Dual-Magnet Cathode Layout for Low-Pressure Sputtering Stability
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Solution Overview
Problem
Existing magnetron sputtering apparatuses face challenges in forming films with good covering properties over substrates with high aspect ratio recesses and in efficiently removing re-deposition films from the non-eroded center region of the target.
Innovation Solution
The cathode unit incorporates first and second magnet units that generate distinct leakage magnetic fields, enabling self-holding discharge for high-density plasma and allowing for separate plasma generation for film formation and re-deposition film removal. The magnet units are configured to rotate and move relative to the target to prevent magnetic field interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single magnet unit with balanced configuration is used, then the plasma distribution is uniform and film formation is stable, but the re-deposition film in the non-eroded center region cannot be efficiently removed
Solution Approach 1:
The single magnet unit is divided into two separate magnet units: a first magnet unit for generating plasma and forming films, and a second magnet unit for removing re-deposition films. This segmentation allows each magnet unit to be optimized for its specific function, resolving the contradiction between film formation stability and re-deposition removal efficiency.
Solution Approach 2:
The patent implements periodic switching between film formation mode and re-deposition removal mode by controlling the activation of the first and second magnet units. During film formation, only the first magnet unit is activated; during re-deposition removal, the second magnet unit is activated. This periodic action allows the system to maintain film formation stability while periodically removing re-deposition films to prevent yield degradation.
2Manufacturing precision
If the magnet unit is rotated to improve film coverage, then the covering properties over recessed portions improve, but magnetic field interference increases and plasma confinement becomes unstable
Solution Approach 1:
By separating the magnet units into first and second independent units with different functions, the patent eliminates magnetic field interference between rotating components. The first magnet unit remains stationary during film formation to maintain stable plasma confinement, while the second magnet unit can be rotated independently for re-deposition removal without affecting plasma stability.
Solution Approach 2:
The patent introduces a control system as an intermediary that coordinates the operation of the first and second magnet units. This control system manages the periodic switching between film formation and re-deposition removal modes, ensuring that magnetic field interference is minimized and plasma confinement remains stable throughout the process.
3Duration of action of stationary object
If DC power is continuously applied to the target, then the sputtering process maintains steady state, but re-deposition film accumulates in the non-eroded region
Solution Approach 1:
The patent implements periodic interruption of the continuous sputtering process by switching between film formation mode (DC power applied, first magnet unit active) and re-deposition removal mode (DC power interrupted, second magnet unit active). This periodic action prevents re-deposition film accumulation while maintaining overall process continuity and productivity.
Solution Approach 2:
The patent periodically removes the harmful re-deposition film from the non-eroded center region using the second magnet unit, thereby recovering the target surface for continued efficient sputtering. This discarding and recovering cycle maintains target performance and prevents yield degradation from particle generation by thick re-deposition films.
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 allows for the formation of copper films with excellent coverage over substrates with high aspect ratio recesses while periodically removing re-deposition films, thereby improving product yield and film quality.
Implementation Method 1
a first magnet unit that causes a first leakage magnetic field, in which a position where a vertical component of a magnetic field becomes zero, to act on a space in front of the sputtering surface including a center of the target inward, and a second magnet unit that causes a second leakage magnetic field, in which a position where the vertical component of the magnetic field becomes zero, to act locally on the space in front of the sputtering surface located between the center of the target and an outer edge portion of the target
Implementation Method 2
enable self-holding discharge under low pressure of the plasma confined by the second leakage magnetic field
Implementation Method 3
endless plasma is generated unevenly from the center of the target in the space in front of the sputtering surface
Implementation Method 4
the sputtering surface of the target is sputtered by ions of the sputtering gas ionized by the plasma
Implementation Method 5
a copper film can be formed with good covering properties over the entire surface of the substrate including the inner surface of the recess
Data Source
AI summary
A cathode unit includes first and second magnet units that are driven to rotate around an axis on a side opposed to a sputtering surface of a target. The first magnet unit is configured to cause a first leakage magnetic field to act on a space in front of the sputtering surface including a target center inward. The second magnet unit is configured to cause a second leakage magnetic field to act locally in the space in front of the sputtered surface located between the target center and the outer edge of the target and to enable self-holding discharge under low pressure of plasma confined by the second leakage magnetic field.