This article presents a cryptographic key protection technique from physical security attacks through Si-backside of IC chip. Flip-chip packaging leads to a serious security hole that allows emerging backside physical security attacks. The proposed backside buried metal (BBM) structure forming a meander wire pattern on the Si-backside detects unexpected disconnection of the meander and warns the malicious attempts to expose a vulnerable Si substrate. Moreover, the BBM meander also shields key information of cryptographic circuit from both passive side-channel attacks and active laser fault injection as well. Unlike other conventional laminate-based protection, this backside monolithic approach does not require frontside wiring resources or additional packaging layers, resulting in only 0.0025% size-overhead. The BBM meander was formed on the backside of a 0.13-μm\mu \text{m} CMOS cryptographic chip by wafer-level via-last BBM processing.

中文翻译：

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针对倒装芯片器件物理安全攻击的硅背面保护电路


本文提出了一种通过 IC 芯片的 Si 背面防止物理安全攻击的加密密钥保护技术。倒装芯片封装会导致严重的安全漏洞，从而允许新兴的背面物理安全攻击。所提出的背面埋金属 (BBM) 结构在硅背面形成曲折线图案，可检测曲折线的意外断开，并警告暴露易受攻击的硅基板的恶意尝试。此外，BBM 蜿蜒还可以保护密码电路的关键信息免受被动侧信道攻击和主动激光故障注入的影响。与其他传统的基于层压板的保护不同，这种背面单片方法不需要正面布线资源或额外的封装层，因此尺寸开销仅为 0.0025%。 BBM 曲折是通过晶圆级后通孔 BBM 处理在 0.13-μm\mu \text{m} CMOS 加密芯片的背面形成的。