FinFET Patterning via Sequential Mask Etching
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Solution Overview
Problem
Current lithography techniques face limitations in forming small device patterns, particularly for fin-like field effect (FinFET) devices, due to resolution constraints, leading to issues like corner rounding and poor line cutting, especially around inside corners.
Innovation Solution
A method involving a set of three patterned masks is used to pattern elongated protrusions on a substrate, where each mask layer is applied sequentially to form a non-rectangular pattern, with specific etch processes and materials ensuring precise alignment and prevention of alteration, allowing for the formation of features with sharp corners and accurate dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current lithography techniques are used to form small device patterns, then device scaling is achieved, but corner rounding and poor line cutting occur especially around inside corners
Solution Approach 1:
The patent divides the patterning process into multiple sequential steps using different masks (first mask for initial pattern, second mask for corner refinement, third mask for inside corner protection). This segmentation allows each mask to address specific geometric requirements independently, preventing corner rounding by protecting inside corners during etching while maintaining overall pattern accuracy.
Solution Approach 2:
The patent applies preliminary protective actions by forming mask layers before etching processes. The third mask layer is specifically applied to protect inside corners before the etch process, preventing the harmful rounding effect from occurring in the first place. This preliminary protection ensures corner sharpness is maintained throughout subsequent processing.
2Productivity
If lithography resolution is increased to form smaller patterns, then device integration density improves, but manufacturing complexity increases
Solution Approach 1:
The complex patterning requirement is segmented into three separate mask steps, each with a specific function. The first mask establishes the basic pattern, the second mask refines corner geometry, and the third mask protects inside corners. This segmentation transforms a single complex high-resolution lithography step into multiple simpler steps that can be executed with existing lithography tools, maintaining productivity while managing complexity.
Solution Approach 2:
Multiple mask layers serve as intermediaries between the lithography tool and the final pattern. These mask layers translate the limitations of current lithography resolution into precise geometric outcomes by using sequential patterning and protection steps. The masks mediate the etching process to achieve sharp corners and accurate dimensions without requiring beyond-state-of-the-art lithography resolution.
Data Source
AI summary
A method for patterning a plurality of features in a non-rectangular pattern on an integrated circuit device includes providing a substrate including a surface with a first layer and a second layer. Forming a plurality of elongated protrusions in a third layer above the first and second layers. Forming a first patterned layer over the plurality of elongated protrusions. The plurality of elongated protrusions are etched to form a first pattern of the elongated protrusions, the first pattern including at least one inside corner. Forming a second patterned layer over the first pattern of elongated protrusions and forming a third patterned layer over the first pattern of elongated protrusions. The plurality of elongated protrusions are etched using the second and third patterned layers to form a second pattern of the elongated protrusions, the second pattern including at least one inside corner.