Evaluation of wet-developable KrF organic BARC to improve CD uniformity for implant application

Abstract

As integrated circuit manufacturing moves towards smaller feature sizes, ion implant photo levels are becoming critical layers with lithography demands as tight as 180 nm line/space patterning capability. Advanced materials are required for junction levels to improve the critical dimension (CD) control and resolution. Dyed KrF resists are reaching the limit in their ability to control CD variation due to parasitic light reflections from the underlayer. The use of a bottom anti-reflective coating (BARC) under KrF resists reduces the reflective effect from the oxide substrate, leading to better CD control. Unfortunately, a standard organic BARC that requires plasma etch before implantation can cause silicon substrate oxidation damage as well as increased wafer cost due to additional process steps. The use of a new developer-soluble organic BARC shows an advantage in optics without degrading the underlying substrate before implantation. The advantage of using an ESCAP resist in combination with a wet-developable BARC over the single resist layer scheme has been clearly demonstrated and the system is well adapted to ion implant layers for 65 nm technology.