Aluminium-Scandium as bondpad chipmetallisation for copper wire bonding

在这个项目中，它的目的是处理和调查的钪合金作为替代芯片金属化铜线键合。钪含量为0.1至0.3%的铝合金在室温下显示出高达140-200 MPa的增加的屈服强度，而纯铝的屈服强度为20 MPa。钪是一种合金元素，其形成粒径小于10 nm的耐热球形Al 3Sc沉淀。由于Al基体与Al_3Sc颗粒之间存在1.9%的晶格失配，析出相提高了强度并抑制了晶粒长大过程，在超声引线键合过程中，所用的纯Al、AlSi_1和AlSi_1Cu_（0.5）合金倾向于通过动态再结晶和动态回复而发生软化。通过改变键合力和超声功率，研究了1-5 μm厚AlSc层在与铜丝超声键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，预期Al飞溅减少。研究结果将有助于改善铜线键合工艺，减少缩孔。

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.