Here are the details from Movieline's sister site Deadline:
After almost 3 months of negotiations with series producer Warner Bros TV, Big Bang leads Johnny Galecki, Kaley Cuoco, and Jim Parsons have agreed to a major salary hike that would bring the trio's salaries to $200,000 an episode for the upcoming fourth season, up from about $60,000 last season. The salaries will rise to $250,000 in Season 5, then $300,000 in Season 6 and 350,000 in Season 7. Additionally, they will each receive .25 point of the series' lucrative backend and will be paid $1+ million as an advance against it now and another $1 million in Season 7. That effectively adds another $50,000 to their per-episode paycheck over the life of the deal.
Still not Charlie Sheen-level bank, but you're getting there. Good work, gang.