Modification and Characterization of Interfacial Bonding for Thermal Management of Ruthenium Interconnects in Next-Generation Very-Large-Scale Integration Circuits
Modification and Characterization of Interfacial Bonding for Thermal Management of Ruthenium Interconnects in Next-Generation Very-Large-Scale Integration Circuits
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DOI：
10.1021/acsami.1c20366
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发表时间：
2022-01-31
影响因子：
9.5
通讯作者：
Watanabe, Takanobu
中科院分区：
文献类型：
--
作者：
Zhan, Tianzhuo;Sahara, Keita;Watanabe, Takanobu
钌可以在下一代超大规模集成电路（VLSI）中取代铜互连。然而，必须优化Ru互连线与周围介质之间的界面键合，以降低热管理的热边界电阻（TBR）。在本研究中，采用不同的粘附层来修饰Ru/SiO2界面上的结合。利用频域热反射技术测量了薄膜堆的总热阻。与普通Ti和Ta粘附层相比，含氮量高的TiN和TaN显著降低了Ru/SiO2界面的TBR。粘附层厚度在2 ~ 10 nm范围内，对TBR的影响较小。深埋层和界面的硬x射线光电子能谱定量地揭示了TBR的降低是由于界面两侧原子之间的电子转移导致的TaN粘附层附近界面的键合增强。三维电热有限元模拟结果表明，降低总热压比可显著降低Ru互连层的温升。我们的研究结果强调了TBR在VLSI电路热管理中的重要性，并为Ru互连取代当前基于cu的互连铺平了道路。
Ruthenium may replace copper interconnects in next-generation very-large-scale integration (VLSI) circuits. However, interfacial bonding between Ru interconnect wires and surrounding dielectrics must be optimized to reduce thermal boundary resistance (TBR) for thermal management. In this study, various adhesion layers are employed to modify bonding at the Ru/SiO2 interface. The TBRs of film stacks are measured using the frequency-domain thermoreflectance technique. TiN and TaN with high nitrogen contents significantly reduce the TBR of the Ru/SiO2 interface compared to common Ti and Ta adhesion layers. The adhesion layer thickness, on the other hand, has only minor effect on TBR when the thickness is within 2-10 nm. Hard X-ray photoelectron spectroscopy of deeply buried layers and interfaces quantitatively reveals that the decrease in TBR is attributed to the enhanced bonding of interfaces adjacent to the TaN adhesion layer, probably due to the electron transfer between the atoms at two sides of the interface. Simulations by a three-dimensional electrothermal finite element method demonstrate that decreasing the TBR leads to a significantly smaller temperature increase in the Ru interconnects. Our findings highlight the importance of TBR in the thermal management of VLSI circuits and pave the way for Ru interconnects to replace the current Cu-based ones.