Fears that Moore’s law – which dictates the exponential growth of processing power – would falter this year have been allayed after IBM revealed processors with circuits just 7nm wide.

Moore’s law states that every 18 to 24 months processing power will double and it has been steadily observed to be true since 1965, enabling the rapid technological progress over the last four decades.

It had been thought the law could finally be disproved as it became too difficult to make ever smaller transistors. (The smaller the transistors, the more can be fitted onto the same size chip, which increases the number of calculations the chip can make and so increase its processing power.)

Moore’s law explained. Guardian

The last major chip breakthrough was in making 14nm transistors, and doubts were raised about whether silicon-based processors could get much smaller due to the physics of atom sizes and the microscopic scale.

Transistors use grooves etched in silicon to guide electrons around the chip. The channels do a similar job to that of wires, but on a much smaller scale. Making these grooves just 7nm wide means you can fit more transistors on the chips.

For comparison a strand of human hair, at 100,000nm thick, is about 10,000 times wider than the channel. A red blood cell is a thousand times bigger, at 7,500nm in diameter. A strand of DNA is in the same order of magnitude, but slightly smaller at just 2.5nm wide.

Red blood cells Photograph: Ikon images/REX

At 7nm it is extremely difficult to control the electrons flowing through the transistors, but IBM claims to have worked out a system and prototype chips that operate at that scale.

The product of its partnership with New York State, GlobalFoundries, Samsung, and a $3bn investment in next-generation chips announced last year, IBM claims its new processors will be four times more powerful than today’s chips with up to 20bn transistors on a single chip.

To reach 7nm IBM and partners switched to a silicon-germanium material, instead of pure silicon, for crucial sections of the chip. New manufacturing techniques will be required to produce the chips which may complicate high-speed mass manufacturing currently possible at larger sizes.

While the prototype chips prove that 7nm transistors are possible and that the march of increasing processor power can continue for one more generation, IBM warned that it would take two years before chips made at 7nm scale would be available to buy.

IBM is licensing the technology to partner GlobalFoundaries, which produces chips for AMD, Qualcomm and Broadcom among others, meaning chips built at 7nm could appear in anything from computers to smartphones.

Other manufacturers, including Taiwan Semiconductor Manufacturing Company which makes chips for a variety of companies such as Apple, have been working on similar scale chips but have yet to demonstrate working prototypes.

The next jump beyond 7nm will likely require all-new materials and manufacturing techniques, if it is at all possible.

• The question: Will Moore’s law fail in the next 20 years?