(A) study of contact properties between Al-based source/drain and indium oxide active layer in top-gate bottom-contact structured thin-film transistors for vertical-TFT

Abstract

In this work, we investigate the contact properties between low resistive Al-based source/drain (S/D) and InOx active layer in top-gate bottom-contact structured thin-film transistors (TFTs) for vertical-TFT (V-TFT). V-TFT is the promising structure for the development of next generation displays with the smallest pixel pitch values. In addition, improving RC delay in high-resolution pixel arrays requires the introduction of low resistive metal. Since Cu is difficult to dry-etch in fine sized patterns, Al is advantageous in terms of resistivity and process. However, V-TFT is the bottom-contact structure where oxide semiconductor is deposited after S/D process. This causes the oxidation of Al and degrades the contact properties. Therefore, we fabricated top-gate bottom-contact structured TFTs, which are the mimic structure of V-TFT, and analyzed their electrical characteristics. Mo/Al/Mo and Ti/Al/Ti S/D were applied to the device as Al-based electrodes. The quantitative analysis of the contact resistance between InOx and the Al-based S/D and the thin-film analysis were performed to determine the factors affecting the bottom-contact properties.