Surface Treatment

Laser crystallization drives faster, brighter displays with HD resolution. Excimer laser powers in excess of 1 kW and high precision UV optical systems are driving yield and productivity.

The trend towards mobile communications, smart phones, personal computing, and digital photo and video drives the market for advanced small and medium-sized displays with the highest resolution, high brightness and long battery life for a perfect user experience. For these displays, the LTPS (Low Temperature Poly Silicon) TFT backplane is inevitable to enable stable performance of AMLCD and AMOLED displays.

Coherent is the market leader for excimer lasers and UV optical systems that are the enabling components of the annealing system. Highest laser power of more than 1 kW and optimized line beams of up to 750 mm are used worldwide for the manufacturing of LTPS-based LCD and OLED displays.

Increase wear resistance and fatigue strength on the work piece surface.

Laser heat treatment increases wear resistance and increases the fatigue strength due to the compressive stresses induced on the work piece surface. The ability to precisely control the physical extent of the illuminated region, together with the short timescale of energy transfer into the material, gives rise to the main benefits of laser surface modification over other techniques. Several key benefits include rapid processing, precise localized control over case depth/hardness, minimal to no part distortion, superior wear and corrosion resistance and increased fatigue strength.

In flexible display manufacturing, frontplane layers and MicroLEDs fabricated on intermediate substrates must be detached to obtain the final flexible OLED or MicroLED device. Excimer laser-based processing at 308 nm or 248 nm provides high yield and scalable throughput. Excimer laser systems deliver the necessary pulse energy, are layer selective, and can process wafers and displays of all sizes. They are the preferred solution for MicroLED lift-off (LLO), MicroLED forward transfer (LIFT) and as well flexible OLED lift-off from all carrier substrates including transparent and colorless polyimide (CPI).