How does phase change memory work

Non-volatile : Phase change RAM is a non-volatile type of memory, i. This helps it to specifically compete with flash memory. This means that without the need for a deleting process, data can be written directly to it.

This gives it a major advantage over flash that needs a period of deletion before it can be written to new files. This has the bonus that it allows code to be run directly from the memory, without the need to copy the data to RAM.

Scalability : Another aspect where it may have benefits is the scalability of P-RAM for the future, but this is yet to be understood.

If the memory cell size is decreased, it is observed that the amount of electrons deposited on the floating gate is reduced and this makes it more difficult to identify these smaller charges accurately.

P-RAM does not store a charge, but depends on a shift in resistance instead. As a consequence, it is not vulnerable to the same issues of scaling. Because no deletion phase is needed, this offers a major overall improvement over flash. Economic viability : Despite the numerous promises regarding the benefits of P-RAM, few enterprises have been able to produce chips that have been commercialized successfully.

Multiple bit storage per Flash cell : Flash's ability to store and detect multiple bits per cell also gives Flash an advantage over P-RAM in memory space.

Both the positives and drawbacks need to be weighed when looking at using phase change memory. A number of manufacturers have implemented phase change memory, but it is still not commonly used as many developers might be skeptical of a modern invention like this. Nevertheless, PCM has many distinct benefits to deliver on a variety of instances in phase change memory. As described above, phase change memory is a product that is seeing substantial investment from major suppliers. Multiple manufacturers have been openly discussing their PCM activities and technologies with differing degrees of success at this stage.

A three bit per cell PCM chip is among IBM's research developments, which could provide more stability and storage than previous research which demonstrated 1 bit per cell options. Since at least , Intel has been working on PCM, when it unveiled the platform at its developer conference. Micron revealed that it was leaving the PCM market in following several fits and starts.

For over a decade, Samsung has been focusing on diverse versions of PCM technology. The key use case that the business is currently working on is for embedded use inside mobile phones, but there is still the possibility for possible commercial storage systems.

Memory chip is the specific application of the concept of embedded system chip in the memory industry. Therefore, whether it is a system chip or a memory chip, it is through embedding software in a single chip to achieve multi-function and high performance, as well as support for multiple protocols, multiple hardware, and different applications.

Phase change memory PCM is an advanced non-volatile memory technology recently sold in a computer system as storage-class memory. For non-von Neumann computing, such as in-memory computing and neuromorphic computing, PCM is also being investigated. A very high-speed semiconductor memory that will speed up the CPU is a cache memory. Between the CPU and the main memory, it serves as a buffer. It is used to carry the data and program pieces that are most commonly used by the CPU.

Sections of data and programs are transferred by the operating system from the disk to the cache memory, from which the CPU can reach them. Flash memory is a non-volatile computer memory storage medium that allows multiple erases or writes during operation.

This technology is mainly used for general data storage, as well as the exchange and transmission of data between computers and other digital products, such as memory cards and USB flash drives. The memory controller is an important part of the computer system that controls the memory and is responsible for data exchange between the memory and the CPU. The memory controller determines the maximum memory capacity that the computer system can use, the number of memory banks, memory type and speed, memory particle data depth and data width, and other important parameters.

An electrical charge just a few nanoseconds in duration melts the chalcogenide in a given spot; when the charge ends, the spot's temperature drops so quickly that the disorganized atoms freeze in place before they can rearrange themselves back into their regular, crystalline order. Going in the other direction, the process applies a longer, less-intense current that warms the amorphous patch without melting it.

This energizes the atoms just enough that they rearrange themselves into a crystalline lattice, which is characterized by lower energy or electrical resistance.

To read the recorded information, a probe measures the electrical resistance of the spot. The amorphous state's high resistance is read as a binary 0; the lower-resistance, crystalline state is a 1. Speed Potential PRAM enables the rewriting of data without a separate erase step, giving the memory the potential to be 30 times faster than flash, but its access, or read, speeds don't yet match those of flash.

Once they do, PRAM-based end-user devices should quickly become available, including bigger and faster USB drives and solid-state disks. PRAM also holds out the possibility of newer, faster computer designs that eliminate the use of multiple tiers of system memory. A person using a computer with PRAM could turn it off and back on and pick up right where he left off -- and he could do so immediately or 10 years later. Such computers would not lose critical data in a system crash or when the power went out unexpectedly.

PRAM memory could also significantly increase battery life for portable devices. History Interest in chalcogenide materials began with discoveries made by Stanford R. Ovshinsky of Energy Conversion Devices Inc. His work revealed the potential for using those materials in both electronic and optical data storage. In , he filed his first patent on phase-change technology. In , the company formed Ovonyx Inc. ECD licensed all of its intellectual property in this area to Ovonyx, which has since licensed the technology to Lockheed Martin Corp.

Ovonyx's licenses center around the use of a specific alloy of germanium, antimony and tellurium. The final phase of the material is modulated by the magnitude of the injected current and the time of the operation. A resistive element provides the heating - it extends from a bottom electrode to the chalcogenide layer.

Current passing though the resistive heater element provides heat which is then transferred to the chalcogenide layer. Additionally recent developments of the technology have achieved two additional states, effectively doubling the storage of a given sized device. The advantage of the phase change technology is that the state remains intact when power is removed from the device, thereby making it a non-volatile form of storage.

Phase change random access memory, P-RAM offers a number of significant advantages for data storage over its main competitor which is Flash memory:. When looking at using phase change memory, both the advantages and disadvantages need to be considered. Phase change memory has been introduced by a number of manufacturers, yet it is still not widely used as many developers may be cautious of a new technology like this. Nevertheless, phase change memory, PCM has some distinct advantages to offer for a number of occasions.

Phase change memory basics The phase change memory, PCM or phase change random access memory, P-RAM, exploits the a unique property of a substance called chalcogenide glass. This enables it to compete directly with flash memory.