Experimental Investigation of Program Voltage (20 V) Generation With Boost Converter for 3-D-Stacked NAND Flash SSD

This paper experimentally demonstrates program voltage (20 V) generation under emulated condition of a 3-D solid-state drive (3-D-SSD) which vertically integrates boost converter on an flame retardant type 4-interposer and Si-chips. The proposed program voltage generator is a boost converter using a coil on the interposer. A measured peak magnetic field power is approximately -49 dBm above the coil, which satisfies the international regulation. The magnetic field induces the eddy current in a conductor material. The eddy current degrades the boost converter performance due to the lowered effective inductance of the coil. The effects on the performance of the boost converter as a function of the distance from the coil to the conductor are experimentally investigated. A 3-D-SSD requires a >0.84-mm space between the coil and conductor to generate the program voltage. By inserting NAND flash memory chips between the coil and the conductor, a 3-D-SSD can be successfully realized without the output voltage degradation.