Interpretation of Donor Activation in Boron and Argon Implanted Self-Aligned Bottom-Gate IGZO TFTs

This work provides an interpretation of donor activation in self-aligned bottom-gate (SA-BG) Indium-Gallium-Zinc Oxide (IGZO) TFTs with ion-implantation of boron (11B+) and argon (40Ar+) species as the source/drain treatment. Device fabrication strategies that switched the order of ion implantation and passivation annealing processes were investigated. Hypotheses in the mechanisms involved with donor activation have been developed from observed similarities and differences in the electrical operation of SA-BG TFTs fabricated using both implant-last and anneal-last approaches. Results suggest a defect-induced mechanism is responsible for donor behavior associated with argon implantation, whereas donor behavior associated with boron is attributed to the formation of an electrically active donor species involving chemical bonding. A detailed discussion on developed arguments arrived at through analysis of TFT electrical characteristics is presented. Materials analysis in support of the interpretation and associated arguments is in progress.