This article proposes a physical unclonable function (PUF) based on the contact formation probability. The contact here is the interconnect layer between the metal and the silicon in a chip. As the contact is designed smaller than the size given in the design rule, the contact formation becomes stochastic in a certain range of contact hole sizes and can be a random source for the PUF. Consequently, once the contact state is determined to be either open or short, its connectivity does not change over time under noisy environmental conditions, such as temperature, supply voltage, humidity variations, and so on. The reliability of the proposed contact PUF is verified through seven reliability tests defined by the Joint Electron Device Engineering Council (JEDEC) standards. No bit errors occur in any of the 366 chips tested. The bitcell is designed using a digital standard cell structure and scattered throughout the chip embedded in other logic gates. This makes it difficult to find the bitcell position. The proposed contact PUF is fabricated using 0.13- $\mu \text{m}$ CMOS technology. It achieves 49.99% uniqueness and 0.99973 entropy and passes all applicable randomness tests given by the National Institute of Standards and Technology (NIST) SP 800-22.

中文翻译：

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基于无纠错码的接触形成概率的误码率 < 2.3 x 10⁻⁸ 的物理不可克隆函数

本文提出了一种基于接触形成概率的物理不可克隆函数（PUF）。这里的接触是芯片中金属和硅之间的互连层。由于触点设计得比设计规则中给出的尺寸小，因此触点的形成在一定的接触孔尺寸范围内变得随机，并且可以成为 PUF 的随机来源。因此，一旦确定触点状态为开路或短路，其连接性在嘈杂的环境条件（例如温度、电源电压、湿度变化等）下不会随时间变化。所提议的接触式 PUF 的可靠性通过联合电子设备工程委员会 (JEDEC) 标准定义的七项可靠性测试进行了验证。在测试的 366 个芯片中没有任何一个发生位错误。位单元是使用数字标准单元结构设计的，并分散在嵌入其他逻辑门的芯片中。这使得很难找到位单元位置。所提出的接触 PUF 是使用 0.13-$\mu\text{m}$ CMOS 技术制造的。它实现了 49.99% 的唯一性和 0.99973 的熵，并通过了美国国家标准与技术研究院 (NIST) SP 800-22 给出的所有适用的随机性测试。