A test structure and method thereof for determining a defect in a sample of semiconductor device includes at least one transistor rendered grounded. The grounded transistor is preferably located at at least one end of a test pattern designed to be included in the sample. When the test structure is inspected by charged particle beam inspection, the voltage contrast (VC) of the transistors in the test pattern including the grounded transistor is observed for determination of the presence of defect in the sample.