Method and system of surface topography measurement for lithography

A method, comprising:

• providing a workpiece to a semiconductor apparatus, the workpiece comprising a material layer, wherein the material layer comprises a plurality of strips, wherein each of the strips includes a first exposure field and a second exposure field, wherein the first exposure field and the second exposure field are configured with different exposure parameters;
• scanning the first exposure field in the plurality of strips along a first route and a second route different from the first route in each of the plurality of strips to generate first topography measurement data;
• scanning the second exposure field in the plurality of strips along the first route and the second route in each of the plurality of strips to generate second topography measurement data;
• and
• generating data of depth of focus for each of the first exposure field and the second exposure field according to the first topography measurement data and the second topography measurement data, respectively.

A semiconductor apparatus, comprising:

• a stage configured to support a workpiece, the workpiece comprising a material layer, wherein the material layer includes a strip having a first exposure field and a second exposure field, wherein the first exposure field and the second exposure field are configured with different exposure parameters;
• a level sensor device over the stage;
• and
• a control unit configured to:
• move the workpiece by the stage to a first site of the semiconductor apparatus;
• scan the first exposure field along a first route and a second route, different from the first route, in the strip to generate first topography measurement data;
• scan the second exposure field along the first route and the second route in the strip to generate second topography measurement data;
• move the workpiece by the stage to a second site of the semiconductor apparatus;
• and
• generate data of depth of focus for each of the first exposure field and each of the second exposure field according to the first topography measurement data and the second topography measurement data.