Very deep sub-micron, entirely digital, position resolution sensors.

非常深的亚微米、全数字位置分辨率传感器。

• 批准号: ST/X004724/1
• 负责人: Gianluigi Casse
• 金额: $ 75.52万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FX004724%2F1
• 关键词: Very; deep; sub; micron; entirely

The project introduces a novel type of silicon radiation detectors constituted by an entirely digital circuit. This is a total change of design approach with respect to the current, well established architecture of solid state sensors. These have been very successful and are the main tool for many applications in science and technology. One strength of silicon sensors is their position resolution. They have been introduced and developed for tracking charged particles in high energy physics experiment and have gone through the years to a continuous series of improvements. Nonetheless their hit position resolution has not improved for many years. A value of 1 micron was already achieved over 30 years ago, and the current best devices have resolution larger than a few microns. The main reason for the inability of improving the hit location precision on a pixel sensor is the minimum size required by the analogue circuit amplifying the signal released by the ionising radiation, making the minimum pixel dimensions of the order of a few tens of microns. The approach here proposed to realise a breakthrough for the hit resolution performance of silicon sensors consists in designing a sensor based on an entirely digital circuit. The sensing mechanism is binary, with a sensor cell changing state from one to the other of two possible values when ionising radiation is crossing a given pixel (similar to the operation of a solid state digital memory). This digital circuit is comprising a limited number of transistors (from 3 to 10), allowing for a very small pixel footprint. Depending on the feature size of the selected CMOS technology node, a single pixel could be as small as 100x100 nm2, enabling an enhancement of up to two orders of magnitude in resolution when compared to current state-of-the-art. The concept of a digital radiation sensor with the above characteristics has been validated by the proponents of the project, with successful measurements of the charge generated by a pulsed blue laser and alpha particles from a 141 Am radioactive source. The initial measurements on the very first digital sensor prototypes have also indicated the subsequent research steps to improve the detection efficiency performance (number of recorded hits over the total number of crossing ionising particles) of these devices. The results have shown that a very shallow charge collection was achieved with the prototype resulting in a reduced efficiency, limited to hits happening in correspondence of the sensitive transistor gate, rather then over the whole sensor area. This project will correct this inefficiency with dedicated design of the sensitive node and produce very precise resolution pixel sensors with high efficiency over the full ionising radiation spectrum (minimum ionising particles, charged ions, photons). The new sensors would have countless applications. In science, they would revolutionize experiments in nuclear and particle physics, allowing for a large reduction of the tracking volume, with great benefits in terms of the scope and cost of future experiments. The new sensors will also be able to track particle paths shorter than 1 micron inside a single silicon layer, allowing for directional detection of recoiling nuclei or electrons. This would enable their use for detection of elusive Weakly Interactive Massive Particle (WIMP) candidates for Dark Matter. WIMPs can interact with nuclei in the silicon lattice causing these to recoil over distances a few hundred nm. Detecting these short tracks and being able to determine the direction of the incoming particle provides a powerful handle to extract the WIMP signal from otherwise insurmountable neutrino background. These are only examples of the huge scope of these novel devices.

该项目推出了一种由全数字电路构成的新型硅辐射探测器。相对于当前完善的固态传感器架构，这是设计方法的彻底改变。这些都非常成功，并且是许多科学技术应用的主要工具。硅传感器的优势之一是其位置分辨率。它们是为了在高能物理实验中跟踪带电粒子而引入和开发的，并且多年来不断进行一系列改进。尽管如此，他们的命中位置分辨率多年来一直没有提高。 30 多年前就已经达到了 1 微米的数值，而目前最好的设备的分辨率已经超过了几微米。像素传感器无法提高命中位置精度的主要原因是放大电离辐射释放的信号的模拟电路所需的最小尺寸，使得最小像素尺寸为几十微米量级。这里提出的实现硅传感器命中分辨率性能突破的方法包括设计基于全数字电路的传感器。传感机制是二元的，当电离辐射穿过给定像素时，传感器单元将状态从两个可能值中的一个更改为另一个（类似于固态数字存储器的操作）。该数字电路包含有限数量的晶体管（3 到 10 个），从而实现非常小的像素占用空间。根据所选 CMOS 技术节点的特征尺寸，单个像素可小至 100x100 nm2，与当前最先进的技术相比，分辨率可提高两个数量级。具有上述特性的数字辐射传感器的概念已得到该项目支持者的验证，成功测量了脉冲蓝色激光和来自 141 Am 放射源的 α 粒子产生的电荷。第一个数字传感器原型的初步测量也表明了后续研究步骤，以提高这些设备的检测效率性能（记录的命中数与交叉电离粒子总数的比）。结果表明，原型实现了非常浅的电荷收集，导致效率降低，仅限于敏感晶体管栅极对应的击中，而不是整个传感器区域。该项目将通过敏感节点的专用设计来纠正这种低效率，并生产在整个电离辐射光谱（最小电离粒子、带电离子、光子）上具有高效率的非常精确的分辨率像素传感器。新传感器将有无数的应用。在科学领域，它们将彻底改变核物理和粒子物理的实验，从而大幅减少跟踪体积，从而在未来实验的范围和成本方面带来巨大的好处。新传感器还能够跟踪单个硅层内短于 1 微米的粒子路径，从而能够定向检测反冲原子核或电子。这将使它们能够用于检测暗物质中难以捉摸的弱相互作用大质量粒子（WIMP）候选者。 WIMP 可以与硅晶格中的原子核相互作用，导致它们在几百纳米的距离内反冲。检测这些短轨迹并能够确定入射粒子的方向，为从难以克服的中微子背景中提取 WIMP 信号提供了强大的手段。这些只是这些新颖设备的巨大范围的例子。