Dual-Frequency Plasma Reactor for Ultra-High Aspect Ratio Etching
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Solution Overview
Problem
Conventional plasma etching reactors face challenges in achieving ultra-high aspect ratio etching due to limited ion energy and charge accumulation issues, leading to inefficient energy utilization and costly RF energy waste, especially in deep trench or through-hole etching processes.
Innovation Solution
A capacitively coupled plasma etching reactor utilizing an ultra-low-frequency RF power supply (10 KHz to 300 KHz) in combination with a high-frequency RF power supply (at least 4 MHz) to create dual-accelerating electric fields, allowing for extended ion acceleration cycles and effective neutralization of charges within the etched hole, thereby enhancing ion energy and etching efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional plasma etching reactors use standard RF power supplies to etch deep through-holes, then the etching depth increases, but ion energy becomes insufficient and charge accumulation occurs on sidewalls, causing etching failure
Solution Approach 1:
The patent applies parameter changes by using a dual-frequency RF power supply system (combining low-frequency 13.56 MHz and ultra-low-frequency 100 KHz signals) to modify the ion acceleration mechanism. This enables ions to gain sufficient energy to reach the bottom of ultra-deep holes while the ultra-low-frequency component neutralizes sidewall charge accumulation, resolving the contradiction between etching depth and etching success rate.
2Force
If RF power is increased to enhance ion energy for deep etching, then ion energy increases, but energy waste increases and cost rises
Solution Approach 1:
The patent employs periodic action through the ultra-low-frequency RF component (100 KHz) that periodically neutralizes charges on sidewalls during the etching process. This periodic charge neutralization reduces the need for continuously high RF power, allowing ions to maintain sufficient energy for deep etching while significantly reducing overall RF energy consumption and waste.
3Productivity
If conventional single-frequency RF power supply is used, then device complexity is low, but ion acceleration efficiency is insufficient for ultra-high aspect ratio etching
Solution Approach 1:
The patent merges two different frequency RF power supplies (13.56 MHz and 100 KHz) into a single integrated system that works synergistically. The high-frequency component provides continuous ion generation and acceleration, while the ultra-low-frequency component periodically neutralizes charges, together achieving ultra-high aspect ratio etching with enhanced ion acceleration efficiency despite increased device complexity.
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 solution enables deeper and more uniform etching with reduced energy consumption, avoiding lateral etching and achieving aspect ratios greater than 40:1 while minimizing power input, thus overcoming the limitations of prior art in ultra-high aspect ratio etching.
Implementation Method 1
the high-frequency energy inputted by a the high-frequency RF power supply HF (e.g., with frequencies of 27 MHz, 60 MHz) ionizes the reactant gas introduced into the reaction chamber to generate plasma P
Implementation Method 2
the electric field inputted by the low-frequency RF power supply LF (e.g., with a frequency of 2 MHz) into the base enables generation of enough DC bias voltage in the sheath of the upper substrate surface to accelerate ions to move downward to bombard substrate for etching
Implementation Method 3
A capacitively coupled plasma etching reactor utilizing an ultra-low-frequency RF power supply (10 KHz to 300 KHz) in combination with a high-frequency RF power supply (at least 4 MHz) to create dual-accelerating electric fields, allowing for extended ion acceleration cycles and effective neutralization of charges within the etched hole, thereby enhancing ion energy and etching efficiency
Data Source
AI summary
Disclosed are a plasma reactor for ultra-high aspect ratio etching and an etching method therefor, wherein the plasma reactor comprises: a reaction chamber inside which a reaction space is formed; a base disposed at the bottom of the reaction space and configured for supporting a to-be-processed substrate; a gas showerhead disposed at the top inside the reaction chamber; wherein a first radio frequency power supply outputs a radio frequency power with a first frequency to the base or the gas showerhead so as to form and maintain plasma in the reaction chamber; and a second radio frequency power supply which outputs a radio frequency power with a second frequency to the base so as to control the ion energy incident to the base; wherein the first frequency is not less than 4 MHz, and the second frequency is not less than 10 KHz but not more than 300 KHz.