can any body explain what is manufacturing grid ,place ment grid, routing grid and what is diffence between them ?and what is the necessity of these ?I think these grids are decided by the fabs ,so on what basis they will decide these grid values?Is these values are same for all different tools (virtuoso,L-Edit,soc Encounter...)?
Manufacturing Grid is given by fab people it depends on the process.. while masking they use this as references lines.
Routing Grid is formed by Tools while routing it forms as rectangles equal to size of grid and and it routes in between that.. see magma docs for further explainations..
Placement grid depend on process.. the standard cell will have equal height. depends on process. the rows are formed using this placement grid and cells are placed in that grid...
Its values are given by the process technology file .tf file or some times in lef file itself..