High Pressure Bevel Etch Process for Semiconductor Wafers
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Solution Overview
Problem
Bevel edge processing of semiconductor wafers faces challenges such as arcing, surface charge, and discharge issues due to RF voltage, which can lead to defects and yield losses, especially in high-pressure regimes, and existing methods struggle to efficiently etch and passivate aluminum layers at the wafer edge.
Innovation Solution
A method involving a bevel plasma processing chamber with pressures between 3 to 100 Torr, where a chlorine-containing gas is used to etch aluminum layers and a fluorine-containing gas is used for passivation, while maintaining RF voltage below a threshold to prevent arcing, and controlling gas chemistry and power settings to widen the process window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure (3 to 100 Torr) is used in bevel etching, then productivity and process stability are improved, but arcing and discharge issues occur due to RF voltage
Solution Approach 1:
The patent changes the pressure parameter from conventional low pressure to high pressure (3-100 Torr) to improve productivity and process stability. It also adjusts RF power settings and gas chemistry parameters to widen the process window while preventing arcing and discharge issues that typically occur at high pressure.
Solution Approach 2:
The patent applies different gas chemistry compositions at different locations - using specific gas mixtures near the wafer periphery for bevel etching while maintaining different conditions in the chamber center, allowing high pressure operation without arcing at critical regions.
2Manufacturing precision
If RF voltage is increased to improve etching performance, then manufacturing precision is improved, but arcing and surface charge issues worsen
Solution Approach 1:
The patent optimizes RF power settings within a specific range that provides sufficient etching precision while avoiding the threshold for arcing and surface charge accumulation. It also adjusts pressure and gas flow parameters to balance etching performance with electrical stability.
Solution Approach 2:
The patent uses specific gas chemistry compositions that act as intermediaries to facilitate charge dissipation and prevent surface charge accumulation, allowing higher RF power to be used for improved precision without causing discharge issues.
3Productivity
If aluminum layers are etched at the wafer edge, then device yield is improved by removing defects, but aluminum corrosion occurs on exposed surfaces
Solution Approach 1:
The patent performs passivation of exposed aluminum surfaces immediately after etching while the wafer is still in the chamber, preventing corrosion before it can occur. This preliminary protective action ensures that the aluminum layers remain stable after the beneficial defect removal.
Solution Approach 2:
The patent introduces passivation gases (fluorine-containing or oxygen-containing) that form protective intermediary layers on exposed aluminum surfaces, preventing direct exposure to corrosive environments while maintaining the cleaned bevel edge structure.
4Manufacturing precision
If multiple process steps (etching and passivation) are performed separately, then manufacturing precision is maintained, but loss of time increases
Solution Approach 1:
The patent merges the etching and passivation steps into a single continuous process sequence within the same chamber without breaking vacuum or transferring the wafer. This combining maintains precision through consistent process conditions while eliminating transfer time and reducing overall processing time.
Solution Approach 2:
The patent implements continuous process operation where passivation immediately follows etching without interruption, maintaining the useful action of material modification and protection continuously. This eliminates idle time between steps while preserving the precision benefits of controlled sequential processing.
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 approach effectively reduces arcing, improves yield by preventing defects, and allows for efficient etching and passivation of aluminum layers at the wafer edge, enhancing the reliability of semiconductor device fabrication.
Implementation Method 1
energizing the process gas into a plasma at a periphery of the semiconductor substrate; and bevel processing the semiconductor substrate with the plasma
Implementation Method 2
The at least one layer comprising aluminum is etched around the bevel of the wafer, comprising flowing an aluminum etching gas comprising a chlorine containing component into a bevel edge processing chamber, forming the aluminum etching gas into a plasma, which etches the at least one layer of the stack comprising aluminum
Implementation Method 3
flowing an aluminum passivation gas comprising a fluorine containing component into the bevel edge processing chamber, forming the passivation gas into a plasma, which passivates exposed parts of the at least one layer comprising aluminum
Implementation Method 4
Part of the at least one layer comprising aluminum is passivated after stopping the flow of the aluminum etching gas
Data Source
AI summary
A method of bevel edge processing a semiconductor in a bevel plasma processing chamber in which the semiconductor substrate is supported on a semiconductor substrate support is provided. The method comprises evacuating the bevel etcher to a pressure of 3 to 100 Torr and maintaining RF voltage under a threshold value; flowing a process gas into the bevel plasma processing chamber; energizing the process gas into a plasma at a periphery of the semiconductor substrate; and bevel processing the semiconductor substrate with the plasma.