The ISE Design Suite Bitgen tool generates bitstreams.
In the Vivado Design Suite, use the write_bitstream Tcl command. For more information, see:
• Vivado Design Suite Tcl Command Reference Guide (UG835) [Ref 4]
• Vivado Design Suite User Guide: Programming and Debugging (UG908) [Ref 5]
Note: The BitGen command options are Tcl properties in the Vivado Design Suite. See this link in the Vivado Design Suite User Guide: Programming and Debugging (UG908) [Ref 5] for details on the new properties and values.