Wafer-Level Optical Device Testing via Integrated Waveguides
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Solution Overview
Problem
Testing optical devices on a wafer is challenging due to difficulties in aligning light sources with the devices, making the process time-consuming and inaccurate, which hinders efficient identification and removal of defective devices before they are separated from the wafer.
Innovation Solution
Incorporating testing waveguides on the wafer that provide optical communication between light-generating and receiver components, allowing external electronics to operate and test the devices' performance before separation, with the waveguides extending across the boundary of each device to facilitate communication and later serving as input/output waveguides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light sources are aligned with optical devices on a wafer for testing, then device performance can be evaluated, but the alignment process becomes time-consuming and inaccurate
Solution Approach 1:
The patent introduces alignment marks as intermediary reference features fabricated on the wafer. These marks serve as mediators between the external alignment system and the optical devices, enabling precise and rapid alignment without direct manual adjustment of each device. The alignment marks provide a common reference frame that simplifies the alignment process and improves both speed and accuracy.
Solution Approach 2:
The alignment marks are fabricated on the wafer during the device manufacturing process, before the actual testing occurs. This preliminary action of pre-positioning reference features eliminates the need for time-consuming alignment procedures during testing, as the alignment system can directly reference these pre-established marks.
2Productivity
If multiple optical devices are fabricated on the same wafer, then production efficiency is improved, but identifying and removing defective devices becomes more difficult
Solution Approach 1:
The patent uses alignment marks as intermediary reference features that are also used for device identification and location. These marks serve dual purposes: facilitating alignment and enabling precise identification of each device's position on the wafer, which simplifies the process of locating and removing defective devices after testing.
Solution Approach 2:
The testing system provides feedback by identifying which specific devices fail performance criteria. This feedback, combined with the alignment mark reference system, enables precise tracking of defective device locations, allowing for targeted removal of only the failed devices while preserving good devices on the same wafer.
3Ease of manufacture
If devices are tested before removal from the wafer, then cost is reduced by avoiding removal and re-testing, but alignment complexity increases
Solution Approach 1:
The alignment marks serve as intermediaries that simplify the alignment system's task. Rather than requiring complex alignment procedures for each device, the system uses these pre-fabricated reference marks to rapidly and accurately locate devices, thereby reducing alignment complexity while enabling cost-effective wafer-level 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
Enables accurate and efficient testing of optical devices on the wafer, reducing the need for further processing of defective devices and improving the cost-effectiveness by identifying and removing failed devices before separation, thus optimizing the wafer production process.
Implementation Method 1
light-generating components that each generates a light signal in response to application of electrical energy to the light-generating component
Implementation Method 2
receiver components that each outputs an electrical signal in response to receipt of light
Implementation Method 3
testing waveguides that each extends from within a boundary of one of the optical devices across the boundary of the optical device and also provides optical communication between a first portion of the optical components and a second portion of the optical components
Data Source
AI summary
A wafer includes multiple optical devices that each includes one or more optical components. The optical components include light-generating components that each generates a light signal in response to application of electrical energy to the light-generating component from electronics that are external to the wafer. The optical components also include receiver components that each outputs an electrical signal in response to receipt of light. The wafer also includes testing waveguides that each extends from within a boundary of one of the optical devices across the boundary of the optical device and also provides optical communication between a first portion of the optical components and a second portion of the optical components. The first portion of the optical components includes one or more of the light-generating components and the second portion of the optical components include one or more of the receiver components.