Wafer Test System with Optical Sensing for Die Failure Detection
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Solution Overview
Problem
Existing wafer test systems are inadequate in determining a high percentage of semiconductor integrated circuits that may fail, leading to potential failures after packaging or during use.
Innovation Solution
A wafer test system comprising a chuck, a probe head, a probe card, a sensing device, and a determination unit that performs electrical tests, senses active states, and determines die failure based on test results and active state information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only electrical test is performed on wafers, then the test process is simple and fast, but the die sorting capability is insufficient and many potential failures are missed
Solution Approach 1:
The patent combines electrical test and optical test into a single integrated wafer test system. The determination unit receives both electrical test results from the probe card and active state information from the sensing device, then综合分析 both data sources to determine die failure. This merging of test methods significantly improves die sorting capability while maintaining a unified test process.
Solution Approach 2:
The determination unit serves as an intermediary that processes and integrates information from both electrical test and optical test channels. It receives electrical test results and active state information, performs comprehensive analysis, and outputs final die failure determination. This intermediary component enables the system to leverage both test methods without requiring complex direct integration between probe card and sensing device.
2Reliability
If electrical test and optical test are both performed, then the die sorting capability is improved, but the device complexity increases
Solution Approach 1:
The determination unit is designed with multi-functionality, handling both electrical test result processing and optical test active state information analysis. This single component performs multiple functions: receiving electrical test data, receiving optical sensing data, integrating both data types, and making final failure determination. This universality reduces overall system complexity despite using multiple test methods.
Solution Approach 2:
The system performs preliminary optical testing through the sensing device during the electrical test process. The active state information is sensed concurrently with electrical testing, allowing the determination unit to have both types of data ready for integrated analysis. This preliminary action of optical sensing prepares the system for more accurate die sorting without requiring separate testing steps.
3Measurement precision
If traditional electrical test alone is used, then the test process is simple, but many dies that may fail are not identified
Solution Approach 1:
The patent adds an optical dimension to the traditional electrical test by incorporating a sensing device that detects active states. This creates a two-dimensional testing approach: electrical tests measure electrical characteristics while optical tests measure active state information. The determination unit integrates both dimensions of data to achieve more accurate failure detection, moving beyond single-dimensional electrical testing.
Solution Approach 2:
The patent supplements electrical measurement with optical sensing to detect active states. The sensing device uses optical fields rather than electrical contacts to gather additional information about die status. This substitution of optical detection for purely electrical measurement enables detection of potential failures that electrical tests alone would miss, improving measurement precision.
Data Source
AI summary
A wafer test system includes a chuck for supporting a wafer including a plurality of dies, a probe head for inputting a test signal for an electrical test to the probe card and receiving an electrical test result corresponding to the test signal, a probe card for inputting test signals to the dies through a plurality of pins and receiving test result, a sensing device mounted on the surface of the probe card, for sensing an active state occurring in the wafer when the electrical test is performed, and a determination unit for receiving the electrical test result and the active state information for the dies and determining whether each of the dies has failed using the result of the electrical test on the wafer and active state information.