Patent ID: 6962405

Claim:
An ink jet recording head substrate comprising: a first conductive-type semiconductor substrate on which a plurality of electro-thermal converting elements, first wirings commonly connected to said plurality of electro-thermal converting elements and connected to a driving power supply and adapted to supply an electric power to said plurality of electro-thermal converting elements, second wirings for connecting said plurality of electro-thermal converting elements to grounding potential, and a plurality of switching elements provided between said second wirings and said electro-thermal converting elements and adapted to establish electrical connection to said plurality of electro-thermal converting elements are provided; and wherein said switching element is an insulation gate type electric field effect transistor including: a second conductive-type first semiconductor area provided on one main surface of said semiconductor substrate; a first conductive-type second semiconductor area provided on said surface of said semiconductor substrate adjacent to said first semiconductor area to provide a channel area and comprised of semiconductor having impurity density higher than that of said first semiconductor area; a second conductive-type source area partially provided on a surface of said second semiconductor area opposed to said semiconductor substrate; a second conductive-type drain area partially provided on a surface of said first semiconductor area opposed to said semiconductor substrate; and a gate electrode provided on said channel area via a gate insulation film; and further wherein wiring resistance of said second wiring connected to said source area is smaller than wiring resistance of said first wiring connected to said drain area.