Test Key Array With Crossed L-Shaped Traces For Defect Detection
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Solution Overview
Problem
The miniaturization of semiconductor devices and shrinking scribe line sizes in the dual damascene structure make it difficult to detect manufacturing defects such as over-etching and misalignment, especially in the vertical and horizontal directions, during the wafer acceptable test (WAT) process.
Innovation Solution
A test key array with a lower conductive pattern of first L-shaped traces and an upper conductive pattern of second L-shaped traces, crossed to form cross regions with conductive plugs that electrically connect both patterns, allowing for simultaneous detection of defects by analyzing signals from first and second pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the dual damascene structure is used with miniaturized devices and shrunk scribe lines, then device density and integration are improved, but the ability to detect manufacturing defects such as over-etching and misalignment deteriorates
Solution Approach 1:
The test key structure is segmented into multiple conductive patterns (first conductive pattern, second conductive pattern, third conductive pattern) arranged in different orientations. This segmentation allows independent testing of different directional alignments and etching depths, enabling precise defect detection despite miniaturization. Each conductive pattern acts as an independent test element that can reveal specific types of manufacturing defects.
Solution Approach 2:
The invention extends the test key structure from a single-plane configuration to a multi-layered three-dimensional arrangement with conductive patterns on different levels (first, second, and third conductive patterns). This dimensional expansion provides multiple testing dimensions that can simultaneously assess vertical alignment, horizontal alignment, and etching depth, thereby maintaining defect detection capability despite device miniaturization.
2Area of stationary object
If the scribe line width is reduced to accommodate smaller devices, then wafer capacity and device density are improved, but the margin for manufacturing defects such as over-etching is reduced
Solution Approach 1:
The test key structure performs preliminary testing of the manufacturing process by incorporating dedicated test elements (conductive patterns) that are specifically designed to reveal potential defects before actual device fabrication. The multi-pattern configuration allows early detection of over-etching and misalignment issues, enabling process adjustment before full production, thus maintaining reliability despite reduced scribe line width.
Solution Approach 2:
The conductive patterns in the test key structure serve as feedback mechanisms that provide information about manufacturing process quality. By measuring the electrical characteristics of these patterns, the system generates feedback about alignment accuracy and etching depth, allowing real-time or near-real-time process control and adjustment to maintain reliability even with narrower scribe lines.
3Ease of manufacture
If conventional test key structures are used, then manufacturing simplicity is maintained, but the ability to detect both vertical and horizontal misalignment simultaneously is insufficient
Solution Approach 1:
The test key structure achieves multi-functionality by incorporating multiple conductive patterns (first, second, and third conductive patterns) with different orientations and configurations within a single test key element. This universal structure can simultaneously detect vertical misalignment, horizontal misalignment, and etching depth variations, replacing the need for multiple separate test structures and maintaining manufacturing simplicity while enhancing detection capability.
Data Source
AI summary
The present invention provides a test key array including a lower conductive pattern, and the lower conductive pattern includes a plurality of first L-shaped traces parallel to each other, an upper conductive pattern, where the upper conductive pattern includes a plurality of second L-shaped traces parallel to each other, the lower conductive pattern crosses to the upper conductive pattern, and a plurality of cross regions are defined between the lower conductive pattern and the upper conductive pattern, and a plurality of conductive plugs, disposed on parts of the cross regions, electrically connecting to the lower conductive pattern and the upper conductive pattern.