Everyone knows that the transistors in a modern microprocessor are on the small side. So small, in fact, that it’s hard to get a grasp on the concept. Some of the critical film layers in the transistor are only a few atoms thick and well over a million transistors would fit inside the period at the end of this sentence.So how do we actually make these infinitesimal structures? One technique that is becoming increasingly common is atomic layer deposition, or ALD. The ALD process builds up material directly on the surface of the chip, a fraction of a monolayer at a time, to produce the thinnest, most uniform films possible.