Thanks for the lectures professor. Since higher metal layers are wider and all metal layers have different design rules like minimum width and length , how could all metals exactly occupy full grid space
Good question, maybe you understood the answer when you watched the rest of the lecture parts, but if not, I will clarify. The Maze Routing, as it is shown here, is very crude. It doesn't take into account all of the very complex features of modern VLSI routing, such as design rules, number of metal layers, etc. The basic idea is that we provide "global routing", which basically maze routes the nets and provides track assignment and then only later provide "detailed routing", which connects the nets according to all constraints. So at the very high level of the grids over here, we really need to only know if there is room to route across this grid cell, and that is usually a function of the number of tracks available vs. those that have already been used (i.e., congestion). During detailed route, the maze routing will be a much smaller scale problem (we're only routing a single GBOX) but with a much more complicated design space, so it will be a bit different.
Thanks for the lectures professor. Since higher metal layers are wider and all metal layers have different design rules like minimum width and length , how could all metals exactly occupy full grid space
Good question, maybe you understood the answer when you watched the rest of the lecture parts, but if not, I will clarify.
The Maze Routing, as it is shown here, is very crude. It doesn't take into account all of the very complex features of modern VLSI routing, such as design rules, number of metal layers, etc. The basic idea is that we provide "global routing", which basically maze routes the nets and provides track assignment and then only later provide "detailed routing", which connects the nets according to all constraints.
So at the very high level of the grids over here, we really need to only know if there is room to route across this grid cell, and that is usually a function of the number of tracks available vs. those that have already been used (i.e., congestion). During detailed route, the maze routing will be a much smaller scale problem (we're only routing a single GBOX) but with a much more complicated design space, so it will be a bit different.