Resolution, Line-Edge Roughness, Sensitivity Tradeoff, and Quantum Yield of High Photo Acid Generator Resists for Extreme Ultraviolet Lithography

Self Cite

Secondary electrons play critical roles in several imaging technologies, including extreme ultraviolet (EUV) lithography. At longer wavelengths of light (e.g. 193 and 248 nm), the photons are directly involved in the photochemistry occurring during photolysis. EUV light (13.5 nm, 92 eV), however, first creates a photoelectron, and this electron, or its subsequent daughter electrons create most of the chemical changes that occur during exposure. Despite the importance of these electrons, the details surrounding the chemical events leading to acid production remain poorly understood. Previously reported experimental results using high PAG-loaded resists have demonstrated that up to five or six photoacids can be generated per incident photon. Until recently, only electron recombination events were thought to play a role in acid generation, requiring that at least as many secondary electrons are produced to yield a given number of acid molecules. However, the initial results we have obtained using a Monte Carlo-based modeling program, LESiS, demonstrate that only two to three secondary electrons are made per absorbed EUV photon. A more comprehensive understanding of EUVinduced acid generation is therefore needed for the development of higher performance resists.

Section: Introductionmentioning

confidence: 99%

Secondary Electrons in EUV Lithography

Torok

Herbol

et al. 2013

Self Cite

“…The sensitivity and the resolution of the CARs share a tradeoff relationship, because a longer acid diffusion length is required to induce the necessary amount of chemical reactions when the acid concentration is reduced. This trade-off relation was simulated by different models [4,41] and confirmed experimentally [10][11][12]41]. The experimental results of high sensitization without any loss in resolution cannot be explained by the models based on the conventional single EB exposure processes [4,41], but can be explained by the new process (PF combination lithography of PS-CAR).…”

Section: Experiment Results and Discussionmentioning

confidence: 59%

“…Therefore, for developing next-generation resists, pattern formation efficiency should be increased to a value close to the physical limit [18]. Following this approach, the performance of EUV resists has improved steadily year on year owing to global efforts [10][11][12][30][31][32]. However, this orthodox approach is inadequate to compensate for the one order lower intensity of EUV light sources than the desired intensity.…”

Section: Sensitivity Enhancement Methodsmentioning

confidence: 99%

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Super High Sensitivity Enhancement by Photo-Sensitized Chemically Amplified Resist (PS-CAR) Process

Tagawa

Enomoto

Oshima

2013

Over the past decade, the low intensity of extreme ultraviolet (EUV) light sources has been the most critical issue in the development of a promising, next-generation, high volume manufacturing (HVM) EUV lithography method. Specifically, enhancing the sensitivity of EUV resists to compensate for this low intensity is one of the most critical challenges for HVM implementations of EUV lithography. However, EUV light source power intensity remains one order less than the required value. Sensitivity enhancement of an EUV resist without any loss in other important properties such as resolution is inadequate to compensate for the low intensity of EUV sources in conventional EUV single exposure. Therefore, we propose a method for increasing the resist sensitivity considerably by combining the lithography of 1 st EUV pattern exposure with a 2 nd UV flood exposure (PF combination lithography) and a photosensitized chemically amplified resist (PS-CAR). This method achieves high sensitivity enhancement not only with EUV but also with electron-beam, ArF, and other types of pattern exposure. Thus, a sensitivity increase of more than one order without any loss in space resolution was achieved compared with conventional lithography by PF combination lithography of 1 st EB pattern exposure with 2 nd UV flood exposure and PS-CAR. Differences between EB and EUV resists include energy absorption processes, and the resist sensitivities of EUV can be predicted easily from the exposure results of EB lithography. Therefore, the reaction mechanism of EUV pattern exposure-UV flood exposure combination lithography of PS-CAR can be essentially evaluated with EB pattern exposure-UV flood exposure combination lithography of PS-CAR.

“…For this experiment, the base titration method originated from Szmanda's work was used. 8 For our resist, we calculate a C-value of 0.024 cm 2 /mj. In order to achieve this C-value, a quantum yield for acid generation of 1.9 acids/photon is required.…”

Section: Resultsmentioning

confidence: 99%

Advances in Low Diffusion EUV Resists

Thackeray¹,

Cameron²,

Wagner³

et al. 2012

This paper reports on our development of low diffusion EUV resists based on polymer-bound PAG (PBP) technology. With our low diffusion resist, a wide process window for 30-nm hp of 280nm DOF over a 10% exposure range is achieved on the CNSE based Alpha Demo Tool (ADT) fullfield scanner. Line width roughness of 3.1nm is also achieved. Excellent resist profiles can be achieved on organic ULs or Si hardmask materials. This resist also shows only 1.1 nm carbon growth on witness plate mirrors for cleanables, and no reflectivity loss after mirror cleaning, making it a promising candidate for use on all NXE tools. We also have shown good pattern transfer for a Si HM stack using this resist. Finally, we report 17-nm hp resolution at a dose of 14.5mJ for a higher absorption resist.