While he didn't explicitly coin the phrase, he frequently used it in his music and interviews, contributing significantly to its popularization. He also released mixtapes titled "Dirty South" in the 1990s.
However, it's worth noting that the term "Dirty South" was already in use in the early 1990s to refer to the Southern hip-hop scene in general. It was used to describe the raw, gritty, and sometimes controversial nature of the music and culture coming from the South.
So, while DJ Screw might not have been the first to use the phrase, his adoption of it and its prominence in his work definitely helped solidify its association with the sound and culture he championed.