How to take sitecollection backup in sharepoint online

Hi,

I need to create a SharePoint online site with same UI and Functionality of another SharePoint online site where I am having site collection admin permissions, can any one guide me to take a backup from source site and restore in destination site as a site collection.

Kindly let me know if any one already gone through this.

Thanks

Prabhat.

Madhu Prabhat