Designed for micro-display applications such as augmented-reality or virtual-reality tools and
wearable devices, the blue or green GaN/InGaN μLED arrays use Leti’s proprietary self-aligned
technology. That process is key to achieving such a small pixel pitch. A combination of several
damascene metallization steps used to create a common cathode is also expected to provide
good thermal dissipation and prevent voltage drops within the micro-LED matrix. Electro-optical
measurements showcase record efficiency and brightness exceeding requirements for device
integration.
The results were presented Feb. 2 at SPIE Photonics West in San Francisco in a paper:
“Processing and Characterization of High-Resolution GaN/InGaN LED Arrays at 10-Micron
Pitch for Micro-Display Applications”.
“Leti’s self-aligned process allows the creation of high-resolution μLED matrices with a reduced
pixel pitch of 10 μm and paves the way towards even smaller pitches for next-generation
devices,” said Ludovic Dupré, one of the paper’s authors. “In addition, the use of the
damascene metallization process of the cathode, which also is a new process developed at
Leti, is a breakthrough compared to previous demonstrations of micro-LED matrices. The
common cathode indeed fills the whole volume between the micro-LEDs and provides metallic
spreading of electrical current between them, as well as thermal dissipation. These results are
promising for integrating a micro-LED matrix in micro-display devices by hybridization on
CMOS active matrices, and first prototypes are currently being tested.”