Fram’s future is higher density

Time:2020-9-6

Many of the recent memory problems appear in the form of 3D xpoints on ReRAM, MRAM and PCRAM. But ferroelectric RAM (FRAM) has been successful in small niche devices.



Last year’s annual report on emerging memory, touted the three key emerging memories of ReRAM, MRAM and PCRAM. But it also points out that fram has proven itself in specific markets such as mass transit cards, game systems and power meters, and its main attraction lies in the low power consumption of write operations. Fram products have been around for a long time, mainly as a dedicated cache for caching applications. There are even some flexible fram devices, “but for niche applications, they are relatively low density.



In fact, fram has been around for 35 years. Its nonvolatile and low power consumption are the reasons why it continues to receive attention because it is critical to many applications. Because of its low switching energy, fram is usually attractive and requires very low energy to switch this material. Therefore, if you are programming or increasing bit rate, you need to invest very little energy to reverse this polarization. Compared with other technologies, fram has the lowest switching energy.



But it also faces challenges, including high processing costs, large memory cells and larger chip sizes. Scalability is essential to go beyond small density niche applications.



Fram's future is higher density

 

The fram technology of FMC uses ha oxide as gate insulator, so we can use standard HKMG transistor and modify its gate insulator to make it ferroelectric, so as to produce nonvolatile HKMG transistor.



An effective extension of FRAM may be the use of oxide F, which is commonly used to help fabricate high-k gate dielectric layers in standard CMOS logic processes. That sparked a new interest in ferroelectric memories. So far, there are no new products that can use this material, but several research projects are under way. It shows promise for some high density and CMOS compatibility.



However, fram still faces challenges similar to MRAM and ReRAM, including transistor size limitations.



Oxide f can be used as gate insulator for almost all high potassium metal gate (HKMG) process nodes. Therefore, standard HKMG transistors can be used and their gate insulators can be modified to make them ferroelectrics, so as to produce non-volatile HKMG transistors fefets. In terms of performance, the company’s technology can read and write in the order of magnitude of 10 to 15 nanoseconds, while maintaining a retention time of up to 10 years at 85 degrees.



Since the fefet memory of FMC is derived from the standard HKMG logic transistor, the concept has the same inherent scalability as the CMOS reference line. This scalability is essential to keep manufacturing costs low, including keeping the chip area consumed by nonvolatile memory as small as possible. Fefet technology will break down two to three layers at 28 or 22 nm. The focus of FMC is now on technology development, which can be recognized by foundry.



Being able to integrate with existing CMOS processes and realize 3D is the key to scalability. It can also be directly integrated into transistor specifications. This reduces footprint and simplifies the process, which is an important driver of scalability.



At the same time, fram has many small density, market segmentation applications. Cypress Semiconductor ram business unit said it not only has non-volatile and low energy consumption characteristics, but also radiation resistance. Overall, it is a fairly stable memory – in its current commercially available form – for applications such as data logging and backup.



Fram's future is higher density

 

Cypress initially launched excelon fram for automotive and industrial applications, with a low pin count and small package option density of up to 8MB



The Cypress FRAM product includes its Excelon series, which is designed for high-speed non-volatile data recording required by autopilot cars, but is also being gradually applied to medical, wearable, Internet of things sensors, industrial and other advanced automotive applications. Chandrasekharan said excelon fram already offers 2 Mb, 4 MB and 8 MB density options, while 16 MB is under development. Because fram significantly reduces power consumption, retains data and is insensitive to radiation, it is considered to be a good alternative to EEPROM and NOR flash memory in these applications. Many use cases have been found in implantable medical devices, and these implants are expected to work for up to a decade.



But cypress is also looking forward to a higher density of oxide, because fram may go beyond the scope of data recording and become de facto nonvolatile storage.



FMC also thinks that its fram technology has become a feasible storage class memory, and because of its versatility, it has great potential in machine learning and artificial application. The goal is not to replace higher density memory such as DRAM, but to address the practical application of its technology.