Atomic Layer Deposition for OLED and MicroLED Display Technologies

Daniel Higgs, PhD Business Development Manager

Fast and efficient ALD enables cost-effective encapsulation of microOLEDs and sidewall passivation of microLEDs



Display technologies have evolved rapidly over the decades, from 19” cathode ray tubes to <1um-pitched microLEDs. Consumers demand thinner screens, higher pixel densities, flexible/curved screens, and near-eye viewing distances. Organic Light Emitting Diode (OLED) displays have found success as a high performing low-cost technology in the market with a compound annual growth rate (CAGR) of 13.6% reaching $72.8 billion in 2026. MicroLEDs are a slightly newer, competitive and higher-performing technology with a CAGR of 89.3% reaching $18.8 billion by 2026. Despite the expected growth in OLED and microLED technologies, they both suffer from technical drawbacks. OLEDs suffer from short lifetimes due to moisture/oxygen infiltration and MicroLEDs struggle with scaling production due to the decreased pitch size leading to poor sidewall passivation and low pixel efficiencies. Atomic layer deposition (ALD) has the ability to improve both OLED and microLED technologies by depositing defect-free films to provide a hermetic encapsulation, and sidewall passivation to improve lifetimes.

TO LEARN MORE, DOWNLOAD THE MICRODISPLAY WHITE PAPER

ALD BENEFITS FOR MICRO DISPLAYS

Endurance

Sustained performance in harsh environments.

Light-weight

Ultra-thin film encapsulation.

Precise

100% conformal and pin hole free.

  • Pristine conformality in high-aspect ratio structures 
  • Hermetic sealing encapsulation layers with minimal thickness 
  • Ultra-low particle generation 
  • Low stress films 
  • Improved lifetime of OLEDs 
  • Increased quantum efficiencies for microLEDs 

ALD Improves Performance AND Lifetimes!

ALD for OLED Technology 

OLEDs exhibit an attractive price-to-performance ratio but are susceptible to moisture and oxygen ingress through the organic layers within the pixel. Due to this sensitivity, OLEDs have the most stringent water vapor and oxygen transmission rate requirements of all optoelectronics technologies at 10-6 g/m2 /day and 10-3 cm3/m2 /day, respectively. Once moisture has penetrated the encapsulation surface, dark spots or “dead pixels” will appear due to the hydrolyzation of electrodes or electron injection layers.

Common VS ALD OLED Encapsulation Stack
ALD maintains both excellent step coverage and barrier protection against humidity eliminating the need for the organic film layer. Previous research using calcium corrosion tests have shown ALD alumina films have an effective water vapor transmission rate (WVTR) on the order 10-6 g/m2/day at room temperature which is sufficient for demanding applications such as OLEDs. While these ALD films have been deposited with thicknesses up to 50 nm, the critical thickness has been shown to be down to 5 nm. In a recent study, Riedl et al. demonstrated an ALD Al2O3/ZrO2 nanolaminate barrier structure on OLEDs where a lifetime in excess of 20,000 hours was achieved.

ALD for MicroLED Technology 

Deposition on the pixel sidewalls is an effective process to passivate the dangling bond and defects caused by the dry etching process to create the pixel trench. ALD enables passivation at ultra-high aspect ratios and outperforms PECVD passivation for EQE improvements in the same film according to a recent study with red microLED devices. Several other studies have shown ALD is the preferred passivation technique due to its excellent uniformity, high-quality film density, angstrom level thickness control and perfect surface coverage. In a 2018 study, ALD passivated sidewalls in a III-V microLED device exhibited 10% higher efficiency and conformal step coverage compared to PECVD deposited films

PECVD VS ALD Sidewall Passivation

Deposition on the pixel sidewalls is an effective process to passivate the dangling bond and defects caused by the dry etching process to create the pixel trench. ALD enables passivation at ultra-high aspect ratios and outperforms PECVD passivation for EQE improvements in the same film according to a recent study with red microLED devices. Several other studies have shown ALD is the preferred passivation technique due to its excellent uniformity, high-quality film density, angstrom level thickness control and perfect surface coverage. In a 2018 study, ALD passivated sidewalls in a III-V microLED device exhibited 10% higher efficiency and conformal step coverage compared to PECVD deposited films.

Huang Chen, Sung-Wen, et al. “Full-Color Monolithic Hybrid Quantum Dot Nanoring Micro Light-Emitting Diodes with Improved Efficiency Using Atomic Layer Deposition and Nonradiative Resonant Energy Transfer.” Photonics Research, vol. 7, no. 4, 2019, p. 416., doi:10.1364/prj.7.000416.

TO LEARN MORE, DOWNLOAD THE MICRODISPLAY WHITE PAPER

Atomic Layer Deposition for OLED and MicroLED Display Technologies

Daniel Higgs, PhD Business Development Manager

Fast and efficient ALD enables cost-effective encapsulation of microOLEDs and sidewall passivation of microLEDs



Display technologies have evolved rapidly over the decades, from 19” cathode ray tubes to <1um-pitched microLEDs. Consumers demand thinner screens, higher pixel densities, flexible/curved screens, and near-eye viewing distances. Organic Light Emitting Diode (OLED) displays have found success as a high performing low-cost technology in the market with a compound annual growth rate (CAGR) of 13.6% reaching $72.8 billion in 2026. MicroLEDs are a slightly newer, competitive and higher-performing technology with a CAGR of 89.3% reaching $18.8 billion by 2026. Despite the expected growth in OLED and microLED technologies, they both suffer from technical drawbacks. OLEDs suffer from short lifetimes due to moisture/oxygen infiltration and MicroLEDs struggle with scaling production due to the decreased pitch size leading to poor sidewall passivation and low pixel efficiencies. Atomic layer deposition (ALD) has the ability to improve both OLED and microLED technologies by depositing defect-free films to provide a hermetic encapsulation, and sidewall passivation to improve lifetimes.

TO LEARN MORE, DOWNLOAD THE MICRODISPLAY WHITE PAPER

ALD BENEFITS FOR MICRO DISPLAYS

Endurance

Sustained performance in harsh environments.

Light-weight

Ultra-thin film encapsulation.

Precise

100% conformal and pin hole free.

  • Pristine conformality in high-aspect ratio structures 
  • Hermetic sealing encapsulation layers with minimal thickness 
  • Ultra-low particle generation 
  • Low stress films 
  • Improved lifetime of OLEDs 
  • Increased quantum efficiencies for microLEDs 

ALD Improves Performance AND Lifetimes!

ALD for OLED Technology 

OLEDs exhibit an attractive price-to-performance ratio but are susceptible to moisture and oxygen ingress through the organic layers within the pixel. Due to this sensitivity, OLEDs have the most stringent water vapor and oxygen transmission rate requirements of all optoelectronics technologies at 10-6 g/m2 /day and 10-3 cm3/m2 /day, respectively. Once moisture has penetrated the encapsulation surface, dark spots or “dead pixels” will appear due to the hydrolyzation of electrodes or electron injection layers.

Common VS ALD OLED Encapsulation Stack
ALD maintains both excellent step coverage and barrier protection against humidity eliminating the need for the organic film layer. Previous research using calcium corrosion tests have shown ALD alumina films have an effective water vapor transmission rate (WVTR) on the order 10-6 g/m2/day at room temperature which is sufficient for demanding applications such as OLEDs. While these ALD films have been deposited with thicknesses up to 50 nm, the critical thickness has been shown to be down to 5 nm. In a recent study, Riedl et al. demonstrated an ALD Al2O3/ZrO2 nanolaminate barrier structure on OLEDs where a lifetime in excess of 20,000 hours was achieved.

ALD for MicroLED Technology 

Deposition on the pixel sidewalls is an effective process to passivate the dangling bond and defects caused by the dry etching process to create the pixel trench. ALD enables passivation at ultra-high aspect ratios and outperforms PECVD passivation for EQE improvements in the same film according to a recent study with red microLED devices. Several other studies have shown ALD is the preferred passivation technique due to its excellent uniformity, high-quality film density, angstrom level thickness control and perfect surface coverage. In a 2018 study, ALD passivated sidewalls in a III-V microLED device exhibited 10% higher efficiency and conformal step coverage compared to PECVD deposited films

PECVD VS ALD Sidewall Passivation

Deposition on the pixel sidewalls is an effective process to passivate the dangling bond and defects caused by the dry etching process to create the pixel trench. ALD enables passivation at ultra-high aspect ratios and outperforms PECVD passivation for EQE improvements in the same film according to a recent study with red microLED devices. Several other studies have shown ALD is the preferred passivation technique due to its excellent uniformity, high-quality film density, angstrom level thickness control and perfect surface coverage. In a 2018 study, ALD passivated sidewalls in a III-V microLED device exhibited 10% higher efficiency and conformal step coverage compared to PECVD deposited films.

Huang Chen, Sung-Wen, et al. “Full-Color Monolithic Hybrid Quantum Dot Nanoring Micro Light-Emitting Diodes with Improved Efficiency Using Atomic Layer Deposition and Nonradiative Resonant Energy Transfer.” Photonics Research, vol. 7, no. 4, 2019, p. 416., doi:10.1364/prj.7.000416.

TO LEARN MORE, DOWNLOAD THE MICRODISPLAY WHITE PAPER

Our website uses cookies to ensure you get the best experience. By continuing to use our site, we'll assume you are aware and accept the use of cookies.