Ideas and Innovation Blog

DuPont experts to present at SPIE Advanced Lithography 2020

February 20, 2020

DuPont experts to present findings at SPIE Advanced Lithography 2020

Next week marks the 45th SPIE Advanced Lithography conference and exhibition, where industry experts – including lithographers, layout designers, materials scientists, and metrology/process control engineers – will share how they are collaborating to enable cost-effective patterning solutions. The 2020 event is set to take place at the San Jose Convention Center from February 23-27.

A full spectrum of lithography and patterning topics are encompassed by this year’s symposium across seven complementary conferences. Participants come from a broad array of backgrounds to share and learn about state-of-the-art lithographic tools, resists, metrology, materials, etch, design, process integration, and novel new approaches. At the symposium, scientists from DuPont Electronics & Imaging will offer multiple presentations focused on lithography-related materials challenges and the company’s latest approaches to addressing them. Below is a list of the papers DuPont will be presenting, with brief descriptions.

Advances in Patterning Materials and Processes Conference

Linewidth roughness reduction strategies utilizing power spectral density analysis

Charlotte Cutler, Dan Millward, Choong-Bong Lee, James Thackeray, John Nelson, Jason DeSisto, Rochelle Rena, and Chris Mack (Fractilia, LLC)
Session 5: Fundamentals and Modeling
Tuesday, February 25 – 2:20 P.M.

Linewidth roughness (LWR) remains a difficult challenge in resist materials. Previous work focused on showing how roughness power spectral density (PSD) parameters were affected by aerial image and basic resist parameters such as diffusion, highlighting the relationship between PSD(0) and correlation length in optimizing LWR. This talk will show how LWR improvement can be achieved by several strategies that focus on both PSD(0) and correlation length and not a single LWR number.

Challenges and Opportunities of KrF Photoresist Development for 3D NAND Application

Yang Song, Mingqi Li, Jong Park, Xisen Hou, Yusuke Matsuda, Cong Liu, Emad Aqad, Janet Wu, Huiying Liu, Huan He, Paul Baranowski, Chengbai Xu
Session 6: Integration
Tuesday, February 25 – 4:30 P.M.

The integrated circuit (IC) industry has achieved the low cost of a bit by going towards smaller geometries. However, further miniaturization of the critical dimensions could not be realized by current lithographic techniques with similarly low production cost. Miniaturization of critical features while keeping the manufacturing cost low has led to the development of stacked 3D structures for NAND application. The 3D NAND structures can be realized by using krypton fluoride (KrF) photoresist coated at high thickness, and a staircase pattern can be generated through multiple etch steps. Pushing KrF lithography to high coating thickness creates several challenges for the next-generation formulations, such as film transparency and film cracking.

The photoresist used in KrF lithography is based on poly(hydroxystyrene) (PHS) type polymers, which is associated with unique technical challenges for printing micrometer-scale features due to its high absorbance at 248 nm and its high glass transition temperature (Tg). Here we report the development of KrF photoresist materials for 3D NAND application with sufficient film transmittance at exposure wavelength, which generates desired straight profile with no footing. Our results show that the film cracking is mitigated by additive and process condition, and film delamination is solved by adding an adhesion promotion layer.

Planarized spin-on carbon (SOC) hardmask

Iou-Sheng Ke, Sheng Liu, Keren Zhang, Li Cui, Suzanne Coley, Shintaro Yamada, James Cameron
Session 10: Underlayers
Wednesday, February 26 – 4:30 P.M.

In the multilayer patterning process, underlayer material is often used to enable device size shrinkage for advanced integrated circuit manufacturing. This underlayer material, spin-on carbon (SOC) with high etch resistance, plays an important role in both gap fill and the process of transferring high-aspect-ratio patterns. Good global planarization performance over various pattern topographies not only impacts the following lithography process window but also boosts the overall device integration yield. As CD size decreases in advanced nodes (e.g., 10 nm and beyond) with multiple patterning steps, long-range planarized SOC material is needed to control CD uniformity. This presentation will report the development of a novel planarized SOC material with good fab drain line compatibility. Other key performance parameters, such as gap fill, etch rate toward various gas, solvent strip resistance and cured film thermal stability, will also be highlighted.

Design considerations for high-etch-resistance SOC underlayers

Li Cui, Iou-Sheng Ke, Anton Chavez, Keren Zhang, Paul LaBeaume, Suzanne Coley, Shintaro Yamada, James Cameron
Poster Session: Underlayers
Wednesday, February 26 – 5:30 P.M.

As semiconductor device CDs continue to shrink, the multilayer patterning process to transfer fine-line patterns onto a substrate is becoming important. The tri-layer processes consist of a photoresist film, a silicon-containing layer and a carbon-rich underlayer. The distinctive difference in etch selectivity toward fluorine and oxygen-based reactive ion etching (RIE) chemistry is critical to provide highly selective pattern transfer to the substrate. In response to the need for high-etch-resistance underlayers, carbon-rich SOC materials have been developed with good solubility in preferred casting solvent, high thermal stability and high dry-etch resistance. This presentation will investigate design considerations for high-etch-resistance SOC underlayers. To better understand the structure-property relationships of high-etch-resistance SOC film, the cured films were investigated using multiple IR, UV and x-ray spectral techniques.

Metrology, Inspection, and Process Control for Microlithography Conference

Nanoscale molecular analysis of positive-tone photoresist films with varying dose

Michael Eller (California State Univ., Northridge), Mingqi Li, Xisen Hou, Stanislav Verkhoturov (Texas A&M Univ.), Emile Schweikert (Texas A&M Univ.), Peter Trefonas
Poster Session
Wednesday, February 26 – 5:30 P.M.

One of the challenges of characterizing a surface at the nanoscale is that analytical tools providing nanoscale topological information have limited capabilities when it comes to molecular characterization. This session will present the methodology and capabilities of massive cluster secondary ion mass spectrometry (SIMS) for molecular characterization at the nanoscale. In this study, positive-tone photoresist films were studied, along with the effects of increasing light dose followed by development on the chemical composition of the top-most part of the film.

If you’ll be attending SPIE Advanced Lithography 2020, please plan to join one or more of these sessions. We look forward to seeing you, sharing our technical insights, and connecting with the lithography community!