix HFS512GEM9X152N FA PC811 SSD. Two SK hynix H25T1TD48C-X630 NAND flash memory packages, an SSD controller, and a DRAM are identified on the SK hynix SSD board. There are four H25FTD0 NAND dies packaged inside each of the SK hynix H25T1TD48C-X630 packages. The SK hynix 238L 512 Gb TLC NAND die is built with peripheral circuit under cell (PUC) structure and contains five levels of metallization with three levels below and two levels above the memory array. This analysis provides an overview of the internal voltages required to program, read, and erase the flash memory cells. The waveform analysis tests the flash in an active probe arrangement and voltage traces of the signals are recorded during program, read and erase operations while the device is active on the source SK hynix SSD. The SSD operated in SLC and TLC modes while performing the signal measurements. The measured signals are the common sourceline and one global wordline randomly selected from a group of circuit test pads/points identified on the top layer of the flash die near the wordline switch circuitry. FIB probe pads are placed on the signals on one memory plane of one flash die in the memory package to measure the signals.