The amount is largely enough for a family of 5 with only one partner working, relative to where they live (DC in this case). I think $250K-$300 + Housing + Transport (I suppose for their safety?) is largely enough.
I don't think increasing pay would reduce corruption. A corrupt person is a corrupt person regardless. If you paid a corrupt justice a million dollars a year, why would they not decide to make it 5 million on the side?
After that it's up to the person in question...