SPEF Stands for Standard Parasitic Extraction Format.

SPEF file is generated by parasitic extractors like CALIBRE XRC.SPEF is fed to STA tool to do post layout Static Timing Analysis.

SDF stands for Standard Delay Format

SDF is widely used for transferring the Delay information between tools.Normally SDF is used in Pre Layout Static Timing Analysis.


SPEF file describes spice netlist and RC infromation.
After running LVS(LVS correctly), you can generate SPEF file from RC extraction tool(Xcalibre,Calibre-XRC--Mentor Star-RCXT--synopsys) or APR tool.

As for SDF file, it describes cell delay(from synthesis library) and interconnect delay(from SPEF file).
You can generate it from APR tool and PrimeTime(STA analysis tool).
If you want to get accuracy SDF file to do STA analysis.
I recommend you can use rc extraction tool to generate SPEF file and load into PrimeTime to generate SDF file to do STA analysis.