Pulsed Laser Deposition Target Surface Smoothing

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Solution Overview

Problem

Pulsed laser deposition methods face issues with uneven target surface roughening, crack formation, and contamination due to repeated plasma plume generation, leading to deviations in plasma direction and layer uniformity, especially on large substrates.

Innovation Solution

The method involves smoothing the target surface structure before each laser irradiation by melting the upper layer with a low-energy beam and allowing it to solidify, followed by particle bombardment to remove adhering particles, ensuring a smooth surface for consistent plasma plume generation and deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a spot on the target is repeatedly irradiated to generate plasma plumes, then the deposition process can be maintained, but the surface structure of the spot becomes roughened and cracks form, leading to target material breaking loose and contamination

Engineering Contradiction:

Improvedeposition process continuityVSAvoidsurface structure integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The target surface is pre-smoothed by melting the upper layer with a laser beam before plasma plume generation. This preliminary action removes surface irregularities and prevents crack formation during subsequent irradiation cycles, ensuring consistent plasma plume quality and preventing target material fragmentation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the physical state of the target surface by melting it temporarily to alter its surface properties. The laser beam parameters (energy, duration) are controlled to melt only the upper layer without causing bulk heating or damage, transforming the rough surface into a smooth liquid surface that solidifies into a crack-free structure

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If the laser beam is moved over the target material to distribute wear evenly, then target lifetime is extended, but the surface roughening and crack formation still occur at each irradiated spot

Engineering Contradiction:

Improvetarget lifetimeVSAvoidplasma plume consistency

Core Design Contradiction:

Duration of action of stationary objectVSManufacturing precision

Solution Approach 1:

Before the laser beam moves to the next spot, each spot is pre-smoothed by melting the upper layer. This ensures that even though multiple spots are used over time, each spot maintains consistent surface properties, producing uniform plasma plumes throughout the extended target lifetime

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The target surface undergoes periodic smoothing cycles where the laser beam returns to previously irradiated spots to melt and smooth the surface again. This periodic maintenance of surface quality ensures consistent plasma plume generation across multiple deposition cycles and extended target usage

Inventive Principle:

Principle #19Periodic action

3Manufacturing precision

If droplets of target material adhere to the spot surface, then contamination occurs during subsequent plasma plume generation, but removing them requires additional processing steps

Engineering Contradiction:

Improvedeposited layer qualityVSAvoidsurface preparation steps

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention converts the harmful effect of adhering droplets into a beneficial process. The laser beam that would normally cause damage is instead used to melt and smooth the surface, naturally removing droplets and irregularities. The same energy source that creates the problem also solves it by transforming the surface state

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention utilizes phase transition of the target material from solid to liquid and back to solid. The laser beam melts the upper layer, causing droplets to merge and smooth out, then the liquid surface solidifies into a smooth, droplet-free structure. This phase transition naturally eliminates contamination without additional removal steps

Inventive Principle:

Principle #36Phase transitions

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 approach ensures high-quality plasma plumes with consistent characteristics, reducing target wear and contamination, and maintaining uniformity in the deposited layer on large substrates by maintaining a smooth target surface for each pulse.

Implementation Method 1

irradiating a spot on the target with a pulsed laser beam to generate a plasma plume of target material

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

smoothing the surface structure of the spot on the target prior to irradiating the spot with a pulsed laser beam

Methodology Applied

Scientific EffectMelting: Melting

Data Source

PatentUS11177117B2Method for pulsed laser deposition

Publication Date: 2021.11.16 LAM RES CORP

AI summary

The invention relates to a method for pulsed laser deposition including the steps of: providing a target and a substrate facing the target; irradiating a spot on the target with a pulsed laser beam to generate a plasma plume of target material and depositing the plasma plume on the substrate; and smoothing the surface structure of the spot on the target prior to irradiating the spot with a pulsed laser beam.