Back‐channel‐etched thin‐film transistor using c‐axis‐aligned crystal In–Ga–Zn oxide

Abstract

Our crystalline In–Ga–Zn oxide (IGZO) thin film has a c‐axis‐aligned crystal (CAAC) structure and maintains crystallinity even on an amorphous base layer. Although the crystal has c‐axis alignment, its a‐axis and b‐axis have random arrangement; moreover, a clear grain boundary is not observed. We fabricated a back‐channel‐etched thin‐film transistor (TFT) using the CAAC‐IGZO film. Using the CAAC‐IGZO film, more stable TFT characteristics, even with a short channel length, can be obtained, and the instability of the back channel, which is one of the biggest problems of IGZO TFTs, is solved. As a result, we improved the process of manufacturing back‐channel‐etched TFTs.

(Invited) The Behavior of C-axis-aligned A-b-plane-anchored Crystal (CAA Crystal)

“…TEM observation of a CAAC-IGZO film shows that pellets arrange in a direction parallel to the surface of the substrate and stack (10). However, our previous study did not clarify how pellets randomly taking off from the target are arranged on the substrate to have c-axis alignment, how they interconnect, and why they are larger than pellets in nc-IGZO and a-like IGZO films in the initial state as shown in Fig.…”

A Bottom-Gate Indium-Gallium-Zinc Oxide Thin-Film Transistor With an Inherent Etch-Stop and Annealing-Induced Source and Drain Regions

“…8(c)], leaving only the permeable SiO x covering the channel region. Conventionally, the making of an inverted staggered TFT with a bottom gate [1], [16] resulted in an undesirable but inevitable etching of the back channel. This etching could only be prevented by the formation and patterning of an etch-stop layer [21].…”

“…The SiN y layer is subsequently patterned so that it is removed from the channel region. The underlying SiO x layer, which need not be patterned, acts like an inherent back-channel etch-stop and prevents the channel region from the etch used to define the S/D regions [1]- [16]. The elimination of the patterning step for the etch-stop implies a corresponding reduction in the manufacturing cost of the resulting display panels.…”

A foldable OLED display with an in-cell touch sensor having embedded metal-mesh electrodes

“…Figure shows the relationship of the crystallinity of various IGZOs. We have reported in that a CAAC‐IGZO thin film has crystals oriented along the c‐axis and vertically to the film surface.…”