分子奈米層在半導體矽基金屬化作為擴散阻障層的應用

Application of Molecule Nanolayer as Diffusion Barrier for Silicon-based Metallizations in Semiconductors

因具有低電阻與高電遷移阻抗，半導體導線連線系統已轉向銅製程，然而銅與矽間附著力不佳，且易於高溫下發生原子擴散生成銅矽化合物，導致元件接點劣化。為抑制原子擴散，一般會引入擴散阻障層在銅/矽界面。隨著積體電路微縮發展，以氣相沉積製作之無機阻障層面臨厚度與均勻性的挑戰。分子奈米層以自組裝有機矽烷分子形成約1–2 nm超薄膜，深具發展潛力成為新型阻障層。矽烷分子之結構由水解基團、脂肪鏈與末端官能基團組成，透過調整化學結構可強化對矽基材與銅金屬的附著性與擴散阻障效果。本文簡要回顧相關的文獻，介紹數種具擴散阻障功效的矽烷分子。

Copper has become the mainstream material for interconnect systems in semiconductors due to its low resistivity and high electromigration resistance. However, copper shows poor adhesion to silicon, and Cu-Si compounds are prone to form as a result of atomic interdiffusion at elevated temperatures which degrades the joint’s performance. A diffusion barrier layer is usually introduced at the interface between copper and silicon to suppress atomic interdiffusion. As integrated circuits continuously scale down, inorganic barriers deposited by vapor deposition face challenges in achieving an ultrathin thickness with uniformity and low defect density. Molecule nanolayers (MNLs), formed by self-assembled organosilane molecules, offer strong potential as ultrathin (~1–2 nm) diffusion barriers. These molecules consist of hydrolyzable head groups, alkyl chains, and terminal groups with specific functionality, which firmly bond with the Si substrate and copper metallization, and can be tailored to enhance adhesion and barrier performance through modification of molecular structures. This article briefly reviews related works and introduces several organosilane molecules with potential diffusion barrier efficacy.