Semiconductor Test Structure With Backside Pads for Four-Terminal Sensing
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Solution Overview
Problem
The increasing complexity and area requirements for monitoring semiconductor process variations due to the scaling of advanced technology nodes necessitate improvements in semiconductor structures, particularly in the placement and accessibility of test structures.
Innovation Solution
A semiconductor structure design that includes a test structure with a first electrically conductive connection extending from a front side to a backside test pad, allowing access and monitoring without the need for external probes on small signal lines, and utilizing backside test pads to reduce area and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If monitoring structures are placed within scribe line or design to monitor process variations, then measurement capability is improved, but area required and device complexity increase
Solution Approach 1:
The patent utilizes the vertical dimension by extending conductive connections through the substrate thickness to reach the backside surface. This allows test pads to be placed on the backside, effectively using the third dimension (substrate thickness) to resolve the area conflict on the front surface while maintaining monitoring capability.
Solution Approach 2:
The patent divides the substrate into front side and back side, placing different functional elements on each side. Test structures and signal lines are on the front side, while test pads are on the back side, segmenting the monitoring function from the processed area to reduce interference and area requirements.
2Ease of manufacture
If more process steps are added to advanced nodes, then manufacturing capability is improved, but parameters to track increase and complexity increases
Solution Approach 1:
The substrate itself serves multiple functions: it is both the processed material containing circuit patterns and the mounting platform for test pads. The conductive connections serve dual purposes as both signal pathways and structural elements, reducing the need for separate dedicated test structure components.
Solution Approach 2:
The existing substrate and conductive connection structures are utilized for testing purposes without requiring separate dedicated test infrastructure. The substrate's own physical and electrical properties are leveraged to provide testing capabilities, making the system self-sufficient for monitoring.
3Measurement precision
If external probes are used to access small signal lines for testing, then measurement access is improved, but ease of operation deteriorates due to difficulty in contacting small features
Solution Approach 1:
The test pads are moved to the backside surface of the substrate, creating a large accessible area that is easy to probe. The conductive connections extend vertically through the substrate to link these large backside pads to the small front-side signal lines, making probing straightforward while maintaining precise signal access.
Solution Approach 2:
The conductive connections act as intermediaries between the large, easily accessible backside test pads and the small, difficult-to-access front-side signal lines. This intermediary structure transfers electrical signals while bridging the gap between easy-to-probe and precise measurement requirements.
Data Source
AI summary
A semiconductor structure is provided. The semiconductor structure includes a plurality of transistors arranged at a front side of a semiconductor substrate and a test structure located at the front side of the semiconductor substrate. Further, the semiconductor structure comprises a first electrically conductive connection extending from the test structure through the semiconductor substrate to a backside test pad arranged at a backside of the semiconductor substrate.