Regardless of the impression of thinning resist supplies, it’s attainable to seek out acceptable settings to strengthen the metrology high quality output.

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One of many many constrains of excessive numerical aperture excessive ultraviolet lithography (Excessive NA EUVL) is expounded to withstand thickness. The truth is, one of many penalties of shifting from present 0.33NA to 0.55NA (excessive NA) is the depth of focus (DOF) discount. As well as, because the resist characteristic strains shrink right down to 8nm half pitch, it’s important to restrict the side ratio to keep away from sample collapse. The direct consequence of such a state of affairs is {that a} resist thickness of 30nm, normally used for 32nm pitch dense line/house (LS), won’t be appropriate for 16nm pitch, the place the goal thickness is anticipated to be 15nm thickness or much less to make sure an identical side ratio. The query we have to reply is how the resist thickness discount will impression the varied metrology strategies wanted to correctly arrange a course of.

To deal with this query, a set of wafers utilizing each chemical amplified resist (CAR) and metallic oxide resist (MOR) at completely different thicknesses and with several types of underlayer have been generated for LS patterns at 32nm pitch. We first investigated the impression of movie thickness by scanning electron microscope (SEM) on the imaging of CAR resist strains. To start out with, our present best-known strategies (BKMs) have been used to amass the SEM photographs. As resist thickness decreases, noise degree and picture distinction are noticed to degrade dramatically. Such a picture high quality degradation could instantly impression the standard of the CD measurements each by way of accuracy and precision.

On this paper we investigated the skinny resist wafer set described above utilizing varied strategies, equivalent to vital dimension scanning electron microscope (CD SEM), atomic pressure microscopy (AFM), low voltage SEM (LV SEM), scatterometry, sample shift response (PSR), and optical defect inspection. The impression of the resist thickness is estimated for every method, and optimum settings have been investigated to attenuate the relative impression on metrology. Our outcomes indicated that, usually, various operation situations and BKM settings, typically drastically completely different from the standard operation situation, have to be used to ensure the metrology necessities. Our outcomes present that, regardless of the impression of thinning resist supplies, it’s attainable to seek out acceptable settings to strengthen the metrology high quality output.

Authors: Gian Francesco Lorussoa, Christophe Berala, Janusz Bogdanowicza, Danilo De Simonea, Mahmudul Hasana, Christiane Jehoula, Alain Moussaa, Mohamed Saiba, Mohamed Zidana, Joren Severia, Vincent Trufferta, Dieter Van Den Heuvela, Alex Goldenshteinb, Kevin Houchensb, Gaetano Santorob, Daniel Fischerc, Angelika Muellenderc, Joey Hungd, Roy Koretd, Igor Turovetsd, Package Ausschnitte, Chris Mackf, Tsuyoshi Kondog, Tomoyasu Shohjohg, Masami Ikotag, Anne-Laure Charleya, Philippe Leraya

aimec, Kapeldreef 75, 3001 Leuven, Belgium;
bUtilized Supplies, 8, Prof. A. D. Bergman St 4, Rehovot, Israel;
cCarl Zeiss SMT GmbH, Carl-Zeiss-Straße 22, 73447 Oberkochen, Germany;
dNOVA, 5 David Fikes St., Rehovot 7632805, Israel;
eKAC, Spherical Pond, Maine, USA;
fFractilia, Austin Texas, USA;
gHitachi Excessive-Tech Corp., Japan.

PROCEEDINGS OF SPIE, Occasion: SPIE Superior Lithography + Patterning, 2022, San Jose, California, United States

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