Ok, its been a long time since I last post something related with this thread, but after a training that I attend and the research and some experiments I got what I needed. I will try to share with you what I learn, it may be useful for other people in this forum.
So, regarding partitioning:
- Everyone in the training told me to stay away from it, it is too complicated and the tool is still not good in this, at least the top-down approach. They told me that if I really do need it, I should go bottom-up. To do bottom-up you basically create your module design as if it was a normal flat design, then in innovus, after everything is ok, you just need to export the .lib (timing files), .def, .lef, and .v files of your design (you can find the commands to do it in the Innovus command reference guide). Then, if you are using a cadence flow, you have all the files you need to use this module as a blackbox on other designs, you just have to add the .lib files to the cadence synthesis tool. If you are using design compiler from synopsys however, you will need to convert the .lib file into a .db file. To do so, just use the synopsys lybrary compiler to do this conversion.
There is another approach when what you need is a structured cell positioning in your design. You can use a structural placement file (.sdp) to tell the tool where to put some cell in the design (you can read more about this in the chapter about structural placement in Innovus user guide). basically this .sdp is a file that tells innovus where to place the cells relative to each others. Because you are able to achieve a very uniform placement using this, the routing will also follow a certain pattern (if you are doing a design with a structure that repeats itself, like in a Tapped Delay Line), which makes propagation timings very uniform across all cells.
And that's it. If you really need a hierarchical design, than I advise you to go bottom-up, the tool works better with it. If all you need is a detailed placement of a part of you circuit, to achieve timings uniformity, than go for structural placement (. sdp file is very easy to create and to understand).
Hope this can be useful for anyone,
Thanks for the help