Cyclic Ammonium Hydroxide Developer for Resist Pattern Integrity
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Solution Overview
Problem
In the field of microelectronic device manufacturing, particularly in EB and EUV lithography, there is a challenge in achieving minimal edge roughness and preventing pattern collapse or bridge defects during the development of photosensitive resist materials, as existing developers like TMAH suffer from swell issues, leading to reduced sensitivity and resolution.
Innovation Solution
An aqueous solution of cyclic ammonium hydroxide, specifically 1-butyl-1-methylpyrrolidinium hydroxide or similar compounds, is used as a developer for chemically amplified positive resist compositions, which minimizes swell and enhances alkaline dissolution, thereby reducing edge roughness and preventing pattern collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional developers like TMAH are used, then the development process is simple and cost-effective, but the resist film swells leading to pattern collapse and bridge defects
Solution Approach 1:
The patent changes the chemical parameters of the developer by using cyclic ammonium hydroxide (specific compounds with defined molecular structures) instead of conventional TMAH. This parameter change eliminates resist film swelling while maintaining effective development, thereby preventing pattern collapse and bridge defects without significantly complicating the overall process
Solution Approach 2:
The patent employs a composite developer formulation consisting of cyclic ammonium hydroxide combined with specific surfactants (nonionic and/or anionic types) at optimized concentrations. This composite approach enhances the developer's performance in preventing pattern collapse while maintaining ease of use and compatibility with existing lithography processes
2Manufacturing precision
If the resist film thickness is reduced to improve resolution, then the resolution increases, but the pattern becomes more prone to collapse due to higher aspect ratio
Solution Approach 1:
By changing the developer chemistry to cyclic ammonium hydroxide-based formulations, the patent enables the use of thinner resist films without pattern collapse. The modified developer parameters (chemical composition, pH, surfactant content) provide sufficient support to high aspect ratio patterns, allowing resolution improvement through film thinning while maintaining pattern stability
3Manufacturing precision
If the accelerating voltage is increased to reduce pattern feature size, then the resolution improves, but the sensitivity of the resist film decreases
Solution Approach 1:
The patent uses chemically amplified positive resist compositions with specific polymer structures and acid labile groups that maintain high sensitivity even when used with high accelerating voltage EB lithography. The developer formulation (cyclic ammonium hydroxide with surfactants) is optimized to work synergistically with these resist compositions, ensuring that sensitivity is preserved while achieving the desired fine pattern features
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 use of cyclic ammonium hydroxide as a developer effectively suppresses pattern collapse and bridge defects, allowing for the formation of resist patterns with minimal edge roughness and improved resolution, even at feature sizes below 20 nm.
Implementation Method 1
a base resin adapted to accelerate alkaline dissolution under the action of acid
Implementation Method 2
When a resist film of photosensitive resist material, typically chemically amplified positive resist composition is developed in the developer of the invention, any swell of the resist film during development is suppressed
Data Source
AI summary
An aqueous solution containing 0.1-20 wt % of a cyclic ammonium hydroxide is a useful developer for photosensitive resist materials. A resist pattern is formed by applying a chemically amplified positive resist composition onto a substrate to form a resist film, exposing the resist film to high-energy radiation, and developing the exposed resist film in a cyclic ammonium hydroxide-containing aqueous solution.