Granted Patent
Utility
US 6,228,541 · App. 09/292,936
Phase-shifting photomask blank, phase-shifting photomask, method for producing them and apparatus for manufacturing the blank
Inventors:
Akihiko Isao, Susumu Kawada, Tsuneo Yamamoto, Jun Amano, Ryoichi Kobayashi, Nobuyuki Yoshioka
Patented Case
View Patent ↗
Granted: May 8, 2001
Filed: Apr 16, 1999
Inventors
Akihiko Isao
Susumu Kawada
Tsuneo Yamamoto
Jun Amano
Ryoichi Kobayashi
Nobuyuki Yoshioka
Assignees (at issue)
ULVAC Coating Corporation
MITSUBISHI ELECTRIC CORPORATION
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.