Top Shield for Sputtering System Vacuum Transfer
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Solution Overview
Problem
Current sputtering systems for semiconductor wafers face inefficiencies due to the need for multiple single-wafer process chambers, leading to high equipment and processing costs, slow throughput, non-uniform deposition, poor temperature control, contamination, and non-uniform target erosion.
Innovation Solution
A multi-chamber batch processing system with a separate pre-clean chamber and sputtering chamber, utilizing a robotic arm for vacuum transfer, multiple targets for concurrent deposition, oscillating magnets for uniform target erosion, and advanced shielding to prevent cross-contamination, along with a direct-drive rotating pallet for thermal and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple single-wafer process chambers are used for depositing different materials, then material deposition capability is improved, but equipment costs and processing costs increase
Solution Approach 1:
The patent combines multiple sputtering chambers into a single multi-chamber vacuum system where multiple targets can deposit different materials onto the same wafer sequentially without breaking vacuum. This merging approach maintains material deposition capability while reducing the number of separate equipment pieces, thereby lowering equipment costs and simplifying the overall system.
Solution Approach 2:
The patent creates a universal vacuum chamber that can handle multiple materials and processing steps within a single system. The chamber is designed to accommodate different target materials and can perform various deposition functions, making the equipment multi-functional and reducing the need for multiple specialized chambers.
2Adaptability or versatility
If multiple single-wafer process chambers are used for sequential deposition, then material layering capability is improved, but system throughput decreases
Solution Approach 1:
The patent implements continuous processing by maintaining vacuum throughout the entire multi-chamber system, allowing wafers to be transferred between chambers without breaking vacuum and without requiring re-loading. This continuous action eliminates idle time between deposition steps and dramatically increases system throughput compared to separate single-wafer chambers.
Solution Approach 2:
The patent nests multiple processing chambers within a shared vacuum environment, where chambers are connected through vacuum lockers and transfer mechanisms. This nested configuration allows multiple deposition operations to occur in sequence within the same vacuum ecosystem, maintaining material layering capability while improving throughput through efficient wafer transfer.
3Reliability
If wafers are transferred between chambers by breaking vacuum, then chamber isolation is improved, but wafer contamination increases
Solution Approach 1:
The patent uses vacuum as an inert environment throughout the entire multi-chamber system. By maintaining vacuum conditions in all chambers and transfer regions, the system prevents oxidation and contamination of wafer surfaces during transfer, eliminating the need to break vacuum while preserving chamber isolation through vacuum lockers and controlled access ports.
Solution Approach 2:
The patent introduces vacuum lockers and transfer chambers as intermediary regions between processing chambers. These intermediaries allow wafer transfer while maintaining vacuum isolation, preventing direct exposure to atmospheric contamination while enabling movement between chambers through controlled vacuum pathways.
4Reliability
If targets are isolated during pre-clean process using shutters, then target protection is improved, but shutter contamination occurs
Solution Approach 1:
The patent extracts the target isolation function from physical shutters by using magnetic field confinement and plasma control. Targets are protected during pre-clean operations by controlling plasma generation and magnetic field configuration rather than using mechanical barriers, eliminating shutter contamination while maintaining target protection.
Solution Approach 2:
The patent replaces mechanical shutter systems with magnetic field-based plasma confinement. Instead of using physical shutters to isolate targets during pre-clean, the system uses controlled magnetic fields to confine plasma away from targets when needed, eliminating mechanical contact and associated contamination while achieving the same protective function.
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 system increases throughput, reduces contamination and equipment costs, achieves uniform deposition, and improves target utilization, while maintaining precise temperature control and preventing undesirable chemical reactions.
Implementation Method 1
The robotic arm transfers the wafers one-by-one to the sputtering chamber from the ICP chamber without the wafers being exposed to the atmosphere, thus avoiding undesirable chemical reactions on the wafer surface, e.g: oxides.
Implementation Method 2
Multiple targets, of the same or different materials, may concurrently deposit material on the wafers as the pallet is rotating. This enables higher throughput, creates a uniform deposition
Implementation Method 3
Sputtering is sometimes referred to as physical vapor deposition, or PVD. In a sputtering operation, thin films comprising materials such as Al, Au, Cu, Ta are deposited in a vacuum on silicon wafers or other substrates.
Implementation Method 4
Multiple magnets (one for each target) in the magnetron assembly in the sputtering chamber oscillate (0.5-10 second period) over its associated target for uniform target erosion and uniform deposition on the wafers.
Implementation Method 5
Copper tubing in the table couples RF energy to the wafers, and a coolant running through the copper tubing controls the temperature of the wafers.
Implementation Method 6
The aluminum is anodized (or another insulator is formed) to provide an insulating film on its surface. This prevents the pallet from being etched in the ICP chamber, avoiding particulates from the pallet contaminating the wafers.
Implementation Method 7
Having a separate pre-clean chamber, such as an inductively coupled plasma (ICP) chamber, increases throughput, provides a faster etch rate, results in less contamination of the sputtering chamber, and results in less damage to the electronic circuits on the wafer.
Data Source
AI summary
A multi-chamber processing system is described for depositing materials on multiple workpieces (wafers, display panels, or any other workpieces) at a time in a vacuum chamber. The system includes a sputtering chamber and a separate pre-clean chamber, where wafers can be transferred between the two chambers by a robotic arm without breaking a vacuum. The wafers are mounted one-by-one onto a rotating pallet in the pre-cleaning chamber and sputtering chamber. The pallet is firmly fixed to a rotatable table in the sputtering chamber. Copper tubing in the table couples RF energy to the wafers, and a liquid running through the copper tubing controls the temperature of the wafers. Multiple targets, of the same or different materials, may concurrently deposit material on the wafers as the pallet is rotating. Multiple magnets (one for each target) in the magnetron assembly in the sputtering chamber oscillate over their respective targets for uniform target erosion and uniform deposition on the wafers. An electrically insulated target backing plate between each magnet and a target has a liquid channel running through it for controlling temperature. The distance between the magnets and the targets is made very small by a thin aluminum plate fixed to the bottom segment of the target backing plate by a dip brazing process. Various shields are described to prevent cross-contamination from the targets and prevent the sputtered target material from entering gaps in the chamber and shorting out insulators.