Multi-Die IC Split-Circuit-Boundary Scan Chain for Pre-Bond Testing
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Solution Overview
Problem
Existing design-for-test features in multi-die integrated circuits are insufficient for pre-bond testing of logic and post-bond testing of inter-die connections, leading to challenges in identifying and addressing faulty components, which can result in non-faulty dies being discarded.
Innovation Solution
The implementation of a split-circuit-boundary scan chain at the inter-die boundary, enabled by an automated design tool that splits an integrated circuit into portions and applies additional testing components to form a split-circuit-boundary scan chain for pre-bond and post-bond testing, including the use of flip-flops, bypass MUXs, and delay MUXs to facilitate thorough testing of inter-die connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an integrated circuit is split into multiple dies for fabrication, then the probability of manufacturing faults decreases and cost effectiveness improves, but the ability to test the circuit adequately worsens because existing design-for-test features are insufficient for pre-bond and post-bond testing
Solution Approach 1:
The integrated circuit is segmented into multiple dies that can be fabricated separately and then bonded together. Each die contains portions of the circuit logic and design-for-test features. This segmentation allows independent fabrication and testing of individual dies while maintaining the ability to test the complete circuit after bonding through the scan chain components that interface between dies.
Solution Approach 2:
Scan chain components (flip-flops, multiplexers, shift registers) are placed at the boundaries between dies to act as intermediaries. These components enable test signals to be passed between dies during both pre-bond testing (on individual dies) and post-bond testing (on the assembled multi-die circuit), thereby maintaining testability across the distributed architecture.
2Ease of manufacture
If existing design-for-test features are used in multi-die integrated circuits, then the circuit can be tested to some extent, but pre-bond testing of logic and post-bond testing of inter-die connections cannot be performed effectively, leading to potential discarding of non-faulty dies
Solution Approach 1:
Design-for-test features including scan chain components are incorporated into each die during the preliminary fabrication stage, before the dies are bonded together. This preliminary action enables pre-bond testing of individual dies to be performed, allowing faulty dies to be identified and discarded before bonding, thereby preventing waste of non-faulty dies.
Solution Approach 2:
The scan chain components provide feedback mechanisms that allow test results to be observed and analyzed. During pre-bond testing, feedback from individual die tests identifies which dies are faulty. During post-bond testing, feedback from inter-die connection tests identifies bonding or interface issues, enabling targeted repairs or replacements without discarding the entire multi-die circuit.
3Difficulty of detecting and measuring
If scan chains are added to support pre-bond and post-bond testing in multi-die circuits, then testability improves, but the device complexity and number of components increases
Solution Approach 1:
The scan chain components are designed to serve multiple functions: they enable pre-bond testing of individual dies, post-bond testing of inter-die connections, and normal circuit operation. By making these components universal and multi-functional, the patent avoids adding dedicated separate testing infrastructure, thereby limiting the increase in device complexity while still achieving comprehensive testability.
Data Source
AI summary
A multi-die integrated circuit with improved testability can include at least two dies that combined comprise an integrated circuit for a self-contained system, which includes logic and design-for-test features. The integrated circuit is split into at least two portions, where each portion is disposed on a corresponding one of the at least two dies. As part of the improved testability for both pre-bond testing of logic and post-bond testing of inter-die connections, at least one of the at least two dies further comprises a split-circuit-boundary scan chain. An automated design tool can be used to determine optimal ways for the integrated circuit for a self-contained system to be split into at least two portions for the corresponding at least two dies. In addition, a split-circuit-boundary scan chain option can be applied for each portion, via the automated design tool, to ensure boundary scans are available on timing paths.