New high repeatability wafer geometry measurement technique for full 200mm and 300mm blank wafers

New metrology technique for measuring the free shape of a patterned 300mm wafer held vertically

“…The newly invented phase measuring technique: Wave Front Phase Imaging (WFPI), is based on registering the intensity distribution of the same field-of-view (FoV) at two different optical planes of the reflected light from the silicon wafer. This can be done by either having a single camera on a linear translation stage and moving the camera a short distance to acquire both intensity images, or by splitting the light and guiding the rays onto two different cameras located at different distances away from the silicon wafer being imaged 6 .…”

“…The light will be reflected off the silicon wafer surface and carry the phase change (ϕ ≠ 0) that is attributable to the surface topography only. The reflected light beam with ϕ ≠ 0 will then pass through the main lens and then onto the image sensor, or two image sensors if a dual camera system is used, to acquire the two intensity images at two different distances away from the silicon wafer 6 .…”

New wave front phase sensor used for 3D shape measurements of patterned silicon wafers

“…The light will be reflected off the silicon wafer surface and carry a phase change (ϕ ≠ 0) that is attributable to the surface topography. The reflected light beam with ϕ ≠ 0 will the pass through the main lens and then onto the image sensor, or two image sensors if a dual camera sensor is used, to acquire the two intensity images at two different distances away from the silicon wafer 13 .…”

“…A special algorithm is used to calculate the phase change based on these two intensity images. The surface phase map is proportional to the relative surface height map 13 . A WFPI system acquires wafer shape maps with spatial resolution of 65µm with an optical limitation of 3.2µm if higher pixel image sensor arrays are added 14 .…”

New technique for measuring free-form wafer shape for feed-forward overlay corrections

“…The newly invented phase measuring technique: Wave Front Phase Imaging (WFPI), is based on registering the intensity distribution of the same field-of-view (FoV) at two different optical planes of the reflected light from the silicon wafer. This can be done by either having a single camera on a linear translation stage and moving the camera a short distance to acquire both intensity images, or by splitting the light and guiding the rays onto two different cameras located at different distances away from the silicon wafer being imaged 4 .…”