Substrate Processing Particle Attachment Prevention
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Solution Overview
Problem
In substrate processing apparatuses, positively charged particles are attracted and attached to wafers due to self-bias potential generation after plasma processing, leading to defects in semiconductor devices, as existing techniques fail to effectively prevent particle attachment post-processing.
Innovation Solution
A method involving the adjustment of electron density control power to lower the electron density above the substrate for a short period after plasma processing, while maintaining the bias power, to prevent particle attachment by increasing the electric field force and overcoming gravity, thereby removing particles from the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the plasma processing is stopped and bias power is removed, then the plasma processing is completed, but particles are attracted to the substrate by electrostatic force
Solution Approach 1:
The invention applies preliminary action by maintaining the bias power supply for a predetermined time after plasma processing to prevent particle attachment before it occurs. By keeping the electric field active during the transition period, positively charged particles are repelled from the substrate, preventing the harmful electrostatic attraction that would otherwise occur when bias power is removed.
Solution Approach 2:
The invention implements preliminary anti-action by using the electric field from the bias power to counteract the electrostatic attraction force before particles can attach to the substrate. The maintained bias power creates a repulsive force that opposes and prevents the harmful particle-substrate attraction during the critical transition period after plasma processing.
2Object-affected harmful factors
If multiple plasma processings are performed continuously to prevent self bias potential generation, then particle attachment is prevented, but processing time increases
Solution Approach 1:
The invention applies continuity of useful action by maintaining the bias power supply continuously for a predetermined time after plasma processing ends. This continuous application of the electric field ensures uninterrupted particle repulsion without requiring additional plasma processing cycles, thus preventing particle attachment while avoiding the time loss associated with multiple sequential plasma treatments.
3Productivity
If bias power is supplied to attract plasma to the mounting table, then plasma processing is effective, but particles float around the substrate interface
Solution Approach 1:
The invention uses preliminary action by maintaining the bias power supply after plasma processing to address the particle floating issue before it causes problems. The continued electric field prevents particles from settling on the substrate during the transition period, resolving the harmful effect while preserving the benefits of the bias power during active 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
Effectively prevents particle attachment to the substrate by impulsively applying the electric field force, ensuring particles are removed instead of falling and attaching, thus reducing defects in semiconductor devices.
Implementation Method 1
a plasma is generated in the accommodation chamber and the plasma (electrons and positive ions) is attracted to the wafer mounted the mounting table by supplying a bias power to the mounting table
Implementation Method 2
after the plasma processing, positively charged particles may attracted and attached to the wafer by an electrostatic force
Implementation Method 3
a negatively charged particle is mainly affected by a gravity FG
Implementation Method 4
a negatively charged particle is mainly affected by a gravity FG, a force FE generated from an electric field caused by a bias power supplied to the mounting table, and a viscous force FN of a gas flowing inside the accommodation chamber
Data Source
AI summary
In a particle attachment preventing method in a substrate processing apparatus, an electron density control power supplied from the second power supply is adjusted such that an electron density above the substrate gets lower than during a plasma processing, for a preset short period of time after the plasma processing is ended, and a bias power supplied from the first power is maintained for the preset short period of time. The second power supply is a high frequency power supply for supplying a high frequency power having a frequency that is higher than that of the bias power, and in said adjusting of the electron density control power, the high frequency power supplied from the second power supply is lowered as compared with that during the plasma processing.