Double Patterning Pattern Verification Method
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Solution Overview
Problem
In semiconductor manufacturing, the miniaturization of devices leads to reduced line width and space, causing optical diffraction issues in photo-mask patterns, which result in deformation and resolution problems during the transfer of integrated circuit layouts onto semiconductor wafers, and existing double-exposure techniques face challenges in forming fine-sized devices.
Innovation Solution
A pattern verification method is introduced for the double patterning technique (DPT) process, involving a hard mask etching process, decomposition of target patterns into first and second patterns, and subsequent optical proximity correction (OPC) processes, followed by inspections to ensure accurate formation of the desired patterned hard mask and target layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the interval between transparent regions in a mask is scaled down to achieve fine-sized devices, then device miniaturization is improved, but optical diffraction increases and reduces resolution
Solution Approach 1:
The patent divides the pattern formation process into two separate exposure steps using two different photo-masks. The first photo-mask creates a preliminary pattern with larger features, and the second photo-mask refines it to create the final fine pattern. This segmentation allows each exposure to work at a manageable pitch while achieving the desired fine final pattern through cumulative effect.
Solution Approach 2:
The first exposure process performs a preliminary pattern formation before the final pattern is completed. By pre-forming a pattern with larger features, the subsequent second exposure can focus on refining and sharpening the edges, making the final fine pattern achievable while avoiding the diffraction problems of direct single-exposure at high resolution.
2Adaptability or versatility
If light passes through transparent regions with different interval sizes, then pattern complexity is improved, but light deformation occurs and reduces transfer accuracy
Solution Approach 1:
The patent segments the pattern into two separate exposures with different photo-masks. Each photo-mask has a consistent, manageable pitch that avoids the deformation problems of mixed-pitch masks. The first photo-mask handles the coarse pattern while the second handles the fine details, eliminating the need for complex mixed-interval transparent regions in a single mask.
Solution Approach 2:
The first photo-mask and its resulting pattern act as an intermediary layer between the original design and the final pattern. This intermediate pattern serves as a foundation that guides and constrains the second exposure process, ensuring accurate transfer while avoiding the optical deformation issues of direct single-step pattern transfer.
3Ease of manufacture
If double-exposure technique is used to decompose target pattern, then manufacturability is improved, but process complexity increases
Solution Approach 1:
The patent incorporates inspection processes between the two exposure steps to verify pattern quality. The inspection results provide feedback that allows for optical proximity correction (OPC) adjustments in the pattern design before the final exposure. This feedback loop ensures manufacturability while managing process complexity through controlled verification and correction at key stages.
Solution Approach 2:
The patent applies optical proximity correction by adjusting pattern parameters (such as line width, spacing, and shape) based on the specific exposure conditions and inspected results. These parameter changes optimize each exposure step for its specific purpose, improving overall manufacturability while keeping each individual step relatively simple and controllable.
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 precise formation of the target pattern by considering every step in the DPT process, including OPC, lithography, and etching, thereby overcoming the limitations of current technologies in achieving fine-sized device production.
Implementation Method 1
The photo-mask pattern is then proportionally transferred to a photoresist layer positioned on the semiconductor wafer
Implementation Method 2
When the light passes through the mask, diffraction occurs and reduces resolution
Implementation Method 3
a hard mask etching process to form a patterned hard mask
Data Source
AI summary
The present invention provides a pattern verifying method. First, a target pattern is decomposed into a first pattern and a second pattern. A first OPC process is performed for the first pattern to form a first revised pattern, and a second OPC process is performed for the second pattern to form a second revised pattern. An inspection process is performed, wherein the inspection process comprises an after mask inspection (AMI) process, which comprises considering the target pattern, the first pattern and the second pattern.