TSV Validation Structure Using a Smaller Reference Via
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Solution Overview
Problem
The formation of through substrate vias (TSVs) in integrated circuits, particularly in gallium nitride (GaN) devices on silicon carbide (SiC) substrates, is challenging due to the difficulty and time-consuming nature of etching SiC, which can result in over-etching or under-etching, leading to improperly formed TSVs.
Innovation Solution
A method is introduced to validate the formation of standard TSVs by using a non-standard TSV as a reference. The non-standard TSV is formed using a smaller opening in the mask, resulting in a slower etch rate, and is then tested for conductivity. If the non-standard TSV is properly formed, it provides confidence that the standard TSVs, formed using a larger opening, are also properly formed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SiC substrate is etched to form TSVs, then electrical connections are established from first side to second side of substrate, but etching process is difficult and time-consuming leading to over-etching or under-etching
Solution Approach 1:
The patent introduces a test TSV structure with a smaller opening than standard TSVs. This test structure is formed in advance during the same etching process to preliminarily validate whether the etching parameters (time, temperature, chemistry) are correct. By testing on a smaller opening first, the process can be validated before committing to full production TSV formation, preventing both over-etching and under-etching of the main TSVs.
Solution Approach 2:
The test TSV structure acts as an intermediary between the etching process development and full TSV production. It serves as a mediator that allows process validation without directly testing the standard TSVs, providing a safe way to determine optimal etching parameters that will then be applied to form the actual electrical connection TSVs.
2Measurement precision
If standard TSVs are directly formed and tested, then electrical connectivity can be validated, but this requires direct testing of each TSV which reduces efficiency
Solution Approach 1:
The patent creates a test TSV structure that is a simplified copy or representation of the standard TSV formation process. Instead of testing each standard TSV individually, a representative test structure with smaller opening is formed and tested. The validation results from this test copy are then used to infer the quality of all standard TSVs, significantly improving validation efficiency while maintaining measurement precision.
Solution Approach 2:
The test TSV structure serves multiple functions: it validates the etching process, determines optimal etching parameters, and provides a reference for judging standard TSV quality. By using this single test structure, the patent achieves what would otherwise require testing multiple or all standard TSVs, thereby improving productivity without sacrificing validation accuracy.
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
This method allows for the validation of standard TSVs without directly testing them, providing a reliable means to ensure proper formation and electrical connectivity, thus improving the efficiency and accuracy of TSV formation in integrated circuits.
Implementation Method 1
a substrate is etched by an etching material from the first surface to a second surface
Implementation Method 2
a conductive material is arranged within the TSV to form a conductive path between the first surface to the second surface
Data Source
AI summary
An integrated circuit comprises a substrate that includes a first surface and a second surface. A first through substrate via (TSV) is formed between the first surface and the second surface and a first conductive material is arranged within the first TSV to form a conductive path between the first surface and the second surface through the substrate. A second TSV is formed between the first surface and the second surface and a second conductive material arranged within the second TSV to form a conductive path between the first surface and the second surface through the substrate. In examples the first TSV has a larger cross-sectional area than the second TSV, the cross-section of the first TSV and second TSV being in a plane parallel to the first surface or the second surface.