The development of displays has progressed rapidly in recent years, and this has resulted in high quality displays which deliver sharp and bright images, wide viewing angles, vivid colours, all in a touch-sensitive layer.
Displays can be of two types: thin-film transistor liquid crystal displays (TFT-LCD) or based on organic compounds light-emitting diodes (OLED) that offer high quality image at low power consumption. LCD and OLED displays incorporate both extremely hard materials (molybdenum and titanium nitride) and extremely soft materials (silver alloys). A SEM analysis of these structures is complicated because of the thickness of glass (or plastic) substrates, organic interlayers, and integral touch screens.
  • TESCAN offers a series of instruments well-suited for the display industry. Displays are delicate structures which can be easily damaged by an electron beam.
  • As a response, the TESCAN MAIA3 FEG-SEM provides superb resolution even at low accelerating voltages, ideal for damage-free and charging-free imaging and resolving the beam-sensitive small structures in displays without the need of using protective coatings.
  • In addition to optical techniques, TESCAN FIB-SEM systems can be used to find the location of defects in display panels and prepare polished cross-sections with minimal damage.
  • GAIA3 is ideally suited to perform small area cross-sectioning of a couple of tens of microns wide in TFT. However, FIB-cutting through the full extent of a red-green-blue (RGB) pixels TFT array is an extremely challenging task. Such an application requires milling over hundreds of microns in all three directions, a task that would take tens of hours or even weeks to get accomplished with a conventional Ga ion source FIB.
  • The XEIA3 system – a Xe plasma ion source FIB – is the solution for preparing large-scale cross-sections in TFT displays, and for the characterisation of defects such as thin layers formed from etching residue, micro-voids in the multilayers, fragile aluminium whisker protrusions on the electrodes, or portions of the TFT multilayer damaged by mechanical stress. The cross-sectioning tasks take few hours at most with the XEIA3 system. Moreover the system achieves excellent UH resolution for the most delicate structures.
Cross-section of metal contacts and data lines in a TFT array prepared with a Ga source FIB

Documents for download

Thin-film transistor display lamella preparation using Xe Plasma FIB
In this application note we describe and present the preparation process of a TEM specimen from a TFT display array on glass substrate. The lamella was prepared using the TESCAN UHR-SEM/plasma FIB XEIA3 microscope.
pdf – 1.1 MB