Title :
Integrated temperature microsensors for characterization and optimization of thermosonic ball bonding process
Author :
Mayer, Michael ; Paul, Oliver ; Bolliger, Daniel ; Baltes, Henry
Author_Institution :
Phys. Electron. Labs., Zurich, Switzerland
fDate :
6/1/2000 12:00:00 AM
Abstract :
A novel ball bond process optimization method based on the thermal response of an integrated aluminum microsensor is reported. The in situ temperature during ball bonding is measured and analyzed. The ultrasonic period shows distinct stages corresponding to scrubbing of the ball on the pad, intermetallic bond growth, and ball deformation by ultrasonic softening. A peak of the signal indicates the end of interconnection growth. This can be used for bond time optimization. When optimizing bonding force, the sensor signal correlates with ball shear strength. Using this method, bonding force process windows can be determined by on-line measurements. A test measurement shows that at a chip temperature of 34°C, the bonding force optimized by the microsensor method is 260 mN whereas it is 252 mN when using conventional shear testing for optimization. In summary, the method produces a wealth of new insights in transient thermal phenomena of the ball bonding process and promises to simplify the evaluation of process windows
Keywords :
aluminium; integrated circuit bonding; integrated circuit manufacture; integrated circuit measurement; integrated circuit packaging; lead bonding; microsensors; process monitoring; temperature sensors; ultrasonic bonding; 34 C; Al; ball shear strength; bond time optimization; bonding force optimisation; bonding force process windows determination; diagnostic tool; in situ temperature measurement; integrated Al microsensor; integrated temperature microsensors; interconnection growth; intermetallic bond growth; process characterization; thermosonic ball bonding process; transient thermal phenomena; ultrasonic period; wire bonding; Aluminum; Bonding forces; Force measurement; Intermetallic; Microsensors; Optimization methods; Semiconductor device measurement; Temperature; Testing; Ultrasonic variables measurement;
Journal_Title :
Components and Packaging Technologies, IEEE Transactions on
DOI :
10.1109/6144.846780
