Semiconductor Wafer Prober With Conductive Shielding
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Solution Overview
Problem
Existing probers for inspecting semiconductor devices with electrodes on both sides of a wafer face challenges such as increased parasitic inductance and stray capacitance, leading to measurement errors and inefficiencies, especially in dynamic characteristics and large current tests, due to lengthy cable connections and external noise interference.
Innovation Solution
A prober design that includes a chuck stage surrounded by conductive cover conductors, with probes for front and back electrodes, and an inductance cancel bar, maintaining a constant and minimized electrical connection path, and using a guard or shield to reduce external noise and stray capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a lengthy cable is used to connect the chuck stage and measurement device to enable inspection of all semiconductor devices on a wafer, then the ability to inspect multiple devices is improved, but parasitic inductance increases making transient characteristics measurement difficult
Solution Approach 1:
The patent transitions from a single-point contact configuration to a distributed multi-point contact configuration. Multiple contact pads are arranged on the chuck stage surface, allowing simultaneous contact with multiple semiconductor devices across the wafer. This spatial distribution enables short cable connections for each contact point while maintaining the ability to inspect multiple devices, thus resolving the contradiction between inspection capability and measurement precision.
2Reliability
If the chuck stage is used as a conductive electrode to contact back-side electrodes of all semiconductor devices, then electrical connection to both sides of the wafer is achieved, but stray capacitance and external noise interference increase causing measurement errors
Solution Approach 1:
The patent divides the chuck stage into multiple electrically isolated contact pads rather than using a single continuous conductive surface. Each contact pad is separated by insulating material, creating discrete electrical connection points. This segmentation reduces stray capacitance between adjacent contact areas and minimizes external noise interference, while still providing electrical connection to multiple back-side electrodes simultaneously across the wafer.
3Ease of operation
If probes for front-side and back-side electrodes are placed at a certain distance apart, then simultaneous contact with both sides is enabled, but the electrical connection path length increases causing parasitic inductance
Solution Approach 1:
The patent positions the front-side probe and back-side contact pad at locations that are electrically equipotential or near-equipotential with respect to the semiconductor device under test. By carefully selecting the spatial arrangement and using the semiconductor device's internal structure as a reference, the electrical path length between front and back contacts is minimized. This reduces parasitic inductance while still enabling simultaneous contact with both sides of the device through the wafer thickness.
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 design enables accurate electrical characteristic inspection of semiconductor devices by minimizing parasitic inductance and stray capacitance, ensuring precise capacitance measurement and reducing measurement errors.
Implementation Method 1
a guard or shield to reduce external noise and stray capacitance
Implementation Method 2
maintaining a constant and minimized electrical connection path, and using a guard or shield to reduce external noise and stray capacitance
Data Source
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AI summary
An object of the present invention is to provide a prober that is able to carry out accurate inspection of semiconductor device in wafer state by reducing the effect of the external noises and the leakage of current and further by eliminating the stray capacitance of the chuck stage against the prober housing. The present invention attains this object by providing a prober comprising a chuck cover conductor that comprises a bottom conductor and a side conductor and an open top, wherein a chuck stage can be contained within a space surrounded by the bottom conductor and the side conductor; an upper cover conductor which has opening through which the conducting support members of the probe for front-side electrodes and the probe for back-side electrodes can be passed, and which is large enough to cover, in a plane view, at least the open top of the chuck cover conductor when the contact member of the probe for front-side electrodes moves relatively within a wafer under inspection; and, a conducting means that brings the chuck cover conductor and the upper cover conductor into contact and makes them electrically continuous.