A Logic-Compatible Embedded Flash Memory for Zero-Standby Power System-on-Chips Featuring a Multi-Story High Voltage Switch and a Selective Refresh Scheme

• Published in: IEEE journal of solid-state circuits Vol. 48; no. 5; pp. 1302 - 1314
• Main Authors: Song, Seung-Hwan, Chun, Ki Chul, Kim, Chris H.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.05.2013; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Circuit properties; Computer architecture; Design. Technologies. Operation analysis. Testing; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Embedded flash memory; embedded nonvolatile memory; Exact sciences and technology; Integrated circuits; Integrated circuits by function (including memories and processors); Logic gates; Microprocessors; multi-story high voltage switch; Nonvolatile memory; selective WL refresh; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Switching, multiplexing, switched capacity circuits; Threshold voltage; Transistors; zero-standby power system-on-chip; Voltage threshold; High density; Random access memory; Embedded flash memory; Adaptive method; Implementation; Non volatile memory; Selector switch; PCM material; Built in self repair; VLSI circuit; Ageing; Transistor; System on a chip; selective WL refresh; embedded nonvolatile memory; Standby system; Embedded systems; High voltage; Electrical network; Overload; Flash memory; zero-standby power system-on-chip; Integrated circuit; multi-story high voltage switch
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2013.2247691

Embedded flash memory implemented using standard I/O devices can open doors to new applications and system capabilities, as it can serve as a secure on-chip non-volatile storage for VLSI chips built in standard logic processes. For example, it is indispensable for adaptive self-healing techniques targeted for mitigating process variation and circuit aging related issues where system information must be retained during power down periods. Embedded non-volatile memory can also enable zero-standby power systems by allowing them to completely power down without losing critical data. There has been numerous device and circuit level research on high-density non-volatile memories such as flash, STT-MRAM, PRAM, and RRAM. However, only few attempts have been made to develop a cost effective moderate-density non-volatile solution using standard I/O devices. In this paper, a logic-compatible embedded flash memory that uses no special devices other than standard core and I/O transistors is demonstrated in a generic logic process having a 5 nm tunnel oxide. An overstress-free high voltage switch and a selective WL refresh scheme are employed for improved cell threshold voltage window and higher endurance cycles.