An 8×64 pixel dot matrix microdisplay in 0.35-μm complementary metal-oxide semiconductor technology

摘要

Microdisplay technologies for near-to-eye applications mostlyuse a complementary metal-oxide semiconductor (CMOS) processingchip as backplane for pixel addressing, with extensive post-processingon top of the CMOS chip to deposit organic LED or liquid crystal layers.Here, we examine the possibility of integrating emissive microdisplayswithin the CMOS chip, with absolutely no post processing needed. Thiswill dramatically reduce the manufacturing cost of microdisplays andmay lead to new microdisplay applications. Visible electroluminescenceis achieved by biasing pn junctions into avalanche breakdown mode.The most appropriate CMOS pn junction is selected and innovative techniquesare applied to increase the light extraction efficiency from theCMOS chip using the metal layers of the CMOS process. An 8 × 64 dotmatrix microdisplay was designed and manufactured in a 0.35-μm CMOStechnology. The experimental results show that a luminance levelof 20 cd∕m2 can be reached, which is an adequate luminance value inorder to comfortably read data being displayed in relatively dark environments.The electrical power dissipation per pixel being activated is0.9 mW∕pixel. It is also shown that the pixels can be switched at a ratefaster than 350 MHz.