CMOS compatible fabrication of micro, nano convex silicon lens arrays by conformal chemical vapor deposition.

Haijie Zuo,Xin Gai,Duk-Yong Choi,Barry Luther-Davies,Baoping Zhang

doi:10.1364/oe.25.003069

Haijie Zuo, Xin Gai + Show 3 more

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https://doi.org/10.1364/oe.25.003069

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Abstract

We present a novel CMOS-compatible fabrication technique for convex micro-nano lens arrays (MNLAs) with high packing density on the wafer scale. By means of conformal chemical vapor deposition (CVD) of hydrogenated amorphous silicon (a-Si:H) following patterning of silicon pillars via electron beam lithography (EBL) and plasma etching, large areas of a close packed silicon lens array with the diameter from a few micrometers down to a few hundred nanometers was fabricated. The resulting structure shows excellent surface roughness and high uniformity. The optical focusing properties of the lenses at infrared wavelengths were verified by experimental measurements and numerical simulation. This approach provides a feasible solution for fabricating silicon MNLAs compatible for next generation large scale, miniaturized optical imaging detectors and related optical devices.

Highlights

Microlens arrays have been commonly incorporated in a variety of optical systems for optical sensors [1,2,3,4,5,6], 3D displays [7], lighting and photovoltaic devices [8,9,10,11], as well as in optofluidic lab-on-a-chip devices [12, 13]
Enormous effort has been devoted to developing new methods of fabricating various kinds of microlens arrays, such as the VLSI-based binary method [14]; greyscale lithography [15]; polymer reflow [9,16,17]; femtosecond laser micromachining [18]; electrically templated de-wetting [19,20]; and most recently, planar metamaterial focusing [21,22] and plasmonic focusing [23,24], etc
In this letter we report a simple, yet efficient method for generating large scale, high quality, convex microlens arrays by CMOS compatible processes with the lens size ranging from several microns to as small as several hundred nanometers

Summary

Introduction

Microlens arrays have been commonly incorporated in a variety of optical systems for optical sensors [1,2,3,4,5,6], 3D displays [7], lighting and photovoltaic devices [8,9,10,11], as well as in optofluidic lab-on-a-chip devices [12, 13]. Enormous effort has been devoted to developing new methods of fabricating various kinds of microlens arrays, such as the VLSI-based binary method [14]; greyscale lithography [15]; polymer reflow [9,16,17]; femtosecond laser micromachining [18]; electrically templated de-wetting [19,20]; and most recently, planar metamaterial focusing [21,22] and plasmonic focusing [23,24], etc Among these methods, thermal polymer reflow has been the most widely used as it is compatible with standard semiconductor processes and the lens curvature can be defined by a properly regulated temperature. Most of alternative methods requires sophisticated processes and suffer from low yield, which is not compatible with modern CMOS process, it is hard to ensure high yield whilst remaining cost-effective

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