Extreme Ultraviolet-Printability and Mechanistic Studies of Engineered Hydrogen Silsesquioxane Photoresist Systems

Abstract

Hydrogen Silsesquioxane (HSQ) photoresist has shown extremely high-resolution performance for Electron-Beam Lithography (EBL) and Interference Lithography (IL) and can be a potential photoresist candidate for Extreme Ultraviolet Lithography (EUVL). To optimize this system for sub-10 nm patterning, it is important to understand the EUV and electron-induced chemistry underpinning the functionality of this resist material. Here we present a EUVprintability study on HSQ photoresist at a resolution of 16 and 22 nm combined with a mechanistic study on EUV and electron-induced desorption of HSQ film. Firstly, patterning results showed that the simple HSQ cages require a high EUV-dose and an aggressive developer to print dense features. EUV-and electron-induced desorption experiments revealed that hydrogen and silane are the dominant species fragmented from HSQ, indicating dehydrogenation and redistribution pathways as the crosslinking mechanism. Quantum chemical calculations suggested that the Neutral Dissociation (ND) is the dominant mechanism in HSQ cross-linking at low energies, i.e., below its ionization threshold, whereas Dissociative Ionization (DI) contributes significantly at higher energies. A distinct structure is observed at about 8 eV and a clear peak at about 11 eV indicating a significant contribution through Dissociative electron attachment (DEA) at these energies. Based on these results, an engineered HSQ system is designed by adding silanol or carbinol (R-CH3OH)-groups to the partially crosslinked HSQ-cages to increase its Tetramethylammonium hydroxide (TMAH)-developer and EUV-sensitivity. Finally, 2.38% v/v TMAH is used to develop a 16 nm printed dense line-space (L/S) with a line-edge-roughness (LER) of 6.4 nm but requiring an EUV-dose of over 100 mJ/cm 2 .

Molecular Glass Resists Based on Tetraphenylsilane Derivatives: Effect of Protecting Ratios on Advanced Lithography

“…As predicted by Moore’s Law, the density of integrated circuits (ICs) has been improved exponentially for high-performance semiconductor devices and the photolithographic fabrication of nanoscale semiconductor devices requires increasingly high-resolution techniques. , Extreme ultraviolet lithography (EUVL) and electron beam lithography (EBL) are key advanced lithographic technologies for the production of feature sizes lower than 20 nm. − As the feature size decreases, the requirements for resists’ performance have gradually increased. It is still a great challenge to develop resist materials fulfilling all the requirements for advanced lithography such as high resolution (R) and sensitivity (S), low line edge roughness (LER), high etching resistance, and low outgassing. − The traditional polymeric materials are unfavorable for achieving high-resolution lithographic patterns with low LER due to their characteristics, such as polydispersity, large molecular size, chain entanglement, and poor compatibility with photoacid generators (PAGs). − …”

Self-Aligned Contact Doping of WSe2 Metal–Insulator–Semiconductor Field-Effect Transistors Using Hydrogen Silsesquioxane

“…The self-aligned contact doping can be completed by introducing appropriate gate dielectric materials and doping techniques. In this study, hydrogen silsesquioxane (HSQ) was used as a patternable gate dielectric material, which served as an inorganic compound and a negative resist in the electron-beam (e-beam) lithography and extreme ultraviolet (EUV) lithography. , One of the advantages of this spin-on-glass material is its width (less than 10 nm) and thickness, which can be managed by optimizing the viscosity and speed of spin coating. , Furthermore, recent studies have reported doping on WSe 2 via plasma treatment. − Although plasma treatment may be an appropriate method, a few energetic particles can significantly damage the ultrathin materials. However, remote oxygen plasma is known to transfer only oxygen radicals onto the active material to minimize the damage caused by the energetic particles .…”

Synthesis of End-Cap Enabled Self-Immolative Photoresists For Extreme Ultraviolet Lithography

“…Examples include chainscissionable polymers, 11−13 metal-oxide nanoparticles, 14−16 and cross-linkable, inorganic compounds. 17 Despite improvements in resolution, these novel resists are markedly below current sensitivity demands.…”

“…As one of the primary causes of the RLS barrier is acid diffusion, which is inherent to all PAGs, nonchemically amplified resists have garnered increased attention. Examples include chain-scissionable polymers, − metal-oxide nanoparticles, − and cross-linkable, inorganic compounds . Despite improvements in resolution, these novel resists are markedly below current sensitivity demands.…”