A wafer structure is disclosed and includes a chip substrate and a plurality of inkjet chips. The chip substrate is a silicon substrate fabricated by a semiconductor process. At least one inkjet chip is directly formed on the chip substrate by the semiconductor process and diced into the at least one inkjet chip for inkjet printing. Each of the inkjet chip includes a plurality of ink-drop generators produced by a semiconductor process and formed on the chip substrate. Each of the ink-drop generators includes a thermal-barrier layer, a resistance heating layer, a conductive layer, a protective layer, a barrier layer, an ink-supply chamber and a nozzle.