MASK HAVING IMPLANT STOPPING LAYER
Methods of forming a mask for implanting a substrate and implanting using an implant stopping layer with a photoresist provide lower aspect ratio masks that cause minimal damage to trench isolations in the substrate during removal of the mask. In one embodiment, a method of forming a mask includes: depositing an implant stopping layer over the substrate; depositing a photoresist over the implant stopping layer, the implant stopping layer having a density greater than the photoresist; forming a pattern in the photoresist by removing a portion of the photoresist to expose the implant stopping layer; and transferring the pattern into the implant stopping layer by etching to form the mask. The implant stopping layer may include: hydrogenated germanium carbide, nitrogenated germanium carbide, fluorinated germanium carbide, and/or amorphous germanium carbon hydride (GeHX), where X includes carbon. The methods/mask reduce scattering during implanting because the mask has higher density than conventional masks.
1 . A mask comprising:
an implant stopping layer over a substrate,
wherein the implant stopping layer includes at least one of hydrogenated germanium carbide, nitrogenated germanium carbide, fluorinated germanium carbide and amorphous germanium carbon hydride (GeHX), where X includes carbon; and
a photoresist over the implant stopping layer.
2 . The mask of claim 1 , wherein the implant stopping layer has a density greater than the photoresist.
3 . The mask of claim 1 , wherein the implant stopping layer prevents doping of the substrate during a halo, extension, deep source/drain ion implantation process.