The first MIRI paper to use the term is "Aligning Superintelligence with Human Interests: A Technical Research Agenda" from 2014, the original version of which appears not to exist anywhere on the internet anymore, replaced by the 2017 rewrite "Agent Foundations for Aligning Machine Intelligence with Human Interests:A Technical Research Agenda". Previous papers sometimes offhandedly talked about AI being aligned with human values as one choice of wording among many.

Edit: the earliest citation I can find for Russell talking about alignment is also 2014.

I recall Eliezer saying that Stuart Russell named the 'value alignment problem', and that it was derived from that. (Perhaps Eliezer derived it?)

I have just asked Stuart Russell this question at an event I co-hosted featuring him as the speaker. He says he did not coin the name of the problem. Still unclear who did, but the conceptualization of the problem goes at least as far back as Norbert Weiner in the 1960s and likely further back still.