Wavy Fan-Out Circuit Lines Expand Process Window
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Solution Overview
Problem
The existing fan-out circuit line structures face challenges in achieving a large process window during the exposure process, leading to issues like photoresist peeling or print out problems due to semi-iso line exposure at the junction of the dense-line area and fan-out region, especially with increased line density and miniaturization.
Innovation Solution
A line structure for fan-out circuits is developed with a photomask pattern that includes a main pattern and an assistant pattern, where the assistant pattern is designed to enhance the process window by providing a wavy side profile for connecting lines, allowing for effective formation of dense lines and pads without forming dummy patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light source having a large light intensity in a single direction is used for exposure to ensure the resolution of the dense-line area, then the resolution of dense lines is improved, but the photoresist collapses and cannot be formed at the junction of dense-line area and fan-out region
Solution Approach 1:
The photomask pattern is segmented into two distinct parts: a main pattern for forming connecting lines and an assistant pattern for forming semi-iso lines. This segmentation allows each pattern to be optimized independently - the main pattern uses a wavy line design to reduce optical interference, while the assistant pattern provides additional light intensity to ensure proper formation of semi-iso lines at the junction area.
Solution Approach 2:
The assistant pattern acts as an intermediary element that mediates between the main pattern and the photoresist. It provides the additional light intensity needed at the junction area where the main pattern alone would cause photoresist collapse, thereby enabling proper formation of semi-iso lines without compromising the resolution of dense lines.
2Reliability
If dummy patterns are formed to improve the process window, then the process window is improved, but photoresist peeling or print out problem of dummy patterns occurs
Solution Approach 1:
Instead of adding dummy patterns to improve the process window, the invention inverts the approach by using a wavy line main pattern that inherently reduces optical interference and improves the process window. The assistant pattern then provides the necessary light intensity without requiring dummy patterns, thus avoiding photoresist peeling or print out problems.
3Quantity of substance
If line density increases and miniaturization progresses to reduce line spacing and line width, then the integration density is improved, but the resolution of dense lines during exposure deteriorates
Solution Approach 1:
The main pattern uses a wavy line design instead of straight lines. This curvature reduces optical interference and diffraction effects that become problematic at high line densities, thereby maintaining resolution during miniaturization. The wavy pattern modifies the light distribution to prevent constructive interference that would otherwise cause exposure problems.
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
The solution expands the process window, preventing photoresist peeling or print out issues and ensuring the formation of semi-iso lines, thereby maintaining the integrity of the line structure without dummy patterns.
Implementation Method 1
due to optical interference and diffraction
Implementation Method 2
due to optical interference and diffraction
Implementation Method 3
due to optical interference and diffraction
Data Source
AI summary
A line structure for fan-out circuit having a dense-line area and a fan-out area is provided. The line structure includes a plurality of dense lines arranged in the dense-line area parallel to a first direction, a plurality of pads disposed in the fan-out area, and a plurality of connecting lines arranged in the fan-out area parallel to a second direction. The connecting lines respectively connect one of the dense lines with one of the pads, wherein at least one of the connecting lines is a wavy line.