With the advantage of high surface-roughness tolerance, the pillar–concave Cu–Cu direct bonding without chemical-mechanical planarization (CMP) is investigated in detail, including the mechanism of thermal compensation, analysis of roughness, bonding strength, and bonding reliability. With the special design of Cu bond structure, excellent bonding results can be achieved under low thermal budget (150 °C for 1 min, atmosphere) with even high roughness of bonding surface. In addition, the pillar–concave scheme applied to fan-out panel-level package (FOPLP) has been demonstrated, showing the high feasibility of this scheme to realize applications in heterogeneous integration.

中文翻译：

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3-D / 2.5-D异质集成中低温Cu-Cu直接键合的柱-凹结构研究

利用高表面粗糙度公差的优势，对没有化学机械平面化（CMP）的柱形凹面Cu-Cu直接键合进行了详细研究，包括热补偿机理，粗糙度分析，键合强度和键合可靠性。通过特殊的铜键结构设计，在低热预算（150°C，1分钟，大气压）下，即使键合表面具有较高的粗糙度，也可以获得出色的键合效果。此外，已经演示了应用于扇形面板级封装（FOPLP）的支柱-凹面方案，表明该方案在异构集成中实现应用的高度可行性。