Semiconductor chemical sensor device with specific heater structure

A semiconductor device (50) comprises a semiconductor base, a heater (20) formed over the semiconductor base from conductive material, such as polysilicon, and a layer (22) for heating by the heater. The heater (20) comprises first (24) and second (26) arms extending over the semiconductor base from a heater portion (28) and an opening (34) extending vertically through the heater portion (28). A first heater contact (30) is coupled to an end of the first arm (24) and a second heater contact (32) is coupled to an end of the second arm (26). The layer (22) is formed over the opening (34) and heater portion (28) such that a vertical axis through the center (36) of the opening (34) extends through the center (36) of the layer (22).