The theoretical limit for carbon-based chips is 1 nanometer.
Carbon-based chips are still only a research direction, and there is no physical production. And the advantage of carbon-based chips is not the size of the nanoscale process, but its powerful performance. In theory, if it were to be made into a carbon-based chip, it would have ten times the performance of a silicon-based chip, but the power consumption could be reduced to a quarter. With high performance and low power consumption, the formula is that the twenty-eight nanometer carbon-based chip is equal to the seven-nanometer silicon chip, which means that we can obtain the world's most advanced e-UV lithography machine as long as we use the twenty-eight nanometer lithography machine. The physical limit is the size of the carbon atoms themselves arranged into carbon nanotubes, which is about 1 nanometer.
Silicon-based chips 2nm is almost the limit, and carbon-based chips can not break this limit, but carbon tube technology is expected to develop conventional two-dimensional silicon-based chip technology into three-dimensional chip technology. This will at least increase the overall power of current chips by more than 1,000 times