Wafer Plasma Annealing Sequence for High-Selectivity Etching
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Solution Overview
Problem
Current semiconductor wafer processing technologies face challenges in achieving high etch selectivity and reliability, particularly with dry-etching methods like ion beam etching, which damage the wafer and require subsequent processes to remove the damaged layer, while wet-etching struggles with high aspect ratio patterns and surface tension limitations.
Innovation Solution
A wafer processing apparatus and method that alternately and repeatedly performs plasma processes and annealing processes using process gases like fluorine and NF3, with controlled internal pressure and temperature adjustments, to enhance etch selectivity and reduce equipment complexity by integrating both processes in a single chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion beam etching is used for fine etching at atomic level, then etching precision is improved, but a damaged layer is formed on the wafer requiring subsequent removal processes
Solution Approach 1:
The patent converts the harmful ion bombardment effect into a beneficial annealing effect. By controlling the plasma process parameters and using specific gas compositions, the ion bombardment that would normally create damage is transformed into a controlled heating effect that anneals the wafer, removing damaged layers in-situ during the etching process itself.
Solution Approach 2:
The patent merges the etching process and annealing process into a single integrated process. By alternating plasma on-states (for etching) and plasma off-states (for annealing) within the same chamber using the same hardware, the system eliminates the need for separate annealing equipment and subsequent removal processes.
2Reliability
If separate annealing equipment is used to remove damaged layer, then damaged layer removal is achieved, but equipment complexity and process time increase
Solution Approach 1:
The patent combines the annealing function with the plasma processing chamber by utilizing the same hardware components (power supply, gas distribution structure, electrodes) for both etching and annealing operations. This integration eliminates separate annealing equipment while maintaining the ability to perform both functions effectively.
Solution Approach 2:
The plasma processing apparatus is designed to perform multiple functions: etching during plasma on-states and annealing during plasma off-states. The same power supply, gas distribution structure, and chamber configuration serve both purposes, making the equipment universal and reducing overall system complexity.
3Loss of substance
If wet-etching technology is used for cleaning, then particle removal capability is improved, but cleaning performance decreases due to surface tension of high aspect ratio patterns
Solution Approach 1:
The patent replaces wet-etching (chemical/mechanical process) with plasma-based processing (physical/chemical process). The plasma process uses ion bombardment and reactive species to remove particles and clean surfaces, overcoming the surface tension limitations of wet-etching for high aspect ratio patterns.
4Measurement precision
If plasma process and annealing process are performed separately, then process control is simplified, but productivity decreases due to multiple equipment transfers
Solution Approach 1:
The patent performs both plasma process and annealing process in the same chamber without transferring the wafer to different equipment. The power supply controls the plasma on/off states to sequentially perform etching and annealing, eliminating transfer time and increasing productivity while maintaining process control through coordinated power and gas flow management.
Solution Approach 2:
The patent implements continuous processing by alternating plasma on-states and off-states within the same chamber. The wafer remains in the chamber throughout the entire process, with plasma turned on for etching and turned off for annealing, eliminating idle transfer time and maintaining continuous useful action.
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 improves etch selectivity and reliability by effectively processing materials like silicon oxide and silicon nitride without the need for separate annealing equipment, reducing equipment costs and increasing productivity by integrating plasma and annealing processes within a single apparatus.
Implementation Method 1
generating plasma using the first process gas; performing a plasma process on the wafer using the plasma
Implementation Method 2
due to ion bombardment applied to a wafer for example, a damaged layer is formed after etching
Implementation Method 3
performing an annealing process on the wafer after the performing of the plasma process; performing an annealing process on the wafer includes lowering an internal pressure of the wafer processing apparatus
Data Source
AI summary
A wafer processing method includes supplying a first process gas into a wafer processing apparatus, lowering a temperature of the wafer, generating plasma using the first process gas, supplying a second process gas and mixing the second process gas with the plasma, performing a plasma process on the wafer using the plasma and the second process gas, and performing an annealing process on the wafer on which the plasma process has been performed. The lowering of the temperature of the wafer includes increasing an internal pressure of the wafer processing apparatus.