The Effect of the Polymer Coating on Residual Current of Mos Devices

The influence of polyimides on seniconductor devices has been studied by measuring the residual current in an MOS test device in which the gate position was0 incompletely covered by the gate electrode. Residual currents were found to be a function of the heat-treatment temperature of the coated polyamic acid. At first the residual current decreased with increasing heat-treatment temperature, untill a minimum value was reached, then it increased with temperature. These phenomena are d´iscussed with respect to the physical and chemical properties of the polyimide, e. g. flowing temperature, adhesion characteristics, decomposition temperature, impurities, and amount of unreacted amidic acid groups. Unreacted amidic acid groups and decomposition of polyimide caused a high residual current, while good adhesion of the polyimide to the MOS device brought about a low residual current.