Electrically conductive parts 84 a, 84 b made of an electrically conductive material such as Cu extending upward in the drawing are electrically connected to the heat-generating layer 80, whereas electrode pads 86 a, 86 b are attached to the upper ends of the electrically conductive parts 84 a, 84 b, respectively. [0039]FIG. 4 is a plan view of the heat-generating layer 80.