Microstructure Characterisation of a Microprocessor Wire Bonding with EBSD
Ball bonding is a type of wire bonding, commonly used for electrical interconnections in semiconductor devices.
Overview of the selected microprocessor: micro-XRF map acquired with M4 TORNADO.
Ball bonding is a type of wire bonding commonly used for electrical interconnections in semiconductor devices. A weld is created between the gold ball and the surface of the chip using heat, static pressure and ultrasonic energy.
Optimum bonding settings are tricky to design because of the interactions between process variables. EBSD analysis on wire bonding is the perfect tool to help understand device failure by identifying structural changes or deformation at metal interconnects. Combined EDS/EBSD analysis enables:
- simultaneous chemical and microstructural characterization of different layers
- evaluate crystal formation and growth
- localize plastic strain
- calculate the amount of twin boundaries
- determine grain size
- reveal amorphous material and cavity
样品是准备EBSD分析using broad ion beam milling. BSE image of the cross-section preparation using Leica TXP and TIC3X instruments.
Orientation contrast image acquired with ARGUS imaging detector. It reveals the microstructure, and despite some curtaining induced by ion milling, the sample is well prepared; internal strain in the gold bond is clearly visible by ARGUSTM color-coded orientation contrast.
EBSD orientation distribution map of the heat affected gold bond. Very high indexing rate (>95%) is achieved at fast speed measurement. No carbon coating was applied. Grain size vary from 200 nm to 22 µm.
High concentrations of dislocations and low angle boundaries in the gold bond are revealed with the low angle misorientation distribution map (or kernel average misorientation map). The influence of broad ion milling polishing is negligible for misorientation distribution greater than 0.5°.