What is nanometer

Important for CPUs: The nanometer specification

Friedrich Stiemer

Processors are complex semiconductors that use billions of tiny transistors. Their size is given in nanometers. But what exactly does this value actually mean?

EnlargeImportant for CPUs: The nanometer specification

Processors are complex semiconductors that use billions of tiny transistors. The microscopic components switch on and off. In this way they enable calculations to be carried out. How much current is necessary for this depends on the size (or the structure width) of the transistor. The size is given in nanometers (nm), which corresponds to a millionth of a millimeter. Intel's CPUs have been using 10 nm since the end of 2019, while AMD's processors and Apple's smartphone chips rely on 7 nanometers. The nanometer value also allows a rough estimate of how powerful a processor really is. This is what makes the development of manufacturing processes so important for the chip industry.

But what exactly do the nanometers actually mean? To explain this, we first need to look at the basics of CPU manufacturing. This is done with the help of so-called photolithography, in which an image from the processor is etched onto a piece of silicon. This process is also known as the process node and is measured by how small the respective manufacturer can produce the transistors. Because smaller transistors are more energy efficient, they can do more calculations without getting too hot - this is usually the limiting factor in CPU performance. Narrower transistors also allow smaller chip sizes (dies), which increases the density with the same size on the semiconductors and thus reduces costs. And in the end this also means more cores per chip.

EnlargeThe nanometers of the built-in transistors are mainly responsible for the performance and efficiency of a CPU.

However, this does not automatically mean that 7 nm CPUs are twice as fast as models with 14 nm. In practice, the performance does not scale congruently with the number of transistors. The way each semiconductor manufacturer specifies the sizes also varies. For this reason, they serve more as a means of making a rough assessment than of an exact differentiation. For example, Intel's 10-nanometer production takes on TSMC's 7-nanometer process, although the nanometer specifications differ visibly.

However, reducing the structure widths not only affects the performance, but also the power consumption. This is particularly important for notebooks and mobile devices such as smartphones. Compared to 14 nm chips with 7 nm allow a 25 percent higher performance with the same power requirement. Or to put it another way: You get the same performance for only half of the energy requirement. This results in longer battery runtimes and higher-performance chips in even smaller device dimensions. For example, the A12X smartphone processor from Apple already calculates faster than somewhat older desktop processors from Intel. And that with only passive cooling and such a small format.

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