Semiconductor Wafer Inspection Overdriving Control
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Solution Overview
Problem
Conventional inspection apparatuses struggle to accurately determine the overdriving amount of a mounting table when a semiconductor wafer is in simultaneous contact with a probe card, leading to potential damage from excessive contact load or unreliable inspections due to insufficient contact.
Innovation Solution
The implementation of displacement sensors at multiple locations on the mounting table, which measure the distance between the table and the probe card, allowing a control unit to adjust the lifting amount to achieve the desired overdriving level, ensuring accurate and secure electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the mounting table is overdriven to ensure electrical contact between the wafer and probe card, then contact reliability is improved, but the contact load increases causing potential damage to the wafer
Solution Approach 1:
The patent applies preliminary action by measuring the distance between the mounting table and probe card before overdriving the mounting table. Displacement sensors are positioned to detect the initial gap, and the control unit calculates the precise overdriving amount needed to achieve contact without excessive force. This pre-measurement and calculation approach allows the system to apply just enough overdriving to ensure reliable contact while avoiding harmful excessive contact loads that could damage the wafer.
2Object-affected harmful factors
If the contact load is reduced to prevent wafer damage, then wafer safety is improved, but inspection reliability deteriorates due to contact failure
Solution Approach 1:
The patent implements feedback control by using displacement sensors to continuously monitor the distance between the mounting table and probe card during the overdriving process. The control unit receives real-time feedback from these sensors and dynamically adjusts the overdriving amount to maintain optimal contact conditions. This feedback mechanism ensures that the contact load remains within the safe range that prevents wafer damage while still achieving sufficient contact pressure for reliable inspection, thereby resolving the contradiction between wafer safety and inspection reliability.
3Stability of the object's composition
If the overdriving amount is increased to ensure contact, then contact stability is improved, but the risk of wafer damage increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the overdriving amount based on real-time distance measurements from displacement sensors. Instead of using a fixed or excessive overdriving amount, the system dynamically adjusts this critical parameter according to the actual gap between the mounting table and probe card. The control unit calculates the optimal overdriving value that achieves stable contact while maintaining contact load within safe limits, thereby ensuring contact stability without increasing wafer damage risk.
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
This solution enables precise detection and achievement of the desired overdriving amount, enhancing inspection reliability by preventing damage from excessive contact loads and ensuring consistent electrical contact with the semiconductor wafer.
Implementation Method 1
one or more displacement sensors, provided at one or more location of the mounting table, each of the sensors measuring a distance between the mounting table and the probe card or a vicinity thereof
Data Source
AI summary
An inspection apparatus for inspecting electrical characteristics of an inspection target object includes a movable mounting table for mounting the inspection target object thereon, a probe card disposed above the mounting table, and one or more displacement sensors, provided at one or more location of the mounting table, each of the sensors measuring a distance between the mounting table and the probe card or a vicinity thereof. The inspection target object is brought into electrical contact with the probe card by overdriving the mounting table.