Multi-Color SAQP for DRAM STI Active Cut Patterning
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Solution Overview
Problem
Current dynamic random access memory (DRAM) active-cut patterning techniques, such as cross self-aligned double patterning (X-SADP) and lithography-etch-lithography-etch (LELE) schemes, lead to reduced shallow trench isolation (STI) active island areas as technology nodes advance, causing yield issues and buried wordline patterning problems.
Innovation Solution
The implementation of a multi-color self-aligned quadruple patterning (SAQP) method using carbon-based gapfill materials and a spacer-on-spacer scheme, which includes conformal gapfill processes, spin-on-carbon layers, and selective etching to enhance active area patterning and increase the shallow trench isolation area by up to 25%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cross self-aligned double patterning (X-SADP) or lithography-etch-lithography-etch (LELE) schemes are employed for DRAM active-cut patterning, then patterning capability is achieved, but shallow trench isolation active island area is reduced
Solution Approach 1:
The patent divides the patterning process into four distinct steps (SAQP - self-aligned quadruple patterning) rather than using traditional double patterning. This segmentation allows for more precise control over the active area dimensions by creating patterns in incremental stages, thereby maintaining larger active island areas while achieving the required patterning precision.
Solution Approach 2:
The patent introduces a fourth patterning dimension by performing additional etching and spacer formation steps beyond the conventional double patterning approach. This enables independent control of pattern dimensions in multiple directions, allowing optimization of active area size while maintaining patterning capability.
2Productivity
If technology node advances are made to improve memory density, then integration capacity increases, but active area shrinks causing yield issues
Solution Approach 1:
The patent changes the critical parameters of the patterning process by using a four-step SAQP methodology with specific spacer material selections and deposition thicknesses. This allows decoupling of memory density improvements from active area reduction, enabling technology node advancement without the typical active area shrinkage that causes yield issues.
Solution Approach 2:
The patent uses spacer materials as intermediaries between the lithography pattern and the final etched structure. By carefully controlling spacer deposition and etching processes, the active area dimensions can be precisely controlled independent of the lithography resolution limits, allowing density improvement without active area loss.
3Device complexity
If conventional patterning schemes are used, then manufacturing process is simpler, but buried wordline patterning and yield issues occur
Solution Approach 1:
The patent performs preliminary spacer formation and pattern definition steps before the final active area etching. This preliminary action ensures that the active area boundaries are precisely established before buried wordline patterning occurs, preventing yield issues while the additional process steps are managed through systematic workflow integration.
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 effectively increases the active area and provides a higher margin for buried wordline patterning, reducing the number of patterning steps and costs while maintaining high selectivity and efficiency.
Implementation Method 1
A conformal gapfill process is performed to fill the trench with carbon gapfill material to form a carbon line
Implementation Method 2
A spin-on-carbon (SOC) layer is deposited on the carbon material to fill the opening in the overburden carbon material and cover the carbon gapfill material
Data Source
AI summary
Apparatuses and methods to provide a patterned substrate are described. A plurality of patterned and spaced first lines and carbon material lines and formed on the substrate surface by selectively depositing and etching films extending in a first direction and films extending in a second direction that crosses the first direction to pattern the underlying structures.