Probe Card for High-Frequency Silicon Photonics Testing

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Solution Overview

Problem

Conventional automatic test equipment faces challenges in reliably testing high-speed/high-frequency pins of silicon photonics devices at the wafer level, especially in high-volume production, due to limited failure coverage, particularly on the modulator part of photonics circuits.

Innovation Solution

A probe card and pogo tower system that connects the wafer probe interface to a probe card, allowing for simultaneous testing of digital and photonic pins using coaxial connectors and pogo pins, enabling high-frequency signal testing up to 70 GHz, with a movable cantilever arm for secure and flexible alignment, and optical coupling for precise measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional automatic test equipment is used to test silicon photonics devices at wafer level, then testing can be performed, but reliable testing of high-speed/high-frequency pins is not achieved due to limited failure coverage

Engineering Contradiction:

Improvefailure coverageVSAvoidtesting capability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The probe card is divided into distinct functional regions: a first region with first contact pads for electrical testing and a second region with second contact pads for photonic testing. This segmentation allows simultaneous and reliable testing of both high-speed digital pins and photonic pins, achieving comprehensive failure coverage that conventional unified interfaces cannot provide.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from conventional single-dimension testing approaches to a multi-dimensional testing architecture by adding a spatial dimension through the probe card's regional differentiation. The first region handles electrical characteristics while the second region handles photonic characteristics, enabling simultaneous multi-parameter testing that was previously impossible at wafer level.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If separate process steps are used to test electrical and photonic parameters, then specialized testing can be performed, but test time increases and productivity decreases

Engineering Contradiction:

Improvespecialized testing capabilityVSAvoidtest time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The probe card merges electrical testing and photonic testing capabilities into a single integrated interface. The first contact pads enable electrical parameter measurement while the second contact pads enable photonic parameter measurement, allowing both types of testing to be performed simultaneously in a single test step, thereby reducing total test time while maintaining specialized measurement capabilities for both domains.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The probe card serves multiple functions through its dual-region design. It can simultaneously perform electrical characterization, photonic characterization, and high-speed digital signal testing through the coordinated operation of first and second contact pads, eliminating the need for separate testing processes and reducing overall test time.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If standard wafer probe interface is used, then compatibility with existing equipment is maintained, but testing of high-frequency pins up to 70 GHz is not reliable

Engineering Contradiction:

Improveequipment compatibilityVSAvoidhigh-frequency testing accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The probe card segments the contact interface into first contact pads for electrical testing and second contact pads for high-frequency and photonic testing. This segmentation enables the standard wafer probe interface to reliably support high-frequency pin testing up to 70 GHz by providing dedicated contact points optimized for high-frequency signals, while maintaining compatibility with existing automatic test equipment through the standard probe interface architecture.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11782072B2Test arrangement for testing high-frequency components, particularly silicon photonics devices under test

Publication Date: 2023.10.10 ADVANTEST CORP

AI summary

The invention relates to a probe card (PC) for use with an automatic test equipment (ATE), wherein the probe card (PC) comprises a probe head (PH) on a first side thereof, and wherein the probe card (PC) is adapted to be attached to an interface (IF) and wherein the probe card (PC) comprises a plurality of contact pads on a second side in a region opposing at least a region of the interface (IF), arranged to contact a plurality of contacts of the interface (IF), and wherein the probe card (PC) comprises one or more coaxial connectors (CCPT) arranged to mate with one or more corresponding coaxial connectors (CCPT) of the interface (IF). The invention relates further to pogo tower (PT) for connecting a wafer probe interface (WPI) of an automatic test equipment with the probe card (PC).