Generally speaking, RAW photograph formats (including IIQ files from Phase One cameras), can be exported and saved to JPEG or TIFF formats in any digital photo editor with support of IIQ format. The best way how to achieve iiq to tiff conversion would be to look for software provided or recommended by the manufacturer of your camera. In any case the file resulting from iiq to tiff conversion will be just export picture without any of the metadata saved in the original raw file.
Open IIQ file Open TIFF fileA fully-featured photo manipulation and editing software