The researchers have described how they scaled up the established processes for making flexible silicon chips to the size required for delivering high-performance bendable systems in the future, and discuss the barriers which will need to be overcome in order to make those systems commonplace.
They show how they have been able to make an ultrathin silicon wafer capable of delivering high-performance computing while remaining flexible.
Flexible electronics have many potential applications, including implantable electronics, bendable displays, wearable technology which can provide constant feedback on users’ health. The BEST group has already made significant progress in wearable technology, including a flexible sensor and accompanying smartphone app which can provide feedback on the pH levels of users’ sweat.
“Silicon is a brittle material which breaks easily under stress, which has made it very difficult to use in bendable systems on anything other than the nano-scale,” says Professor Ravinder Dahiya who led the group, “what we’ve been able to do for the first time is adapt existing processes to transfer wafer-scale ultrathin silicon chips onto flexible substrates. The process has been demonstrated with wafers four inches in diameter, but it can be implemented for larger wafers as well. In any case, this scale is sufficient for manufacturing ultra-thin silicon wafers capable of delivering satisfactory computing power.”
The team’s paper outlines the techniques they have developed to transfer several different types of ultra-thin silicon chips of around 15 microns in thickness onto flexible substrates – a human blood cell, for comparison, is about five microns in width.