NRAM, the wonder product of nanotechnology, is the patented trademark of the non volatile memory produced by Nanterno Inc, USA. The companyâ„¢s objective is to deliver a product that will replace all existing forms of memory, such as DRAM (Dynamic RAM), SRAM (Static RAM), and flash memory, and ultimately hard disk storage. In other words a universal memory chip suitable for countless existing and new applications in the field of electronics.
NRAM will be considerably faster and denser than DRAM, have substantially lower power consumption than DRAM or flash, be as portable as flash memory and be highly resistant to environmental forces (heat, cold, magnetism). And as a non volatile chip, it will provide permanent data storage even without power.
The proprietary NRAM, design, invented by Dr.Thomas Rueckes, Nanternoâ„¢s chief Scientific Officer, uses carbon nanotubes as the active memory elements. Carbon nanotubes are the members of the fullerene family and have amazing properties, including the ability to conduct
electricity as well as copper while being stronger than steel and as hard as diamond. The wall of a single-walled carbon nanotube is only one carbon atom thick and the tube diameter is approximately 100,000 times smaller than a human hair. Dr Rueckesâ„¢ pioneering design takes advantage of these unique properties while cleverly integrating nanotubes with traditional semiconductor technologies for immediate manufacturability.
WHAT IS NANOTECHNOLOGY
In 1960, Nobel laureate Richard Feynman predicted that by the year 2000 products would be built one molecule or one atom at a time. This was a truly bold vision because it would represent a new paradigm for manufacturing and constitute a fundamental economic shift analogous to a second industrial revolution. This shift is referred today as the nanotechnology revolution, and many people consider Dr.Feynmanâ„¢s quote the birth of nanotechnology. The National Science Foundation predicts that by 2010, nanotechnology will pervade virtually every corner of the economy and represent $1 trillion in goods and services.
The term nanotechnology is based on the root nanos, meaning one billionth. It refers to technology that uses components or features that measure 100 nanometers or less. A structure that is one nanometer is one billionth of a meter-it would take approximately 150,000 such structures to span the diameter of a human hair.
Why do companies want to get small? Because getting small means getting smarter, more powerful and more economical. Consider the first computerâ„¢s developed in the 1940â„¢s. They were the size of a large room, were very expensive to build, required virtually constant maintenance, needed a considerable amount of electricity to power, and were useable only by a handful of highly trained specialists. Compare that to todayâ„¢s common laptop computers. They are millionâ„¢s of times faster and more powerful than the first computers, thousands of times smaller, a mere fraction of the cost, require virtually no maintenance, run on very little electricity and are useable by almost anyone.
Miniaturization has led to an exponential growth in computerâ„¢s effect on our everyday lives because: (1) processing power has enabled them to do an almost unthinkable amount of work almost instantaneously; and (2) large percentages of our population and businesses are able to computers as diverse tools because they are easy to use and relatively inexpensive to build and operate. Virtually all of the major advances in the electronic industries, from the vacuum tube to modern computer chip, are a direct result of miniaturization and utilizing new materials. Nanotechnology is the next step in the evolution of miniaturization. It increases the value of existing products and opens the door to new technologies and products.
At the simplest level, nanotechnology is the manipulation single atoms and molecules to create objects that can be smaller than 100 nanometers. A nanometer is a billionth of a meter, which is about a hundred-thousandth of the diameter of a human hair, or 10 times the diameter of a hydrogen atom.
Manufactured products are made from atoms. The properties of those products depend on how those atoms are arranged. If we rearrange the atoms in coal we can make diamond. If we rearrange the atoms in sand (and add a few other trace elements) we can make computer chips. If we rearrange the atoms in dirt, water and air, we can make potatoes.
There are two more concepts commonly associated with Nanotechnology:
1. Positional assembly
2. Self replication
Positional assembly refers to the arrangement of molecules so as to get the right molecular parts in the right places. The need for positional assembly implies an interest in molecular robotics eg., robotic devices that are molecular both in their size and precision. These molecular scale positional devices are likely to resemble very small versions of their everyday macroscopic counterparts.
The self replicating systems are able both to make copies of themselves and to manufacture useful products. If we can design and build one such system the manufacturing costs for more such systems and the products they make (assuming they can make copies of themselves in some reasonably inexpensive environment) will be very low.
You wonâ„¢t think about installing Microsoft Office anymore. Youâ„¢ll think about growing software. The line is blurring in several ways. Scientists are learning to imitate biological patterns; biological entities are being used in technology products; and in the distant future, nanomachines may be circulating through our bloodstreams, attacking tumors and dispersing medicine.
NOT JUST COMPUTERS
The computer industry is just one example of the advantages related to miniaturization. Getting small is a means of increasing the power and value of diverse products and services in most industries. For instance, many advances in biotechnology and the development of new drugs are the direct result of miniaturization and utilization of novel materials. As with computing power, diagnostic and research power increase as tools decrease in size. Getting small allows biotechnology companies and researchers to do more complex experiments in shorter periods of time, for less money, using less material. This greatly accelerates discovery and ultimately shortens the time from concept to market for new advanced drugs and other products. Further, nanotechnology enables companies and researchers to design revolutionary new products using new materials and substances not accessible with other technologies.
Dr.Feynman was correct in his prediction of building devices from the ground up-atom by atom or molecule by molecule. He was incorrect, however, in his prediction that this would occur routinely by the year 2000. The question has been, how would you build nano-scale structures and manipulate quickly and cheaply?
Carbon nanotubes are a product of nanotechnology. They were invented by Sumayyo Ejyma. A carbon nanotube can be single walled or multi walled. A single walled nanotube is only one carbon atom thick. It can be considered as a sheet of graphite curled into the form of tube. Its properties can be changed by changing the direction of the curl. It can be made highly conducting or semiconducting based on the direction of the curl.
A carbon nanotube is highly elastic. It can be made in the shape of a spring, brush or spiral. They have very low specific weight. Another very useful property of the nanotubes is that their high mechanical and tensile strength. A carbon nanotube can be made into a length of up to 100 microns. They are chemically inert.
In near future it is possible that microprocessors may be converted into Ëœnanoprocessorsâ„¢. Researchers are in progress to find out the possibility of using nanotechnology in microprocessors. The chemical inertness property of the carbon nanotubes makes them suitable for making containers for carrying hazardous and highly reactive chemicals.
Conceptually, the nanolithography method is quite simple. It is the process by which molecules of virtually any material are literally drawn onto virtually any smooth surface. The basis of this idea was first accepted over 4,000 years ago, when a quill pen was dragged across a piece of paper to deposit ink. A major difference between these two processes, however, is that quill-drawn lines are more than 1,000,000 times larger those drawn by the nanolithography process, which can be smaller than 10nm wide. We reasoned that, when you get down to it, drawing is simply building, but at a very small scale. Therefore, nanolithography could have great value as a method of ultra-small, or nano-scale, manufacturing.
FABRICATION OF NRAM
This nanoelectromechanical memory, called NRAM, is a memory with actual moving parts, with dimensions measured in nanometers. Its carbon nano-tube-based technology takes advantage of Vander Waals forces to create the basic on-off junctions of a bit. Van der Waals forces are interactions between atoms that enable non-covalent binding. They rely on electron attractions that arise only at the nano-scale level as a force to be reckoned with. The company is using this property in its design to integrate nano-scale material properties with established CMOS fabrication techniques.
A nanotube is a form of fullerene carbon in which the hexagonally connected graphite sheet is curled up to form a tube of nanometer-scale diameters they grow, the tubes align perpendicular to each other with a slight gap between each pair.
Nanterno has said that each junction contains multiple nanotubes, providing redundancy and protection against catastrophic bit-failure. Nanterno also said the array was produced using only standard semiconductor processes, thereby making manufacture of the NRAM in existing wafer fabs more likely. It also results in substantial redundancy for the memory, because each memory bit depends not on one single nanotube, but upon a large number of nanotubes that resemble a fabric.
The biggest challenge was figuring out how to place the nanotubes in the correct positions. Each nanotube is approximately 50-to-100,000 times smaller than a piece of your hair. This means theyâ„¢re about 1-to-2 nanometers in diameter, and a nanometer is a billionth of a meter.
To build the array of nanotubes, Nanterno used a manufacturing method that involved depositing a very thin layer of carbon nanotubes over the entire surface of a wafer, and then using lithography and etching to remove the nanotubes that are not in the correct position to serve as elements in the array. This manufacturing method solved the problem of growing nanotubes reliably in large arrays. At the end of our process only the nanotubes in the correct positions are remaining. The present size of the array is 10GBit, but the process could be used to make even larger arrays. Nanterno claims to have developed an array of ten billion suspended nanotube junctions on a single silicon. The main variable now controlling the size is the resolution of the lithography equipment.
STORAGE IN NRAM
NRAM works by balancing the nanotubes on ridges of silicon. Under differing electric charges, the tubes can be physically swung into one of two positions representing one and zero. Because the tubes are so smallâ€under a thousand of atomsâ€this movement is very fast and needs very little power, and because the tubes are a thousand times as conductive as copper it is very easy to sense their position to read back the data. Once in position, the tubes stay there until a signal resets them: with a tensile strength twenty times than of a steel, they are expected to survive around a trillion write cycles.
The bit itself is not stored in the nanotube, but rather is stored as the position of the nanotube. Up is bit one, down is bit zero. Bits are switched between states through the application of electrical fields.
The technology works by changing the charge placed on a lattice work of crossed nanotubes. By altering the charges, engineers can cause the tubes to bind together or separate, creating the ones and zeros that form the basis of computer memory. If we have two nanotubes perpendicular to each other, one is positive and another is negative, they will bent together and touch. If we give both of them similar charges, they will repel. These two different states allow us to store information as ones and zeroes with the up position representing a one and the down position representing a zero. The chip stays in the same state until you make another change in the electric field. So when you turn the computer off, it doesnâ„¢t erase the memory. We can keep all your data in the RAM and it gives your computer an instant boot.
Reading from the NRAM is done by measuring the resistance between the nanotube and the electrode below. If the nanotube is up, you obviously have a vastly different resistance than if the nanotube is down and touching the electrode. So if the resistance is very high, the stored bit is one, otherwise zero.
ADVANTAGES OF NRAM
NRAM is faster and denser than all existing memory technologies. It uses only one tenth of the power used by existing DRAM or flash memory to store information. NRAM is a nonvolatile memory. That means that when you turn the power off, you don't lose the data. And that means that you never have to wait for your computer to boot up again; it turns on instantly. Each memory bit in an NRAM depends not on a single nanotube but on a large number of nanotubes woven together. Thus the NRAM offers substantial redundancy of memory. NRAM is highly resistant to environmental forces (heat, cold and magnetism).
NRAM can be manufactured using the existing machineries in semiconductor factories. So no high capital is needed for its production. NRAM is compatible with all existing hardware devices such as the PC, digital camera, mp3 players etc.
Nantero seems to lag behind MRAM developers -- Motorola and IBM, to name two -- in bringing its technology out of the research phase and into actual product development.
The downside, is the fact that the DRAM market is oversupplied and those chipmakers frequently have to sell at a loss, making it difficult for any new technology to break in.
BARRIERS TO MARKET
Nantero is developing an alternate technology in a field that already offers multiple memory options. The company will need to convince potential users of the benefits of NRAM over existing methods.
USES OF NRAM
NRAM could enable instant-on computers which boot and reboot instantly, PDAs with 10 gigabytes of memory, MP3 players with thousands of songs and replace flash memories in digital cameras and cell phones. Other possible uses include high speed network servers. And because the technology is considerable faster and denser than DRAM, Nanterno believes NRAM could eventually replace hard disk storage.
Nanotubes, atomic-scale carbon based structures, are set to begin the migration from the lab into the wafer fab. In the first effort of its kind, the Institute of Electrical and Electronics Engineers (IEEE) has begun to develop a standard that will define electrical test methods for individual nanotubes. The standard will seek to establish a common metrics foundation for the many research programs underway on the use of nanotubes in electronics.
The standard, IEEE P1650 , Standard Test Methods for Measurement of Electrical Proper ties of Carbon Nanotubes, will recommend the tools and procedures needed to generate reproducible electrical data on the structures. The initial meeting of the IEEE P1650 Working Group will be held at IEEE head quarters in Piscataway, NJ, US in September.
The efforts applied in nanotechnology have surfaced a strong need for common ways to evaluate the electrical characteristics of nanotubes, so what is done by one group can be confirmed by others. The standard will seek to meet this need. The tests defined in the standard will help form a bridge between the lab and the production.
In May 2003, Nanterno announced it had created an array of billion suspended nanotube junctions on a single wafer. The process involves depositing a very thin layer of carbon nanotubes over the entire surface of the wafer, then using lithography and etching to remove the nanotubes that are not in the right position to serve as elements in the array. The announcement was significant because it demonstrates we can create NRAM using standard equipment, which means NRAM can be made in any existing factory.
Nanterno hopes to have a chip storing one gigabyte (one billion bytes) out by 2003. Within three to five years, however, the company hopes to have a chip with capacity measured in terabytes (one trillion bytes).
It's hard to imagine a more exciting area than nanoelectronics. Every day at our lab our engineers are coming up with new ideas and new ways to build products on a molecular level that have never been done before. And the whole field of nanotechnology is one that will, over the next few decades, affect just about every area of human life, from electronics to medical care and beyond, so it's great to be right there on the leading edge. Thus, with the beginning of the usage of NRAM which gives instant-on computers, we can obtain a very fast and ever existing Random Access Memory for very vast applications.
In the field of computer science, memory is an important resource which must be carefully managed. While the average home computer nowadays has a thousand times as much memory as IBM 7094,the largest computer in the world in 1960â„¢s, programs are getting bigger and faster than memories. To paraphrase Parkinsonâ„¢s law, Programs expand to fill the memory available to hold them. So any attempt to produce faster and denser memory is always welcome.
NRAM is the trademark of the Nanterno Inc, USA. It is a non-volatile RAM which is based on nanotechnology. It is expected to hit the market by the end of 2003.NRAM is faster and denser than all forms of memory currently available. NRAM is expected to replace all other forms of memory.
2. WHAT IS NANOTECHNOLOGY
3. FABRICATION OF NRAM
4. STORAGE IN NRAM
5. ADVANTAGES OF NRAM
6. CHALLENGES FACED
7. USES OF NRAM
8. FUTURE SCOPE