In-Situ Sputter Etching Without a Shutter Before PVD
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Solution Overview
Problem
Traditional sputter etching and deposition processes require separate chambers, leading to reduced throughput, increased maintenance, and surface contamination issues due to the need for a moveable shutter, which generates process gas flow asymmetry and particle contamination.
Innovation Solution
An in-situ sputter etching method within a sputtering chamber where a wafer and target are exposed without a shutter, using a plasma with positively charged gas ions and adjustable negative potentials to eject surface material onto removable shields, preventing contamination from redepositing on the wafer or target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate etching and deposition equipment are used, then etching and deposition processes can be performed independently, but throughput is reduced and maintenance requirements increase
Solution Approach 1:
The patent combines separate etching and deposition functions into a single integrated sputtering chamber. The chamber can perform both sputter etching (by applying negative potential to the substrate) and sputter deposition (by applying negative potential to the target) without requiring physical reconfiguration or shutter mechanisms, thereby improving throughput while maintaining process independence through software-controlled mode switching.
2Object-affected harmful factors
If a moveable shutter is used to separate etching and deposition zones, then surface contamination can be prevented, but particle contamination and process gas flow asymmetry are introduced
Solution Approach 1:
The patent removes the moveable shutter component entirely from the system. Instead of using a physical barrier to separate etching and deposition zones, the invention relies on electrical potential control to define process zones. By applying negative potential to either the substrate or target, the system creates virtual boundaries that prevent contamination without introducing particles or gas flow asymmetry associated with mechanical shutters.
3Productivity
If in-situ etching is performed without a shutter, then throughput is improved and maintenance is reduced, but surface impurities may redeposit on the wafer
Solution Approach 1:
The patent controls the redistribution of surface impurities by dynamically adjusting electrical potentials during the process. By applying negative potential to the substrate during etching and then to the target during deposition, the system creates directional ion flux that sweeps contaminants toward the target rather than allowing them to redeposit on the wafer. This parameter control ensures clean surfaces while maintaining continuous in-situ 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 method enables efficient in-situ etching and deposition without a shutter, reducing surface impurities and maintaining film crystallinity, particularly beneficial for aluminum nitride and metal-doped aluminum nitride films, by ensuring net removal of material from both the wafer and target surfaces.
Implementation Method 1
Sputter etching describes kinetic bombardment of a surface with noble gas ions, which do not chemically react with surface molecules and atoms but cause them to be ejected by kinetic energy transfer
Implementation Method 2
Oxygen ashing is understood to cause the breaking of molecular bonds in large organic molecules, resulting in their conversion into much smaller molecules
Data Source
AI summary
The present invention provides a method for in-situ etching of a wafer prior to sputter deposition, the method comprising the following steps. A sputtering chamber having a sputtering target is provided. The wafer is placed into the sputtering chamber. A gas is introduced into the sputtering chamber such that the gas at least partially ionized as a plasma, wherein the plasma includes positively charged gas ions. A first negative potential is applied to the wafer while a second negative potential is simultaneously applied to the sputtering target and while no shutter is positioned between the wafer and the sputtering target.