Electrostatic discharge sensitivity tests for ISFET sensors

A set of tests using a standard electrostatic discharge (ESD) generator and a test setup to apply ESDs over ISFET-based chemical sensors in a reproduc ible way is proposed. The tests are used to study the ESD sensitivity Of Si O2/Si3N4 gate ISFETs as well as to prove the effectiveness of a designed pr otection system based on an integrated platinum ring electrode and a protec tive element. It is shown that ISFET's show high sensitivity to ESD when th ey are in contact with a solution and discharges are applied to ISFET conta ct pins or when ISFET contact pins are connected to the ground and discharg es are applied to a solution drop deposited on the gate zone. These tests e mulate typical situations occurring while an operator is handling sensors a nd serve to determine in which of these situations it is recommendable for lab personnel to use static control measures like wrist straps to ground la b personnel. These tests in which ISFETs showed maximum sensitivity to ESD were used to study the performance of the designed protection system. (C) 2 001 Elsevier Science B.V. All rights reserved.