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NeoFlash

Introduction

eMemory’s NeoFlash is a true logic-based single poly embedded flash memory solution. With only 2–3 additional non-critical masks, NeoFlash can be implemented seamlessly on CMOS logic processes, especially in advanced nodes. Owing to its simple process, robust design, and low cost, NeoFlash promises an excellent embedded flash solution for system-on-a-chip applications.

Technical Principles

NeoFlash consists of two p-channel transistors in series: a thick-gate transistor for data selection and a SONOS transistor for data storage.

NeoFlash provides outstanding program and erase performance with superior reliability and data retention. NeoFlash utilizes hot electron injection for fast programming and a channel Fowler-Nordheim (F-N) tunneling mechanism for uniform erasing, which enables it to meet speed and reliability requirements of emerging high-speed embedded NVM applications. The programming mechanism of a NeoFlash cell is typically channel hot-hole induced hot-electron injection. Electrons accumulate in the silicon nitride storage layer and pinch off the channel below, from drain side to source side. This channel-length self-modulation minimizes the programming stress on the gate oxide and enables retention rates superior to those of N-type SONOS flash devices. NeoFlash cell uses channel F-N tunneling for erasure, as this is a well-known solution for a variety of flashes.

Advantages

NeoFlash’s sophisticated design means it does not fall prey to the operation window drift and closure problems commonly associated with flash technologies of this type. In addition, the maximum operating voltage is only 6V; thus, it does not need the high-voltage processing necessary for other embedded flash solutions.

NeoFlash can be embedded in CMOS logic processes with only 2–3 additional non-critical masks. While floating gate flash technology requires a complex and expensive double poly process (needing up to 11 additional mask layers), NeoFlash’s single poly architecture and stripped-down manufacturing give it powerful advantages in the embedded flash category, especially in advanced nodes.

Specifications

NeoFlash can be used for code storage and data storage with general purpose MCUs and touch panel controller applications. Existing silicon IPs with density up to 2M bits are available on 0.11um to 0.18um CMOS process platforms, as listed below.

NeoFlash General
Density 32k8~64k32(2M)
Process Nodes 0.11um~0.18 um
Retention 10 years @ 85° C
Program Power External Vpp pad or internal charge pump
Key Features Compact IP size
Down to 30ns (or up to 33MHz)

Applications

NeoFlash is the best solution for code storage and parameter setting. In MCU-like chips, NeoFlash provides the best cost structure with large flash density for code storage. Many sensor controllers need to record sensor characteristics provided by different vendors in order to give the best system performance. NeoFlash also provides a wide density range (16Kbits~2Mbits) for these kinds of applications.

Availability

eMemory has developed NeoFlash with a density larger than 256K bits at two foundries and two IDMs. The technology has entered mass production for 0.16um/0.18um 1.8/5V and 0.11um 1.2/3.3V processes.