Cryogenic Wafer Test Surface for Fast Cooling and Magnetic Shielding
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Solution Overview
Problem
Current cryogenic wafer testing systems face challenges in achieving high throughput and maintaining thermal and magnetic shielding while efficiently using cryogens, leading to structural failures due to thermal expansion and contraction, and high coolant consumption.
Innovation Solution
The development of a novel wafer testing apparatus with a magnetically isolated shell and concentric thermal buffer zones for precise temperature control, direct cooling of bare wafers without carriers, and the use of flexible, thermally conductive straps to maintain a flat and level surface under vacuum conditions, reducing the need for adhesives and minimizing thermal shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If wafers are cooled concurrently with the working environment using a carrier, then the thermal environment is maintained, but the throughput is very low due to substantial cooling time required
Solution Approach 1:
The carrier is pre-cooled to cryogenic temperature before the wafer is placed on it. This preliminary cooling action allows the wafer to be rapidly cooled without requiring the entire working environment to be cooled, thereby reducing cooling time and increasing throughput while maintaining proper thermal conditions for testing
2Ease of operation
If the wafer is mechanically constrained to a carrier, then the wafer is held in place, but the additional handling steps risk loss of devices from damage
Solution Approach 1:
The patent replaces mechanical constraint systems (clamps, adhesives, mechanical fasteners) with a magnetic field-based positioning system. The magnetic field gently holds the wafer in place without physical contact or mechanical stress, eliminating the risk of device damage associated with mechanical handling while maintaining precise wafer positioning during testing
3Ease of operation
If adhesive materials are used to adhere the wafer to a carrier, then the wafer is secured, but the wafer must be cleaned of adhesive after testing, necessitating a burdensome additional step
Solution Approach 1:
The patent eliminates adhesive materials by using a magnetic field to secure the wafer to the carrier. This substitution removes the need for chemical adhesives and the subsequent cleaning step, reducing process complexity while maintaining secure wafer attachment throughout the testing procedure
4Strength
If significant thermal mass is added to the wafer through carriers and adhesives, then the wafer is supported, but the throughput is reduced and energy and helium consumption increase
Solution Approach 1:
The patent employs a thin, flexible magnetic shielding layer instead of thick, rigid carrier structures. This thin-film approach provides necessary mechanical support and magnetic shielding while minimizing thermal mass, thereby reducing the energy and helium consumption required to cool the system and maintain cryogenic temperatures during high-throughput testing
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 approach enables high-quality, high-throughput testing under cryogenic conditions with reduced structural stress and coolant consumption, improving efficiency and safety by maintaining precise temperature and magnetic shielding.
Implementation Method 1
concentric thermal buffer zones for precise temperature control
Implementation Method 2
flexible, thermally conductive straps to maintain a flat and level surface under vacuum conditions
Implementation Method 3
magnetically isolated shell within which a testing system may be maintained at the desired cryogenic temperatures
Data Source
AI summary
Cryogenic testing systems for testing electronic components such as wafers under cryogenic conditions are provided. The novel designs enable fast throughput by use of a cryogenically maintained test surface to which wafers may be rapidly introduced, cooled, and manipulated to contact testing elements while maintaining high quality cryogenic conditions. Thermal shielding is achieved by floating shields and/or flexible bellows that provide effective thermal shielding of the test environment while enabling manipulation of wafers with a wide range of motion. Also provided are novel door assemblies, chuck configurations, and vacuum plate bases that enable effective maintenance of cryogenic conditions and high throughput.