Harnessing halftone lithography in manufacturing display panels

Halftone lithography (HT) is a photolithographic technique that uses a mask with partially transparent regions to modulate the intensity of light during exposure. Unlike conventional binary masks, HT masks incorporate regions of varying transmittance, allowing graded UV exposure that produces intermediate photoresist thicknesses upon development. This capability enables multiple resist thickness levels to be defined in a single exposure step, eliminating the need for multiple exposures and additional masks. This process simplification lowers manufacturing costs, improves resolution and mechanical robustness, and reduces optical scattering, enabling widespread use of HT lithography not only in LCD fabrication but also in other display technologies such as organic light-emitting diodes (OLEDs). This review provides an overview of HT lithography, discusses prior efforts to reduce mask count in display panel fabrication, and examines its recent applications in the display industry.