Semiconductor Micro Pattern Formation via Dual Auxiliary Layer Focus Control
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Solution Overview
Problem
The development of exposure equipment for forming micro patterns in semiconductor devices with high integration levels is inadequate, leading to poor critical dimension (CD) due to overlay issues between neighboring patterns, particularly when using the double exposure etch (DEET) method, and the spacer formation method is limited to forming only simple and uniform micro patterns.
Innovation Solution
A method involving multiple auxiliary layers and exposure processes is employed, where a target etch layer, hard mask layer, and auxiliary layers are formed over a semiconductor substrate, with specific focus control during exposure processes to form mask patterns, allowing for the etching of the target etch layer using these patterns, thereby addressing the CD issue and enabling the formation of micro patterns with various forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the DEET method is employed to form hard mask pattern, then micro pattern can be formed, but critical dimension becomes poor due to overlay between neighboring patterns
Solution Approach 1:
The patent segments the exposure process into two separate steps: first exposing the first auxiliary layer to form first exposure patterns, then exposing the second auxiliary layer to form second exposure patterns. This segmentation allows each layer to be exposed independently with optimized focus conditions, avoiding the overlay problems that plague conventional DEET methods while still enabling complex micro pattern formation.
Solution Approach 2:
The patent introduces a vertical dimension by stacking multiple auxiliary layers at different heights (first auxiliary layer and second auxiliary layer separated by isolation layer). By controlling focus at different vertical positions during exposure, the method achieves precise pattern formation in three-dimensional space, thereby improving critical dimension control while maintaining pattern formation versatility.
2Manufacturing precision
If the spacer formation method is employed, then micro patterns can be formed, but only simple and uniform critical dimension patterns can be formed
Solution Approach 1:
The patent performs preliminary exposure actions on different auxiliary layers at different focus positions before final pattern transfer. By pre-forming exposure patterns in the first auxiliary layer and then in the second auxiliary layer, the method creates a foundation for diverse micro pattern shapes while maintaining uniform critical dimensions, overcoming the limitations of spacer formation method.
Solution Approach 2:
The patent applies different focus conditions to different auxiliary layers: the first auxiliary layer is exposed with focus brought into it, while the second auxiliary layer is exposed with focus brought into it separately. This local optimization of exposure conditions for each layer enables both uniform critical dimensions and diverse pattern shapes to be achieved simultaneously.
3Adaptability or versatility
If multiple exposure processes are performed with focus control, then micro patterns with various forms can be formed, but process complexity increases
Solution Approach 1:
The patent uses auxiliary layers that serve multiple functions: they act as masks during exposure, provide structural support during etching, and enable focus control during different exposure steps. By designing auxiliary layers with multi-functionality, the method achieves diverse micro pattern formation without proportionally increasing process complexity, as the same layers perform multiple roles throughout the fabrication process.
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 method effectively forms micro patterns with precise critical dimensions and various shapes, reducing the number of process steps and production costs, while overcoming the limitations of conventional techniques by controlling focus and etch selectivity between layers.
Implementation Method 1
A first exposure process is performed by bringing a focus into the first auxiliary layer. A second exposure process is performed by bringing a focus into the second auxiliary layer.
Implementation Method 2
The isolation layer and the first auxiliary layer are etched by means of an etch process using the second auxiliary patterns as an etch mask
Data Source
AI summary
A method for fabricating a semiconductor device includes forming a target etch layer over a substrate, a first auxiliary layer over the target etch layer, an isolation layer over the first auxiliary layer, and a second auxiliary layer over the isolation layer. A first exposure process is performed, where the first auxiliary layer is in focus and the second auxiliary layer is out of focus. A second exposure process is performed, where the second auxiliary layer in focus and the first auxiliary layer is out of focus. The second auxiliary layer is developed to form first mask patterns. The isolation layer and the first auxiliary layer are etched by using the first mask patterns to form second mask patterns. The second mask patterns are developed to form third mask patterns that are used to facilitate subsequent etching of the target etch layer.