Semiconductor Mask Segmentation for Peripheral Metal Wiring Precision
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Solution Overview
Problem
Existing semiconductor device metal wiring formation techniques using off-axis illumination fail to achieve desired shape and size in peripheral regions due to mismatched focus, resulting in either excessive connection or cutting of metal wirings.
Innovation Solution
A mask with a cell exposure region and a peripheral exposure region, featuring first and second mask patterns with specific width and spacing configurations, ensures uniform pitch and accurate formation of signal and dummy metal patterns in the peripheral region, matching the pitch of the cell region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If off-axis illumination is used to form metal wirings with narrow pitch in the cell region, then the metal wirings in the cell region can be formed with desired precision, but the metal wirings in the peripheral region cannot be formed with desired shape and size due to focus mismatch
Solution Approach 1:
The mask is divided into two distinct exposure regions: a cell exposure region with first mask patterns configured for narrow pitch metal wirings, and a peripheral exposure region with second mask patterns configured for wider pitch metal wirings. This segmentation allows each region to have optimized focus characteristics for its specific pitch requirements, resolving the contradiction between precision for narrow pitch and adaptability for different pitches.
Solution Approach 2:
Different mask patterns with different optical properties are assigned to different spatial locations on the mask substrate. The first mask patterns in the cell exposure region have properties optimized for narrow pitch, while the second mask patterns in the peripheral exposure region have properties optimized for wider pitch. This local differentiation enables each region to achieve optimal focus and imaging quality for its specific requirements.
2Productivity
If the pitch between metal wirings is narrowed to increase integration density, then more functionality can be packed into the device, but the metal wirings in the peripheral region become difficult to form with accurate size and shape
Solution Approach 1:
The mask substrate is segmented into specialized zones: the cell exposure region handles narrow pitch patterns for high integration density, while the peripheral exposure region handles wider pitch patterns for accurate size and shape formation. This segmentation allows the device to achieve high integration density in critical areas without sacrificing manufacturing precision in peripheral areas.
Solution Approach 2:
The mask provides more focus options than a conventional single-focus mask by incorporating multiple focus zones. The off-axis illumination system is configured to provide sufficient angular diversity to satisfy both narrow pitch and wider pitch requirements simultaneously, enabling partial optimization for different regions rather than a compromise uniform focus.
3Ease of operation
If a single focus setting is used for the mask, then the exposure process is simple and quick, but the metal wirings in the peripheral region cannot achieve desired shape and pattern
Solution Approach 1:
Multiple focus requirements are merged into a single mask structure by spatially arranging different mask patterns on the same substrate. The first and second mask patterns coexist on the mask substrate, each optimized for its specific pitch range. This merging allows simultaneous satisfaction of multiple focus requirements without requiring multiple separate exposure steps or complex focus adjustment procedures.
Solution Approach 2:
The mask substrate serves multiple functions: it acts as both a cell exposure mask for narrow pitch patterns and a peripheral exposure mask for wider pitch patterns. This multi-functionality is achieved by integrating different pattern configurations on a single substrate, eliminating the need for separate masks or complex focus switching while maintaining manufacturing precision across different regions.
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 enables the formation of metal wirings in the peripheral region with a designed shape and size, preventing shorts and cuts by maintaining a uniform pitch and width, similar to the cell region, using off-axis illumination.
Implementation Method 1
a metal wiring of a semiconductor device may be formed by an exposure process using a mask
Implementation Method 2
exposure processes using an off-axis illumination have been being used to form metal wirings having the narrow pitch
Data Source
AI summary
A mask including a mask substrate including a cell exposure region and a peripheral exposure region, the cell exposure region configured to expose a metal layer in a cell region of a semiconductor device, the peripheral exposure region configured to expose a metal layer in a peripheral region of the semiconductor device, a first mask pattern configured to expose the metal layer in the peripheral exposure region of the mask substrate to form a signal metal pattern, and a second mask pattern configured to expose the metal layer in the peripheral exposure region of the mask substrate to form a dummy metal pattern, the second mask pattern being adjacent to the first mask pattern, and the second mask pattern having a substantially same width as a width of the first mask pattern may be provided.