Wafer Tester Voltage Retargeting for Parallel Current Balancing
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Solution Overview
Problem
Current microelectronic circuit testing methods face challenges in efficiently testing multiple devices in parallel while maintaining accurate voltage and current distribution, especially for densely packed wafers like VCSELs, due to high costs and technical difficulties in routing power lines and detecting defects.
Innovation Solution
A tester apparatus with a voltage targeting system that connects electronic devices in clusters in parallel, using a voltage source and adjusters to ensure each device receives the correct current, and employs a filtering system to adjust voltages based on measured currents, allowing for efficient testing and defect detection across large areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual constant current sources are used for each microelectronic device, then each device receives accurate current, but the cost and device complexity increase significantly
Solution Approach 1:
The patent combines multiple individual constant current sources into a single constant current source that serves multiple microelectronic devices. This is achieved by connecting devices in parallel groups and using one constant current source per group, thereby reducing the total number of power sources while maintaining current accuracy through shared measurement and control circuitry.
Solution Approach 2:
The patent makes a single constant current source capable of serving multiple devices simultaneously by implementing parallel connections with shared control. The measurement circuitry and control logic are designed to universally manage current distribution across multiple devices, eliminating the need for dedicated individual sources.
2Ease of manufacture
If power lines are routed to each individual device, then each device receives power, but the routing complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges power line routing by connecting multiple devices in parallel to shared power lines. Instead of routing individual power lines to each device, the system uses common power distribution paths with parallel connections, significantly simplifying the physical routing and reducing manufacturing complexity.
Solution Approach 2:
The patent segments the device array into groups that share common power lines. By organizing devices into parallel-connected groups, the system reduces the total number of power lines required while ensuring each device receives adequate power, thereby simplifying the overall power distribution network.
3Productivity
If multiple devices are tested in parallel, then testing productivity increases, but voltage and current distribution control becomes more difficult
Solution Approach 1:
The patent implements feedback control by measuring the actual current through each device or group of devices and using this measurement to adjust the constant current source output. This closed-loop control ensures accurate current distribution across multiple parallel-tested devices, maintaining control precision while enabling high-throughput parallel testing.
Solution Approach 2:
The patent introduces measurement circuitry and control logic as intermediary elements between the constant current source and multiple devices. These intermediaries facilitate precise current management by monitoring and adjusting power distribution, enabling complex parallel testing scenarios to be controlled through standardized interface circuits.
Data Source
AI summary
A tester apparatus is described. Various components contribute to the functionality of the tester apparatus, including an insertion and removal apparatus, thermal posts, independent gimbaling, the inclusion of a photo detector, a combination of thermal control methods, a detect circuitry in a socket lid, through posts with stand-offs, and a voltage retargeting.