Data Output Buffer Feedback for Semiconductor Defect Discrimination
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Solution Overview
Problem
The increasing miniaturization of semiconductor devices leads to reduced pad sizes, making it difficult to distinguish between defective package balls and false defects caused by misalignment during testing, resulting in reduced productivity due to overscreening of non-damaged package balls.
Innovation Solution
A data output buffer with pull-up and pull-down circuits and drivers that utilize feedback signals to differentiate between true and false defective parts by controlling the activation state of drive signals based on test signals, preventing overscreening by adjusting operations according to the presence of contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If micro-bump pads are reduced in size for miniaturization, then device integration is improved, but measurement precision deteriorates due to inability to distinguish defective parts from misalignment
Solution Approach 1:
The testing process is segmented into multiple phases: initial connection phase, testing phase, and restoration phase. The buffer operation mode is segmented into normal mode and test mode. This segmentation allows different testing strategies to be applied at different stages, improving measurement precision without requiring larger pads.
Solution Approach 2:
Before actual defect detection, the system performs preliminary actions by activating pull-up and pull-down drivers to establish known good states. Test signals are applied in advance to verify connection integrity, allowing the system to distinguish between connection issues and actual defects before final measurement.
Solution Approach 3:
The system implements feedback mechanisms through pull-up feedback signals and pull-down feedback signals that provide real-time information about connection status. This feedback allows the testing system to adjust its interpretation of measurement results, improving accuracy by accounting for contact resistance and misalignment effects.
2Reliability
If strict defect screening is applied to ensure reliability, then product quality is improved, but productivity deteriorates due to overscreening of non-damaged package balls
Solution Approach 1:
The buffer operation mode is made dynamic, switching between normal mode and test mode based on the testing requirements. The pull-up and pull-down drivers are dynamically activated during testing and deactivated during normal operation. This dynamic operation allows comprehensive testing without permanent performance degradation, maintaining productivity while improving reliability.
Solution Approach 2:
The system changes operational parameters by activating different driver configurations during testing versus normal operation. Test signals with different characteristics are applied, and the buffer's operating state is changed to facilitate defect detection. These parameter changes enable accurate defect identification without causing overscreening, thus maintaining both reliability and productivity.
Data Source
AI summary
A data output buffer may be provided. The data output buffer may include a pull-up circuit configured to output a pull-up feedback signal by pull-up driving an output node. The data output buffer may include a pull-up driver configured to output the pull-up drive signal by driving a pull-up signal, and selectively activate the pull-up drive signal based on the pull-up feedback signal. The data output buffer may include a pull-down circuit configured to output a pull-down feedback signal by pull-down driving the output node based on a pull-down drive signal. The data output buffer may include a pull-down driver configured to output the pull-down drive signal by driving a pull-down signal, and selectively activate the pull-down drive signal based on the pull-down feedback signal.