If you have the 3D Analyst Extension, you can run the Raster Domain GP tool to create the polygon feature class in a geodatabase or shapefile. If you don't have the 3D Analyst extension but do have the Spatial Analyst extension, then you can 1. Multiply the raster by 0 to create a constant value raster using the Raster Calculator (integer cell type) 2. Convert the output from Step 1 to a polygon using the Raster to Polygon GP tool. Hope this helps!
