Double Patterning Resist Crosslinking for 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 the need for two separate resist materials and complex processes, which hinder the achievement of high-resolution patterns, especially for 32-nm node devices.
Innovation Solution
A pattern forming process involving a first positive resist composition with hydroxynaphthyl and/or hydroxyacenaphthylene units, crosslinked by high-energy radiation with wavelengths between 200 nm to 320 nm, allowing a single dry etching step and reducing the pitch between pattern features to half.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional double patterning process is used, then pattern formation is achieved, but multiple etching steps are required reducing throughput and causing misregistration
Solution Approach 1:
The patent merges the functions of two separate resist patterns into a single resist pattern by crosslinking the first resist pattern after the first exposure. This allows both patterns to be formed using the same resist material and exposure process, eliminating the need for multiple etching steps and reducing process complexity while maintaining high resolution
Solution Approach 2:
The patent applies preliminary crosslinking treatment to the first resist pattern after the first exposure before forming the second pattern. This preliminary action ensures the first pattern remains insoluble during subsequent processing steps, preventing misregistration and enabling single-etching operation
2Manufacturing precision
If two separate resist materials are used for double patterning, then pattern resolution is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent makes the first resist material universal by enabling it to serve dual functions: as a soluble resist during the first exposure to define the first pattern, and as an insoluble crosslinked resist during the second exposure to define the second pattern. This eliminates the need for separate resist materials while maintaining high resolution capability
Solution Approach 2:
The patent changes the solubility parameter of the first resist material through crosslinking. After the first exposure, the resist material undergoes crosslinking transformation that alters its chemical properties, making it insoluble in the developer used during the second exposure. This parameter change enables the same material to function differently at different process stages
3Measurement precision
If the first resist pattern is made insoluble through crosslinking, then overlay accuracy is improved, but additional exposure step is required
Solution Approach 1:
The patent makes the crosslinking process continuous by performing it during or immediately after the first exposure without interrupting the patterning sequence. The crosslinking action continues the useful action of pattern formation rather than adding a separate discrete step, minimizing time loss while ensuring overlay accuracy
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 enhances the resolution and accuracy of pattern formation by ensuring the first resist pattern is insoluble in alkaline developers, enabling a single dry etching step and improving overlay accuracy, thus addressing the limitations of existing double patterning techniques.
Implementation Method 1
crosslinked by high-energy radiation with wavelengths between 200 nm to 320 nm
Data Source
AI summary
A pattern is formed by applying a first positive resist composition onto a substrate, heat treatment, exposure, heat treatment and development to form a first resist pattern; causing the first resist pattern to crosslink and cure by irradiation of high-energy radiation of 200-320 nm wavelength; further applying a second positive resist composition onto the substrate, heat treatment, exposure, heat treatment and development to form a second resist pattern. The double patterning process reduces the pitch between patterns to one half.