Three-Color Hardmask for Selective Fin Etching
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Solution Overview
Problem
In semiconductor fabrication, particularly for FinFETs, the selective removal of fins is challenging due to errors in edge placement and critical dimension, leading to damage or removal of neighboring fins during the lithographic process.
Innovation Solution
A three-color hardmask fin pattern is formed using self-assembled fins with selective etchability, allowing for the precise removal of one fin type without damaging nearby fins of different compositions, achieved through a process involving seed layers, directed self-assembly, and selective etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic masking is used to remove fins, then the process is simple and fast, but edge placement errors and critical dimension errors cause neighboring fins to be damaged or removed
Solution Approach 1:
The patent divides the uniform hardmask structure into multiple segments with different materials (first hardmask material, second hardmask material, third hardmask material) arranged in alternating patterns. This segmentation allows selective etching of specific fin regions while protecting others, resolving the contradiction by enabling precise fin removal without damaging neighboring fins.
Solution Approach 2:
The patent applies different hardmask materials at different locations along the fin structure. The first hardmask material is used where fin removal is desired, while the second and third hardmask materials are used where fin protection is needed. This local differentiation of material properties enables precise spatial control over etching outcomes.
2Length of moving object
If the lithographic process operates near its limit to achieve tighter pitch, then device scaling is improved, but masking errors increase significantly
Solution Approach 1:
The patent forms the multi-material hardmask structure before the fin etching process. By pre-establishing the alternating pattern of different hardmask materials that define where fins should be removed or protected, the process eliminates the need for precise lithographic masking at the final fin pitch, thereby resolving the contradiction between tight pitch and masking accuracy.
3Ease of manufacture
If a single hardmask material is used for fin formation, then the process is simple and fast, but selective removal of individual fins is not possible
Solution Approach 1:
The patent changes the material parameter of the hardmask from a single uniform material to multiple materials with different etch selectivities. This parameter change enables selective removal of fins by choosing appropriate etch conditions that preferentially remove one material over others, resolving the contradiction between manufacturing simplicity and fin selectivity.
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 ensures accurate and selective removal of fins, reducing errors and maintaining the integrity of neighboring fins, thereby improving the precision and reliability of fin formation in semiconductor fabrication.
Implementation Method 1
Self-assembled fins are formed by directed self-assembly on the seed layer fins
Implementation Method 2
The exposed fin of the first color is etched away with a selective etch that does not remove fins of a second color or a third color
Data Source
AI summary
Methods of forming fins include masking a region on a three-color hardmask fin pattern, leaving a fin of a first color exposed. The exposed fin of the first color is etched away with a selective etch that does not remove fins of a second color or a third color. The mask and all fins of a second color are etched away. Fins are etched into a fin base layer using the fins of the first color and the fins of the third color.