Self-Aligned Double Patterning With Variable Spacers for Line Spacing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing optical proximity effect in integrated circuits during down-scaling poses a challenge, causing features to short to each other, which is addressed by the introduction of double patterning technology to separate closely located features into two photolithography masks, reducing the optical proximity effect.
Innovation Solution
The implementation of self-aligned double patterning (SADP) using a mandrel layer and a spacer layer, where the spacer layer is etched to create a mask with varying widths, allowing for customizable separation between metal lines, enabling both tighter and looser spacings within the same die to control capacitance effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If double patterning technology is used to separate closely located features into two photolithography masks, then the optical proximity effect is reduced, but the device complexity and manufacturing process complexity increase
Solution Approach 1:
The patent segments the patterning process into two separate photolithography masks, dividing the features into two groups that can be processed independently. This segmentation allows each mask to have larger feature spacing, reducing the optical proximity effect while maintaining the ability to create fine-pitch patterns through the combination of both masks.
Solution Approach 2:
The patent introduces an intermediary layer (such as a mandrel layer or spacer layer) that facilitates the double patterning process. This intermediary structure serves as a template or guide for forming the final pattern, enabling the separation of closely located features into two distinct masking steps while providing structural support during fabrication.
2Manufacturing precision
If uniform spacer width is used in SADP, then manufacturing precision is improved, but adaptability to different capacitance requirements deteriorates
Solution Approach 1:
The patent implements local quality by allowing different regions of the device to have different spacer widths tailored to their specific capacitance requirements. Critical areas with high sensitivity to capacitance effects receive thicker spacers for greater separation, while less sensitive areas use thinner spacers to maintain tighter spacing and reduce die area. This regional differentiation optimizes both manufacturing precision and adaptability.
Solution Approach 2:
The patent introduces dynamic flexibility into the SADP process by enabling variable spacer widths across different locations. This is achieved through techniques such as selective spacer formation, pattern-dependent spacer deposition, or multi-step etching processes that can create different spacer thicknesses in different regions, allowing the structure to adapt to varying electrical performance requirements.
3Area of stationary object
If tighter spacing between metal lines is used, then die area is reduced, but capacitance effects between lines increase
Solution Approach 1:
The patent utilizes parameter changes by varying the spacer width (a geometric parameter) to control the spacing between metal lines. By adjusting this parameter locally, the design can optimize the balance between die area and capacitance effects, creating tighter spacing where area is critical and wider spacing where capacitance control is paramount.
Solution Approach 2:
The patent applies local quality principles by implementing different spacing strategies in different areas of the die. High-capacitance-sensitive regions receive enhanced spacing through thicker spacers to minimize harmful capacitance effects, while regions where area optimization is prioritized use thinner spacers for tighter packing, achieving a localized optimization of both parameters.
Data Source
AI summary
A method includes patterning a mandrel layer over a target layer to form first mandrels and second mandrels, the first mandrels having a larger width than the second mandrels. A spacer layer is formed over the first mandrels and the second mandrels, and altered so that a thickness of the spacer layer over the first mandrels is greater than a thickness of the spacer layer over the second mandrels. Spacers are formed from the spacer layer which have a greater width adjacent the first mandrels than the spacers which are adjacent the second mandrels. The spacers are used to etch a target layer.