The Latics defeated Millwall 2-0 at Wembley.
Scharner, who played in the League Cup final during his first stint at Wigan, said: "It's unbelievable. We are in the final.
"The chairman deserves it most, and the supporters.
"In the second half they were trying to get an equaliser but we kept a clean sheet and I'm so happy to reach the final."
"It doesn't matter," he said. "The final is always tough and both teams are very strong."