BackgroundExtreme ultraviolet (EUV) lithography is crucial to achieving smaller device sizes for next-generation technology, although organic resists face substantial challenges, such as low etch resistance, which limit the resolution of smaller features.AimEvaluate the potential for area-selective deposition (ASD) to improve EUV pattern resolution (e.g., by increasing etch resistance).ApproachWe evaluate thermal compatibility, atomic layer deposition growth rate, and selectivity for TiO2 ASD on various organic EUV resist materials using water contact angle, Rutherford backscattering spectrometry, and X-ray photoelectron spectroscopy. The effects of photo-acid generator (PAG) and EUV exposure on polymer properties and selectivity are considered.ResultsThe organic resist materials studied demonstrate thermal compatibility with TiO2 ALD (125°C for 60 min). The TiO2 ALD process from TiCl4 and H2O proceeds readily on poly(tert-butyl methacrylate), poly(p-hydroxystyrene), and poly(p-hydroxystyrene-random-methacrylic acid) polymers, with and without PAG incorporation, in either the as-formed or EUV exposed state. However, TiO2 is inhibited on poly(cyclohexyl methacrylate).ConclusionsWe demonstrate that as-formed EUV resists can serve as either the growth or nongrowth surface during TiO2 ASD, thereby enabling resist hardening and tone inversion applications, respectively. These results serve as a basis for further ASD studies on EUV resist materials to improve pattern resolution in next-generation devices.
Extreme ultraviolet (EUV) lithography is crucial to achieving smaller device sizes for next-generation technology, although organic resists face substantial challenges, such as low etch resistance, which limit the resolution of smaller features. Area-selective deposition (ASD) is one potential avenue to improve pattern resolution from organic EUV resists by selectively depositing material on one region of the resist, while preventing material deposition on an adjacent region. We therefore evaluate the compatibility of various organic EUV resists with area-selective atomic layer deposition (ALD) processes, including considering the effects of photo-acid generator (PAG) and EUV exposure on polymer properties and selectivity. The thermal stability of thin resist materials at the TiO2 deposition temperature (125°C for 60 minutes) is confirmed with water contact angle and atomic force microscopy. Upon TiO2 ALD from TiCl4 and H2O, Rutherford backscattering spectrometry reveals successful TiO2 deposition on poly(tert-butyl methacrylate), poly(p-hydroxystyrene), and poly(p-hydroxystyrene-random-methacrylic acid) polymers, regardless of PAG or EUV exposure. However, TiO2 inhibition is observed on poly(cyclohexyl methacrylate). Thus, we demonstrate that EUV polymers can serve as either the growth or non-growth surface during TiO2 ASD, an insight that can be used to enable resist hardening and tone inversion applications, respectively. These results serve as a basis for further ASD studies on EUV resist materials to improve pattern resolution in next-generation devices.
Deposition-based patterning is becoming an important need in advanced manufacturing. Several new approaches are emerging where chemical etching is being coupled with atomic layer deposition to achieve area-selective deposition of dielectrics and metals. During ALD, selectivity is generally lost when undesired nuclei form on the targeted non-growth surface. These undesired nuclei can sometimes be removed by periodic etching, improving the overall selectivity. However, it is not known to what extent these coupled deposition/etching sequences can proceed while maintaining good selectivity. As desirable deposition and etching reactions proceed, other changes in the process can occur to enhance unwanted nucleation and/or impede desired etching, thereby limiting the net selectivity. Recent experiments in our lab have used in-situ probes to explore coupled thermal ALD and ALE super-cycles, performed sequentially under isothermal conditions in a single reaction chamber, to achieve area selective deposition of TiO2 on SiO2 with hydrogen-terminated silicon (100) as the desired non-growth surface. We find that as ALD/ALE super-cycles proceed, small changes occur in the ALD and ALE reactions, particularly during the transition from ALD to ALE, or from ALE to ALD. Likewise, a new thermally-driven ALE process for tungsten has been applied in ALD/ALE super-cycles to improve W ASD. In this case, the ALE process alters the ALD surface leading to significant changes in the ALD. Modeling studies allow us to quantitatively analyze the ASD results and compare our findings to other known approaches. These insights will be helpful to understand opportunities and challenges in advanced deposition-based patterning.
Miniaturizing electronic devices to the molecular scale is the next major step in the electronics revolution. To do this, however, three major unsolved challenges must be overcome. These are: (1) Synthesis of new molecules with functionality that allows them to act as nonlinear electronic elements and to attach them in a specific orientation to contact structures (2) Bridging the molecular (created via bottom-up fabrication) with the lithographic (created via top- down fabrication) length scales for device construction and (3) definition of new lithographic approaches that accommodate molecular installation during processing. Here, an approach and its implementation will be discussed that addresses each of these issues. In addition, the approach is designed to facilitate the demonstration of gain at the molecular level which can result from a state change within the molecular architecture rather than as the response of a molecule to a change in bias of an underlying (macroscopic) gate electrode.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.