Lithography and OPC friendly triple patterning decomposition method for VIA

ArF immersion lithography is still a key candidate below 10nm node. Many challenges should be overcome when CD shrinks to such a tiny size. In the whole manufacturing flow, triple patterning (TP) is an important process. TP decomposition is used to decompose customers' layout into three individual masks. Each of the decomposed masks can be imaged in a single exposure. Although the TP decomposition method is fully studied, rare research is focused on the influence of decomposition result on other processes, such as lithography, OPC (Optical Proximity correction), etch, etc. Thus, a decomposition result that is unfriendly to other processes may appear. In this paper, we propose a lithography and OPC friendly triple patterning decomposition method. The decomposition is classified into critical decomposition and optional decompositions. The critical decomposition is applied for pitches which are smaller than the minimum pitch of single exposure. The optional decomposition is firstly applied for pitches which are in the range of forbidden pitch, and then applied for pitches in the other ranges. The critical decomposition is assigned the highest priority, and the optional decomposition for the forbidden pitch is assigned the second highest priority, the decomposition for other pitches are assigned lower priorities. The balance process is also improved correspondingly. The results show the number of forbidden pitch can be reduced by 10.8% at most. In addition, the proposed method can be easily extended to suitable for other multiple patterning processes. And the idea of assigning different priorities in the decomposition can be also used for process optimization further.