An issue of reducing a product manufacture
unit cost exists in
wireless IC chips which are required to be disposable because the
wireless IC chips circulate in a massive scale and require a very high collection cost. It is possible to increase the communication distance of a
wireless IC
chip with an on-
chip antenna simply contrived for reduction of the
production unit cost by increasing the size of the antenna mounted on a wireless IC
chip or by increasing the output power of a reader as in a conventional way. However, because of the circumstances of the applications used and the read accuracy of the reader, the antenna cannot be mounted on a very small chip in an in-chip antenna form. When an AC
magnetic field is applied to an on-chip antenna from outside,
eddy current is produced in principle because the
semiconductor substrate is conductive. It has been fount that the thickness of the substrate can be used as a design parameter because of the
eddy current. Based on this finding, according to the invention, the thickness of the substrate is decreased to reduce or eliminate the
energy loss due to the
eddy current to utilize the electromagnetic wave energy for the
semiconductor circuit operation as originally designed. With the thickness reduction, it is possible to increase the communication distance by preventing ineffective absorption of energy and thereby increasing the current flowing through the on-chip antenna.