Upgrade of the CMS Tracker for the High Luminosity LHC

The LHC machine is planning an upgrade program which will smoothly bring the luminosity to about $ 5 \times 10^{34}$cm$^{-2}$s$^{-1}$ in 2028, possibly reaching an integrated luminosity of 3000 fb$^{-1}$ by the end of 2037. This High Luminosity LHC scenario, HL-LHC, will require a preparation program of the LHC detectors known as Phase-2 Upgrade. The current CMS Tracker, including both inner pixel and outer strip systems, is already running beyond design specifications and will not be able to survive HL-LHC radiation conditions. CMS will need a completely new device in order to fully exploit the demanding operating conditions and the delivered luminosity. The upgrade plan includes extending the Pixel Detector in the forward region from the current coverage of $ \lvert \eta \rvert < 2.4 $ to $ \lvert \eta \rvert < 4$, where up to seven forward- and four extension disks will compose the new detector. Additionally, the new outer system should also have trigger capabilities. To achieve such goals, R\&D activities are ongoing to explore options and develop solutions that would allow including tracking information at Level-1. The design choices for the CMS Tracker upgrades are discussed along with some highlights of the R\&D activities.