Wafer-Level Laser Diode Integration With Planarized Heat Sink

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Solution Overview

Problem

Integration of laser diodes with HAMR recording heads faces challenges such as misalignment and electrostatic discharge (ESD) events, leading to optical inefficiencies and potential damage during assembly.

Innovation Solution

The integration process involves transfer printing a laser diode onto a planarized heat sink with a coupled bleed resistor, which provides ESD protection and precise alignment, using semiconductor processing techniques to form a thin film resistor and planarize the heat sink surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If separate processes are used to form HAMR recording head and laser diode, then manufacturing flexibility is improved, but alignment precision deteriorates

Engineering Contradiction:

Improvemanufacturing flexibilityVSAvoidalignment precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent divides the manufacturing process into separate stages: forming the HAMR recording head on a first substrate, forming the laser diode on a second substrate, and then transferring the laser diode to the first substrate. This segmentation allows each component to be manufactured independently with optimized processes while achieving precise alignment through the transfer printing method.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary transfer substrate and transfer printing process as a mediator between the separately manufactured HAMR recording head and laser diode. This intermediary mechanism enables precise alignment (within 50-150 nm) by controlling the transfer process, resolving the alignment precision issue while maintaining manufacturing flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If transfer printing process is used to integrate laser diode with HAMR recording head, then integration efficiency is improved, but ESD damage risk increases

Engineering Contradiction:

Improveintegration efficiencyVSAvoidESD damage risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by forming a bleed resistor on the HAMR recording head substrate before the transfer printing process. This ESD protection structure is prepared in advance, so when the laser diode is transferred and makes contact, any electrostatic discharge is safely diverted through the bleed resistor, preventing catastrophic damage while maintaining high integration efficiency.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The bleed resistor serves as a cushioning mechanism against ESD events. By providing a predetermined safe discharge path before any ESD event occurs, the system protects the laser diode from potential damage during the transfer printing process and subsequent operation, enabling high-yield integration.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If misalignment occurs between laser diode and waveguide, then assembly simplicity is improved, but optical efficiency deteriorates

Engineering Contradiction:

Improveassembly simplicityVSAvoidoptical efficiency

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces mechanical alignment methods with a controlled transfer printing process that uses adhesion forces and precise positioning. The laser diode is transferred to the exact location on the HAMR recording head substrate, ensuring proper alignment with the waveguide without complex mechanical adjustment mechanisms, thus maintaining assembly simplicity while achieving high optical efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method reduces ESD damage and improves alignment, enhancing the optical efficiency and yield of the integrated laser diode, achieving alignment within 50-150 nm precision and increasing transfer print yield to 90% or more.

Implementation Method 1

The bleed resistor has a relatively large electrical resistance and provides a path to discharge electrostatic build up, particularly at the moment in which the laser diode makes contact with the heat sink

Methodology Applied

Scientific EffectElectrostatic discharge: Electrostatic Discharge

Implementation Method 2

The planarization process provides a relatively smooth surface, which also may help to improve the yield of the transfer print process

Methodology Applied

Scientific EffectPlanarization:

Implementation Method 3

A laser diode formed on a second substrate is transfer printed onto the planarized heat sink to form an integrated laser diode

Methodology Applied

Scientific EffectTransfer printing:

Data Source

PatentUS20260024957A1Laser heat sinking for integrating laser diode into recording heads at wafer level

Publication Date: 2026.01.22 SEAGATE TECH LLC

AI summary

A method comprising the steps of forming a recording head comprising a waveguide, a heat sink and a bleed resistor on a first substrate, is described. The bleed resistor is coupled to the heat sink and the substrate. The top surface of the heat sink is planarized to form a planarized heat sink. A laser diode formed on a second substrate is transfer printed onto the planarized heat sink to form an integrated laser diode.