Plasma Etching Polarity Control for Vertical High-Aspect Sidewalls
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Solution Overview
Problem
Existing etching methods struggle to maintain a vertical sidewall shape in high aspect ratio etching, leading to uneven CD-expanded areas and bowing due to ions reflecting diagonally from the mask, especially as etching progresses.
Innovation Solution
A substrate processing apparatus with radially arranged electromagnets and a control unit that modifies the polarity of these electromagnets to control plasma density and ion direction, using specific polarity modification patterns to cause the normal direction of ions to precess, thereby suppressing the formation of uneven CD-expanded areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional etching methods are used to etch high aspect ratio features, then etching can proceed through deep structures, but uneven CD-expanded areas and bowing occur due to ions reflecting diagonally from the mask
Solution Approach 1:
The patent applies dynamics by making the magnetic field configuration changeable during the etching process. Electromagnets arranged radially around the upper electrode dynamically adjust the magnetic field distribution to control ion trajectories, preventing diagonal reflection and maintaining vertical sidewalls throughout the etching depth
Solution Approach 2:
The patent changes physical parameters by adjusting the polarity and strength of electromagnetic fields during etching. By modifying the magnetic field parameters, the ion incident angle distribution is controlled to maintain vertical sidewalls and prevent CD expansion unevenness while achieving deep etching
2Manufacturing precision
If electromagnets are arranged radially around the upper electrode with polarity modification patterns, then ion direction can be controlled to maintain vertical sidewalls, but device complexity increases
Solution Approach 1:
The patent segments the electromagnetic control system into multiple independent electromagnets arranged radially around the upper electrode. Each electromagnet can be controlled individually with specific polarity modification patterns, allowing precise local control of ion trajectories to maintain vertical sidewalls
Solution Approach 2:
The patent introduces electromagnetic fields as an intermediary between the plasma source and the substrate. The radially arranged electromagnets mediate ion trajectories by creating controlled magnetic fields that guide ions vertically onto the substrate, preventing diagonal reflection and CD expansion
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 method effectively suppresses the formation of uneven CD-expanded areas even in the middle and later stages of etching, ensuring a more vertical etching process, particularly for high aspect ratio features on substrates like stacked films of oxide and nitride.
Implementation Method 1
arrange electromagnets outside an upper electrode, and control the magnetic poles of the electromagnets
Implementation Method 2
control the ions (charged particles) and neutral etchant (cold radicals) during a high aspect ratio etching
Implementation Method 3
generating plasma from a processing gas supplied into the chamber, and etching the substrate
Data Source
AI summary
A substrate processing method includes: providing a substrate processing apparatus including a chamber, a substrate support that supports a substrate in the chamber, an upper electrode facing a center of the substrate, and a plurality of electromagnets arranged radially around the center of the upper electrode; selecting a polarity modification pattern to be used for the plurality of electromagnets during an etching; and generating plasma from a processing gas supplied into the chamber, and etching the substrate based on the polarity modification pattern.