The Japanese giant Hitachi has developed the world’s smallest and thinnest Radio Frequency Identification (RFID) chip. Measuring only 0.15 x 0.15 millimeters in size and 7.5 micrometers thick, the wireless chip is a smaller version of the previous record holder – Hitachi’s 0.4 x 0.4 mm “Micro-Chip”. The company used semiconductor miniaturization and electron beam technology to write data on the chip substrates to achieve this decrease in size. The new chips have a wide range of potential applications from military to transportation, logistics and even consumer electronics.
Nicknamed “Powder” or “Dust”, these chips consist of 128-bit ROM (Read Only Memory) that can store a 38-digit number. Hitachi says the distance between each circuit element was reduced using the Silicon-on-Insulator (SOI) process, where an insulation layer and a monocrystalline silicon layer are formed upon the silicon base substrate, and the transistor is then formed on this SOI substrate. When compared to the conventional process where a transistor is formed directly upon the silicon substrate, this technology significantly reduces parasitic capacitance and current leakage, improving the transistor’s performance. The SOI process also prevents the interference between neighboring devices, which often causes product malfunctions. Thanks to an insulator surrounding each device, Hitachi experts say that even when the devices are in close proximity, higher integration is achieved on an even smaller area.
The surface area of the new chips was reduced to a quarter of the original 0.3 x 0.3 mm, 60µm-thick chip developed by Hitachi in 2003. The company says that developments in thin chip fabrication technology enabled the significant decrease in width – to one-eighth of that of the previous model. With more chips that can be fabricated on a single wafer, productivity was increased by over four times, and Hitachi expects this will open the way to new applications for wireless RFID chips.
The µ-Chip uses an external antenna to receive radio waves, which can be transformed and wirelessly transmitted as a unique ID number. The data is written during the fabrication process, using ROM, and is therefore non-rewritable, providing a high level of authenticity. “By taking advantage of the merits of compactness, high authenticity and wireless communication, and combining it with Internet technology, the µ-Chip may be utilized in a broad range of applications such as security, transportation, amusement, traceability and logistics” – said Hitachi engineers who worked on the project.
Hitachi is continuing to develop technologies that increase communication’s distance range and decrease antenna size, whilst preserving high reliability and aiming for improved productivity. The company said that the enhanced compactness and thinness of the new chip has further broadened the range of possible applications, including gift certificates that can be authenticated. The new RFID “powder” can also be incorporated into thin paper, such as currency, creating so-called “bugged” money.