Optical Proximity Correction for Dual Damascene Alignment
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Solution Overview
Problem
Conventional OPC methods for dual damascene structures in semiconductor manufacturing face challenges in maintaining precise alignment and connection between metal interconnection systems due to optical diffraction issues, particularly with decreasing line widths and spacings, leading to deformation of transfer patterns.
Innovation Solution
A method involving a two-step OPC process where the first pattern undergoes a correction process to form a revised pattern with a specific shift, and the second pattern is aligned based on this shift, ensuring accurate positioning through an additional aligning process by moving the second pattern by a calculated distance, thereby maintaining the connection between related structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the interval between transparent regions in a mask is scaled down with device size to obtain fine-sized devices, then the device size is reduced, but optical diffraction occurs and resolution is reduced
Solution Approach 1:
The patent applies preliminary action by performing optical proximity correction (OPC) on the mask pattern before the actual photolithography process. The OPC process pre-compensates for optical diffraction effects by modifying the mask pattern in advance, adding serifs, corners, or other geometric features that counteract the expected diffraction. This allows fine-sized devices to be manufactured while maintaining resolution, as the diffraction effects are compensated for before exposure.
2Manufacturing precision
If the mask pattern is modified to compensate for diffraction, then resolution is improved, but the alignment between different pattern layers becomes more difficult to maintain
Solution Approach 1:
The patent implements feedback by using the measured or calculated shift from the first OPC process as input for the second OPC process. The shift amount determined from analyzing the first pattern's OPC results is fed back into the correction of the second pattern, ensuring that alignment compensation is systematically applied. This feedback mechanism maintains alignment precision while preserving the resolution improvements from diffraction compensation.
3Ease of manufacture
If conventional OPC methods are used for dual damascene structures, then the process is simple, but the connection and alignment between metal interconnection systems is not precise
Solution Approach 1:
The patent applies segmentation by dividing the OPC process into two distinct sequential steps: a first OPC process for the first pattern (e.g., mandrel layer) and a second OPC process for the second pattern (e.g., fill metal layer). Each step is optimized for its specific layer while considering the other, allowing precise control of connections and alignments in dual damascene structures without overwhelming process complexity.
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 approach enhances the connection between dual damascene structures by ensuring precise alignment and preventing unwanted defects, thereby expanding the process window for forming structures within tolerance values.
Implementation Method 1
When the light passes through the mask, diffraction occurs and reduces resolution
Data Source
AI summary
An optical proximity correction (OPC) process is provided. The method comprising receiving a first pattern corresponding to a first structure of a semiconductor structure, and a second pattern corresponding to a second structure of said semiconductor structure. Next, a first OPC process is performed for the first pattern to obtain a revised first pattern, wherein the revised first pattern has a first shift regarding to the first pattern. A second OPC process is performed for the second pattern to obtain a revised second pattern, wherein the second OPC process comprises moving the second pattern according to the first shift.