Lithography options and challenges for sub-45nm node interconnect layers

For the 45nm node and beyond, pitches below 90nm are required. This is becoming very challenging for lithography exposure tools and materials. Currently two main options are being pursued in order to further shrink the pitch: 193nm double patterning and EUV lithography. The status of these two options is discussed in this paper. While shrinking the pitch, also resist thickness and Depth-Of-Focus (DOF) for vias and trenches is reducing rapidly. In order to compensate for this, new materials have become available for patterning interconnects. An overview of these material developments is given in this paper.