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.