Feed-forward of multi-layer and multi-process information using XPS and XRF technologies
Methods and systems for feed-forward of multi-layer and multi-process information using XPS and XRF technologies are disclosed. In an example, a method of thin film characterization includes measuring first XPS and XRF intensity signals for a sample having a first layer above a substrate. The first XPS and XRF intensity signals include information for the first layer and for the substrate. The method also involves determining a thickness of the first layer based on the first XPS and XRF intensity signals. The method also involves combining the information for the first layer and for the substrate to estimate an effective substrate. The method also involves measuring second XPS and XRF intensity signals for a sample having a second layer above the first layer above the substrate. The second XPS and XRF intensity signals include information for the second layer, for the first layer and for the substrate.
1. A method of thin film characterization, the method comprising:
measuring first XPS and XRF intensity signals for a sample having a first layer above a substrate, the first XPS and XRF intensity signals including information for the first layer and for the substrate;
determining a thickness of the first layer based on the first XPS and XRF intensity signals;
combining the information for the first layer and for the substrate to estimate an effective substrate;
measuring second XPS and XRF intensity signals for the sample, after forming a second layer above the first layer above the substrate, the second XPS and XRF intensity signals including information for the second layer, for the first layer, and for the substrate; and
determining a thickness of the second layer based on the second XPS and XRF intensity signals, the thickness accounting for the effective substrate.
2. The method of claim 1 , wherein the measuring of the first XPS and XRF intensity signals comprises simultaneously measuring the first XPS and XRF intensity signals.
3. The method of claim 1 , wherein the combining of the information for the first layer and for the substrate comprises combining signals in a global, simultaneous fit by direct methods to estimate the effective substrate.
4. The method of claim 1 , wherein the combining the information for the first layer and for the substrate comprises combining signals in a global, simultaneous fit by model-based methods to estimate the effective substrate.
5. The method according to claim 1 , wherein the information for the first layer and for the substrate comprises intensity data for relevant atomic species of the substrate and the first layer.
6. The method according to claim 1 , wherein the combining comprises applying a model-independent approach based on fundamental atomic sensitivity factors (ASFs).
7. A system for characterizing a thin film, said system comprising:
an X-ray source for generating an X-ray beam;
a sample holder for positioning a sample in a pathway of said X-ray beam;
a first detector for collecting an X-ray photoelectron spectroscopy (XPS) signal generated by bombarding said sample with said X-ray beam; wherein the sample comprises a first layer above a substrate;
a second detector for collecting an X-ray fluorescence (XRF) signal generated by bombarding said sample with said X-ray beam; wherein the bombarding is executed after forming a second layer on the first layer; and
a computing device configured to determine a thickness of the second layer of the sample based on the XPS and XRF signals.