TSV Key Ring Pattern Layout for Fine Overlay Measurement
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Solution Overview
Problem
Existing semiconductor technologies face challenges in accurately measuring the overlay of through-silicon vias (TSVs) with fine sizes due to the small width of active layers, leading to measurement errors and difficulties in aligning TSVs with underlying patterns.
Innovation Solution
A through-silicon via (TSV) key is introduced, comprising a first TSV extending through the substrate and surrounding ring patterns, allowing for precise overlay measurement by using the TSV as an inner measurement point and the ring patterns as outer measurement points, even for TSVs with diameters less than 7 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional overlay measurement methods are used for fine-sized TSVs, then the measurement process remains simple, but measurement precision deteriorates due to small active layer width
Solution Approach 1:
The patent introduces ring patterns as intermediary reference structures that surround the TSV. These ring patterns serve as mediators between the TSV and the measurement system, providing clearly distinguishable outer measurement points that improve overlay measurement precision without directly modifying the TSV structure itself
Solution Approach 2:
The patent transitions from measuring only the TSV position in one dimension to measuring both the TSV position and the ring pattern position. By adding the ring pattern dimension, the system can perform overlay measurement with higher precision by comparing multiple reference points rather than relying solely on the small TSV structure
2Length of moving object
If the active layer width is reduced for smaller TSV sizes, then device scaling is achieved, but measurement precision deteriorates due to insufficient feature size for accurate measurement
Solution Approach 1:
The patent segments the measurement reference into two distinct parts: the TSV itself serving as the inner measurement point and the surrounding ring patterns serving as outer measurement points. This segmentation allows the measurement system to use both the scaled-down TSV and the larger ring patterns together, maintaining measurement precision even as TSV dimensions are reduced
Solution Approach 2:
The ring patterns act as intermediary structures that bridge the gap between the small TSV and the measurement system's resolution capabilities. By introducing these intermediate reference features with larger dimensions, the system can accurately measure overlay for sub-7μm TSVs that would otherwise be too small for precise measurement
Data Source
AI summary
A through-silicon via (TSV) key for overlay measurement includes: a first TSV extending through at least a portion of a substrate in a first direction that is perpendicular to a top surface of the substrate; and at least one ring pattern, which is apart from and surrounds the first TSV in a second direction that is parallel to the top surface of the substrate, the at least one ring pattern being arranged in a layer that is lower than a top surface of the first TSV in the first direction, wherein an inner measurement point corresponds to the first TSV, an outer measurement point corresponds to the at least one ring pattern, and the inner measurement point and the outer measurement point are arranged to provide an overlay measurement of a TSV.