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Moore’s law states that the transistor density per chip area is doubling every 18–24 months without the increase of production cost. ssss1 depicts the achievements of 2D IC of Si technology according to Moore’s law. From 1970 to 1985, the density has increased from 1K to 1M per chip, which is an increase of 1000 times. From 1985 to 2005, the increase was from 1M to 1G, which is another increase of 1000 times. It is the most successful event of sustainability for about 40 years of any human activity.

ssss1 A sketch of the achievements of 2D IC of Si technology according to Moore’s law.

ssss1 An image of part of the device structure of the mainframe computer in 2002. The size of the module is about 10 × 10 cm.

The law has had two significant impacts. First, the price of one transistor is now cheaper than the printing of one alphabet on a newspaper, which is a significant consequence of the Moore’s law that circuit density can be doubled without the increase of production cost. Hence, we can have very low cost use of transistors. Second, it enables the reduction of physical size of a computer so that handheld and mobile devices can be made. ssss1 shows part of a mainframe computer in 2002. The module size is about 10 × 10 cm, and between two of the ceramic plates in the module, there are 10 × 11 = 110 pieces of Si chips. According to Moore’s law shown in ssss1, the circuit density per chip in 2002 is about 256 M. If we can integrate the central processing unit (CPU) and the memory on the 110 chips into a single chip, we can build a mobile device or a mobile computer by using a single chip! No doubt, we also need to reduce the packaging structure, as well as to replace a keyboard by the finger‐touching technique. It is worth mentioning that in ssss1, while we do not see the chips but we see the electronic packaging structure, wherein the bright solder joints are everywhere. It shows how important is solder joint technology in electronic device manufacturing. This is because solder joint is still the best way to join two Cu wires, even two nanowires of Cu.