Novel solder structures for high reliability flip chip applications - Scaling to high-density applications

随着技术的普及（智能手机、智能手表、医疗监控）、生活方式（家庭助理）和交通方式（辅助和自动驾驶），微电子行业开始开发功能越来越强大、越来越可靠、体积越来越小、功耗更低、成本更有竞争力的系统。这些系统的核心是由半导体芯片组成的网络，这些芯片必须相互连接，并与外界相连。倒装芯片技术使用短而微小（人类头发大小）的金属结构，是实现这种连接的前沿手段，可以达到最高的密度和性能。尽管有这样的能力，倒装芯片技术必须继续发展，以便与系统需求保持同步。小型化是关键的焦点。随着密度的增加，结构变得更小，平衡抵消问题变得更加困难——保持电气完整性的解决方案（使用铜代替焊料，或改变焊料成分）是以牺牲机械完整性为代价的。我们的发明通过提出一种在整个倒装芯片互连过程中实际变化的独特结构来解决这种平衡行为。最初的异质结构是通过对已知的用于生产焊料互连的制造方法的合理调整来生产的。这种结构增加了组装过程中关键点的机械阻力，然后在组装结束之前进行改变，从而产生最终的均匀焊料结构，并具有优化的电气性能。我们已经展示了合理的微型几何形状（150微米）的结构和行为，但认识到需要缩小到未来一代所需的尺寸（50微米）。我们提出这个项目是为了将结构和制造方法发展到这个较小的规模。项目的成功将使加拿大的创新扩大微电子互连技术的范围。

The proliferation of technology on our persons (smart phones, smart watches, medical monitoring) and within our modes of living (home assistants) and transportation (aided and autonomous driving) incite the microelectronics industry to develop systems that are increasingly powerful and reliable yet ever compact with lower power consumption and competitive cost. At the heart of these systems is the network of semiconductor chips that must connect with each other and to the outside world. Flip chip technology, using short, tiny (human hair size) metallic structures, is the leading edge means to effect such connections at the highest density and performance possible. Despite such capability, flip chip technology must continue to evolve in order to keep in step with system demands. Miniaturization is a key focal point. As densities increase and the structures are even tinier, it becomes more difficult to balance counteracting issues - solutions to maintain electrical integrity (using copper instead of solder, or changing the solder composition) come at the expense of mechanical integrity. Our invention resolves this balancing act by proposing a unique structure that actually changes during the overall flip chip interconnection process. An initially heterogeneous structure is produced using reasonable adaptations to the known manufacturing methods for producing solder interconnections. This structure increases mechanical resistance at critical points in the assembly process then changes before the end of assembly to create a final, homogeneous solder structure with optimized electrical properties for operation. We have demonstrated the structure and behavior at reasonably miniature geometries (150 micrometers) but recognize the need to scale down to the size (50 micrometers) required of future generations. We propose this project to evolve both the structure and its manufacturing methods to this smaller scale. Project success will enable a Canadian innovation to extend the reach of microelectronic interconnection technology.