WaferSense Auto Vibration Sensors (AVS), which are designed like a wafer, can move along the path of an entire wafer, gathering, measuring and showing precise vibration exposure. The AVS is placed in wafer stockers, standard cassettes, or wafer boats that hold 150 wafers in the 200 mm fab.
The AVS can travel through the whole diffusion tool, thus checking vibrations and three-axis accelerations at stocker sites with fans turned on and off. The wireless sensor uses Bluetooth technology to deliver wireless real-time information on tool vibration as it travelled via the semiconductor process.
Engineers were able to examine vibration information and overlay vibration fingerprints using companion software that displays information on a GUI. Finally, the diffusion furnace team finds extreme fan vibrations in wafer storage sites near to the fans that resulted in higher defects and wafer handling issues.
After recognizing the reason for the wafer defects, engineers rectified wafer storage cassettes in order to prevent wafers from moving. The data logging abilities of the AVS enabled the fab to introduce new process control standards and preventative maintenance standards for the tools as well as the engineers.
Source: http://www.cyberopticssemi.com/