Fluoro-alcohol materials with tailored interfacial properties for immersion lithography

Abstract

Immersion lithography has placed a number of additional performance criteria on already stressed resist materials. Much work over the past few years has shown that controlling the water-resist interface is critical to enabling high scan rates (i.e. throughput) while minimizing film pulling and PAG extraction (i.e. defectivity). Protective topcoat polymers were developed to control the aforementioned interfacial properties and emerged as key enablers of 193 nm immersion lithography. Achieving the delicate balance between the low surface energies required for high water contact angles (generally achieved via the incorporation of fluorinated groups) and the base solubility required for topcoat removal is challenging. More recently, additional strategies using fluoropolymer materials to control the water-resist interface have been developed to afford topcoat-free resist systems. In our explorations of fluoroalcohol-based topcoat materials, we have discovered a number of structure-property relationships of which advantage can be taken to tailor the interfacial properties of these fluorinated materials. This paper will address the effect of structure on immersion specific properties such as water contact angle, aqueous base contact angle, and dissolution rate.

Orientation Control of Block Copolymers Using Surface Active, Phase-Preferential Additives

“…The SAP additive was chosen based on three design parameters: (i) lower surface energy than the individual blocks of the BCP, (ii) preferential, noncovalent interaction with the more polar PC block, and (iii) not reactive with either block to prevent degradation of the BCP during the thermal annealing process. To this end, a SAP additive bearing hexafluoroalcohol (HFA) (Scheme b) groups was selected as it satisfies all of the above three criteria − for the orientation control of the PC BCPs. First, due to the presence of low surface energy fluorinated groups, HFA-containing polymers segregate at the air interface when added to photoresist formulations and function as in situ topcoats in 193 nm immersion lithography. − Second, the acidic, fluorinated tertiary alcohol on the HFA group acts as hydrogen bond donor (HBD) that preferentially interacts with the carbonyl groups of the PC block of the BCP .…”

“…To this end, a SAP additive bearing hexafluoroalcohol (HFA) (Scheme b) groups was selected as it satisfies all of the above three criteria − for the orientation control of the PC BCPs. First, due to the presence of low surface energy fluorinated groups, HFA-containing polymers segregate at the air interface when added to photoresist formulations and function as in situ topcoats in 193 nm immersion lithography. − Second, the acidic, fluorinated tertiary alcohol on the HFA group acts as hydrogen bond donor (HBD) that preferentially interacts with the carbonyl groups of the PC block of the BCP . Lastly, unlike a more nucleophilic primary alcohol group, it is known that the HFA group does not initiate the ROP of cyclic carbonyl monomers or promote chain transfer or intermolecular trans-esterification reactions which could degrade the PC block. , …”

The Photopolymer Science and Technology Award

“…These materials importantly combine clean aqueous development with solubility in hydrophobic solvents and high transparency at 193nm, making them ideal for use in immersion lithography topcoats. This concept has been extended to the resists for immersion [13] and organic bottom antireflective coating [14] Allen gave several presentations at the Photopolymer Conference about this topic [15] including extensions of HFA polymer technology to the challenge of water purification [16].…”