Maximum packing density and minimum size of semiconductor devices

The absolute upper limit to packing density and the absolute minimum size of semiconductor devices, whether integrated or non-integrated, is investigated, It is found that absolute limitations exist based on physical phenomena, the mose important of which are statistical variations in impurity distribution, ultimate resolution of fabrication methods, power density and bombardment by cosmic rays. On the basis of these phenomena it is shown that for a medium size computer (10⁵components), with a reasonable mean time between failures (1 month) the maximum packing density is approximately 10¹⁰components per cubic inch. This corresponds to a minimum size of the components which is within a factor of 2-5 of the dimensions of the active region of many devices of today. Therefore as far as the devices themselves are concerned the end of the road to smaller size has already been reached. A comparison of various components, and various forms of these components is given.