Low Overdrive Probes with Compliant Substrate for Semiconductor Testing
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Solution Overview
Problem
Current semiconductor probe designs face challenges in maintaining stable contact with decreasing grid array pitch sizes due to increased stress and limited space, requiring a balance between vertical overdrive and signal integrity, while also needing to absorb local and device-wide variations.
Innovation Solution
The solution involves a probe card with a combination of low-overdrive MEMS probes and secondary compliant probes, such as elastomeric interposers, which absorb vertical overdrive, allowing for effective contact and compliance without exceeding material yield stress, and utilizing a probe card with multiple layers of secondary probes to provide additional overdrive capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the probe length is reduced to accommodate smaller pitch sizes, then the space for each probe is reduced, but the stress on the probe increases by a factor of four for the same overdrive
Solution Approach 1:
The patent divides the overdrive function into two segments: the probe itself provides minimal overdrive (5-20 microns) to contact the electrical structure, while the probe card substrate provides the remaining overdrive (20-50 microns) through its compliance. This segmentation allows the probe to be shorter with reduced stress while still achieving the required total overdrive.
Solution Approach 2:
The probe card substrate acts as an intermediary between the probe and the semiconductor device. It provides the additional overdrive capacity through its compliant structure, allowing the probe to remain short while still achieving stable contact. The substrate absorbs the excess overdrive that would otherwise be applied directly to the probe.
2Length of moving object
If a long vertical probe is used to provide large overdrive, then the overdrive capability is improved, but the signal integrity and cross talk requirements are compromised
Solution Approach 1:
The patent segments the overdrive function between the probe and probe card substrate. The probe remains short (providing minimal overdrive) to maintain signal integrity, while the substrate provides the remaining overdrive capacity. This eliminates the need for long probes that would compromise signal quality.
3Quantity of substance
If the probe cross-section is reduced to fit more probes in limited space, then the probe density is improved, but the resistivity increases and current carrying capacity is reduced
Solution Approach 1:
The patent segments the overdrive function so that the probe itself requires minimal overdrive capability. This allows the use of thinner probes with smaller cross-sections that can fit higher density arrangements while still maintaining adequate current carrying capacity, as the probe card substrate provides the additional compliance needed.
4Stability of the object's composition
If a rigid probe card is used, then the structural stability is improved, but the ability to absorb vertical overdrive is reduced
Solution Approach 1:
The patent changes the mechanical parameters of the probe card substrate to provide controlled compliance. The substrate is designed with specific flexural properties that allow it to absorb vertical overdrive through elastic deformation while maintaining overall structural stability. This enables the rigid probe card to adapt to variations in device height and planarity.
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 stable contact with semiconductor devices across fine pitches while maintaining signal integrity and current carrying capacity, effectively addressing the challenges of local and system variations without damaging the semiconductor device.
Implementation Method 1
The each probe of the plurality of probes absorbs a portion of vertical overdrive after contacting their corresponding electrical structures. The probe card absorbs any remaining vertical overdrive.
Data Source
AI summary
A method for testing a semiconductor device is disclosed. The method comprises positioning a probe card comprising a plurality of probes above the semiconductor device and moving the probe card in a vertical direction towards the semiconductor device. The plurality of probes are moving in a vertical direction towards a plurality of electrical structures of the semiconductor device until each probe of the plurality of probes has made mechanical contact with a corresponding electrical structure of the plurality of electrical structures with a minimum quantity of force. The each probe of the plurality of probes absorbs a portion of vertical overdrive after contacting their corresponding electrical structures. The probe card absorbs any remaining vertical overdrive. The vertical overdrive is a continuing vertical movement of the plurality of probes after a first probe of the plurality of probes mechanically contacts a first corresponding electrical structure.