Electron–hole pairs generated in ZrO₂nanoparticle resist upon exposure to extreme ultraviolet radiation

Abstract

Metal oxide nanoparticle resists have attracted much attention as the next-generation resist used for the high-volume production of semiconductor devices. However, the sensitization mechanism of the metal oxide nanoparticle resists is unknown. Understanding the sensitization mechanism is important for the efficient development of resist materials. In this study, the energy deposition in a zirconium oxide (ZrO 2 ) nanoparticle resist was investigated. The numbers of electron-hole pairs generated in a ZrO 2 core and an methacrylic acid (MAA) ligand shell upon exposure to 1 mJ cm %2 (exposure dose) extreme ultraviolet (EUV) radiations were theoretically estimated to be 0.16 at most and 0.04-0.17 cm 2 mJ %1 , respectively. By comparing the calculated distribution of electron-hole pairs with the line-and-space patterns of the ZrO 2 nanoparticle resist fabricated by an EUV exposure tool, the number of electron-hole pairs required for the solubility change of the resist films was estimated to be 1.3-2.2 per NP. NP denotes a nanoparticle consisting of a metal oxide core with a ligand shell. In the material design of metal oxide nanoparticle resists, it is important to efficiently use the electron-hole pairs generated in the metal oxide core for the chemical change of ligand molecules.

Sensitization mechanism of metal oxide nanocluster resists with carboxylic acid ligands

“…18) In the sensitization of ZrO 2 nanocluster resists, both electrons and holes generated through ionization were reported to contribute to the pattern formation in an EUV patterning experiment using a ZrO 2 nanocluster resist with an acid generator. 18,21) In this study, we analyzed the end products produced by ionizing radiation in order to clarify the reaction mechanism following the initial reactions clarified in the previous studies. 4,19,20) In our previous work, 22) the production of CO 2 , which is considered to be one of the end products, was investigated for eight types of carboxylic acids under various conditions using γ-rays ( 60 Co) as a radiation source.…”

Effects of photoacid generator decomposition on dissolution kinetics of poly(4-hydroxystyrene) in tetraalkylammonium hydroxide aqueous solutions

“…Metal, main-chain scission, and molecular glass resists are alternative candidates for highly resolving resists. [14][15][16][17][18][19][20] Against these candidates, the weak point of chemically amplified resists is a low density of sensitization points. In chemically amplified resists, sensitizers such as photoacid generators (PAG) and photodecomposable quenchers work as receivers of information carried by photons.…”

Reaction mechanisms of Sn-complex-side-chain polymer used for extreme ultraviolet lithography, studied by electron pulse radiolysis and γ-radiolysis

“…In a next-generation resist process, the incorporation of elements with a large EUV absorption cross section into the resist formula will be required to suppress shot noise effects. Metal elements such as Ti, 7,8) Zr, 7,[9][10][11][12][13][14] Sn, [15][16][17][18][19] Sb, 20) Hf, 8,9,11) Bi, 21) and Te 22) have been examined as high-EUV absorption units.…”