Die Stack Override Switch for Individual IC Testing
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Solution Overview
Problem
Conventional methods for testing integrated circuit (IC) dies in a die stack require all dies to be fabricated and assembled before testing can begin, which delays the development process due to differing development times among dies in the stack.
Innovation Solution
Incorporating a die stack override switch that allows individual testing of dies by coupling conductive contacts to either die stack emulation circuitry or other circuitry, enabling testing of ready dies without waiting for others, using a die stack override switch controlled by electrical signals to emulate the presence of other dies during testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all dies are fabricated and assembled before testing, then the die stack can be tested as a complete unit, but the development process is delayed due to differing development times among dies in the stack
Solution Approach 1:
The patent divides the die stack into individually testable units by introducing an override switch that allows each die to be tested separately. The switch enables the test signal to be routed to specific dies independently, allowing parallel testing of multiple dies at different development stages rather than requiring complete stack assembly before any testing can occur.
Solution Approach 2:
The patent enables preliminary testing of individual dies before the complete die stack is assembled. By using the override switch to route test signals to specific dies independently, developers can perform testing and validation on ready dies in advance, identifying issues early in the development process rather than waiting for final assembly.
2Productivity
If individual testing of dies is enabled, then development time is reduced, but additional circuitry (override switch and emulation circuitry) is required
Solution Approach 1:
The override switch and emulation circuitry serve multiple functions: they enable individual die testing, maintain compatibility with standard die stack operation, and provide the ability to emulate absent dies. This multi-functionality justifies the added complexity by delivering several benefits from a single architectural addition.
Solution Approach 2:
The override switch acts as an intermediary component that mediates between the test signal source and the individual dies. Rather than requiring complex modifications to each die, the switch provides a centralized control mechanism that simplifies the testing architecture while enabling individual die access.
3Adaptability or versatility
If die stack emulation circuitry is used, then testing can proceed with incomplete stacks, but the switch and emulation circuitry add to the manufacturing complexity
Solution Approach 1:
The emulation circuitry is implemented locally within each die or at specific test access points, allowing only the necessary portions of the system to have enhanced functionality. This localized approach enables testing flexibility without requiring complex modifications across the entire die stack manufacturing process.
Data Source
AI summary
Disclosed herein are structures and techniques for exposing circuitry in die testing. For example, in some embodiments, an integrated circuit (IC) die may include: first conductive contacts at a first face of the die; second conductive contacts at a second face of the die; die stack emulation circuitry; other circuitry; and a switch coupled to the second conductive contacts, the die stack emulation circuitry, and the other circuitry, wherein the switch is to couple the second conductive contacts to the other circuitry when the switch is in a first state, and the switch is to couple the die stack emulation circuitry to the other circuitry when the switch is in a second state different from the first state.