How can I draw a solid spiral?

Well, using inventor, create two sketches, one following your spiral or the direction of it, the other showing the profile. Then hit sweep, select the profile, then the direction. Bang! Spiral.

Thank you, but I meant using Auto-cad.

Please post your questions in the right forum - for AutoCAD-related questions there is the "AutoCAD" forum.
 
To answer your question - there is the "Related CAD tip" #836 - just below the postings.

I apologize for the mistake and thank for the advises.

you can draw a solid spiral by drawing helix and  modifying  it and sweep command, to draw helix just write helix in command line, everything will follow...