Method and apparatus for lithography in semiconductor fabrication

A lithographic system, comprising:

• a vacuum vessel having a first vacuum pressure;
• a housing positioned in the vacuum vessel and having a second vacuum pressure that is higher than the first vacuum pressure, wherein the housing has an opening;
• a reticle chuck positioned in the housing and having an effective surface for holding a reticle, wherein the effective surface is exposed through the opening;
• an exposure tool configured to generate high-brightness light toward the reticle for reflection;
• and
• a wafer stage configured to support a semiconductor wafer so as to allow the semiconductor wafer to receive the high-brightness light reflected from the reticle;
• wherein the reticle chuck is movable between two boundary lines that are perpendicular to the effective surface, and a width of the opening is greater than a distance between the two boundary lines.

A lithographic system, comprising:

• a vacuum vessel;
• a housing positioned in the vacuum vessel and comprising a top housing member and a lateral housing member extending from the top housing member and terminating at a lower edge which is located on a predetermined plane;
• a reticle chuck positioned in the housing and having an effective surface configured to secure a reticle, wherein the effective surface is located between the predetermined plane and the top housing member;
• and
• a gas delivery assembly positioned within the housing and comprising a gas inlet connected to the top housing member for supplying a flow of gas into the housing.