The Senate can impeach federal judges for high crimes and misdemeanors. That power has been exercised extraordinarily rarely. I can think of only one case in my lifetime, where a judge from Mississippi was removed in the 90s IIRC.
I think Congressional oversight of the judiciary has been the very weakest part of the separation of powers doctrine laid out by the founders.
US greatly lacks that separation in between the executive branch and the judiciary for simple reasons:
1. Top tiers judges are nominated by the executive branch, there are no other way up there.
2. For a high tier judge in US, a promotion is effectively a political promotion
3. US law, as I know, has no provisions for disbarring a judge for bad judgement even if it is plainly going against the what is written in the code. Only gross miscarriage of justice (graft, proven act of conspiracy, and 3 or 4 violations of court procedures) allows for impeachment by congress
All of that makes appointing politically aligned judges too attractive for executive branch officials who want to extend their powers through them
Be impeached or subject to other means of removal, if you'll accept this Yale Law Review article:
The Constitution authorizes the impeachment of federal judges, but it nowhere says that they can be removed only through impeachment. Nor do the Constitution’s relevant provisions easily lend themselves to any such reading.