Circuit substrate and liquid discharging apparatus

A circuit substrate for use in a liquid discharging apparatus comprising:

• a pair of electrodes disposed in opposition to each other to form a gap between the electrodes;
• and
• a resistor layer arranged at least between the electrodes, wherein
• a circuit including a plurality of heat generating elements generating heat by energizing between the electrodes, a first wiring layer and a second wiring layer arranged in layer over the first layer to energize between the pair of electrodes of each of the heat generating elements, wherein
• the first wiring layer is formed from metal material containing at least a main ingredient element of the substrate,
• the first wiring layer is electrically connected directly to a diffusion region arranged in the substrate without through a barrier metal, the second wiring layer is electrically connected to the first wiring layer though a metal film for suppressing a diffusion of the main ingredient element of the substrate contained in the first wiring layer, and the resistor layer is arranged over the second wiring layer.