Dual Resist Patterning for Sub-32nm Lithography
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Solution Overview
Problem
Current double patterning processes in lithography require multiple etchings, leading to reduced throughput and misregistration issues due to pattern deformation and low overlay accuracy, especially when trying to achieve sub-32nm feature sizes.
Innovation Solution
A pattern forming process involving a first positive resist composition with lactone adhesive groups and acid labile units, followed by heating to generate an amine compound for inactivation, and a second resist composition with a C3-C8 alcohol solvent that does not dissolve the first resist pattern, allowing for a second resist pattern to be formed without deformation and enabling single dry etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple etchings are performed in double patterning process, then pattern features can be formed with reduced pitch, but throughput is reduced and misregistration occurs due to pattern deformation
Solution Approach 1:
The patent combines multiple etching operations into a single etching step by using a dual-layer resist system where the first resist pattern serves as a mask for the second resist coating, eliminating the need for separate etching steps and reducing misregistration issues
Solution Approach 2:
The first resist pattern is formed and heated to generate a base for inactivation before coating the second resist, preparing the substrate in advance to prevent acid diffusion and pattern deformation during subsequent processing steps
2Stability of the object's composition
If first resist pattern is heated to generate acid for inactivation, then pattern stability is improved, but pattern deformation occurs due to heat
Solution Approach 1:
The patent introduces a base generator that reacts with generated acid to form a stable salt, preventing acid diffusion and pattern deformation while maintaining pattern stability. The base acts as an intermediary that neutralizes the harmful effects of heat-generated acid
Solution Approach 2:
The patent controls the heating temperature and timing parameters to generate the base for inactivation without causing excessive heat damage to the pattern, optimizing the thermal processing conditions to balance stability improvement with shape preservation
3Ease of manufacture
If second resist composition uses common solvent, then coating process is simplified, but first resist pattern dissolves away
Solution Approach 1:
The patent selects a solvent (C3-C8 alcohol) that has different dissolution properties for the first and second resists, making the solvent selective for the second resist while leaving the first resist intact. This local differentiation in chemical compatibility enables the dual-layer system to work
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
This process allows for the formation of a second resist pattern without deforming the first, reducing the pitch between features to half and enabling single dry etching, thereby improving throughput and overlay accuracy for sub-32nm feature sizes.
Implementation Method 1
heating the first resist pattern to generate a base for inactivation to acid
Implementation Method 2
a base generator which generates, upon application of thermal energy, an amine compound
Implementation Method 3
coating a second positive resist composition comprising a solvent containing a C3-C8 alcohol and not dissolving away the first resist pattern
Data Source
AI summary
A pattern is formed by coating a first positive resist composition comprising a base resin, a photoacid generator, and a base generator onto a substrate to form a first resist film, patternwise exposure, PEB, and development to form a first resist pattern, heating the first resist pattern for causing the base generator to generate a base for inactivating the pattern to acid, coating a second positive resist composition comprising a C3-C8 alcohol and an optional C6-C12 ether onto the first resist pattern-bearing substrate to form a second resist film, patternwise exposure, PEB, and development to form a second resist pattern.