METHOD FOR ETCHING A SILICIDED POLY USING FLUORINE-BASED REACTIVE ION ETCHING AND SODIUM HYDROXIDE BASED SOLUTION IMMERSION

摘要

METRO D FOR ETCHING A SILICIDED POLY USING FLUORINE-BASED REACTIVE ION ETCHING ANDSODIUM HYDROXIDE BASED SOLUTION IMMERSIONABSTRACT OF THE INVENTIONA method for removing a silicide poly on an integratedcircuit (IC) chip. Specifically, one embodiment of thepresent invention discloses a method for exposing a gateoxide layer with a fluorine based reactive ion etching (F based RIE) process and immersion in a sodium hydroxide basedsolution. The F-based RIE damages a silicide layer thatcovers a polysilicon gate layer. Damage to the silicidelayer allows for penetration of chemicals to a polysilicongate layer. Immersion of the IC chip in the sodium hydroxidebased solution etches away the polysilicon gate layer and lifts off the silicide layer without altering an underlying gate oxide layer. Also, another embodiment uses a solution including sodium hydroxide and sodium chloride. As such,failure analysis of the gate oxide layer can proceed withoutconcern for damage due to the removal process.