Steiner　minimum　tree　(SMT)　is　an　optimized　model　for　solving　the　routing　problem　of　a　multipin　net　in　very　large-scale　integrated　circuits.　As　the　appearance　of　various　obstacles　on　chips,　the　obstacle-avoiding　problem　has　attracted　much　attention　in　recent　years.　Meanwhile,　since　interconnect　delay　plays　a　major　role　in　chip　delay,　timing　analysis　is　another　critical　problem　worthy　of　consideration　when　constructing　an　SMT.　Furthermore,　the　introduction　of　the　X-architecture　allows　for　better　utilization　of　routing　resources.　In　this　article,　a　timing-driven　obstacle-avoiding　X-architecture　Steiner　minimum　tree　algorithm　with　slack　constraints　(TD-OAXSMT-SC)　is　proposed　to　consider　obstacle-avoiding,　timing　slack　constraints,　and　X-architecture　simultaneously　for　the　first　time.　The　TD-OAXSMT-SC　algorithm　consists　of　four　major　stages:　1)　in　the　routing　tree　initialization　stage,　this　article　constructs　an　X-architecture　Prim-Dijkstra　spanning　tree　as　the　initial　routing　tree　with　minimum　total　delay;　2)　in　the　particle　swarm　optimization　(PSO)-based　routing　tree　iteration　stage,　a　novel　discrete　PSO　algorithm　based　on　genetic　operators　is　proposed　to　obtain　a　high-quality　routing　tree;　3)　in　the　routing　tree　standardization　stage,　two　effective　standardization　strategies　are　proposed　to　obtain　a　routing　tree　that　satisfies　both　obstacle-avoiding　and　timing　slack　constraints;　and　4)　in　the　routing　tree　optimization　stage,　the　connection　of　interconnected　wires　is　optimized　in　a　global　manner,　thus　obtaining　an　optimized　routing　tree.　Experimental　results　show　that　the　proposed　TD-OAXSMT-SC　algorithm　outperforms　the　state-of-the-art　methods　in　routing　quality　with　slack　constraints.　©　2013　IEEE.