Low Temperature Processing using Pulsed Laser for Electronic Oxide-Based Device

Abstract

Traditionally, Thermal treatment is necessary to control of material properties in metal oxides due to the ability such as control of stoichiometry, phase transformation and improvement in purity. However, this process has some problems such as long processing time, energy loss. In addition, thermal process is incompatible with thermally sensitive substrates such as amorphous alloys, polymers and glass. Here in, we introduce the low temperature laser process for oxide-based device instead of thermal process.

The first topic is control of stoichiometry and crystallization about NbOx. ALD growth Niobium oxide (NbO2) thin films have been fabricated by pulsed-laser, which open the possibility to applicate NbO2 metal-insulator transition (MIT) in microelectronics since ALD system has advantages at constructing uniform, conformal, and ultrathin films with atomic level accuracy. Pulsed laser annealing under reducing environment enables crystallization and phase transition by inducing oxygen vacancies in ALD deposited Nb2O5 films. The two-terminal devices based on NbO2 made by laser treatment exhibit reliable and reversible threshold switch with high ION/IOFF ratio and low IOFF. Phase transition of ALD deposited multivalent metal oxide using pulsed laser can develop of ALD grown oxide-based threshold switches for advanced electronic device.

The second theme is about fabrication of c-axis aligned crystal indium gallium zinc oxide (CAAC-IGZO) films at room temperature by pulsed laser. A range of laser condition for CAAC-IGZO structure were studied. The XRD peak of CAAC (0012) near 33 ° is observed. The as-deposited a-IGZO TFTs exhibited an on/off ratio of 1.15×10^3 and a subthreshold swing of 2.61 Vdecade^-1. For laser annealed device, a high on/off ratio of 8.6×10^6 and a subthreshold swing of 0.32 Vdecade^-1. These results occur a development of IGZO TFTs using pulsed laser process.