Multi-Cathode PVD System Uniform Erosion

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Solution Overview

Problem

In plasma sputtering processes, uneven erosion profiles of the sputtering target lead to poor uniformity and step coverage of deposited films, causing issues in semiconductor fabrication and EUV mask blank production due to changes in magnetic fields and preferential erosion at specific locations.

Innovation Solution

A physical vapor deposition (PVD) chamber with multiple cathode assemblies, each comprising a rotating magnet assembly with outer peripheral magnets surrounding an inner magnet, mounted to a plate that can rotate during the deposition process, and a balancing weight to stabilize the rotation, ensuring uniform magnetic flux and erosion profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single cathode assembly with magnetron is used for sputtering, then the sputtering rate can be enhanced through magnetic field concentration, but the erosion profile becomes uneven and asymmetric, leading to poor film uniformity

Engineering Contradiction:

Improvesputtering rateVSAvoidfilm uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The single cathode assembly is divided into multiple cathode assemblies (e.g., three cathodes arranged in a triangular pattern). Each cathode has its own magnetron and produces its own erosion profile. The superposition of multiple erosion profiles from different cathodes results in a more uniform overall erosion pattern, thereby improving film uniformity while maintaining high sputtering rates through parallel operation of multiple cathodes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple cathode assemblies are combined in a single deposition chamber, with their erosion profiles superimposed on the substrate. The magnetic fields and plasma distributions from multiple cathodes merge to create a more uniform deposition environment, resolving the asymmetry problem of single-cathode systems while maintaining high productivity.

Inventive Principle:

Principle #5Merging (Combining)

2Productivity

If high DC power and high magnetic fields are applied to increase sputtering rate, then productivity improves, but target surface temperature rises significantly, requiring complex cooling systems

Engineering Contradiction:

Improvesputtering rateVSAvoidtarget surface temperature

Core Design Contradiction:

ProductivityVSTemperature

Solution Approach 1:

The total power load is segmented across multiple cathode assemblies instead of concentrating it on a single target. Each cathode operates at high power to maintain high sputtering rate, but the thermal load is distributed across multiple targets, reducing the temperature rise at each individual target surface and simplifying cooling requirements.

Inventive Principle:

Principle #1Segmentation

3Productivity

If the target is allowed to erode over time, then material deposition continues, but the changing magnetic field causes plasma instability and sparking that generates damaging particulates

Engineering Contradiction:

Improvedeposition continuityVSAvoidparticulate generation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

With multiple cathodes, the erosion of individual targets has less impact on overall plasma stability. The superposition of magnetic fields from multiple cathodes maintains more stable plasma conditions even as targets erode, reducing sparking and particulate generation while allowing continuous deposition.

Inventive Principle:

Principle #1Segmentation

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 configuration achieves more uniform deposition and reduces particle generation, enhancing the uniformity and reliability of the deposited material layers across the substrate, improving step coverage and reducing defects in semiconductor and EUV mask blank manufacturing.

Implementation Method 1

two magnets of opposing poles magnetically coupled at their back through a magnetic yoke to project a magnetic field into the processing space to increase the density of the plasma and enhance the sputtering rate

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

a rotating cathode assembly... the outer peripheral magnets and an inner magnet mounted to a mounting plate configured to rotate during a physical vapor deposition process

Methodology Applied

Scientific EffectRotation:

Implementation Method 3

Sputtering, alternatively called physical vapor deposition (PVD), has been used for the deposition of metals and related materials

Methodology Applied

Scientific EffectSputtering: Sputtering

Implementation Method 4

Sputtering, alternatively called physical vapor deposition (PVD), has been used for the deposition of metals and related materials

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 5

When a negative DC bias of several hundred volts is applied to target while the chamber walls or shields remain grounded, the argon is excited into a plasma

Methodology Applied

Scientific EffectPlasma: Plasma

Data Source

PatentUS11668003B2Deposition system with a multi-cathode

Publication Date: 2023.06.06 APPLIED MATERIALS INC

AI summary

A deposition system, and a method of operation thereof are disclosed. The deposition system comprises a cathode assembly comprising a rotating magnet assembly including a plurality of outer peripheral magnets surrounding an inner peripheral magnet.