Positive Resist Material for High-Voltage Electron Beam Lithography
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Solution Overview
Problem
Conventional positive resist materials face challenges in achieving high sensitivity and minimizing dimensional variation in exposure patterns, particularly at the 7-nm and 5-nm node levels, due to increased accelerating voltage in electron beam lithography, which reduces sensitivity and increases acid diffusion, leading to image blurring and edge roughness.
Innovation Solution
A positive resist material comprising a base polymer with repeating units having two carboxyl groups substituted with tertiary carbon atoms bonded to double or triple bonds, combined with an acid generator, enhances sensitivity, resolution, and reduces acid diffusion, resulting in improved pattern profiles and edge roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the accelerating voltage of electron beam is increased to improve resolution and dimensional control, then the sensitivity of resist film decreases, leading to productivity reduction
Solution Approach 1:
The patent changes the chemical composition parameters of the resist material by incorporating specific repeating units with carboxyl groups and acid generators that are optimized for high-energy electron beam exposure. This allows the resist to maintain high sensitivity even when exposed to higher accelerating voltages (30-100 kV), thereby resolving the contradiction between improved resolution and maintained productivity
Solution Approach 2:
The patent creates a composite resist system by combining multiple functional components: a base polymer with specific repeating units containing carboxyl groups, acid generators, and other additives. This composite structure enables the resist to simultaneously achieve high sensitivity, high resolution, and good dimensional control when exposed to high-energy electron beams
2Manufacturing precision
If acid diffusion is suppressed to improve resolution, then sensitivity decreases due to shorter acid diffusion distance
Solution Approach 1:
The patent applies local quality by creating distinct functional regions within the resist molecule structure. The repeating units with carboxyl groups provide localized acid generation sites, while the polymer backbone provides controlled acid diffusion pathways. This localized functional differentiation allows resolution improvement through controlled acid diffusion while maintaining sensitivity through efficient acid generation at specific sites
Solution Approach 2:
The patent introduces acid generators as intermediary substances that mediate between the electron beam exposure and the deprotection reaction. These acid generators are strategically positioned within the polymer structure to optimize acid diffusion distance, enabling both high sensitivity (through efficient acid generation) and high resolution (through controlled acid diffusion)
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 proposed resist material exhibits higher sensitivity, resolution, and reduced dimensional variation, effectively addressing the challenges of acid diffusion and edge roughness, making it suitable for fine pattern formation in advanced semiconductor manufacturing.
Implementation Method 1
an acid generator which has a repeating unit having any of formulae (b1) to (b3)... capable of generating a bulky acid
Implementation Method 2
the contrast is improved by enhancing the alkali dissolution rate through deprotection reaction, during heating (PEB), of an acid catalyst that is generated by light exposure
Data Source
AI summary
A positive resist material contains a base polymer containing: a repeating unit having two carboxyl groups whose hydrogen atoms are substituted with two tertiary carbon atoms each bonded to a double bond or triple bond; and a repeating unit having an acid generator shown by any of the following formulae (b1) to (b3). Thus, the present invention provides: a positive resist material having higher sensitivity than conventional positive resist materials, and smaller dimensional variation; and a patterning process using this inventive positive resist material.