Aluminium-Scandium as bondpad chipmetallisation for copper wire bonding

在这个项目中，它打算加工和研究铝钪合金作为铜线键合的替代芯片金属化。在室温下，与纯铝的20 MPa相比，钪含量为0.1 ~ 0.3%的铝合金的屈服强度增加了140 ~ 200 MPa。钪是一种合金元素，可形成晶粒尺寸小于10 nm的耐热球形al3c析出物。由于al基体与al3c颗粒之间存在1.9%的晶格错配，析出物提高了强度，抑制了晶粒的生长过程。在超声波线接过程中，使用的纯铝、AlSi1和AlSi1Cu0,5合金容易发生动态再结晶和动态恢复的软化。这些软化过程可以被极细的al3sc沉淀所抑制。计划通过不同的结合力和超声功率来研究1-5 μ m厚的alsc层在与铜线的超声结合过程中的变形和软化行为。此外，当使用AlSc作为芯片金属化时，预计会减少al飞溅。该结果将有助于通过减少凹坑来改善铜线的粘接工艺。

In this project it is intended to process and investigate an Aluminium-Scandium alloy as an alternative chip-metallisation for copper wire bonding. Aluminium alloys with a content of 0.1 to 0.3 % Scandium show an increased yield strength of up to 140-200 MPa compared to 20 MPa for pure aluminium at room temperature. Scandium is an alloying element which forms heat resisting spherical Al3Sc-precipitattions with particle sizes of less than 10 nm. Resulting from a lattice mismatch of 1.9% between Al-matrix and the Al3Sc-particles, the precipitations improve the strength and inhibit grain growth processes.It is known that in ultrasonic wire bonding process the used pure Aluminium, AlSi1 and AlSi1Cu0,5 alloys tend to undergo softening by dynamic recrystallization and dynamic recovery. These softening processes can be inhibited by the very fine Al3Sc-precipitations.It is planned to investigate the deformation- and softening behavior of 1-5 µm thick AlSc-layers during ultrasonic bonding with copper wire by varying bonding force and ultrasonic power. Additionally, a reduction of the Al-splashing when using AlSc as chipmetallisation is expected. The results will help to improve the copper wire bonding process by reducing cratering.