Abstract
A new technique to detect gate oxide defects has been developed. This method is based on electrochemical wet (ECW) etching of Si in KOH:H 20 electrolyte. Using this method, only leaky poly-Si gates caused by gate oxide defects can be clearly observed. When applying a certain voltage to a Si substrate in KOH:H20 after exposing the polySi gates, normal poly-Si gates can be etched, but poly-Si gates shorted to the Si substrate through gate oxide defects remain unetched because of the anodic oxide which covers the leaky gate. This method has proved to be very effective in obtaining information concerning gate oxide integrity without direct observation of gate oxides, which requires complicated deprocessing and a lot of time. This technique also reveals electrical characteristics of gate oxides which may be difficult to identify by conventional physical analysis.
