Pulse-Time-Modulated Plasma for PE-ALD Surface Potential Control
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Solution Overview
Problem
Plasma Enhanced Atomic Layer Deposition (PE-ALD) processes face challenges with surface potential accumulation on wafers due to repeated plasma treatment, leading to risks like wafer slipping and in-plane uniformity issues, which are not effectively addressed in existing technologies.
Innovation Solution
Implementing pulse-time-modulated RF power during the plasma treatment phase in PE-ALD, with specific pulse durations and duties, to control surface potential and enhance in-plane uniformity by alternating precursor gas and reactant gas supply with a purge process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If plasma treatment is repeated at least several hundred times to deposit a thick film, then film thickness is improved, but surface potential on the wafer increases leading to wafer slip, wafer sticking, and destruction of gate elect loads
Solution Approach 1:
The patent applies periodic action by modulating the RF power in pulse cycles during plasma treatment. The RF power is turned on and off in repeated cycles, creating periodic plasma generation that allows electrons to be removed during off-cycles while maintaining film deposition during on-cycles. This periodic modulation prevents surface potential accumulation while enabling thick film deposition through multiple cycles.
2Manufacturing precision
If PE-ALD is based on equalization process of precursor adsorption and planar plasma treatment, then in-plane uniformity of film is believed to be good, but surface potential problems are not recognized and no solutions are provided
Solution Approach 1:
The patent introduces periodic RF power modulation during the plasma treatment phase while maintaining the sequential precursor adsorption and plasma treatment structure. This periodic action creates controlled electron removal cycles that prevent surface potential buildup, thereby ensuring wafer stability and reliability while preserving the in-plane uniformity achieved through the equalization process.
3Productivity
If RF power having a pulse-time-modulation of 10 to 100 μsec is used for etching, then positive ions and negative ions are alternately emitted to inhibit accumulation of electrons and increase etching speed, but this technology is unrelated to PE-ALD
Solution Approach 1:
The patent adapts the pulse-time-modulation concept from etching to PE-ALD by changing the RF power parameters. Instead of using the 10-100 μsec pulse widths optimized for etching, the patent employs longer pulse cycles suitable for film deposition, allowing the same periodic modulation principle to prevent electron accumulation while enabling film formation rather than material removal. This parameter adaptation makes the technology applicable to PE-ALD.
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 reduces surface potential at each cycle and improves in-plane uniformity of the deposited film, mitigating wafer-related issues and maintaining deposition efficiency.
Implementation Method 1
treating the adsorbed precursor with a reactant gas plasma wherein the reactant gas plasma reacts the precursor adsorbed on the surface
Implementation Method 2
the reactant gas plasma reacts the precursor adsorbed on the surface, thereby forming an atomic sub-layer
Implementation Method 3
adsorbing a precursor on a wafer
Data Source
AI summary
A thin film is formed by alternating multiple times, respectively, a process of adsorbing a precursor onto a substrate and a process of treating the adsorbed surface using a reactant gas and a plasma, wherein the reactant gas is supplied substantially uniformly over the substrate, and the plasma is pulse-time-modulated and applied in the process of supplying the reactant gas.