Wafer Holder Composite Heater Stiffness and Thermal Response
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Solution Overview
Problem
Conventional wafer probers face challenges with deformation under load, thermal expansion, and slow cooling times, which affect positioning precision and throughput during semiconductor burn-in testing, due to the use of thick metal heaters and air-cooling mechanisms.
Innovation Solution
A wafer prober wafer holder with a chuck top and support member design that includes a heat-insulating cavity, a support member with a high Young's modulus and low thermal conductivity, and a cooling module to enhance stiffness, heat insulation, and rapid cooling capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick metal plate heater is used to maintain heater stiffness, then deformation under probe card pressure is reduced, but heater ramp-up and ramp-down time is prolonged
Solution Approach 1:
The heater is constructed as a composite structure with a thin metal layer (high thermal conductivity) bonded to a ceramic baseplate (high stiffness). This composite design provides the necessary structural rigidity to resist probe card deformation forces while the thin metal layer enables rapid heat transfer, significantly reducing ramp-up and ramp-down times compared to a thick metal plate of equivalent stiffness.
Solution Approach 2:
Instead of using a thick metal plate, the invention employs a thin metal layer formed on the front side of a ceramic baseplate. This thin film structure, combined with the stiff ceramic substrate, achieves the required mechanical strength while minimizing thermal mass, thereby enabling faster heating and cooling cycles.
2Loss of energy
If copper is used as the heater material for rapid cooling, then thermal conductivity is improved, but heater stiffness is reduced
Solution Approach 1:
The invention uses a composite structure where a thin copper or copper alloy layer (providing high thermal conductivity for rapid cooling) is bonded to a ceramic baseplate (providing high stiffness). This combination allows the heater to achieve both rapid thermal response and sufficient mechanical strength to withstand probe card pressure without excessive deformation.
Solution Approach 2:
The heater design applies different material properties to different regions: the thin metal layer in contact with the wafer provides high thermal conductivity for efficient heating and cooling, while the ceramic baseplate provides the necessary structural rigidity. This local optimization of material properties resolves the contradiction between thermal performance and mechanical strength.
3Manufacturing precision
If numerous support posts are provided to prevent heater warping, then positioning precision is improved, but device complexity increases
Solution Approach 1:
The ceramic baseplate inherently provides high stiffness and dimensional stability, eliminating the need for numerous support posts to prevent warping. The composite structure maintains positioning precision through the material properties of the ceramic substrate itself, thereby reducing device complexity while preserving manufacturing precision.
4Strength
If the prober size is increased to minimize prober deformation, then positioning precision is improved, but weight increases and drive system precision is compromised
Solution Approach 1:
The use of a ceramic baseplate with high stiffness-to-weight ratio allows the prober to maintain sufficient structural rigidity without increasing overall size and weight. The composite heater structure provides the necessary mechanical strength to resist deformation under load while keeping the moving mass low, thereby preserving drive system positioning precision.
5Speed
If a cooling module is provided directly beneath the metallic heater, then cooling speed is improved, but heater deformation occurs under probe card pressure
Solution Approach 1:
The ceramic baseplate provides the necessary structural support to withstand probe card pressure without deformation, while the thin metal layer bonded to it enables rapid cooling when a cooling module is provided beneath the heater. The composite structure distributes mechanical loads through the stiff ceramic substrate, preventing the deformation issues that would occur with a thin metal heater alone.
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 improves positioning precision, temperature uniformity, and reduces heating and cooling times, enabling faster ramp-up and ramp-down processes while minimizing deformation and thermal expansion issues.
Implementation Method 1
a support member for supporting the chuck top, and has a cavity in a portion of the holder between the chuck top and the support member
Implementation Method 2
The support member preferably is in the form of a closed-ended cylinder, and the Young's modulus of the support member preferably is at least 200 GPa and its thermal conductivity not more than 40 W/mK
Implementation Method 3
The chuck top preferably is furnished with a heating member
Implementation Method 4
a cooling module to enhance stiffness, heat insulation, and rapid cooling capabilities
Data Source
AI summary
The invention provides a wafer-prober wafer holder that allows positional precision and temperature uniformity to be increased, and also allows the chip to be heated and cooled rapidly, and a wafer prober device provided with the same. The wafer-prober wafer holder of the invention is constituted by a chuck top having a chuck top conducting layer on its surface, and a support member for supporting the chuck top, and has a cavity in a portion between the chuck top and the support member. The chuck top preferably is provided with a heating member.