Intel Corp. this week said that it had reached a milestone in its quest to make transistors switch ever faster while using less energy, by integrating a high-k gate with a compound semiconductor transistor. Details were presented this week at the International Electron Devices Meeting (IEDM).
Intel has been researching the possibility of replacing the silicon channel of the transistor by a compound semiconductor material such as indium gallium arsenide (InGaAs). Up until recently, such transistors used a Schottky gate with no gate dielectric, and were subjected to large gate leakage. Intel has now identified and integrated a high-k gate dielectric to reduce leakage with these so-called QWFETs (quantum well field effect transistors).
The prototype device was fabricated on a silicon wafer substrate, pointing towards eventual process synergy with the existing silicon infrastructure. By using a high-k dielectric, gate leakage for short channel devices was reduced by 1000x compared with a Schottky gate, while the electrical oxide thickness was reduced by 33%, leading to higher switching speeds, which in turn leads to improved chip performance.
What should be noted is that unlike silicon, a compound semiconductor is made up of two or more elements, indium, gallium and arsenic for example (InGaAs). Using two or more elements means more opportunity to tune the materials for performance or optical properties but also makes the challenge of fabricating wafers and processing much more complicated.
“If we can make all of the material integration challenges happen and also make dense devices then III-V technology could replace silicon technology starting around the middle of the next decade. There is still much work to be done to achieve this but stay tuned for further progress,” said Mike Mayberry, an Intel specialist.