Hardmask Tone Inversion for Precise Substrate Pattern Transfer
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in reducing pattern misalignment and achieving precise overlay requirements, particularly at advanced technology nodes (7 nm and below), due to the shrinking dimensions of features.
Innovation Solution
The method involves forming multiple hardmask layers and using a tone inversion strategy to reverse the tone of patterns in the top hardmask, allowing for a subtractive etch of underlying layers. This process decouples patterning and tone inversion steps, reducing integration complexity and improving control over pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If feature dimensions are shrunk to double component density at each technology node, then component density is improved, but pattern misalignment increases and overlay precision deteriorates
Solution Approach 1:
The patent divides the single patterning process into multiple sequential patterning steps (e.g., first pattern formation, second pattern formation) with intermediate treatment steps. This segmentation allows each patterning step to work at relaxed dimensions while achieving the final high-density pattern through cumulative effect, thereby maintaining overlay precision despite feature shrinkage.
Solution Approach 2:
The patent performs preliminary pattern formation and treatment steps before final patterning. For example, a first pattern is formed and treated (such as partial etching or deposition) before forming the second pattern. This preliminary action prepares the substrate in a controlled state that facilitates precise subsequent patterning, reducing cumulative alignment errors.
2Quantity of substance
If multiple patterning steps are used to achieve high density, then component density is improved, but process complexity increases
Solution Approach 1:
The patent combines multiple patterning operations into a unified process flow where pattern formation and treatment steps are integrated. For example, the first pattern formation and its treatment are merged with the second pattern formation into a continuous process sequence, reducing the need for separate equipment setups and simplifying process control despite achieving high density.
Solution Approach 2:
The patent designs the patterning process to use the same equipment and process parameters for multiple patterning steps. The etching, deposition, and treatment conditions are kept universal across different pattern formation steps, allowing a single process module to handle multiple patterning operations, thereby reducing overall process complexity.
3Manufacturing precision
If stricter overlay requirements are imposed to reduce misalignment, then pattern alignment is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent employs self-aligned patterning techniques where the second pattern is formed using the first pattern as a reference or mask. For example, the second mandrel is positioned relative to the first pattern structure, allowing the pattern itself to define the alignment reference. This self-service approach automatically ensures precise alignment without requiring external overlay control systems, reducing manufacturing difficulty while maintaining high alignment precision.
Data Source
AI summary
A method for processing a substrate includes forming a first hardmask layer over a target layer and a second hardmask layer over the first hardmask layer, and patterning the second hardmask layer. The method further includes forming a tone inversion mask between portions of the patterned second hardmask layer, removing the patterned second hardmask layer, patterning the first hardmask layer using the tone inversion mask as an etching mask, and etching the target layer using the patterned first hardmask layer as another etching mask.