Inductively Coupled Plasma Nitridation for High Aspect Ratio Step Coverage
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Solution Overview
Problem
Existing methods struggle to form nitride films with good step coverage on substrates with high aspect ratios, particularly in semiconductor device manufacturing, where uniform film thickness across the surface is crucial for device performance.
Innovation Solution
A substrate processing apparatus using inductively coupled plasma (ICP) technology with a resonant coil and impedance matching circuit generates a high-frequency electric field, creating a doughnut-shaped plasma that uniformly nitrides the substrate surface, maintaining low internal pressures between 1 to 100 Pa to achieve uniform film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heated gas or plasmized gas is used to process grooves with high aspect ratio, then the groove can be processed, but it is difficult to form a film having good step coverage
Solution Approach 1:
The patent changes the pressure parameter from atmospheric or high pressure to low pressure (1-100 Pa range), which fundamentally alters the gas behavior and plasma characteristics. This parameter change enables uniform film deposition on high aspect ratio structures by controlling the mean free path of gas molecules and plasma species, allowing them to reach all surfaces including deep groove regions effectively.
Solution Approach 2:
The patent creates a low pressure inert environment in the processing chamber, which prevents unwanted chemical reactions and controls the plasma chemistry. This inert low-pressure environment allows precise control over the nitridation process while ensuring uniform film formation across complex three-dimensional structures with high aspect ratios.
2Productivity
If conventional plasma processing is used, then processing can be performed, but ion acceleration causes sputtering and wafer damage
Solution Approach 1:
The patent changes the pressure parameter to low pressure (1-100 Pa), which reduces the density of gas molecules and decreases the frequency of ion-substrate collisions. This parameter change reduces ion acceleration effects and sputtering damage while maintaining plasma processing capability, thereby protecting the wafer from damage during nitridation.
3Object-affected harmful factors
If low pressure is used to reduce ion damage, then wafer damage is reduced, but deposition rate may decrease
Solution Approach 1:
The patent optimizes the pressure parameter within a specific range (1-100 Pa) rather than using extremely low pressure. This optimized pressure range maintains sufficiently high deposition rates by balancing the mean free path effects with plasma density, while still reducing ion acceleration and sputtering damage compared to atmospheric pressure processing.
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
This approach enables the formation of nitride films with excellent step coverage and uniformity on high aspect ratio substrates, reducing wafer damage and extending apparatus lifespan by preventing ion acceleration and sputtering, while maintaining high deposition rates and film quality.
Implementation Method 1
an electric field combining the coil and the impedance matching circuit has a length of an integer multiple of a wavelength of an applied high-frequency power
Implementation Method 2
an inductive coupling structure which is installed at an outer periphery of the plasma generation space and is configured by a coil and an impedance matching circuit connected to the coil
Implementation Method 3
a plasma generation space where a supplied nitrogen-containing gas is plasma-exited
Implementation Method 4
active species containing a nitrogen element generated by the plasma excitation
Implementation Method 5
nitriding a surface of the substrate with an active species containing a nitrogen element generated by the plasma excitation
Data Source
AI summary
A method of manufacturing a semiconductor device includes: preparing a substrate processing apparatus including a substrate process chamber having a plasma-generation space where a nitrogen-containing gas is plasma-exited and a process space where a substrate is mounted in communication with the plasma-generation space, an inductive coupling structure configured by a coil and an impedance matching circuit, wherein electric field combining the coil and the circuit has a length of an integer multiple of a wavelength of an high-frequency power, and a table to mount the substrate under a lower end of the coil; mounting the substrate on the table; supplying the nitrogen-containing gas into the chamber; starting a plasma excitation of the nitrogen-containing gas by applying the high-frequency power to the coil; and nitriding a surface of the substrate with active species containing a nitrogen element at an internal pressure of the chamber ranging from 1 to 100 Pa.