Showerhead Auxiliary Ground Paths for Plasma Uniformity
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Solution Overview
Problem
VHF CCP reactors for ALD and CVD applications face non-uniformity issues due to the standing wave effect, which affects the uniformity of the wafer deposited film.
Innovation Solution
A wafer processing apparatus with auxiliary ground paths placed above the showerhead is introduced, which helps control the electric field to improve plasma uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If VHF CCP reactor is used for ALD and CVD applications, then high film quality with low temperature is achieved, but non-uniformity occurs due to standing wave effect
Solution Approach 1:
The patent introduces auxiliary ground paths at specific locations above the showerhead to create localized electric field modifications. This allows different regions of the reaction chamber to have tailored electric field characteristics, addressing the non-uniformity problem while maintaining the overall low-temperature VHF CCP process conditions
Solution Approach 2:
The auxiliary ground paths act as intermediary elements between the showerhead and the upper chamber walls. These ground paths modify the electric field distribution by providing additional reference potentials, thereby reducing standing wave effects and improving plasma uniformity without changing the fundamental VHF CCP process
2Manufacturing precision
If auxiliary ground paths are added to control electric field, then plasma uniformity is improved, but device complexity increases
Solution Approach 1:
The grounding system is segmented into multiple auxiliary ground paths positioned at different locations above the showerhead. This segmentation allows independent optimization of electric field control at different chamber regions while keeping each individual ground path relatively simple in structure
Solution Approach 2:
Instead of modifying the showerhead design or adding complex active control systems to improve plasma uniformity, the patent inverts the approach by adding passive ground paths to the chamber walls. This alternative approach achieves uniformity improvement through a simpler structural modification
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
The implementation of auxiliary ground paths significantly reduces non-uniformity, achieving a non-uniformity of 8% compared to the original 18%, thereby enhancing the uniformity of the wafer deposited film.
Implementation Method 1
auxiliary ground lines configured to be placed above the showerhead
Implementation Method 2
there may be a non-uniformity derived from standing wave effect
Implementation Method 3
showerhead placed inside of the reaction chamber configured to generating plasma
Implementation Method 4
radio frequency (RF) power supply configured to generate RF and supply the generated RF to the showerhead
Data Source
AI summary
A wafer processing apparatus with improved film uniformity is presented. The apparatus comprising a radio frequency (RF) enclosure enclosing and defining a reaction chamber; a showerhead placed inside of the reaction chamber configured to generating plasma for processing a wafer in the reaction chamber; a radio frequency (RF) power supply configured to generate RF and supply the generated RF to the showerhead; a plurality of capacitors connected in parallel and/or in serial between the RF power supply and the showerhead; and more than one auxiliary ground lines configured to be placed above the showerhead. The auxiliary ground lines are to be turned on sequentially for improving map profile.