We are talking about two rules that are also beginning to lose relevance.
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Moore's Law was formulated over fifty years ago. Throughout this time, he has for the most part remained fair. Even today, when moving from one process technology to another, the density of transistors on a chip . But there is a problem - the speed of developing new technical processes is slowing down.
For example, Intel has been postponing mass production of its 10nm Ice Lake processors for a long time. While the IT giant will begin shipping devices next month, the architecture was announced around years ago. Also last August, integrated circuit maker GlobalFoundries, which has been working with AMD, 7nm process technology (more on the reasons for this decision, we on HabrΓ©).
ΠΈ For several years they have been predicting death to Moore's law. Even Gordon himself that the rule he formulated will no longer apply. However, Moore's law is not the only pattern that is losing relevance and that processor manufacturers are equal to.
Dennard's scaling law
It was formulated in 1974 by the engineer and developer of dynamic DRAM Robert Dennard (Robert Dennard) together with colleagues from IBM. The rule goes like this:
"By reducing the size of the transistor and increasing the clock speed of the processor, we can easily increase its performance."
Dennard's rule has established a reduction in the width of the conductor (technological process) as the main indicator of progress in the microprocessor technology industry. But Dennard's law of scaling stopped around 2006. The number of transistors in chips continues to increase, but this fact to device performance.
For example, representatives of TSMC (a semiconductor manufacturer) say that the transition from 7nm to 5nm processor clock speed by only 15%.
The reason for the slowdown in frequency growth is current leakage, which Dennard did not take into account in the late 70s. With a decrease in the size of the transistor and an increase in frequency, the current begins to heat up the microcircuit more strongly, which can damage it. Therefore, manufacturers have to balance the power allocated by the processor. As a result, since 2006, the frequency of mass chips has been set at around 4-5 GHz.
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Today, engineers are working on new technologies that will solve the problem and increase the performance of microcircuits. For example, experts from Australia metal-air transistor, which has a frequency of several hundred gigahertz. The transistor consists of two metal electrodes, which act as a drain and source, and are located at a distance of 35 nm. They exchange electrons with each other due to the phenomenon .
According to the developers, their device will allow them to stop "chasing" the reduction of technical processes and concentrate on building high-performance 3D structures with a large number of transistors on a chip.
Kumi Rule
His in 2011 by Stanford professor Jonathan Koomey. Together with colleagues from Microsoft, Intel and Carnegie Mellon University, he on the energy consumption of computing systems, starting with the ENIAC computer built in 1946. As a result, Kumi made the following conclusion:
"The amount of computing per kilowatt of energy at static load is doubling every year and a half."
At the same time, he noted that the power consumption of computers has also increased over the past years.
In 2015 Kumi to his work and supplemented the study with new data. He found that the trend he described had slowed down. The average chip performance per kilowatt of power began to double about every three years. The trend has changed due to the difficulties associated with cooling the chips (), as it becomes more difficult to remove heat with a decrease in the size of transistors.
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Now new technologies for cooling chips are being developed, but so far there is no need to talk about their mass implementation. For example, developers from the University of New York proposed laser 3D printing to apply a thin thermally conductive layer of titanium, tin and silver to the crystal. The thermal conductivity of such a material is 7 times better than that of other thermal interfaces (thermal paste and polymers).
Despite all the factors , the theoretical energy limit is still far away. He cites a study by physicist Richard Feynman, who back in 1985 noted that the energy efficiency of processors would increase 100 billion times. At the time of 2011, this figure increased by only 40 thousand times.
The IT industry is accustomed to high rates of growth in computing power, so engineers are looking for ways to extend the validity of Moore's law and overcome the difficulties dictated by the rules of Koumi and Dennard. In particular, companies and research institutes are looking to replace traditional transistor technology and silicon. We will talk about some of the possible alternatives next time.
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Source: habr.com