Systems for parsing material properties from within SHG signals
Semiconductor metrology systems based on directing radiation on a wafer, detecting second harmonic generated (SHG) radiation from the wafer and correlating the second harmonic generated (SHG) signal to one or more electrical properties of the wafer are disclosed. The disclosure also includes parsing the SHG signal to remove contribution to the SHG signal from one or more material properties of the sample such as thickness. Systems and methods described herein include machine learning methodologies to automatically classify obtained SHG signal data from the wafer based on an electrical property of the wafer.
1. A system for characterizing a sample, comprising:
a second harmonic generation (SHG) metrology system, the SHG metrology system comprising:
an optical source configured to direct a beam of electro-magnetic radiation to a sample; and
an optical detector configured to detect a Second Harmonic Generation (SHG) signal from the sample,
wherein the detected SHG signal includes:
a first portion; and
a second portion, wherein the second portion is attributed to one or more material properties of the sample; and
a secondary analysis device separate from the SHG metrology system, the secondary analysis device configured to measure the one or more material properties of the sample; and
an electronic processing circuit configured to:
remove the second portion of the detected SHG signal from the detected SHG signal to obtain a parsed SHG signal data comprising the first portion of the detected SHG signal; and
estimate a characteristic of the sample from the parsed SHG signal data.
2. The system of claim 1 , wherein the secondary analysis device comprises at least one of: a reflectometer, a spectroscopic ellipsometer (SE), a CV-IV parametric analyzer, an Inductively Coupled Plasma Mass Spectrometry (ICPMS), Vapor Phase decomposition (VPD)-ICPMS, a Total Reflection X-Ray Fluorescence (TXRF), a Secondary Ion Mass Spectrometry (SIMS), a Rutherford Backscattering (RBS), a Scanning/Tunneling Electron Microscope (SEM/TEM), Atomic Force Microscope (AFM), Brightfield/Darkfield Microscopy, Glow Discharge Optical Emission Spectroscopy (GD-OES), X-Ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), or a microwave detected photoconductive decay (μ-PCD).
3. The system of claim 1 , wherein the one or more material properties of the sample includes at least one of: thickness of one or more layers of the sample or presence of a known artifact.
4. The system of claim 1 , wherein the characteristic of the sample estimated from the parsed SHG signal data includes one or more electrical properties of the sample.
5. The system of claim 4 , wherein the one or more electrical properties of the sample includes at least one of: local surface and subsurface metal; organic or inorganic contaminants; trap charge density; strain or doping levels.
6. The system of claim 1 , wherein the electronic processing circuit is configured to remove the second portion by:
adjusting the detected SHG signal by an amount of SHG signal that is expected from a sample having the measured one or more material properties.
7. The system of claim 6 , wherein adjusting the detected SHG signal comprises dividing the detected SHG signal by an amount of SHG signal that is expected from a sample having the measured one or more material properties.
8. The system of claim 1 , wherein the electronic processing circuit is configured to remove the second portion by:
deconvoluting the detected SHG signal by an amount of SHG signal that is expected from a sample having the measured one or more material properties.