Can I backup my iphone using my personal hotspot?

No device can use its own hotspot. Only other devices can connect to the hotspot to share the hosting device’s internet connection. If your phone is sharing it’s cellular data internet connection, it can neither connect to its own hotspot, nor can it backup as it itself must have a WiFi connection for iCloud backup.

You can't. The phone needs to be connected to a WiFi network in order to back up to iCloud.