Study on Compensation of Thermal Stresses in the Fabrication Process of Thin-Film Transistor

Abstract

It is essential to align masks without tolerance in every deposition stepwhen fabricating thin-film transistors (TFTs) on a polymer substrate.However, the shrinkage of the polymer substrate due to thermal effectmay arise during the deposition process. We observed the variation ofshrinkage as a function of the annealing temperature. It was found thatthe substrates keep shrinking up to a critical temperature and stay thesame above that point. The thermal treatment was conducted onsubstrates polycarbonate (PC), the polyarylate (PAR), and poly(ethersulfone) (PES). After predeposition annealing, the shrinkage wasprevented but deformation was observed on the surface. An inorganicthin film with a different thermal expansion coefficient was employed toremove the deformation and this resulted in the elimination of strain.