Planarized Heat Sink Integration for HAMR Laser Diode Alignment

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Solution Overview

Problem

Integration of a laser diode with a HAMR recording head is challenged by misalignment and electrostatic discharge (ESD) issues, leading to optical inefficiencies and potential catastrophic damage.

Innovation Solution

A laser diode is integrated onto a planarized heat sink with a coupled bleed resistor, which provides ESD protection and precise alignment, using a transfer printing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If separate processes are used to form the 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 system is divided into two separately manufactured components: the HAMR recording head and the laser diode. This allows each component to be optimized and manufactured independently using appropriate processes, then combined through transfer printing to achieve both manufacturing flexibility and alignment precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A planarized heat sink with integrated alignment features serves as an intermediary structure between the waveguide and the laser diode. This intermediary provides a stable, precisely planarized surface that facilitates accurate alignment during the transfer printing process while maintaining the benefits of separate manufacturing processes.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If the laser diode is integrated onto the heat sink, then optical efficiency is improved, but susceptibility to ESD damage increases

Engineering Contradiction:

Improveoptical efficiencyVSAvoidESD damage risk

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

A bleed resistor is pre-configured and connected to the heat sink before the laser diode transfer process. This preliminary ESD protection path is already in place to protect the laser diode from electrostatic discharge damage during and after the integration process, addressing the ESD risk before it can cause harm.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The bleed resistor acts as an intermediary protective element between the heat sink and the laser diode. It provides a controlled electrical path that safely dissipates electrostatic charges, preventing direct ESD damage to the sensitive laser diode while allowing the intimate thermal contact needed for optical efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the heat sink surface is planarized, then alignment precision is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvealignment precisionVSAvoidmanufacturing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The heat sink is designed to serve multiple functions: it provides thermal management for the laser diode, acts as a mechanical support structure, and serves as the planarized alignment surface for the laser diode transfer. By integrating these functions into a single component, the need for separate alignment fixtures or additional planarization steps is reduced, balancing manufacturing complexity with alignment precision.

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

The solution enhances optical efficiency and reduces ESD damage, improving the yield and alignment of the integrated laser diode with the waveguide.

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 top surface of the heat sink is planarized to form a planarized heat sink. 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:

Implementation Method 4

laser heat sinking for integrating laser diode into recording heads

Methodology Applied

Scientific EffectHeat conduction: Conduction (thermal)

Data Source

PatentUS12451666B2Laser heat sinking for integrating laser diode into recording heads at wafer level

Publication Date: 2025.10.21 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.