Final Data Capture.

Once the fee, any correspondence, and/or drawings are matched with the application and all requirements have been met for issuance as a patent, the application is then forwarded to the Final Data Capture (FDC) stage of the process . An "Issue Notification" would be the next step in the processing of a patent and is mailed approximately 3 weeks prior to the issue date of the patent.

Source: U.S. Patent and Trademark Office.