LED & CMOS Structured Light Systems for Multi-modal Optical Lithography

近年来，微型有源矩阵发光二极管（LED）阵列已经成为一种平台技术，目前在显示应用中具有巨大的商业利益，但它也在其他领域证明了重要的能力，包括无线光通信，成像和目标定位，以及无掩模光刻。这些器件是通过氮化镓led与互补金属氧化物半导体（CMOS）驱动电子器件的集成工艺制造的，从而提供高达约100 MHz信号速率的直接数字电子控制。微型led阵列在成像/跟踪和无掩模直接写入方面的应用已经分别进行了研究。现在，有一个及时的机会来探索结构光测量和微制造在一个多模态设置中的综合能力，其工作模式都是由微led技术支撑的。这个项目将应用结构光成像的原理，例如所谓的“单像素相机”，用于基于led的直接书写。这种方法允许检测器的使用，其能力大大超出了目前用于直接书写工具的传统相机系统。申请人将探索使用电荷耦合器件光谱仪和CMOS单光子探测器，这将能够检测和定位光谱或荧光寿命特征，否则无法检测到。然后，直接写入功能可用于制造与检测特征完全自动对齐的微结构，从而创建与工业和研发应用具有重要相关性的技术演示。氮化镓LED阵列可在宽波长范围内使用，从深紫外到绿色发射，因此特征检测和直接写入功能可以很容易地适应于一系列不同的目标标记和光刻胶。除了跟踪和对准功能外，LED阵列的结构化照明也有望实现闭环过程控制。3D成像，无论是通过模式投影还是通过光度立体成像的方式，都可以在编写结构时用于设置，从而为编写过程提供实时反馈。实现上述目标的研究需要面临许多挑战，从设备的基本光学设计，到结构光成像方法特有的噪声影响，再到系统集成挑战。有许多需要研究的权衡，例如，照明剂量与成像质量，写入速度与反馈精度，以及压缩感知的可能应用。该项目将深入了解设备操作的参数空间，并确定有用的配置。

In recent years, microscopic active-matrix light-emitting diode (LED) arrays have emerged as a platform technology, which currently sees huge commercial interest for display applications, but which has also proven significant capability in other areas, including wireless optical communications, imaging and object location, and maskless lithography. These devices are fabricated through an integration process of the Gallium Nitride LEDs with complementary metal-oxide semiconductor (CMOS) driver electronics, thus providing direct digital electronic control with up to about 100 MHz signal rates. The application of micro-LED arrays to imaging/tracking and maskless direct writing has previously been investigated separately. Now, there is a timely opportunity to explore the combined capabilities of structured light metrology and micro-fabrication in one multi-modal setup whose operating modes are all crucially underpinned by micro-LED technology.This project is going to apply the principles of structured light imaging, for example so-called "single-pixel cameras", in LED-based direct writing. This approach allows detectors to be used whose capability goes vastly beyond the traditional camera systems that are currently used in direct writing tools. The applicant will explore the use of charged-coupled device spectrometers and CMOS single photon detectors, which will enable the detection and location of spectral or fluorescence lifetime features that are undetectable otherwise. The direct-writing capability can then be used to fabricate micro-structures in perfect automatic alignment with the detected features, thus creating technology demonstrations with significant relevance for industrial and R&D applications. Gallium Nitride LED arrays are available across a broad wavelength range, from deep ultra-violet to green emission, and the feature detection and direct writing functions can therefore readily be adapted to a range of different target markers and photoresists. In addition to the tracking and alignment function, structured illumination with LED arrays also holds promise for closed-loop process control. 3D imaging, either by pattern projection or through means of photometric stereo-imaging, can potentially be employed in the setup while a structure is being written, thus providing real-time feedback to the writing process.Research towards the above objectives entails numerous challenges, from the basic optics design of the setup, to noise effects specific to the structured light imaging methods, to systems integration challenges. There are a number of trade-offs to be investigated, e.g. illumination dose versus imaging quality, writing speed versus feedback accuracy, and possible application of compressive sensing. This project will provide insight into the parameter space of device operation and identify useful configurations.