Detection using semiconductor detector

A method, comprising:

• providing a test wafer comprising a semiconductor detector, wherein the semiconductor detector comprises a first transistor and a second transistor coupled in series, and a gate of the second transistor is a floating gate;
• performing a pre-exposure reading operation on the semiconductor detector;
• impinging electron-beam (e-beam) on the gate of the second transistor of the semiconductor detector;
• performing a post-exposure reading operation on the semiconductor detector;
• and
• adjusting a beam distribution of the e-beam according to data of the pre-exposure reading operation and data of the post-exposure reading operation.

A method, comprising:

• applying a first voltage to a source of a first transistor of a detector unit of a semiconductor detector in a test wafer and applying a second voltage to a gate of the first transistor and a drain of a second transistor of the detector unit, wherein the first transistor is coupled to the second transistor in series, and the first voltage is higher than the second voltage;
• performing a pre-exposure reading operation on the detector unit of the semiconductor detector;
• projecting light of an exposure apparatus to a gate of the second transistor of the detector unit after applying the first and second voltages;
• performing a post-exposure reading operation on the detector unit of the semiconductor detector, wherein the post-exposure reading operation comprises charging the drain of the second transistor to a third voltage different than the second voltage;
• comparing data of the pre-exposure reading operation with the post-exposure reading operation;
• and
• adjusting an intensity of the light based on the compared data of the pre-exposure reading operation and the post-exposure reading operation.