Overview of Selector Devices for 3-D Stackable Cross Point RRAM Arrays

Abstract

Cross point RRAM arrays is the emerging area for future memory devices due to their high density, excellent scalability. Sneak path problem is the main disadvantage of cross point structures which needed to be overcome to produce real devices. Various self-rectifying cells like complementary resistive cell, hybrid RRAM cell, valence modulated conductive oxide RRAM and non-linear resistive memory with tunneling barrier, etc., are proposed to overcome the sneak path problem and to achieve the high density with good on/off ratio. However, it is challenging to fabricate the self-rectifying cells operating at low program/erase voltages with high non-linearity for both read and write operations and exhibiting good retention and endurance characteristics at the same time for a single device. 1S1R devices are more attractive than SRC due to large optimization possibilities to obtain better device performance as they have separate selector cell and memory cell which decouples the control parameters. Various kinds of selector devices like Si-based selector, metal-oxide based selector, threshold switch selector, mixed ionic-electronic conduction selector etc., are under intense research to obtain the best performance cross point memory devices. In this paper, we have briefly discussed about recent progress on various self-rectifying cells and selector devices for obtaining 3-D stackable cross point memory arrays.