Second-harmonic generation for critical dimensional metrology
Systems and methods are disclosed for using second-harmonic generation of light to monitor the manufacturing process for changes that can affect the performance or yield of produced devices and/or determining critical dimensions of the produced device. A sample characterization system directs light onto a sample to produce second harmonic generation (SHG) signals and a detector generates detected SHG signals in response to receiving second harmonic generation (SHG) signals from the sample. A hardware processor receives detected SHG signals and determines a geometric feature of the sample or a variation in the geometric feature of the sample based on the detected SHG signals.
1 . A system for characterizing a sample using second harmonic generation, the system comprising:
a sample holder configured to support a sample;
at least one optical source configured to direct a light beam onto the sample to produce second harmonic generation (SHG) signals;
an optical detection system comprising at least one optical detector configured to receive the SHG signals emitted from the sample and generate detected SHG signals;
one or more hardware processors in communication with the optical detection system, the one or more hardware processors configured to:
receive at least one detected SHG signal; and
determine a geometric feature of the sample or a variation in the geometric feature of the sample based on the at least one detected SHG signal;
identify an unplanned variation in the geometric feature of the sample; and
output an indication of the unplanned variation,
wherein the geometric feature comprises a lateral dimension comprising a width or length for one or more semiconductor devices or part of one or more semiconductor devices that are either completed or yet to be completed.
2 . The system of claim 1 , wherein the geometric feature of the sample is determined at least in part based on a mapping of the detected SHG signals with geometric features of one or more structures on the sample that are either completed or yet to be completed.
3 . The system of claim 1 , wherein the one or more hardware processors receives the at least one detected SHG signal after a first fabrication step performed on the sample.
4 . The system of claim 3 , wherein the system is included in-line in a fabrication system.
5 . The system of claim 4 , wherein the first fabrication step is a step in a fabrication process performed by the fabrication system.
6 . The system of claim 4 , wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a sample processing tool in the fabrication system to adjust the unplanned variation in the sample.
7 . The system of claim 6 , wherein the one or more hardware processors are configured to output the indication of the unplanned variation to the sample processing tool used for performing a second fabrication step on the sample after the first fabrication step, to adjust the unplanned variation in the sample.
8 . The system of claim 1 , wherein the one or more hardware processors are configured to output an indication of the unplanned variation to a user via a user interface of the system.
9 . The system of claim 1 , wherein the geometric feature comprises a critical dimension for one or more semiconductor devices or part of one or more semiconductor devices that are either completed or yet to be completed.
10 . The system of claim 1 , wherein the one or more hardware processors are configured to determine the geometric feature of the sample based on the at least one detected SHG signal.
11 . The system of claim 1 , wherein the one or more hardware processors are configured to determine a variation in the geometric feature of the sample based on the at least one detected SHG signal.