Toward Low-Power Flash Memory: Prospect of Adopting Crystalline Oxide as Charge Trapping Layer

The rapid growth of data center, ubiquitous cloud computing, and mobile gadgets has made flash memory one of the major semiconductor markets. The booming request of flash memory has not only brought substantial economic and societal benefit but led to growing power consumption. The operation voltage of existent flash memory is in the range of 15–17 V which still has much room to be reduced to save power while ensuring environmental sustainability. To enable flash memory at lower voltage, developing innovative materials and structures is a prerequisite. Recently, crystalline oxide is extensively developed as a novel charge trapping layer (CTL) and holds the prospect of becoming a promising candidate for memory applications by demonstrating operation voltage lower than 10 V. In this paper, how crystalline oxide in the form of high-k dielectric and semiconductor material can be employed in flash memory as the CTL to reduce the operation voltage and the mechanism to achieve this goal are reviewed. From the good memory performance in terms of a large memory window of 1.5 V by programming/erasing at voltage lower than 10 V for 1 ms, endurance more than $10^{5}$ operation cycles, desirable retention at 85 °C, employing crystalline oxide as the CTL has ushered in a new field to implement green flash memory devices.