January 15, 2018 at 17:28Future technologies: can memory become not electric, but magnetic?
Modern memory, including Kingston products, copes with its tasks perfectly, but the world is changing and it is possible that after some time we will recall the familiar DRAM as an outdated technology. One candidate for replacement is MRAM.
Each type of memory device has its drawbacks. For example, NAND has a low write speed, SRAM does not allow cells to be located close (and therefore achieve a high density), and, together with DRAM, it is volatile - that is, it is reset to zero when the supply voltage disappears. That is why scientists are constantly searching for more advanced technologies to solve a variety of problems.
Recently, much attention has been paid to the three-dimensional vNAND, which allows you to radically increase the capacity of drives, as well as the new development of Intel and Micron, called 3D XPoint. The latter generally promises to be better than existing memory in almost everything, but manufacturers are still hiding the true technology of this non-volatile memory. Intel's PR machine has created a lot of hype around new technology that has eclipsed equally promising developments, such as MRAM or Magnetoresistive RAM.
The problem of creating fast and non-volatile memory has been facing the computer industry since the advent of the first computer, and at the moment it has not been solved. Judge for yourself - we use DRAM in our computers for high-speed tasks, and SSD drives (usually on NAND chips) to achieve high storage capacity. Theoretically, magnetoresistive effects can correct this injustice and create an intermediate solution. If the presence of an information bit in the memory cell will be recorded not by an electric, but by a magnetic field, then when the voltage is turned off, this same bit will not go anywhere and will remain on the chip for a very long time (until you approach a block with a huge magnet). The study of this possibility began in the first half of the twentieth century and for more than 50 years remained in the category of theoretical research until the first prototypes of MRAM were created. In our country, work was also done to create magnetoresistive memory for use in the military and aerospace fields. But only in 2006 the first commercial magnetic chip appeared on the market. It was manufactured by Freescale Semiconductor, which separated from Motorola in 2004. And the first magnetoresistive "unicorn" was the MR2A16A module, which can accommodate 4 Mbps of data. It was manufactured by Freescale Semiconductor, which separated from Motorola in 2004. And the first magnetoresistive "unicorn" was the MR2A16A module, which can accommodate 4 Mbps of data. It was manufactured by Freescale Semiconductor, which separated from Motorola in 2004. And the first magnetoresistive "unicorn" was the MR2A16A module, which can accommodate 4 Mbps of data.
From a technical point of view, MRAM is very different from other promising types of memory - the same 3D XPoint or ferroelectric memory (FRAM), since MRAM is based on magnetic memory elements operating on the principle of magnetic tunnel junction (MTJ - magnetic tunnel junction).
To understand the essence of this effect, we dive a little into the theory of semiconductors. Each MTJ cell consists of a control transistor, as well as two ferromagnetic layers separated by a thin dielectric layer (tunnel layer). The first layer is a permanent magnet having a specific and clearly fixed magnetic field vector. But the second ferromagnetic layer is already a variable magnet, which changes its polarization (direction of magnetization), for example, depending on the applied magnetic field.
It is possible to determine the bit value in a ferromagnetic cell by checking whether the magnetization vectors of the two layers coincide or whether they are opposite to each other. Due to the effect of tunnel magnetoresistance, with the same polarization of the ferromagnetic layers, the electrical resistance of the cell decreases, and this state of affairs is considered a logical zero. In the opposite case, the cell resistance is determined by the conductive properties of the dielectric in its pure form - and the cell retains the value of a logical unit. In this case, the control transistor acts as a “tester”, which passes current through the cell to determine what bit value is written in it.
A known issue with MRAM is writing a value to a ferromagnetic cell. Initially, for this it was necessary to apply a forming magnetic field. However, this is very costly in terms of energy consumption (which put an end to MRAM for mobile devices), and also limits the development of technology, because when switching to a smaller manufacturing process it will be more difficult to create a point magnetic field that will not spoil the data in neighboring cells.
In response to these challenges, improved STT-MRAM (spin-torque-transfer MRAM) technology has been developed. In the principle of information storage, nothing has changed, but the recording method has become completely different. In STT-MRAM, the spin transfer of electrons entering the free layer occurs. Under normal conditions, the electrons rotate in different directions, but if you specifically send pre-oriented charge carriers to the free ferromagnetic layer, the polarization will change in accordance with the direction that the incoming electron momentum has. Simply put, rewriting information in a cell occurs by sending specially prepared electrons with the same spin.
Initially, the electron spin for recording in the STT-MRAM memory was formed in the same plane as the ferromagnetic layers themselves. However, the transfer of spin to the perpendicular plane made it possible to reduce the switching current of the cell, as well as its size, increasing the density of the cells on the crystal. And now STT-MRAM really begins to resemble the memory of the future, which will be able to combine the best of the two worlds.
Before we can talk about replacing SRAM or DRAM, STT-MRAM technology needs to grow up pretty much, overcome the “childhood illnesses” that are sure to appear, and prove its reliability. But given that commercial samples of the new magnetic memory already exist, there may be specific niches for it.
For example, SSDs and RAID systems often use DRAM chips that store cached operations. But when you turn off the power, all data with DRAM is erased. This can be a problem if important information has not yet been saved to disk and therefore capacitors are installed in the SSD, and additional batteries are installed in the RAID systems. They should help record all information until the power is completely turned off. These elements degrade over time, capacitors and batteries increase the cost of finished products and make them more complex. Meanwhile, STT-MRAM, as a non-volatile memory, can solve this issue, and now manufacturers of such chips are actively promoting a similar method of their use.
At Kingston, we carefully monitor the development of the entire spectrum of new memory technologies, but for commercial products we use only mature solutions that have proven themselves and have shown high levels of reliability. Given the current situation, it is possible that in a few years STT-MRAM or an even more advanced modification of this memory will turn out to be faster and more reliable than the solutions existing today, but so far these technologies are at the stage of the first experiments and are not ready to work as those universal drives, you can choose the best of existing solutions, which, of course, include our RAM modules .
Subscribe and stay with us - it will be interesting!
For more information on Kingston andHyperX refer to the official website of the company .
Each type of memory device has its drawbacks. For example, NAND has a low write speed, SRAM does not allow cells to be located close (and therefore achieve a high density), and, together with DRAM, it is volatile - that is, it is reset to zero when the supply voltage disappears. That is why scientists are constantly searching for more advanced technologies to solve a variety of problems.
Recently, much attention has been paid to the three-dimensional vNAND, which allows you to radically increase the capacity of drives, as well as the new development of Intel and Micron, called 3D XPoint. The latter generally promises to be better than existing memory in almost everything, but manufacturers are still hiding the true technology of this non-volatile memory. Intel's PR machine has created a lot of hype around new technology that has eclipsed equally promising developments, such as MRAM or Magnetoresistive RAM.
Magnetic moment or electric charge?
The problem of creating fast and non-volatile memory has been facing the computer industry since the advent of the first computer, and at the moment it has not been solved. Judge for yourself - we use DRAM in our computers for high-speed tasks, and SSD drives (usually on NAND chips) to achieve high storage capacity. Theoretically, magnetoresistive effects can correct this injustice and create an intermediate solution. If the presence of an information bit in the memory cell will be recorded not by an electric, but by a magnetic field, then when the voltage is turned off, this same bit will not go anywhere and will remain on the chip for a very long time (until you approach a block with a huge magnet). The study of this possibility began in the first half of the twentieth century and for more than 50 years remained in the category of theoretical research until the first prototypes of MRAM were created. In our country, work was also done to create magnetoresistive memory for use in the military and aerospace fields. But only in 2006 the first commercial magnetic chip appeared on the market. It was manufactured by Freescale Semiconductor, which separated from Motorola in 2004. And the first magnetoresistive "unicorn" was the MR2A16A module, which can accommodate 4 Mbps of data. It was manufactured by Freescale Semiconductor, which separated from Motorola in 2004. And the first magnetoresistive "unicorn" was the MR2A16A module, which can accommodate 4 Mbps of data. It was manufactured by Freescale Semiconductor, which separated from Motorola in 2004. And the first magnetoresistive "unicorn" was the MR2A16A module, which can accommodate 4 Mbps of data.
MRAM technology
From a technical point of view, MRAM is very different from other promising types of memory - the same 3D XPoint or ferroelectric memory (FRAM), since MRAM is based on magnetic memory elements operating on the principle of magnetic tunnel junction (MTJ - magnetic tunnel junction).
To understand the essence of this effect, we dive a little into the theory of semiconductors. Each MTJ cell consists of a control transistor, as well as two ferromagnetic layers separated by a thin dielectric layer (tunnel layer). The first layer is a permanent magnet having a specific and clearly fixed magnetic field vector. But the second ferromagnetic layer is already a variable magnet, which changes its polarization (direction of magnetization), for example, depending on the applied magnetic field.
It is possible to determine the bit value in a ferromagnetic cell by checking whether the magnetization vectors of the two layers coincide or whether they are opposite to each other. Due to the effect of tunnel magnetoresistance, with the same polarization of the ferromagnetic layers, the electrical resistance of the cell decreases, and this state of affairs is considered a logical zero. In the opposite case, the cell resistance is determined by the conductive properties of the dielectric in its pure form - and the cell retains the value of a logical unit. In this case, the control transistor acts as a “tester”, which passes current through the cell to determine what bit value is written in it.
The evolution and emergence of STT-MRAM
A known issue with MRAM is writing a value to a ferromagnetic cell. Initially, for this it was necessary to apply a forming magnetic field. However, this is very costly in terms of energy consumption (which put an end to MRAM for mobile devices), and also limits the development of technology, because when switching to a smaller manufacturing process it will be more difficult to create a point magnetic field that will not spoil the data in neighboring cells.
In response to these challenges, improved STT-MRAM (spin-torque-transfer MRAM) technology has been developed. In the principle of information storage, nothing has changed, but the recording method has become completely different. In STT-MRAM, the spin transfer of electrons entering the free layer occurs. Under normal conditions, the electrons rotate in different directions, but if you specifically send pre-oriented charge carriers to the free ferromagnetic layer, the polarization will change in accordance with the direction that the incoming electron momentum has. Simply put, rewriting information in a cell occurs by sending specially prepared electrons with the same spin.
Initially, the electron spin for recording in the STT-MRAM memory was formed in the same plane as the ferromagnetic layers themselves. However, the transfer of spin to the perpendicular plane made it possible to reduce the switching current of the cell, as well as its size, increasing the density of the cells on the crystal. And now STT-MRAM really begins to resemble the memory of the future, which will be able to combine the best of the two worlds.
Finding Your Niche
Before we can talk about replacing SRAM or DRAM, STT-MRAM technology needs to grow up pretty much, overcome the “childhood illnesses” that are sure to appear, and prove its reliability. But given that commercial samples of the new magnetic memory already exist, there may be specific niches for it.
For example, SSDs and RAID systems often use DRAM chips that store cached operations. But when you turn off the power, all data with DRAM is erased. This can be a problem if important information has not yet been saved to disk and therefore capacitors are installed in the SSD, and additional batteries are installed in the RAID systems. They should help record all information until the power is completely turned off. These elements degrade over time, capacitors and batteries increase the cost of finished products and make them more complex. Meanwhile, STT-MRAM, as a non-volatile memory, can solve this issue, and now manufacturers of such chips are actively promoting a similar method of their use.
At Kingston, we carefully monitor the development of the entire spectrum of new memory technologies, but for commercial products we use only mature solutions that have proven themselves and have shown high levels of reliability. Given the current situation, it is possible that in a few years STT-MRAM or an even more advanced modification of this memory will turn out to be faster and more reliable than the solutions existing today, but so far these technologies are at the stage of the first experiments and are not ready to work as those universal drives, you can choose the best of existing solutions, which, of course, include our RAM modules .
Subscribe and stay with us - it will be interesting!
For more information on Kingston andHyperX refer to the official website of the company .