“To improve is to change, and to be perfect is to change often.”
- Winston Churchill
The quote above perfectly describes the relationship humanity has with technology. For years on end, as we strive for perfection, gadgetry has been the protagonist in our lives, making them simpler, safer, and faster. With the rapid-paced evolution of technology, our usage of smaller yet more efficient devices has increased exponentially.
A driving factor for this change has been Moore’s Law. There have been numerous papers and scientists’ experiments about the expiration of Moore’s Law. These papers discuss the several technical issues and economic barriers that this principle may have. The history of integrated circuits from 1975 to 2011 shows transistor counts doubling every twenty-four months as a good estimation.
Although this may seem perfectly sufficient for current gadgets, there’s bound to be a limit to its efficiency. Semiconductors can be minimized only to a certain extent. Silicon atoms themselves are around 0.2nm in diameter.
In this blog, by reviewing the history of Moore’s Law, investigating its possible barriers, and predicting potential nanotechnologies to enhance it, we define a roadmap of future key technologies. In addition, we also estimate the end of Moore’s Law, assuming we will focus on technical capabilities.
History of Moore’s Law
Intel co-founder Gordon E. Moore after whom Moore’s Law is, described the trend in his 1965 paper. In it, Moore quoted that the principle will be applicable for at least the next ten years. He made this prediction based on his observations between 1953 to 1968.
Moore’s prediction was uncannily accurate, in part because the principle is now used in the semiconductor industry to guide long-term planning and to set targets for research and development.
The capabilities of many digital electronic devices depend on Moore’s Law: processing speed, memory capacity, sensors, and even the number and size of pixels in digital cameras. This improvement has dramatically enhanced the impact of digital electronics in nearly every segment of the world economy. It is a driving force of technical and social change in the last few decades.
Barriers to Moore’s Law
Moore’s Law was developed for describing the number of transistors that could be put on a chip at a minimal cost. The main issue for chip designers is that Moore’s Law depends on decreasing the size of transistors and eventually, the laws of physics intervene.
In particular, electron tunneling prevents the length of a gate — the part of a transistor that turns the flow of electrons on or off — from being smaller than 5 nm. Heat extraction is another problem hindering the use of smaller transistors. The number of transistors on the chip directly impacts the heat produced, and the greater the chance of a malfunction. Contemporary methods should be developed to remove that heat from the chip.
Current Barrier of Moore’s Law
Gordon Moore predicts that the density of transistors and computing power doubles every twenty-four months, which has held since there were fewer than 100 transistors in
an integrated circuit, to today’s many millions of transistors on a single-integrated computer chip. This amazing prediction has encouraged some authors to state that “periodically, people predict the death of Moore’s Law.
Intel CTO Justin Rattner recently stated in an interview with Network World that Moore’s Law will likely be the rule for many decades to come. “If Moore’s Law is simply a measure of the increase in the number of electronic devices per chip, then Moore’s Law has much more time to go, probably decades”, he is quoted as saying.
Over the past few years, the gate length of the transistors has decreased drastically. Alongside this, their performance has increased exponentially. The major reasons for this are mainly the following: current leakage, power consumption, and heat sink. These factors will limit the modern consumer demand for products such as smartphones, laptops, and flat-panel devices.
Nanotechnology to Enhance Moore’s Law
Nanotechnology could be a breakthrough in enabling the semiconductor industry to pack more power and speed into tiny computer chips while making them more energy-efficient and less expensive to manufacture. As we discussed previously in this paper, the semiconductor industry is faced with the challenges of developing lithographic technology for feature sizes smaller than 22nm and exploring new classes of transistors that employ carbon nanotubes or silicon nanowires.
Essentially, the best-known techniques to integrate nanotechnology with Moore’s law are:
1. DNA Scaffolding Tiny Circuit Board.
The utility of this approach lies in the fact that the positioned DNA nanostructures can serve as scaffolds, or miniature circuit boards, for the precise assembly of components — such as carbon nanotubes, nanowires, and nanoparticles — at dimensions significantly smaller than possible with conventional semiconductor fabrication techniques. This opens up the possibility of creating functional devices that can be integrated into larger structures, as well as enabling studies of arrays of nanostructures with known coordinates.
2. 3D Tri-Gates Transistor.
An Intel 3D transistor design was introduced in 2011 with its Ivy Bridge microarchitecture. The Tri-Gate design is considered 3D because the gate wraps around a raised source-to-drain channel, called a “fin,” instead of residing on top of the channel in the traditional 2D planar design. In addition, multiple fins are used, which provide greater control of each state.
3. Spintronics.
Spintronics (a portmanteau meaning spin transport electronics), also known as spin electronics, is the study of the intrinsic spin of the electron and its associated magnetic moment, along with its fundamental electronic charge in solid-state devices. The field of spintronics concerns spin-charge coupling in metallic systems; the analogous effects in insulators fall into the field of multiferroics.
Spintronics fundamentally differs from traditional electronics in that, in addition to charge state, electron spins are exploited as a further degree of freedom, with implications in the efficiency of data storage and transfer. Spintronic systems are most often realized in dilute magnetic semiconductors (DMS) and Heusler alloys and are of particular interest in the field of quantum computing and neuromorphic computing.
4. Carbon Nanotube (CNT).
Carbon nanotubes (CNTs) are cylindrical molecules that consist of rolled-up sheets of single-layer carbon atoms (graphene). They can be single-walled (SWCNT), with a diameter of less than 1 nanometre (nm), or multi-walled (MWCNT), consisting of several concentrically interlinked nanotubes, with diameters reaching more than 100 nm. Their length can reach up to several micrometers or even millimeters.
5. Single-Atom Transistor
A single-atom transistor is a device that can open and close an electrical circuit by the controlled and reversible repositioning of one single atom. The single-atom transistor was invented and first demonstrated in 2004 by Prof. Thomas Schimmel and his team of scientists at the Karlsruhe Institute of Technology (former University of Karlsruhe). Utilizing a small electrical voltage applied to a control electrode, the so-called gate electrode, a single silver atom is reversibly moved in and out of a tiny junction, in this way closing and opening an electrical contact.
Therefore, the single-atom transistor works as an atomic switch or atomic relay, where the switchable atom opens and closes the gap between two tiny electrodes called source and drain. The single-atom transistor opens up avenues for the development of future atomic-scale logic and quantum electronics.
Future of Nanotechnology in Enhancing Moore’s Law
Whether there is an ultimate limit to Moore’s Law is an open debate, dependent upon future electronic innovations, material science, and physics. Moore’s prediction as early as 1965 proves that he is a unique technological visionary who quietly led the silicon revolution with his law. We have estimated that the potential future nanotechnologies
will enhance the current known barriers of Moore’s Law.
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