VHF Plasma Film Formation for Low-Damage Silicon Nitride ALD
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Solution Overview
Problem
Existing film forming methods using plasma-enhanced atomic layer deposition (PEALD) cause damage to substrates due to the generation of H radicals, particularly when using NH3 or amine as a nitriding gas, which adversely affect the quality of underlying metal films or resins.
Innovation Solution
A film forming method utilizing radio-frequency power of 100 MHz or higher to generate plasma, avoiding the use of NH3 or amine, and employing a capacitively coupled plasma processing apparatus with specific gas and plasma control mechanisms to suppress damage and enhance film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma is used for film formation (PEALD), then film formation efficiency is improved, but damage to underlying metal films or resins occurs due to H radical generation
Solution Approach 1:
The patent changes the fundamental parameter of plasma generation from conventional RF (13.56 MHz) to VHF (100 MHz or higher). This parameter change fundamentally alters the plasma characteristics, suppressing H radical generation while maintaining effective film formation. The VHF plasma generates different radical species distribution compared to conventional RF plasma, thereby resolving the contradiction between productivity and damage prevention.
Solution Approach 2:
The patent substitutes the conventional RF plasma mechanism with VHF plasma mechanism. By replacing the frequency parameter of the electromagnetic field used to generate plasma, the system achieves different chemical reaction pathways. This substitution eliminates the harmful H radical generation mechanism while preserving the beneficial film deposition function, effectively resolving the technical contradiction.
2Reliability
If conventional RF plasma (13.56 MHz) is used, then film formation can be achieved, but H radicals are generated that damage metal films or resins
Solution Approach 1:
The patent applies parameter change by transitioning from RF frequency (13.56 MHz) to VHF frequency (100 MHz or higher). This fundamental parameter change in the electromagnetic field frequency alters the plasma chemistry, suppressing H radical generation. The VHF plasma excites different molecular vibrations and rotations, leading to different dissociation pathways that favor N radical generation over H radical generation, thereby improving reliability while reducing harmful factors.
Solution Approach 2:
The patent converts the potential harm of plasma into benefit by using VHF frequency to generate plasma that produces N radicals instead of H radicals. The plasma mechanism is transformed from one that damages underlying layers to one that protects them, while still achieving effective film formation. The high frequency plasma creates a more controlled chemical environment that benefits the overall process.
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 reduces substrate damage and improves film quality by generating high-energy N radicals, allowing for low-temperature ALD film formation on fragile underlying layers without using ammonia or amine, thereby enhancing the integrity of silicon nitride films.
Implementation Method 1
a step of generating plasma of the processing gas using a radio-frequency power of 100 MHz or higher
Implementation Method 2
generating plasma of the processing gas using a radio-frequency power of 100 MHz or higher
Implementation Method 3
plasma-enhanced atomic layer deposition (PEALD) using plasma during film formation
Implementation Method 4
it has been proposed to form a silicon nitride layer on a wafer by PEALD using the plasma of a silicon-containing precursor and a nitrogen-containing reactant
Data Source
AI summary
A film forming method forms a film on a substrate by plasma in a processing container including a stage configured to hold the substrate thereon, wherein the film forming method includes: (a) a step of supplying a raw material gas and a reaction gas as a processing gas to the processing container; and (b) a step of generating plasma of the processing gas using a radio-frequency power of 100 MHz or higher.