Displays

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.

Direct patterning of multiple layers plays a vital role in the Flat Panel Display (FPD) industry. The use of lasers helps meet the goal of lower manufacturing cost, high yields and environmentally friendly processing.

Direct laser patterning is achieved by various laser processes such as ablation, engraving, marking, or thermal treatment. Laser processing provides the advantage of being contact-free, flexible and highly reproducible. For most of these laser applications, the number of process steps is greatly reduced. Typical examples for laser direct patterning in the FPD industry include metal electrodes, contact holes, touch panel, and light guide plates.

To cover the large list of material mixes used in microelectronics and flat panel displays, Coherent offers a large product range of lasers. The range covers CO₂ lasers for engraving, Direct Diode for thermal treatment, as well as DPSS and excimer lasers for ablation. Our lasers are perfectly matched to the direct patterning applications and provide the stability and robustness that is demanded by the industry. Global support and access to our fully equipped application centers are provided to ensure successful implementation.

Solid-state lighting is a key element to achieve the global target for reduced energy consumption. Coherent lasers support this goal and drive new processes for advanced LED manufacturing.

The market for high-brightness light-emitting diodes (HB-LED) is poised for explosive growth over the next five years. Declining costs and improving performance have rendered HB-LEDs a viable competitor to conventional cold-cathode fluorescents (CCFLs) for backlighting flat screen televisions. Rapid adoption for LCD display backlighting is driving HB-LED market growth this time around.

The potential for HB-LEDs in general illumination such as retail display, outdoor, and residential lighting represents the largest overall market. Penetration into general lighting applications is expected to accelerate as manufacturing costs come down and device efficiency improves.

Novel laser-based manufacturing concepts such as laser-lift-off (LLO) processing with 193 nm and 248 nm excimer lasers enable vertical LED structures with increased light extraction efficiency.

Laser-based sapphire scribing, as well as wafer or substrate dicing with diode-pumped solid-state lasers at 266 nm and 355 nm or picosecond lasers, further reduce production costs and at the same time significantly enhance yield and efficiency of HB-LEDs.

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).

µLEDs represent an exciting new technology that can extend display applications beyond their current size and operating ranges. Ultraviolet lasers, especially at 248 nm, are proven mass-production tools that can enable cost effective solutions for the key process hurdles . This includes laser lift off (LLO) to remove dies from the sapphire (EPI) wafer. That can be done either as a full area release or selective parallel. The critical laser induced forward transfer (LIFT) process enables an accurate placement of the MicroLEDs on the final display substrate at a high throughput due to the mass transfer per laser pulse. With our experience in providing total systems for TFT blackplane production, Coherent understands the importance of supporting this emerging technology by developing highly integrated solutions. ​