Rotatable Multi-Cathode Shield for Low-Defect RF Sputtering
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Solution Overview
Problem
In semiconductor manufacturing, sputtering processes often result in unwanted coating of the process chamber's inner structures, leading to defects and contamination in wafer processing, particularly when depositing dielectric materials like magnesium oxide using RF power, which affects the purity and defect performance of barrier layers in magnetic random access memory (MRAM) devices.
Innovation Solution
A substrate process chamber with a configuration of three RF cathodes and three DC cathodes, featuring a rotatable shield with compliant grounding loops and shunts made of Mu-metal or stainless steel, which prevents unwanted interactions and cross-contamination by controlling magnetic fields and grounding the shield during RF processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If RF power is used to deposit dielectric materials like magnesium oxide, then the ability to deposit both metal and dielectric materials is achieved, but wafer defects and contamination increase due to unwanted coating of inner structures
Solution Approach 1:
The patent extracts and removes the harmful unwanted coating material from the deposition process by implementing a shield structure that prevents material from reaching the inner chamber surfaces, thereby eliminating the source of contamination and defects
Solution Approach 2:
The patent introduces a shield as an intermediary component between the deposition source and the chamber walls. This shield acts as a mediator that blocks stray material particles, preventing them from coating the inner structures and subsequently contaminating the wafer deposition
2Productivity
If DC powered PVD chambers are used for metal wafer deposition, then cost effectiveness and efficiency are improved, but the process cannot handle dielectric materials due to insulating film formation on electrodes
Solution Approach 1:
The patent merges the advantages of both DC and RF powered systems by implementing a multi-cathode configuration where DC cathodes provide high-speed metal deposition while RF cathodes enable dielectric material deposition, combining the productivity of DC with the versatility of RF in a single chamber
3Object-affected harmful factors
If a shield is introduced to prevent unwanted coating, then contamination is reduced, but device complexity increases
Solution Approach 1:
The patent segments the chamber into distinct functional zones using the shield, creating a clean deposition area separated from the stray material region. This segmentation allows the shield to be a modular component that can be integrated without redesigning the entire chamber 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 configuration significantly reduces wafer defects and improves film uniformity, achieving approximately 1% tunnel magnetoresistance and less than 2% film non-uniformity for MRAM applications, enabling high-volume production of RF magnesium oxide films with enhanced defect performance and prolonged processing kit life.
Implementation Method 1
A substrate process chamber with a configuration of three RF cathodes and three DC cathodes, featuring a rotatable shield with compliant grounding loops and shunts made of Mu-metal or stainless steel, which prevents unwanted interactions and cross-contamination by controlling magnetic fields
Implementation Method 2
Sputtering, also known as physical vapor deposition (PVD), is a method of forming features in integrated circuits. Sputtering deposits a material layer on a substrate. A source material, such as a target, is bombarded by ions strongly accelerated by an electric field.
Implementation Method 3
Alternating current (AC) powered PVD chambers, such as Radio Frequency (RF) PVD chambers, have the ability to neutralize positive charges left on surfaces in the first half of the cycle with negative charges during the second half of the cycle.
Data Source
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AI summary
Methods and apparatus for processing substrates with a multi-cathode chamber. The multi-cathode chamber includes a shield with a plurality of holes and a plurality of shunts. The shield is rotatable to orient the holes and shunts with a plurality of cathodes located above the shield. The shunts interact with magnets from the cathodes to prevent interference during processing. The shield can be raised and lowered to adjust gapping between a target of a cathode and a hole to provide a dark space during processing.