Layer separation for e-beam overlay metrology

A computerized system for layer separation for e-beam overlay metrology that includes a processing and memory circuitry (PMC) associated with an X-ray detector and configured to:

• generate a composite X-ray image from an upper layer signal component and a lower layer signal component of an X-ray signal that is detected by an X-ray detector and is generated in response to illuminating a wafer with an e-beam,
• wherein the wafer includes an upper layer composed of a first material and a lower layer composed of a second and different material;
• the upper layer including a plurality of first patterns and the lower layer includes a plurality of second patterns, wherein at least two of the second patterns are at least partially occluded by at least two of the first patterns, and
• wherein the upper layer signal component and the lower-layer signal component represent the respective first and second patterns in the upper and lower layers;
• and wherein the upper layer and lower layer signal components are segregable by unique wavelengths that depend on their respective constituent first and second materials, and
• wherein the composite X-ray image is representative of respective first patterns in the upper layer and respective second patterns in the lower layer including non-occluded patterns;
• each non-occluded pattern corresponding to a second pattern in the lower layer that was at least partially occluded in the wafer and is non-occluded in the X-ray image.

A method for layer separation for e-beam overlay metrology comprising

• a) accommodating a wafer that includes an upper layer composed of a first material and a lower layer composed of a second and different material;
• the upper layer including a plurality of first patterns and the lower layer includes a plurality of second patterns, wherein at least two of the second patterns are at least partially occluded by at least two of the first patterns;
• b) illuminating the wafer with an electron beam (e-beam);
• c) detecting a generated X-ray signal, that results from the e-beam striking the wafer;
• said generated X-ray signal segregating an upper layer signal component and a lower-layer signal component which represent the respective first and second patterns in the upper and lower layers, wherein the upper layer and lower layer signals are segregated by unique wavelengths that depend on their respective constituent first and second materials;
• the method further includes by a processing and memory circuitry (PMC):
• d) obtaining or generating a composite X-ray image from said upper layer signal component and said lower layer signal component, wherein the composite X-ray image is representative of respective first patterns in the upper layer and respective second patterns in the lower layer including non-occluded patterns;
• each non-occluded pattern corresponding to a second pattern in the lower layer that was at least partially occluded in the wafer and is non-occluded in the X-ray image.

A computerized method for layer separation for e-beam overlay metrology that includes a processing and memory circuitry (PMC) associated with an X-ray detector, the method comprising:

• generating a composite X-ray image from an upper layer signal component and a lower layer signal component of an X-ray signal that is detected by an X-ray detector and is generated in response to illuminating a wafer with an e-beam,
• wherein the wafer includes an upper layer composed of a first material and a lower layer composed of a second and different material;
• the upper layer including a plurality of first patterns and the lower layer includes a plurality of second patterns, wherein at least two of the second patterns are at least partially occluded by at least two of the first patterns, and
• wherein the upper layer signal component and the lower-layer signal component represent the respective first and second patterns in the upper and lower layers;
• and wherein the upper layer and lower layer signal components are segregable by unique wavelengths that depend on their respective constituent first and second materials, and
• wherein the composite X-ray image is representative of respective first patterns in the upper layer and respective second patterns in the lower layer including non-occluded patterns;
• each non-occluded pattern corresponding to a second pattern in the lower layer that was at least partially occluded in the wafer and is non-occluded in the X-ray image.

A non-transitory computer readable storage medium tangibly embodying a program of instructions that, when executed by a computer, cause the computer to perform a method for layer separation for e-beam overlay metrology comprising:

• a) accommodating a wafer that includes an upper layer composed of a first material and a lower layer composed of a second and different material;
• the upper layer including a plurality of first patterns and the lower layer includes a plurality of second patterns, wherein at least two of the second patterns are at least partially occluded by at least two of the first patterns;
• b) illuminating the wafer with an electron beam (e-beam);
• c) detecting a generated X-ray signal, that results from the e-beam striking the wafer;
• said generated X-ray signal segregating an upper layer signal component and a lower-layer signal component which represent the respective first and second patterns in the upper and lower layers, wherein the upper layer and lower layer signals are segregated by unique wavelengths that depend on their respective constituent first and second materials;
• the method further includes by a processing and memory circuitry (PMC):
• d) obtaining or generating a composite X-ray image from said upper layer signal component and said lower layer signal component, wherein the composite X-ray image is representative of respective first patterns in the upper layer and respective second patterns in the lower layer including non-occluded patterns;
• each non-occluded pattern corresponding to a second pattern in the lower layer that was at least partially occluded in the wafer and is non-occluded in the X-ray image.

A non-transitory computer readable storage medium tangibly embodying a program of instructions that, when executed by a computer, cause the computer to perform a method for layer separation for e-beam overlay metrology that includes a processing and memory circuitry (PMC) associated with an X-ray detector, the method comprising:

• generating a composite X-ray image from an upper layer signal component and a lower layer signal component of an X-ray signal that is detected by an X-ray detector and is generated in response to illuminating a wafer with an e-beam,
• wherein the wafer includes an upper layer composed of a first material and a lower layer composed of a second and different material;
• the upper layer including a plurality of first patterns and the lower layer includes a plurality of second patterns, wherein at least two of the second patterns are at least partially occluded by at least two of the first patterns, and
• wherein the upper layer signal component and the lower-layer signal component represent the respective first and second patterns in the upper and lower layers;
• and wherein the upper layer and lower layer signal components are segregable by unique wavelengths that depend on their respective constituent first and second materials, and
• wherein the composite X-ray image is representative of respective first patterns in the upper layer and respective second patterns in the lower layer including non-occluded patterns;
• each non-occluded pattern corresponding to a second pattern in the lower layer that was at least partially occluded in the wafer and is non-occluded in the X-ray image.