Thin-Film Deposition and IGZO Sputtering Target Physics
The IGZO Sputtering Target (Indium Gallium Zinc Oxide) is a specialized material used in the fabrication of Thin-Film Transistors (TFTs) for high-resolution displays (OLED and LCD).
1. Chemical Homogeneity and Sintering
The target is a ceramic block created through a process of Hot Isostatic Pressing (HIP) or vacuum sintering. The ratio of $In_2O_3$, $Ga_2O_3$, and $ZnO$ must be perfectly homogeneous at the atomic level. Any impurities or density variations in the target would result in "Mura" (defects) in the final display panel.
2. Magnetron Sputtering Mechanism
In a vacuum chamber, the IGZO target is bombarded with ionized Argon ($Ar^+$) gas. This "sputters" or dislodges IGZO atoms, which then deposit onto a glass substrate as a thin film. The target's Electrical Conductivity is a critical parameter, as it determines how effectively the plasma can be maintained during the deposition process.
3. Backing Plate Bonding and Thermal Conductivity
Because sputtering generates significant heat, the IGZO target is typically bonded to a copper Backing Plate using Indium solder. This assembly ensures that the heat is conducted away from the ceramic target into a water-cooling system, preventing the target from cracking due to thermal stress.