Abstract
A wafer-level functionality testing and characterisation system for ISFETs (ion-sensitive field-effect transistor) is realised by means of integration of a specifically designedcapillary electrochemical micro-droplet cell into a commercial wafer prober-station. Thedeveloped system allows the identification and selection of “good” ISFETs at the earlieststage and to avoid expensive bonding, encapsulation and packaging processes for non-functioning ISFETs and thus, to decrease costs, which are wasted for bad dies. Thedeveloped system is also feasible for wafer-level characterisation of ISFETs in terms ofsensitivity, hysteresis and response time. Additionally, the system might be also utilised forwafer-level testing of further electrochemical sensors.
Highlights
Today, well-established microelectronic mass-production techniques are used for the fabrication of microsensors and microsystem components, prices are still high
We report on the development and application of a designed capillary electrochemical micro-droplet cell in combination with a commercial wafer prober-station to realise a wafer-level functionality testing and characterisation system for ISFET devices
To test the functionality of the ISFETs, a buffer droplet of pH 7 was applied to the gate area of the selected ISFET on the wafer by means of the micro-droplet cell, and a set of output and transfer curves has been recorded using a semiconductor parameter analyzer or a home-made ISFET-meter
Summary
Well-established microelectronic mass-production techniques are used for the fabrication of microsensors and microsystem components, prices are still high. Wafer-level testing of electrochemical microsensors, in particular ISFETs (ion-sensitive field-effect transistor) is much more difficult, because a non-electrical external stimulus such as liquid chemical substances should be applied to the gate of this device in order to verify its functionality.
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