Mechanistic Study of HafSO_x Extreme Ultraviolet Inorganic Resists

Abstract

Inorganic resists are promising for nanomanufacturing because of their potential for high-resolution and low line-edge roughness patterning and exceptional sensitivity to extreme ultraviolet (EUV) radiation. Hafnium oxide peroxide hydroxide sulfate (HafSO x ) is a model EUV inorganic photoresist, wherein the EUV absorption coefficients for hafnium and O are much higher than for conventional polymer resists. Absorption of EUV radiation leads to electron emission that results in the HafSO x solubility change. We used desorption-based techniques to elucidate thermal- and radiation-induced processes that contribute to the HafSO x solubility switch. We found that low kinetic energy electrons render HafSO x insoluble and result in the desorption of molecular O2. Electron-stimulated desorption and postexposure Raman spectroscopy indicate similar kinetics for peroxide loss in HafSO x . Temperature-programmed desorption studies found that peroxide ligand desorption is best characterized as first order, with a broad distribution of thermal desorption energies. Finally, a pair distribution function analysis of X-ray scattering data of HafSO x solutions and powders provides an atomic-level model of local structure within the film that is consistent with other characterization data of solutions and deposited films.

Effect of Oxygen on Thermal and Radiation-Induced Chemistries in a Model Organotin Photoresist

“…A combination of atomic force microscopy image analysis (not shown) and TPD (Figure 2a,b) intensity area analysis allowed us to estimate the coverages as ∼0.7 and ∼1.7 ML equivalents using a cluster size of 1 nm. 12 In Figure 2, we show TPD profiles for m/z = 41 (C 3 H 5 ) from each of the four different β-NaSn 13 samples described above. Figure 2a shows data overlaid from the 12 nm (green) and 21 nm (blue) thick films.…”

“…The synthesis and characterization of the β-NaSn 13 precursor has been described previously. 12 Thin films of β-NaSn 13 were spin-coated on 100 nm thermally grown oxide on Si(100) substrates for TPD studies and native oxide Si(100) substrates for ESD studies. β-NaSn 13 precursor solutions (90 mM Sn-basis, in 2-heptanone) were spin-coated at 3000 rpm for 30 s to form β-NaSn 13 thin films.…”

“…These clusters can form smooth, conformal films by spin coating with thicknesses which are relevant for photoresist applications. 12 A benefit of β-NaSn 13 is that it is charge neutral 12 and does not require counterions for charge balance. 2 We can therefore use β-NaSn 13 as a model system for the characterization of organotin photoresists, without added complications due to counterions.…”

Discrete Hf18 Metal‐oxo Cluster as a Heterogeneous Nanozyme for Site‐Specific Proteolysis

“…Group IV A materials are used in biomedical, biosensing, and microelectronics applications . Moreover, the Hf‐tetramer [Hf 4 (OH) 8 (H 2 O) 16 ] 8+ that is ubiquitous in Hf aqueous acid solutions is used in high resolution nanolithography . Self‐assembly and properties of Group IV clusters can be tuned with strong ligands such as sulphate and peroxide .…”

“…[28][29][30] Moreover,t he Hftetramer [Hf 4 (OH) 8 (H 2 O) 16 ] 8+ that is ubiquitous in Hf aqueous acid solutions is used in high resolution nanolithography. [31][32][33] Self-assembly and properties of Group IV clusters can be tuned with strong ligands such as sulphate and peroxide. [33][34][35] The Hf 18 1) in particular is an important intermediate between Hf sulphate-peroxide thin film deposition solutions and dielectric HfO 2 thin films and hard masks.…”