innobackupex with --stream=tar timestamp directory created failed

I was try to create backup with following command

innobackupex --user=… --password=… --stream=tar /var/www/db_backup/ | gzip - > /var/www/db_backup/clo_pps_demo.tar.gz

Here stream as tar and destination directory as /var/www/db_backup/ when execute command backup created clo_pps_demo.tar.gz in dest. directory.

I need timestamp directory to creat back like /var/www/db_backup/TEMP_DIR/clo_pps_demo.tar.gz. But TEMP_DIR i mean timestamp directory not created.

perconna version : 2.3.6
mysql version : 5.6