Double Patterned Photoresist Structure via Stacked Layers
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Solution Overview
Problem
Conventional methods for forming double patterned semiconductor structures, such as LELE and DDT processes, are complex and difficult to control, leading to increased processing complexity and cost, and require multiple lithographic and etching processes.
Innovation Solution
A method involving the formation of a negative photoresist layer and a positive photoresist layer over a substrate, where exposure processes create distinct regions in each layer, followed by development and etching to form a double patterned structure using one exposure process and one photo mask, simplifying the process and reducing interactions between development steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If LELE process is used to reduce pitch, then manufacturing precision is improved, but device complexity increases due to multiple lithographic and etching processes
Solution Approach 1:
The patent combines two different photoresist layers (positive and negative tone) into a single stacked structure that undergoes one exposure process. This merging approach achieves the pitch reduction goal of double patterning while eliminating the need for separate lithographic and etching steps, thereby reducing processing complexity.
Solution Approach 2:
The patent introduces a vertical dimension by stacking positive and negative photoresist layers on top of each other. This dimensional change allows the system to achieve double patterned structures through a single planar exposure process, converting a multi-step sequential process into a single parallel operation.
2Manufacturing precision
If DDT process is used to form dual pattern, then pitch is reduced, but ease of operation deteriorates due to difficult control of development processes
Solution Approach 1:
The patent segments the photoresist system into two distinct layers with different tonal characteristics (positive and negative). This segmentation allows each layer to respond differently to the exposure and development processes, enabling independent control of pattern formation and eliminating the mutual interference problem in conventional DDT processes.
Solution Approach 2:
The positive photoresist layer acts as an intermediary that protects specific regions of the negative photoresist layer during development. This intermediary layer enables precise control over which portions of the negative photoresist are removed, simplifying the overall control of the pattern formation process.
3Manufacturing precision
If multiple development processes are performed, then pattern accuracy is improved, but loss of time increases due to multiple processing steps
Solution Approach 1:
The patent enables continuous pattern formation by performing exposure and development operations on the stacked photoresist structure simultaneously. The positive and negative photoresist layers undergo their respective chemical changes in a continuous process without interruption, eliminating the need for separate processing cycles and reducing total processing time.
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 approach simplifies the formation of double patterned structures with improved control and reduced processing complexity, saving costs by using fewer steps and avoiding interactions between development processes, while maintaining high accuracy and topography.
Implementation Method 1
An exposure process can be performed to form a first exposure region in the positive photoresist layer and to form a second exposure region in the negative photoresist layer
Implementation Method 2
A positive-tone development process can be formed to remove the first exposure region from the positive photoresist layer
Data Source
AI summary
A semiconductor structure including a double patterned structure and a method for forming the semiconductor structure are provided. A positive photoresist layer is formed on a negative photoresist layer, which is formed over a substrate. An exposure process is performed to form a first exposure region in the positive photoresist layer and to form a second exposure region in the negative photoresist layer in response to a first and a second intensity thresholds of the exposure energy. A positive-tone development process is performed to remove the first exposure region from the positive photoresist layer to form first opening(s). The second exposure region in the negative photoresist layer is then etched along the first opening(s) to form second opening(s) therein. A negative-tone development process is performed to remove portions of the negative photoresist layer outside of remaining second exposure region to form a double patterned negative photoresist layer.