TSV Electrical Testing via PN Junction Diode
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Solution Overview
Problem
The challenge in the manufacturing process of integrated circuits is to verify the proper operation of through-silicon vias (TSVs) before dicing, as the back end of each TSV is embedded within the substrate and not directly accessible for testing, making it difficult to detect defects and parasitic phenomena.
Innovation Solution
A method involving a semiconductor substrate with opposing conductivity type layers forming a PN junction diode, where TSVs extend through the substrate with their back end embedded in a doped region, allowing for electrical testing by applying a current and sensing it at the junction diode to detect faults or proper operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the back end of TSV is embedded within the substrate to enable vertical interconnection, then the TSV provides effective electrical connection through the substrate, but the back end becomes inaccessible for direct testing
Solution Approach 1:
The patent introduces an intermediary PN junction diode structure formed by doping regions at the back end of the substrate. This diode acts as a mediator that enables indirect electrical testing of the TSV back end through the front surface, resolving the accessibility problem while maintaining the embedded TSV structure's reliability
2Ease of operation
If TSV extends completely through the substrate to enable back-side access, then electrical connection is established, but defect detection before dicing becomes difficult
Solution Approach 1:
The patent implements preliminary electrical testing of TSV functionality through the PN junction diode structure before the dicing operation. This allows defects to be detected and chips to be sorted while still in wafer form, preventing defective units from proceeding to packaging and improving overall yield
3Difficulty of detecting and measuring
If the substrate is thinned to expose TSV back end, then testing accessibility is improved, but substrate integrity and mechanical strength are reduced
Solution Approach 1:
Instead of physically thinning the substrate to access the TSV back end, the patent uses an electrical intermediary (PN junction diode) formed through doping. This approach provides testing accessibility through electrical means while preserving the substrate's mechanical integrity and avoiding the need for aggressive thinning operations
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
Enables effective verification of TSV functionality and detection of defects before dicing, ensuring only functional chips are processed further, thereby improving the yield and quality of integrated circuits.
Implementation Method 1
a first semiconductor layer of a first conductivity type and a second semiconductor layer of a second conductivity type opposite the first conductivity type, said first and second semiconductor layers in contact with each other at a PN junction to form a junction diode
Data Source
AI summary
A substrate includes first and second semiconductor layers doped with opposite conductivity type in contact with each other at a PN junction to form a junction diode. At least one through silicon via structure, formed by a conductive region surrounded laterally by an insulating layer, extends completely through the first semiconductor layer and partially through the second semiconductor layer with a back end embedded in, and in physical and electrical contact with, the second semiconductor layer. A first electrical connection is made to the first through silicon via structure and a second electrical connection is made to the first semiconductor layer. A testing current is applied to and sensed at the first and second electrical connections in order to detect a defect in the at least one through silicon via structure.