Stephan was born in
Zürich,
Switzerland. As a youth, he played in the 1997 and 1998
Quebec International Pee-Wee Hockey Tournaments with a team from Zürich. In 2001, he was named the best goaltender at the U18 World Junior Championships. Stephan first played for
EHC Chur and then for the
Kloten Flyers in Switzerland. In 2002, he was named the best rookie in the Swiss Hockey League. Stephan was drafted 34th overall in the second round of the
2002 NHL entry draft by the
Dallas Stars, and is the third highest Swiss drafted in history. He is the fourth Swiss goalie who an NHL team has drafted after
Pauli Jaks,
David Aebischer and
Martin Gerber. Stephan made his first career NHL start on 13 October 2007 against the
Chicago Blackhawks, since both of the Stars' goaltenders —
Marty Turco and
Mike Smith — were injured. Until the Blackhawks tied the game with two seconds remaining in regulation, Stephan had saved all 39 shots and was looking forward to a shutout in his first game. However, the Blackhawks scored again on their first shot in overtime and won the game 2–1. He would go back to the AHL after the game. Before the 08/09 season started, he would learn that he would be backing up Marty Turco. His first win was on 29 October against the
Minnesota Wild — the Stars won 4–2. Stephan left the Stars on 31 July 2009 to sign for
Genève-Servette in Switzerland. After the
2018–19 season, Stephan joined
Lausanne HC on a three-year deal worth CHF 3 million. On 6 February 2023, during his fourth year with Lausanne HC, Stephan announced he would retire from professional hockey after the
2022–23 season, following 22 professional seasons. ==Career statistics==