Development of an ultraviolet imprinting process for integrating a microlens array onto an image sensor

Area of Science:

• Optoelectronics
• Nanofabrication

Background:

• Microlens arrays enhance image sensor performance by improving light collection efficiency.
• Integrating microlens arrays directly onto image sensors is crucial for miniaturization and advanced optical systems.

Purpose of the Study:

• To evaluate the feasibility of using UV imprinting for microlens array integration on image sensors.
• To assess the precision and uniformity of the fabricated microlens array on a wafer scale.

Main Methods:

• Fabrication of a simulated wafer-scale image sensor chip array.
• UV imprinting of a microlens array with specific dimensions (4.63 µm side length, 1.416 µm sag height, 1.15 µm residual-layer thickness).
• Analysis of dimensional uniformity across the wafer using standard deviation measurements.

Main Results:

• Successful integration of a microlens array onto the simulated image sensor.
• High uniformity achieved, with standard deviations for sag height (<0.038 µm) and residual-layer thickness (<0.164 µm) across the wafer.
• Measured full width at half maximum (FWHM) beam spot size of 1.19 µm with uniform intensity and pitch.

Conclusions:

• UV imprinting is a feasible and precise method for integrating microlens arrays onto image sensors.
• The process demonstrates excellent control over critical dimensions, leading to uniform optical performance.
• This technique holds promise for the development of high-performance, compact imaging devices.