Hybrid X-ray and optical metrology and navigation
A method of characterizing a device under test (DUT) includes illuminating the DUT with a broadband optical beam within an optical field of view (FOV), illuminating the DUT with an X-ray beam within an X-ray FOV overlapping the optical FOV, and concurrently acquiring X-ray metrology information, e.g., one or more X-ray images utilizing various modalities, such as absorption, phase contrast difference, darkfield, small angle X-ray scattering (SAXS) and/or fluorescence, from the X-ray FOV and a plurality of optical images of the optical FOV, each of the optical images corresponding to respective selected wavelengths of the broadband optical beam from each of ultraviolet, visible, and infrared wavelengths, for example including deep ultraviolet, near infrared, or short-wavelength infrared wavelengths. The DUT may be one or more substrates, e.g., stacked, and include electronic devices such as three-dimensional integrated devices.
1 . A method of characterizing a device under test (DUT), the method comprising:
illuminating a region of the DUT with a broadband optical beam within an optical field of view (FOV) at the region;
illuminating a portion of the region of the DUT with an X-ray beam within an X-ray FOV at the portion of the region, the X-ray FOV being smaller than or equal to and overlapping the optical FOV;
concurrently acquiring an X-ray image of the X-ray FOV and a plurality of optical images of the optical FOV, each of the plurality of optical images corresponding to respective selected wavelengths of the broadband optical beam, the selected wavelengths comprising at least one wavelength from each of the ultraviolet (UV), visible (VIS), and infrared (IR) portions of the optical spectrum; and
determining structural properties of the DUT through scatterometry methods using the X-ray image in combination with the plurality of optical images.
2 . The method of claim 1 , wherein acquiring the X-ray image comprises performing refraction imaging by measuring phase object differences, and collecting small angle scattering imaging using the X-ray beam in transmission mode to acquire an X-ray refraction image or a darkfield image.
3 . The method of claim 1 , further comprising:
generating models for three-dimensional structure using the X-ray image and the plurality of optical images through multi-parameterization comprising optical figures of merit (FOM) utilizing hyperspectral imaging (HSI).
4 . The method of claim 1 , further comprising:
generating models for three-dimensional structure using the X-ray image and the plurality of optical images through multi-parameterization comprising an X-ray fluorescence interference field.
5 . The method of claim 1 , further comprising:
generating models for three-dimensional structure using the X-ray image and the plurality of optical images through multi-parameterization comprising X-ray phase shift and small angle X-ray scattering (SAXS) from dark field in transmission mode.
6 . The method of claim 1 , further comprising:
switching between a higher magnification and a lower magnification by switching between the X-ray FOV and the optical FOV.
7 . The method of claim 1 , wherein the DUT is divided into unit areas of analysis, and wherein the method further comprises:
generating, for each of the unit areas of analysis, an X-ray and optical spectral distribution using the X-ray image and the plurality of optical images, the unit areas of analysis being pixels, regions of interest (ROIs), whole dies, or fractions of a die.
8 . The method of claim 1 , wherein the scatterometry methods using the X-ray image in combination with the plurality of optical images comprise reducing a set of floated parameters using the X-ray image, and matching spectra of the plurality of optical images using the reduced set of floated parameters.
9 . The method of claim 2 , further comprising:
acquiring an X-ray fluorescence image concurrently with acquiring the X-ray image and the plurality of optical images.
10 . The method of claim 7 , further comprising:
comparing equivalent areas across different portions of the DUT using spectral matching and pixel binning to increase signal-to-noise ratio.
11 . A system for characterizing a device under test (DUT), the system comprising:
a broadband optical imaging system comprising a broadband optical source configured to illuminate a region of the DUT with a broadband optical beam within an optical field of view (FOV), and an optical detector having the optical FOV; and
an X-ray metrology system comprising an X-ray source to illuminate a portion of the region of the DUT with an X-ray beam within an X-ray FOV at the portion of the region, and an X-ray detector having the X-ray FOV, the X-ray FOV being smaller than or equal to and overlapping the optical FOV,
wherein the broadband optical imaging system and the X-ray metrology system are configured to
concurrently acquire an X-ray image of the X-ray FOV and a plurality of optical images of the optical FOV, each of the plurality of optical images corresponding to respective selected wavelengths of the broadband optical beam, the selected wavelengths comprising at least one wavelength from each of the ultraviolet (UV), visible (VIS), and infrared (IR) portions of the optical spectrum, and
determine structural properties of the DUT through scatterometry methods using the X-ray image in combination with the plurality of optical images.
12 . The system of claim 11 , wherein the broadband optical imaging system comprises broadband optics configured to direct the broadband optical beam to be coincident with the X-ray beam for illumination and collection.
13 . The system of claim 11 , further comprising a sample support configured to support the DUT and comprising coordinates aligned with the optical FOV, the sample support being further configured to navigate in-die or to scribe lines with at least about micron precision.
14 . The system of claim 11 , wherein the X-ray image and the plurality of optical images are acquired in real-time with synchronized frame rates, the plurality of optical images being acquired by an optical scatterometry imaging spectrometer of the broadband optical imaging system.
15 . The system of claim 14 , further comprising a sample support configured to support the DUT and scan with movement coordinated with the real-time acquisition enabling a move, acquire, measure cycle time for production metrology and inspection in wafer foundries or device fabricators.
16 . A system for characterizing a substrate comprising:
a broadband optical source configured to illuminate a region of the substrate with a broadband optical beam within an optical field of view (FOV);
a hyperspectral imaging (HSI) snapshot camera having the optical FOV;
an X-ray source configured to illuminate a portion of the region of the substrate with an X-ray beam within an X-ray FOV at the portion of the region; and
an X-ray detector having the X-ray FOV, the X-ray FOV being smaller than or equal to and overlapping the optical FOV; and
wherein the X-ray detector and the HSI snapshot camera are configured to
concurrently acquire X-ray data from the X-ray FOV and a hyperspectral image cube of the optical FOV, the hyperspectral image cube comprising at least one wavelength from each of the deep ultraviolet (DUV), visible (VIS), and near infrared (NIR) portions of the optical spectrum, and
determine structural properties through scatterometry methods using the X-ray data in combination with the hyperspectral image cube.
17 . The system of claim 16 , wherein the HSI snapshot camera has a wide band of imaging ranging from the DUV portion through the VIS portion to the short-wavelength infrared (SWIR) portion of the optical spectrum, and wherein the hyperspectral image cube further comprises at least one wavelength from the SWIR portion of the optical spectrum.
18 . The system of claim 16 , wherein the HSI snapshot camera comprises a Fabry-Perot interferometer (FPI) in an optical path of the broadband optical beam, the FPI having separate optimized reflective coatings corresponding to ranges of wavelengths of the hyperspectral image cube.
19 . The system of claim 16 wherein the X-ray detector comprises a super-resolving X-ray camera configured to use subpixel shifting.
20 . The system of claim 16 , further comprising:
X-ray optics comprising a capillary X-ray guiding element.