Bisonium Salt Resist Composition for EUV Lithography
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Solution Overview
Problem
Current resist compositions face challenges in achieving high sensitivity while maintaining improved line width roughness (LWR) and critical dimension uniformity (CDU) for advanced microelectronic devices, particularly at the 5-nm node and beyond.
Innovation Solution
A resist composition incorporating a bisonium salt with a divalent anion having a sulfonate anion structure and a carboxylate anion structure, linked to an aromatic group with iodine or bromine atoms, and an onium cation, which acts as both an acid generator and quencher, reducing acid diffusion and enhancing sensitivity and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the PEB temperature is lowered to reduce acid diffusion distance, then LWR and CDU are improved, but sensitivity becomes lower
Solution Approach 1:
The patent changes the chemical parameters of the acid generator by introducing a bisonium salt with specific structural features (divalent anion with sulfonate and carboxylate groups linked to aromatic groups with iodine or bromine atoms). This chemical parameter change enables the system to achieve both low acid diffusion and high sensitivity under the same PEB conditions, resolving the tradeoff between LWR and sensitivity.
Solution Approach 2:
The bisonium salt functions as a composite acid generator that integrates multiple functional groups (sulfonate, carboxylate, aromatic rings with halogen atoms) into a single molecular structure. This composite structure provides both high photon absorption efficiency (for sensitivity) and controlled acid diffusion characteristics (for LWR improvement), simultaneously addressing both requirements.
2Manufacturing precision
If the amount of quencher added is increased to reduce acid diffusion, then LWR and CDU are improved, but sensitivity becomes lower
Solution Approach 1:
The patent merges the functions of acid generator and quencher into a single bisonium salt molecule. The divalent anion structure contains both the sulfonate group (acid-generating component) and the carboxylate group (quencher component), along with aromatic groups containing iodine or bromine atoms for high EUV absorption. This integration eliminates the need to add separate quencher materials, avoiding the sensitivity loss that would result from increasing quencher concentration.
Solution Approach 2:
The bisonium salt serves multiple functions simultaneously: it acts as an acid generator, a quencher, and a high-absorption EUV-sensitive component all in one molecule. This multi-functionality resolves the contradiction by providing acid diffusion control without requiring additional quencher that would reduce sensitivity.
3Productivity
If onium salts with iodine or bromine atoms are used to enhance sensitivity, then sensitivity and physical contrast are improved, but acid diffusion control becomes more difficult
Solution Approach 1:
The patent modifies the chemical parameters of the onium salt by creating a bisonium salt with a specific divalent anion structure containing both sulfonate and carboxylate groups. This structural modification maintains the high sensitivity characteristics (through iodine or bromine atoms for EUV absorption) while introducing built-in acid diffusion control mechanisms through the dual-functional anion structure, thereby resolving the contradiction between sensitivity and acid diffusion control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resist composition exhibits high sensitivity, improved LWR and CDU, and a wide process margin, effectively addressing the tradeoff between sensitivity and LWR while maintaining excellent resolution.
Implementation Method 1
the acid generator is directly excited by exposure to radiation... the inclusion of iodine atoms that absorb a large amount of EUV or bromine atoms that are efficiently ionized improves the efficiency of decomposition of the acid generator during exposure
Implementation Method 2
as the acid diffusion distance is reduced, line width roughness (LWR) and critical dimension uniformity (CDU) of hole patterns are improved... the control of acid diffusion is also important
Data Source
AI summary
A resist composition comprising a bisonium salt containing a divalent anion having a sulfonate anion structure having a fluorine atom or a trifluoromethyl group at α- or β-position and linked to an aromatic group having an iodine atom or a bromine atom and a carboxylate anion structure bonded to the aromatic group having an iodine atom or a bromine atom, via a linking group having 1 or more carbon atoms, and an onium cation.