Infineon takes new approach to plastic chips

Infineon takes new approach to plastic chips
MUNICH, Germany — When an Infineon Technologies researcher presents a technical paper on the company's development of high quality organic transistors and circuits this Wednesday (Feb. 12) at ISSCC, he and his research team based in Erlangen, Germany, will seek to signal to the global semiconductor industry that the emergence of plastic chips is no longer science fiction.

The company maintains that plastic is back, cheaper than silicon and offers an abundance of potential applications.

A core team of five researchers, including organic and inorganic chemists, a surface scientist and electronics engineers, are working at Infineon's research laboratories to develop a wide range of processes to make plastic chips. Many processes are similar to those of conventional chip-making techniques. These include deposition processes and photolithography as well as printing patterning techniques.

Infineon's ISSCC paper will describe the development of circuit models and rapid circuit designs using polymer electronics.

While volume production of plastic chips remains as much as five years away, Infineon project head Guenter Schmid said it has developed "a fully substrate-independent technology." Schmid said this would allow integration of plastic electronic circuits on a variety of commercially available packaging films, including the material used to make potato chip bags.

Polymer electronics have been in development globally over the last several decades. The challenge is to apply organic materials to a variety of products including displays, solar cells, transistors and memory. Infineon's team "started from scratch" in late 1999, Schmid said in an interview, but has set its sights on developing "ultra low-cost electronics for RFID radio frequency identification tags."

Schmid described his team's work in polymer electronics "not as a pure R&D, but as system-level, circuit development" operating in close collaboration with Infineon's circuit designers. The demand for plastic chips is greatest in the RFID area, said Schmid, because there is a growing conviction among experts that "as long as we depend on silicon, RFID may never get cheap enough to put it on a yogurt container or a chewing gum wrapper as a bar code replacement."

Infineon, which offers secure mobile products ranging from mobile handsets and smart cards to RFID tagging and single-access cards, is targeting polymer electronics as a key market to expand its portfolio and serve the market segment for low-cost devices.

Small molecules versus polymer

Many industry experts thought polymers such as Poly (3-hexyl) thiphene, or P3HT, were the wave of the future in plastic chips. The material was favored due to its low cost and solubility. The Infineon team decided instead to use small molecules made of Pentacene.

Schmid said the decision was based largely on the higher charge-carrier mobility of Pentacene and its ease of handling, which requires no expensive purification processes or toxic solvents. "Just to prepare polymers, you first need to purify it, which takes a huge amount of solvent. Then, in order to prepare polymers for direct printing, you need to make ink out of it. In making specific deposition formulations, we often needed to add something, which almost always made the performance of polymers worse," Schmid said.

"In the view of polymer electronics experts, RFID is a high performance area," he added. In order to keep the overall cost of manufacturing as low as possible, and to make their plastic chips functional in RFIDs, the use of small molecules with good external mobility was essential, Schmid said.

A polymer electronics R&D team at Siemens, of which Schmid was a member before Infineon was spun off, is pursuing the polymers approach rather than small molecules. "The race is still open," when it comes to using small molecules versus polymers to make plastic chips, Schmid said. "There is no clear winner yet."