New metrology technique for measuring wafer geometry on a full 300mm silicon wafer

Trujillo-Sevilla, Juan M.; Casanova-González, Óscar; Velasco-Ocaña, Miriam; Ceruso, Sabato; Oliva-García, Ricardo; Gómez-Cárdenes, Óscar; Martı́n-Hernández, Javier; Roqué-Velasco, Alex; García, Álvaro Pérez; Ramos, Juan Manuel Sánchez; Gaudestad, J.

doi:10.1117/12.2605516

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…2a). Two version of this system has been built, one system where the 310mm lens and the sample is placed horizontally 9 , and a second system where the 310mm lens and the sample is placed vertically 5 with the main difference between the two systems being the effect of gravity being removed to a certain degree when the sample is held vertically. In our case, instead of measuring wafer shape, the WFPI system will be used to measure the photomask, which is much smaller than a 300mm silicon wafer (see Fig.…”

Section: Wave Front Phase Imaging (Wfpi)mentioning

confidence: 99%

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New optical metrology technique for measuring the shape of a lithography photo mask

Castro Luis,

Ivanov Kurtev,

Jiménez

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

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Wafer overlay errors due to non-flatness and thickness variations of a mask need to be minimized to achieve a very accurate on-product-overlay (OPO). Due to the impact of overlay errors inherent in all reflective lithography systems, EUV reticles will need to adhere to flatness specifications below 10nm, which metric is not possible to achieve using current tooling infrastructure; current metric is showing Peak-to-Valley (PV) flatness of around 60nm 1 . In this paper, we present a new method to generate a very high-resolution photomask shape measurement of an entire optical photomask used in DUV lithography, by measuring both from front side and backside, a technique based on detecting the wave front phase of the reflected light from a quartz photomask. We introduce Wave Front Phase Imaging (WFPI), a new method for measuring flatness that generates a shape map based on local slope. It collects 810 thousand (K) data points on an 86.4mm× 86.4mm area with a spatial resolution of 96µm.

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Section: Wave Front Phase Imaging (Wfpi)mentioning

confidence: 99%

“…A camera attached to a linear translation stage acquires the two intensity images using a 1 second shutter speed and approximately 12 seconds to move the camera between the two locations, making the total data acquisition time 14 seconds for the full data set. The system acquires data with 96µm pixel size 9 .…”

Section: Wave Front Phase Imaging (Wfpi)mentioning

confidence: 99%

New optical metrology technique for measuring the shape of a lithography photo mask

Castro Luis,

Ivanov Kurtev,

Jiménez

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

View full text Add to dashboard Cite

show abstract

“…A special algorithm is used to calculate the phase change based on these two intensity images 9 . The surface phase map is proportional to the relative surface height map 10 . A WFPI system acquires wafer shape maps with spatial resolution of 24µm-96µm depending on the camera used, with an optical spatial resolution limit of slightly less than 5µm 11 .…”

Section: Wave Front Phase Imaging (Wfpi)mentioning

confidence: 99%

New metrology technique for measuring the free shape of a patterned 300mm wafer held vertically

Trujillo-Sevilla

Casanova-González

Roqué-Velasco

et al. 2023

Metrology, Inspection, and Process Control XXXVII

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On product overlay (OPO) is one of the most critical parameters for the continued scaling according to Moore’s law. Without good overlay between the mask and the silicon wafer inside the lithography tool, yield will suffer1. As the OPO budget shrinks, non-lithography process induced stress causing in-plane distortions (IPD) becomes a more dominant contributor to the shrinking overlay budget2. To estimate the process induced in-plane wafer distortion after cucking the wafer onto the scanner board, a high-resolution measurement of the freeform wafer shape of the unclamped wafer with the gravity effect removed is needed. Measuring both intra and inter die wafer distortions, a feed-forward prediction algorithm, as has been published by ASML, minimizes the need for alignment marks on the die and wafer and can be performed at any lithography layer3. Up until now, the semiconductor industry has been using Coherent Gradient Sensing (CGS) interferometry or Fizeau interferometry to generate the wave front phase from the reflecting wafer surface to measure the free form wafer shape3,4,5. In this paper, we present a new method, Wave Front Phase Imaging (WFPI) for generating a very high-resolution wave front phase map of the light reflected off of the patterned silicon wafer surface. The wafer is held vertically to allow for the free wafer shape to be measured without having the wafer shape be impacted by gravity. We show data using a WFPI patterned wafer geometry tool that acquires 16.3 million data points on a 300mm patterned silicon wafer with 65μm spatial resolution using a total data acquisition time of 14 seconds.

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“…The accurate measurement of the thickness profile, particularly in the presence of non-uniform thin films deposited on substrates with warpage, is a crucial aspect of various applications spatially, in the overlay process of the semiconductor industry. The conventional method of Fizeau interferometer-based shape and geometry measurement has limitations in nanometer-level accurate volumetric profile measurement when non-uniform and complex thin films are deposited upon a warped Si substrate [1]. Spectroscopic ellipsometry can be the best candidate for ultra-thin film volumetric thickness profile metrology rather than spectral reflectometry [2][3].…”

Section: Introductionmentioning

confidence: 99%

Dynamic ultra-thin film thickness line-profile extraction from a warped Si substrate

Kheiryzadehkhanghah,

Hwang,

Choi

et al. 2024

Metrology, Inspection, and Process Control XXXVIII

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This study describes a dynamic ultra-thin film thickness line-profile extraction capability from a warped Si substrate by adding a Mach-Zehnder interferometer scheme to a dynamic spectroscopic imaging ellipsometer system. The proposed system can provide nanometer-precision ultra-thin film thickness line-profile as well as the warped surface profile information of a Si substrate simultaneously and dynamically.

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New metrology technique for measuring wafer geometry on a full 300mm silicon wafer

Cited by 6 publications

References 2 publications

New optical metrology technique for measuring the shape of a lithography photo mask

New optical metrology technique for measuring the shape of a lithography photo mask

New metrology technique for measuring the free shape of a patterned 300mm wafer held vertically

Dynamic ultra-thin film thickness line-profile extraction from a warped Si substrate

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