PURPOSE: To run an electric current adequately to a desired heater and prevent every layer from breaking down due to thermal expansion by forming an anticavitation layer independently over a passivation layer so that the anticavitation layer does not overlap an area above the stepped part of a resistor layer and a conductor layer.

CONSTITUTION: Even when a defect in the step coverage part of a passivation layer 6 occurs at the stepped part 8 of a resistor layer 4 and a conductor layer 5 where the defect in the step coverage part is apt to easily occur due to sputtering when forming the passivation layer 6, an anticavitation layer 7 does not enter into the step coverage part. Consequently, the anticavitation layer 7 no longer communicates with either the resistor layer 4 or the conductor layer 5, so that it is possible to prevent the failure to run an electric current adequately to a desired heater from occurring and also prevent an electric current from running to another heater. In addition, the anticavitation layer 7 does not become heated, unless it communicates, and consequently, each layer is prevented from breaking down.