LG.Philips LCD TFT –

TFT LCD screens are targeting several major applications, from TV sets and computers to car navigation and entertainment systems.

The LCD is injected between two glass plates - the substrate at the bottom and a colour filter at the top.

LCD processing is similar to that of semiconductors, with deposition followed by photolithography and etching.

Thin-film transistors control the direction of polarization of liquid crystals.

TFT-LCD screens are flat, lightweight, and consume less power than CRTs.

Panels made in Korea are assembled into complete modules in Nanjing, China.

LG.Philips LCD began production of seventh-generation TFT LCDs (thin-film transistor liquid crystal displays) at its facility in Paju (Korea) at the beginning of 2006. The ramp up was over six months earlier than previously planned, prompted by increasing demand for LCD TVs and PCs. The expansion made it the world’s largest LCD production facility. Philips made a pilot production run at the end of November 2005, and has started production of 42in panels from its 1,950mm x 2,250mm glass substrates.

The company is investing $10 billion and expects annual sales close to $3 billion, more than 90% of which will be from exports. The 1,650,000m² complex takes the LG.Philips LCD industrial cluster to 3,300,000m², housing next-generation LCD production and R&D facilities. Preparatory work was completed by March 2004.

The fab is located in Paju, Kyonggi Province, north of Seoul. LG.Philips LCD and the Kyonggi provincial government has provided infrastructure including industrial water systems, electricity utilities and roads. The investment has created around 5,000 new jobs.

THIN-FILM TRANSISTOR LCDs

TFT LCDs have three layers. A glass plate substrate with TFT transistors is at the bottom, a glass plate colour filter on top and the liquid crystal is injected between the two. Although LCDs are fluid, they show long-range order like solids. The molecules are roughly bar shaped but with anisotropic values of reflective index, dielectric constant, conductivity and viscosity: all have different values along different axes.

The transistors apply voltages to the liquid crystals to control the vibration direction of polarized light passing through them. This affects the light permeability of the individual LCD pixels to form images.

TFT-LCD screens are flatter and lighter than CRTs, consume less power and generate lower electromagnetic emissions. Besides going into TV sets for the home, TFT LCDs will be used in monitors for mini notebook PCs and hand-held computers, medical equipment, car navigation and entertainment systems and avionics instrumentation.

Philips has been improving the technical limitations of TFT-LCDs, particularly angle, brightness response time. The company now has 20.1in UXGA, 23in WUXGA and 30in WQXGA+ TFT-LCD panels for large-scale, wide monitor-specific TFT-LCDs for desktop monitors.

PRODUCING 45,000 GLASS SHEETS/MONTH

The first phase of the factory should reach a production capacity of 45,000 glass sheets/month by Q3 2006. The factory should reach its initial design capacity of 90,000 input sheets/month by Q1 2007.

After first manufacturing 42in TV panels, Philips will gradually increase production of 47in TV screens. It can produce eight 42in panels or six 47in panels from a single glass substrate.

PROCESSING SHARES DEPOSITION, LITHO AND ETCHING

Processes and processing steps are similar to those in the semiconductor industry, with deposition, photolithography and etching in common. Processing temperatures are generally half the 1,000°C for semiconductor fabrication, though.

The glass plates are heated in a vacuum chamber and source gas is introduced. An RF or DC voltage on electrodes inside the chamber forms a plasma which produces and deposits the precursors on the glass substrate.

During sputtering, the high-energy gas ions inside the plasma collide with the surface of a (negative) target, knocking out the target materials which are deposited onto the (positive) plate.

Photolithography first coats the substrate with a very thin liquid film of photosensitive ‘resist’. Exposing the photoresist to light through a mask transfers the pattern onto the substrate. This is followed by cleaning. Another layer of the photoresist is then deposited to the substrate, exposed, cleaned, and so on, until all the layers have been printed or imaged onto the surface.

Dry etching uses reactive atoms or radicals from the gas plasma to etch away a portion of the object material.

LG.PHILIPS LCD JOINT VENTURE

LG.Philips LCD is a 50:50 joint venture between LG Electronics and Philips Electronics. The company produces TFT-LCDs for notebook PCs, desktop monitors, LCD TVs and special applications including car navigation systems, avionics, miniature notebook PCs, hand-held PCs and medical diagnostic machines. Higher value 18in-and-above screens make up more than 20% of LG.Philips LCD’s total TV LCD production.

The company has also invested a total of 3.3 trillion won (just under $2 billion) to build a new sixth-generation TFT-LCD plant in Gumi, south of Seoul. In addition to its Korean facilities, where the core panels are made, LG.Philips LCD has expanded its Nanjing, China, fifth-generation module plant, where it has produced more than one million TFT-LCDs for desktop monitors (module yield is more than 99%). In Nanjing, panels are equipped with other components before being sold to monitor and TV set manufacturers.