Wafer Elevation Parameter Setting for Stable Probe Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing test apparatuses face challenges in accurately controlling the elevation of wafers due to varying loads applied by probes, which can be influenced by factors such as probe card tilt, probe variation, and wear, leading to inconsistent test results.
Innovation Solution
A test apparatus with a Z-axis movement mechanism using three drive units, each equipped with a motor mechanism and cylinder mechanism, that adjusts the elevation of the wafer by compensating for self-weight through pneumatic pressure and precise torque control, allowing for accurate positioning and contact with probes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the wafer is raised using a simple elevation mechanism, then the structure is simple, but the positioning precision deteriorates due to varying probe loads
Solution Approach 1:
The elevation mechanism is divided into three independent elevation drive mechanisms (first, second, and third) positioned at different locations on the base. Each mechanism independently controls the elevation of the wafer at its specific position, allowing individual compensation for varying probe loads without requiring a completely complex unified system.
Solution Approach 2:
The control unit dynamically adjusts operational parameters (elevation positions) of the three elevation drive mechanisms based on detected dynamic characteristics and varying probe loads. This parameter adjustment enables the system to maintain positioning precision despite changes in external conditions such as probe wear and tilt.
2Manufacturing precision
If three elevation drive mechanisms are used to compensate for varying loads, then the positioning precision is improved, but the device complexity increases
Solution Approach 1:
Each of the three elevation drive mechanisms serves multiple functions: supporting the wafer's weight, compensating for varying probe loads, and enabling precise elevation control. This multi-functionality reduces the need for additional specialized components, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The control unit detects dynamic characteristics of the elevation mechanisms and uses this feedback information to adjust the operational parameters of the drive mechanisms. This closed-loop control enables precise elevation control while keeping the system architecture relatively simple through intelligent control rather than mechanical complexity.
3Productivity
If the probes contact the wafer with varying loads, then the test coverage is maintained, but the measurement precision deteriorates
Solution Approach 1:
The control unit dynamically changes the elevation positions of the wafer using the three elevation drive mechanisms to compensate for varying probe loads. This parameter adjustment ensures that the wafer maintains optimal contact with the probes during electrical testing, thereby maintaining measurement precision while preserving comprehensive test coverage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise control of wafer elevation, reducing torque variations and ensuring consistent contact with probes, thereby improving the reliability and accuracy of electrical tests on semiconductor devices.
Implementation Method 1
The elevating mechanism includes a motor mechanism and a cylinder mechanism, and supports the base by using the three elevation drive mechanisms
Data Source
AI summary
A test apparatus includes a base on which a substrate is to be mounted, an elevating mechanism configured to raise and lower the base, a test unit configured to test the substrate while contacting the substrate that is raised and lowered, and a controller. The controller is configured to control the elevating mechanism, generate a disturbance in the elevating mechanism at a position where the test unit contacts the substrate, acquire a dynamic characteristic of the elevating mechanism due to the disturbance, and set one or more parameters during upward movement of the elevating mechanism, based on the dynamic characteristic of the elevating mechanism.