Above is an example of a blocked etch macro defect identified by EAGLEview where the semiconductor wafers were rotated from their normal semiconductor wafer position on an etch tool. The flat edge of the clamp covered the semiconductor wafers and then these areas did not receive a complete etch.
Blocked Etch defects are typically due to clamp-ring polymer delamination from plasma etch tools. These semiconductor wafer defects are caused by polymer build up on the etcher clamp ring that relocates laminate materials into the wafer placement area. Etch is blocked by a layer of detached polymer film. You can see in some examples above, the semiconductor wafer defect may appear to be identical and affect multiple wafers in a lot or even multiple lots.