ESD Safe Vacuum Wand Tip with Dissipative Material
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Solution Overview
Problem
The increased sensitivity of electronic devices to electrostatic discharge (ESD) due to smaller dimensions and lower operational bias currents results in device failure during handling, with existing insulated handling tools unable to safely discharge wafers, leading to yield losses of 10-20% or higher.
Innovation Solution
A grounded wafer-handling device with a surface and volume resistance in the range of 10^3-10^6 ohms/cm, equipped with a grounding strap, allows for controlled discharge of accumulated charge, preventing sudden ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If insulating materials are used for vacuum wand tips, then the wafers can be handled without direct ground contact, but charge accumulation occurs leading to ESD events and device failure
Solution Approach 1:
The patent changes the electrical resistance parameter of the vacuum wand tip material from insulating (high resistance) to static dissipative (controlled resistance between 10^6-10^10 ohms). This parameter change allows the material to gradually dissipate accumulated charge rather than holding it, preventing sudden ESD discharge while still providing electrical isolation from direct ground contact.
Solution Approach 2:
The patent employs composite material construction where a static dissipative material (such as carbon-loaded PEEK or ceramic with controlled resistance) is used for the vacuum wand tip. This composite approach combines the benefits of mechanical strength and vacuum sealing with controlled electrical properties, creating a material that neither fully insulates nor fully conducts, but rather dissipates charge at a controlled rate.
2Reliability
If grounded conductors are used for handling tools, then charge can be discharged quickly, but sudden current spikes occur causing device failure
Solution Approach 1:
The patent changes the resistance parameter from low (grounded conductor) to controlled medium range (10^6-10^10 ohms), transforming the discharge behavior from sudden spike to gradual dissipation. This parameter optimization allows charge to be removed from the wafer continuously at a safe rate rather than all at once.
Solution Approach 2:
The static dissipative material acts as an intermediary between the insulating vacuum wand and direct ground contact. It provides a intermediate electrical state that allows charge transfer without direct conductor contact, mediating the discharge process to prevent harmful current spikes while still enabling charge removal.
3Object-affected harmful factors
If insulating handling tools are used, then electrical isolation is maintained, but tribocharging occurs during wafer contact
Solution Approach 1:
The patent uses composite static dissipative materials that combine mechanical properties suitable for vacuum handling with controlled electrical properties. These materials reduce tribocharging effects while maintaining the necessary mechanical strength and vacuum sealing capabilities.
Solution Approach 2:
The patent changes the surface resistance parameter of the handling tool to reduce triboelectric charge generation. By using materials with controlled resistance in the 10^6-10^10 ohm range, the tool maintains electrical isolation while minimizing charge accumulation through reduced tribocharging effects.
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 effectively reduces charge accumulation and ensures safe discharge of wafers, minimizing device damage and yield losses by allowing gradual dissipation of electrostatic potential during handling.
Implementation Method 1
a grounded handler such as a wand or any type of end effector is used which has a surface and volume resistance sufficiently large so that charge potential is removed to ground at a controlled rate
Implementation Method 2
the resulting 'spike' in current flow as the wafer discharges itself can result in device failure. This ESD event results in typical yield losses
Implementation Method 3
the act of charge exchange between two objects via friction is called tribocharging, which occurs when one object donates electrons and becomes positively charged and the other accepts electrons and becomes negatively charged
Data Source
AI summary
A device for safely handling electrically sensitive objects. A grounded dissipative material is used to form a handling surface so that electrically charged objects handled by the wand can slowly discharge without becoming damaged.