Wafer Prober Adiabatic Optical Coupling for Photonic IC Testing

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Solution Overview

Problem

The semiconductor industry faces challenges in minimizing the area of silicon real estate sacrificed for test structures, particularly for photonic chips, which require complex optical coupling structures that waste valuable chip area and necessitate sophisticated multichannel optical systems for testing.

Innovation Solution

A wafer prober with an optical waveguide and alignment system that enables adiabatic optical coupling between compact optical coupling elements on the wafer surface and photonic integrated circuits, reducing the need for extensive test structures and allowing for simultaneous optical and electrical testing without complex multichannel systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If grating-based optical coupling structures are used for in-wafer testing, then optical coupling capability is achieved, but substantial wafer surface area is consumed

Engineering Contradiction:

Improveoptical coupling capabilityVSAvoidwafer surface area

Core Design Contradiction:

Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent extracts the optical coupling function from complex grating structures and implements it through simple, compact optical coupling elements that can be directly integrated into the wafer testing system, thereby achieving optical coupling capability while minimizing wafer surface area consumption

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the physical parameters of the optical coupling implementation by using compact optical coupling elements with specific geometric configurations that enable efficient light coupling without requiring extensive grating structures, thus reducing the area required on the wafer surface

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If complex grating structures are formed on wafer surface for optical coupling, then optical coupling is enabled, but additional process steps and substantial area are required

Engineering Contradiction:

Improveoptical coupling functionVSAvoidcoupling structure complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent extracts the essential optical coupling function from the complex grating structure paradigm and implements it through simpler optical coupling elements that require fewer process steps and reduce overall device complexity while maintaining coupling functionality

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using complex gratings to couple light, the patent inverts the approach by using simple optical coupling elements that directly interface with the wafer, thereby simplifying the coupling structure and reducing manufacturing complexity

Inventive Principle:

Principle #13The other way round (Inversion)

3Productivity

If additional test photonic terminals are formed on wafer surface, then in-wafer optical testing is enabled, but substantial area is wasted for non-operational test structures

Engineering Contradiction:

Improvein-wafer testing capabilityVSAvoidwafer area for test structures

Core Design Contradiction:

ProductivityVSArea of stationary object

Solution Approach 1:

The patent implements optical coupling elements that serve dual purposes: they enable in-wafer optical testing during manufacturing while also functioning as operational photonic terminals for the final packaged device, thereby eliminating wasted area from dedicated test structures and achieving multi-functionality

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution significantly reduces the chip area used for optical coupling, enabling efficient in-wafer testing and combining optical and electrical testing, thereby minimizing waste and simplifying the testing process.

Implementation Method 1

The first optical coupling end segment is configured to provide an adiabatic optical coupling to a second optical coupling end segment of a second optical waveguide

Methodology Applied

Scientific EffectAdiabatic optical coupling:

Data Source

PatentUS9904016B2Wafer prober for testing in-wafer photonic integrated circuits

Publication Date: 2018.02.27 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

The invention relates to a wafer prober including an optical waveguide, the optical waveguide having a first optical coupling end segment with a first optical coupling surface being devoid of cladding. The first optical coupling end segment being configured to provide an adiabatic optical coupling to a second optical coupling end segment of a second optical waveguide of a photonic integrated circuit on a semiconductor wafer when the optical waveguide is aligned with respect to the semiconductor wafer according to a set of alignment requirements. The second optical coupling end segment having a second optical coupling surface that is devoid of cladding. The second optical coupling surface is parallel to a wafer surface of the semiconductor wafer. An alignment system configured to align the optical waveguide with respect to the semiconductor wafer according to the set of alignment requirements.