Tech Shout!

Hitachi Ltd. has created and confirmed operation of a 0.15 x 0.15 millimeter, 7.5 micrometer thick contactless IC chip, which it says is presently the smallest and thinnest in the world. A smaller version of the 0.4 x 0.4 mm µ-Chip is at present being marketed by Hitachi, maintaining the same level of functionality.

The company condensed the distance between each circuit element by using Silicon-on-Insulator (SOI) technology, which has an insulating layer in the substrate, instead of the Si (silicon) only substrate currently being used. Compared to the 0.3 x 0.3 mm, 60-micrometer (µm) thick IC chip (0.3 mm IC chip) announced by Hitachi in February 2003, surface area is reduced to a quarter of the original size.

Developments in thin chip fabrication technology have also allowed the chip to be reduced to one-eighth the thickness of the 0.3 mm IC chip, at the same time. This reduction in the size increases the number of chips, which can be fabricated on a single wafer, thus increasing productivity by more than four times.

The µ-Chip is one of the world’s smallest contactless IC chips, which uses an external antenna to receive radio waves (2.45 GHz microwaves), and converts it to energy to wirelessly transmit a 128 bit (1038) unique ID number. As the data is written during the fabrication process using ROM (Read-Only-Memory), it is not viable to rewrite the data, thereby providing a high level of authenticity.

Hitachi said that compared to the existing product which was used at the 2005 World Exposition held in Aichi, Japan, productivity is increased by about 10 times. It expects the technology to open the way to new applications for contactless IC chips.

The admission ticket system for the 2005 World Exposition, which had approximately 22,050,000 visitors, employed the µ-Chip, has a performance record of no incidence of confirmed sham and 0.001% incidence of ticket recognition error. By making use of its plus points of compactness, high authenticity and contactless communication, and combining it with Internet technology, the µ-Chip may be used in a broad range of applications such as security, transportation, amusement, traceability and logistics.

Hitachi has been working on technology such as increasing communication distance and decreasing antenna size, while maintaining those merits, to permit a broader range of applications for the µ-Chip. The enhanced compactness and slimness of this new chip has further broadened the range of possible applications, including securities like gift certificates and a large variety of certificates. The new chip has a double-surface electrode and therefore inspite of its even smaller size, connection with the external antenna can be easily achieved and high productivity maintained.

Features of the IC chip developed:

- World’s smallest size achieved through application of SOI technology.
Using SOI process, each device was surrounded by insulator, thus even when the devices were located in close proximity, intervention between devices could be prevented and thus higher integration achieved on an even smaller area.

- Thin chip achieved through application of SOI technology.
This was accomplished by complete removal of the silicon layer on the reverse side of the SOI substrate on which the circuit is fabricated.