Sputterable Inductive Coil for Plasma Etching Chamber Cleaning
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Solution Overview
Problem
Plasma etching processes face challenges with contamination and poor vacuum levels due to outgassing materials and the buildup of carbonaceous and conductive materials, leading to frequent maintenance needs and downtime in semiconductor processing.
Innovation Solution
A plasma etching apparatus with an electrically conductive coil made from sputterable materials like aluminum or titanium, which adheres particulate and gaseous species to the chamber walls, reducing contamination and improving vacuum conditions by acting as a getter material and maintaining chamber cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plasma etching processes are used with insulating chamber walls, then RF power coupling is maintained, but conductive material builds up on chamber walls causing RF power attenuation and process degradation
Solution Approach 1:
The invention converts the harmful buildup of conductive material on chamber walls into a beneficial self-cleaning mechanism. By intentionally allowing conductive material to deposit on the chamber walls and then using plasma cleaning to remove it, the system transforms the problem of contamination into a useful cleaning function that maintains RF power coupling and prevents process degradation
Solution Approach 2:
The chamber walls perform self-cleaning through plasma treatment. The conductive material that builds up on the walls is subsequently removed by plasma cleaning cycles, allowing the chamber to maintain its own cleanliness without external mechanical intervention. This self-service mechanism reduces maintenance requirements and keeps the chamber in optimal condition for continuous operation
2Reliability
If frequent maintenance operations are performed to clean the chamber, then contamination and vacuum levels are improved, but tool downtime and operational costs increase
Solution Approach 1:
The invention replaces mechanical cleaning operations with plasma-based cleaning. Instead of physically accessing and mechanically cleaning the chamber between runs, the system uses plasma to chemically clean the chamber walls in-situ. This substitution eliminates the need for tool downtime associated with mechanical maintenance while maintaining high vacuum quality and reducing contamination
Solution Approach 2:
The plasma cleaning function is integrated into the normal operational cycle, allowing continuous cleaning action without interrupting production. The chamber is cleaned during transition periods between different processing tasks or at the end of processing cycles, maintaining continuous useful action without requiring separate maintenance downtime
3Productivity
If carbonaceous material accumulates on chamber walls, then etching capacity is maintained, but particulate contamination increases and vacuum levels deteriorate
Solution Approach 1:
The system implements periodic plasma cleaning cycles to remove accumulated carbonaceous material from chamber walls. Rather than allowing continuous accumulation that leads to particulate contamination, the periodic cleaning action maintains etching capacity by removing carbon deposits before they become problematic, while preventing the formation of loose particulates that would contaminate substrates
Solution Approach 2:
The invention changes the chemical state of carbonaceous material on chamber walls through plasma treatment. The plasma process converts accumulated carbon deposits into volatile species that can be pumped away, transforming the harmful particulate carbon into removable gaseous products. This parameter change from solid particulate to gaseous state eliminates contamination sources while maintaining etching performance
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 reduces the frequency of maintenance operations, lowers operational costs, and enhances tool uptime by minimizing contamination and maintaining high vacuum levels, allowing for more efficient and reliable plasma etching processes.
Implementation Method 1
The inductive coil 14 is connected to an RF power generator (not shown) through an impedance matching network (not shown) as is well known in the art. RF power coupled via the coil 14 generates a plasma.
Implementation Method 2
The bias applied to the platen 16 is then used to accelerate ions from the plasma towards the wafer, where ion bombardment etches the surface of the workpiece.
Implementation Method 3
the coil is formed from a metallic material which can be sputtered onto an interior surface of the at least one chamber
Data Source
AI summary
A method is for cleaning a plasma etching apparatus of the type used to etch a substrate and having at least one chamber. The method includes sputtering a metallic material from an electrically conductive coil which is positioned within the at least one chamber onto an interior surface of the at least one chamber to perform a cleaning function.