Double Patterning Resist Process for 32 nm Lithography
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Solution Overview
Problem
Current double patterning processes in lithography face challenges such as reduced throughput due to double dry etchings, pattern misregistration, and deformation of resist patterns due to high-temperature and light irradiation, which affect the accuracy and resolution of feature sizes below 32 nm.
Innovation Solution
A double patterning process involving a first resist pattern formed with a thermal base generator and a second resist pattern formed using a solvent that does not dissolve the first resist pattern, allowing for single dry etching and reducing the pitch between pattern features by half without deforming the first resist pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature heat treatment is applied to form the first resist pattern, then the base for inactivation is generated, but the resist pattern deforms and shrinks, reducing manufacturing precision
Solution Approach 1:
The patent changes the temperature parameter from high-temperature (conventional) to low-temperature (50-150°C) heating to generate the base compound without causing pattern deformation. This parameter change allows base generation while maintaining pattern integrity and avoiding shrinkage issues.
Solution Approach 2:
The patent performs preliminary low-temperature heating to generate the base compound before applying the second resist composition. This preliminary action ensures the first resist pattern is inactivated to acid without deformation, preparing it to resist acid from subsequent exposure while maintaining shape accuracy.
2Ease of manufacture
If conventional solvents are used for the second resist composition, then the second resist can be coated, but the first resist pattern dissolves away, losing pattern integrity
Solution Approach 1:
The patent applies local quality by using a solvent system (C3-C8 alcohol with C6-C12 ether) that has different dissolution properties for the first and second resist patterns. The solvent selectively dissolves the second resist while leaving the first resist pattern intact, achieving local differentiation in dissolution behavior.
Solution Approach 2:
The patent uses a composite solvent system combining C3-C8 alcohol and C6-C12 ether to achieve the desired selectivity. This composite solvent provides both the ability to coat the second resist and the selectivity to preserve the first resist pattern, overcoming limitations of single solvents.
3Manufacturing precision
If double dry etching is performed to create patterns, then feature size is reduced, but throughput decreases due to multiple processing steps
Solution Approach 1:
The patent merges the patterning function into a single resist process by forming both first and second patterns using one dry etching step. The dual-pattern resist structure allows a single etch to create complex features that would otherwise require multiple etching steps, thereby improving throughput while maintaining precision.
Solution Approach 2:
The patent adds a temporal dimension to the patterning process by sequentially forming first and second patterns that are then used together in a single etching step. This dimensional approach allows complex 3D pattern formation from 2D resist layers, reducing the number of processing steps required.
4Area of moving object
If the pitch between pattern features is reduced to increase integration, then device density improves, but pattern deformation occurs during processing
Solution Approach 1:
The patent changes the heating temperature parameter to low-temperature (50-150°C) processing, which allows pitch reduction for increased density while preventing the thermal deformation and shrinkage that occurs with high-temperature processing. This enables fine pitch patterning with maintained shape stability.
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 enables precise formation of pattern features with improved throughput and accuracy, reducing the pitch between features to half while maintaining the integrity of the first resist pattern, thus overcoming the limitations of existing methods.
Implementation Method 1
heating the first resist pattern to generate a base for inactivation to acid
Implementation Method 2
coating a second positive resist composition comprising a photoacid generator and a solvent
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 having both a 9-fluorenylmethyloxycarbonyl-substituted amino group and a carboxyl group 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 an alcohol and an optional 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.