Boundary Scan Input Testing for Bump Pad Semiconductor Circuits
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Solution Overview
Problem
Semiconductor devices that input/output signals using bump pads pose a challenge in testing the state of signal input circuits, as direct probing is not possible at the wafer level, making it difficult to determine the low sensing voltage level (VIL) and high sensing voltage level (VIH) for logic level determination.
Innovation Solution
A semiconductor device with a driving unit that sets and adjusts voltage levels on signal lines coupled to bump pads, a signal input circuit for determining logic values, and an operation unit for parallel input and serial output of these values through a boundary scan test path, allowing for the testing of signal input circuits using a variable voltage level generated internally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct probing is used for testing signal input circuits, then testing can be performed at the wafer level, but direct probing is not possible when using bump pads
Solution Approach 1:
The patent introduces a boundary scan test path as an intermediary mechanism between the external testing equipment and the signal input circuit. This boundary scan path includes scan input probe pads and scan output probe pads that can be accessed externally, while internally connecting to the signal input circuit through the bump pads. The intermediary allows testing to be performed without direct probing of the bump pads themselves.
Solution Approach 2:
The testing system is segmented into multiple functional paths: a boundary scan test path for external access and a signal input circuit path for actual signal processing. The boundary scan test path is separated into scan input, internal routing, and scan output components, allowing independent testing of the signal input circuit without requiring direct access to the bump pads.
2Productivity
If bump pads are used for signal input/output, then signal transmission is enabled, but direct testing of signal input circuit becomes difficult
Solution Approach 1:
The boundary scan test path serves multiple functions: it enables external testing of the signal input circuit, provides a pathway for internal signal routing, and allows for both DC characteristics testing and logic level determination. The same boundary scan infrastructure is used for both testing purposes, making the system multi-functional.
Solution Approach 2:
The boundary scan test path acts as an intermediary that bridges the gap between the externally accessible probe pads and the internally located signal input circuit. This intermediary structure allows testing equipment to measure and control signals without requiring direct physical access to the bump pads, thus solving the measurement difficulty while preserving signal transmission functionality.
3Measurement precision
If signal input circuit is tested through bump pads, then circuit state can be determined, but direct input/output through bump pad is not performed
Solution Approach 1:
The boundary scan test path is pre-configured with scan input probe pads and scan output probe pads that are externally accessible before the actual signal input/output operation through bump pads. This preliminary testing infrastructure is established beforehand, allowing the circuit state to be determined without interfering with the normal input/output functionality through the bump pads.
Solution Approach 2:
The patent segments the testing function from the signal input/output function. The boundary scan test path is separated as an independent testing infrastructure that uses different probe pads (scan input and scan output) from the signal bump pads. This segmentation allows the circuit state to be determined through testing while preserving the adaptability and versatility of the bump pads for their primary signal transmission role.
Data Source
AI summary
A semiconductor device includes a driving unit suitable for driving a plurality of signal lines, which are directly coupled to a plurality of bump pads, to a preset voltage level in a level determination period, and adjusting the preset voltage level in a predetermined order when the level determination period is repeated, a signal input circuit suitable for receiving voltage levels that are inputted through the signal lines and determining logic values for the inputted voltage levels of the signal lines, and an operation unit suitable for receiving voltage levels of the signal lines from the signal input circuit in a parallel manner in the level determination period, latching the logic values of the voltage levels, and serially outputting the logic values through a probe pad.