Vapor‐Phase Infiltrated Organic–Inorganic Positive‐Tone Hybrid Photoresist for Extreme UV Lithography

Abstract

Continuing extreme downscaling of semiconductor devices, essential for high performance and energy efficiency of future microelectronics, hinges on extreme ultraviolet lithography (EUVL) and addressing associated challenges. One of such challenges is a need for improved EUV photoresists featuring simultaneously high sensitivity, resolution, and etch selectivity. Here, a new, positive‐tone, organic–inorganic hybrid EUV photoresist is demonstrated that delivers a high‐resolution EUVL and electron‐beam lithography (EBL) patterning capability combined with high sensitivity and etch resistance. The new resist, poly(methyl methacrylate) infiltrated with indium oxide (PMMA‐InOx), is synthesized via vapor‐phase infiltration (VPI), a material hybridization technique derived from atomic layer deposition. The weak binding of the gaseous indium precursor, trimethylindium, to the carbonyl group in PMMA allows the synthesis of hybrids with inorganic content distributed uniformly in the resist, enabling high EUVL and EBL sensitivities (18 mJ cm−2 and 300 µC cm−2, respectively) and high‐resolution positive‐tone EUVL patterning (e.g., 40 nm half‐pitch line‐space and 50 nm diameter contact hole patterns) with high Si etch selectivity (>30–40). The low exposure doses required to pattern the PMMA‐InOx hybrid resist, high etch resistance, and processing strategies, which are developed, can pave the way for using infiltration‐synthesized hybrid thin films as reliable positive‐tone EUV photoresists for future semiconductor patterning.

Recent Advances in Positive Photoresists: Mechanisms and Fabrication

“…These EUV organometallic photoresists, comprising a combination of organic and inorganic elements, harness the benefits of both components since they use high-optically dense elements, particularly metals, and are classified as either metal nanoparticles or coordinative small molecules [ 5 ]. The inorganic constituent enhances the photosensitivity because of its higher tendency to absorb EUV light, strengthens the mechanical structure, leading to reduced pattern collapse, and provides better etch-resistance, hence, allowing for higher aspect ratios [ 32 ]. The organic component governs the elastic and ductile properties of the photoresist, allowing for crack-free coatings [ 33 ] and a change in solubility properties of the photoresist during development conditions.…”

Volume compensating materials after vapor phase infiltration: effect of different butyl isomers of polymer side-chains on high process temperature durability

“…Vapor phase infiltration (VPI), a type of sequential infiltration synthesis, adds metal atoms into organic polymers and provides inorganic features in the organic polymers in a facile manner. [1][2][3][4][5][6][7][8] Much attention has been paid to such vapor phase modifications, especially from semiconductor process engineers, since this modification may boost dry-etch resistance. [9][10][11][12][13] The fabrication of high-aspect-ratio patterns has become much more important in the semiconductor industry because semiconductor devices tend to extend threedimensionally.…”

Al2O3 growth in PMMA thin films by sequential infiltration synthesis: in situ thickness evolution and mass uptake investigation

“…Sequential infiltration synthesis (SIS), also referred to as vapor phase infiltration (VPI), provides a successful route to grow inorganic materials in polymeric films by the penetration of gaseous precursors into the polymer, [1][2][3] in order to enhance the functional properties of the polymer creating an organic-inorganic hybrid material [4][5][6][7][8][9] or to fabricate inorganic nanostructures when infiltrating in patterned polymer films. [10][11][12][13][14] In particular, SIS has been proposed as a powerful tool to generate inorganic nanostructures starting from self-assembled block copolymer templates. Depending on the specific morphology of the block copolymer template different inorganic nanostructures can be obtained, providing a simple and cost-effective tool to generate periodic inorganic nanostructures over large areas.…”