PVD Chamber Upper Shield Segmentation for Cross-Contamination
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Solution Overview
Problem
In physical vapor deposition (PVD) systems, particularly in multi-cathode chambers used for manufacturing EUV mask blanks, there is a need to reduce defect sources such as particles and cross-contamination between targets of different materials, which affects the quality of the deposited layers.
Innovation Solution
A PVD chamber design with multiple cathode assemblies and a rotatable upper shield having specific shield holes allows for alternate deposition of materials from different targets without rotating the shield, preventing cross-contamination and reducing particle generation by positioning the shield holes to expose only one target at a time, and using raised areas to prevent material deposition on adjacent targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-cathode PVD chamber is used to deposit alternating material layers, then productivity is improved by being able to sputter from multiple targets, but cross-contamination between targets of different materials occurs leading to defects
Solution Approach 1:
The upper shield is segmented into multiple independently controllable sections, each with its own aperture. This allows selective exposure of different targets by moving only the relevant shield section, preventing material from one target from contaminating other targets while maintaining high deposition rates from multiple cathodes.
Solution Approach 2:
The upper shield is made movable rather than fixed, allowing dynamic adjustment of aperture positions and exposures during the deposition process. This enables real-time control over which targets are active and which are protected, eliminating cross-contamination while maintaining productivity.
2Productivity
If high power density sputtering is used to increase deposition rate, then productivity is improved, but target surface temperature rises causing defects
Solution Approach 1:
The system performs preliminary cooling of the target between deposition cycles or between sputtering different materials. The movable shield allows the target to be protected from direct plasma bombardment during intervals, enabling temperature reduction before the next high-power deposition step, thus preventing thermal defects while maintaining high deposition rates.
3Adaptability or versatility
If the upper shield is rotated to expose different targets, then adaptability is improved for depositing different materials, but device complexity increases and particle generation occurs
Solution Approach 1:
The invention extracts the rotation function from the upper shield, making it stationary. Instead, individual aperture sections are made independently movable or selectable. This removes the complexity of rotating the entire shield while maintaining the ability to select different targets, and eliminates particle generation associated with shield rotation.
Solution Approach 2:
The upper shield is divided into separate controllable aperture sections that can be independently positioned or activated. This segmentation replaces the need for rotating the entire shield, simplifying the mechanism while maintaining versatility in target selection for different material depositions.
4Productivity
If multiple targets are exposed simultaneously, then productivity is improved by depositing multiple materials, but cross-contamination occurs between targets
Solution Approach 1:
The system dynamically controls the exposure of different target sections through the movable upper shield. During deposition of alternating layers, only the relevant target aperture is exposed at any given time, preventing cross-contamination while maintaining high overall deposition rates by quickly switching between targets without full rotation.
Solution Approach 2:
The upper shield provides localized protection over each target area, with apertures positioned and sized to expose only the specific target region needed for current deposition. This local control prevents material from one target from reaching other targets, eliminating cross-contamination while allowing efficient multi-material deposition.
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 design enables the deposition of high-quality, defect-reduced multilayer stacks with alternating materials like silicon and molybdenum without rotating the upper shield, reducing particulate generation and maintaining target cleanliness during the process.
Implementation Method 1
Sputtering, alternatively called physical vapor deposition (PVD), is used for the deposition of metals and related materials
Implementation Method 2
a magnetron positioned at the back of the sputtering target including at least two magnets of opposing poles magnetically coupled at their back through a magnetic yoke to project a magnetic field into the processing space
Implementation Method 3
Plasma sputtering may be accomplished using either DC sputtering or RF sputtering
Data Source
AI summary
A physical vapor deposition (PVD) chamber and a method of operation thereof are disclosed. Chambers and methods are described that provide a chamber comprising an upper shield with two holes that are positioned to permit alternate sputtering from two targets.