In-line TSV Depth Measurement via Resistance
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Solution Overview
Problem
Current semiconductor manufacturing techniques lack an in-line method to measure the depth of Through-Silicon-Vias (TSVs) before they are filled with conductive material, preventing timely detection and recovery of inadequately formed TSVs.
Innovation Solution
A resistance measurement trench structure with predetermined dimensions is created in the substrate, allowing for the calculation of TSV depth using a 4-terminal sensing configuration and ohmic contacts, enabling in-line measurement before metal fill.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional electrical testing is used to determine TSV yield, then measurement can be performed after BSM deposition, but the measurement is too late to allow for yield recovery
Solution Approach 1:
The patent implements preliminary action by performing TSV depth measurement using a test structure and resistance measurement method before the BSM deposition step. This allows the measurement to be completed in advance, enabling yield assessment and potential re-etching decisions to be made before the fabrication process reaches the point where poor yields cannot be recovered. The test structure is formed during the TSV formation process itself, allowing measurement at an optimal intermediate stage.
2Productivity
If TSV depth measurement is performed before metal fill, then yield recovery is enabled, but no in-line measurement method was previously available
Solution Approach 1:
The patent introduces an intermediary test structure that includes a test TSV and associated measurement circuitry (such as pad structures and contact structures) formed alongside the actual TSVs. This intermediary structure serves as a proxy for measuring TSV depth indirectly through resistance measurements, avoiding the need for complex direct measurement equipment while enabling in-line measurement capability during the fabrication process.
3Reliability
If TSV yield determination is delayed until after BSM deposition, then measurement is possible, but any poor yields cannot be recovered
Solution Approach 1:
The patent implements preliminary action by performing TSV depth measurement using a test structure and resistance measurement method before the BSM deposition step. This allows the measurement to be completed in advance, enabling yield assessment and potential re-etching decisions to be made before the fabrication process reaches the point where poor yields cannot be recovered. The test structure is formed during the TSV formation process itself, allowing measurement at an optimal intermediate stage.
Solution Approach 2:
The patent implements feedback by using the resistance measurement results from the test structure to determine TSV depth and yield status. This feedback information is then used to make real-time process decisions, such as whether to perform re-etching operations to correct inadequate TSV formation. The feedback loop enables continuous process control and optimization, improving overall TSV yield while preventing defective TSVs from proceeding to subsequent steps.
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 accurate and timely detection of TSV depth, allowing for re-etching and improvement of yield before conductive filling, with self-calibration capabilities and accurate 4-point probe measurements.
Implementation Method 1
A testing circuit contacts the ohmic contacts and measures a resistance therebetween, and a processor connected to the testing circuit calculates a depth of the unfilled TSV structure based on the pre-determined correlation between measured resistance and the depth of the resistance measurement trench structure
Implementation Method 2
The testing circuit comprises a 4-terminal, (Kelvin bridge), sensing configuration, where each connection from the testing circuit to the ohmic contacts include separate pairs of current-carrying and voltage-sensing electrodes
Implementation Method 3
The isolation trenches are implemented to block the measurement current from passing the sides of the resistance measurement trench structure, so that all the current passes underneath the resistance measurement trench structure between the ohmic contacts
Data Source
AI summary
A system, method and device for measuring a depth of a Through-Silicon-Via (TSV) in a semiconductor device region on a wafer during in-line semiconductor fabrication, includes a resistance measurement trench structure having length and width dimensions in a substrate, ohmic contacts on a surface of the substrate disposed on opposite sides of the resistance measurement trench structure, and an unfilled TSV structure in semiconductor device region having an unknown depth. A testing circuit makes contact with the ohmic contacts and measures a resistance therebetween, and a processor connected to the testing circuit calculates a depth of the trench structure and the unfilled TSV structure based on the resistance measurement. The resistance measurement trench structure and the unfilled TSV are created simultaneously during fabrication.