Pulse-Bias Plasma Etching of Carbon Films With Profile Control
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Solution Overview
Problem
Existing etching methods struggle to maintain the profile integrity of recesses in carbon-containing films, particularly in terms of suppressing profile distortion and bowing of the side walls and planar shape distortion of the bottom, especially when etching thick films.
Innovation Solution
An etching method using a plasma process with a pulse bias power supply to a substrate support, where the pulse is periodically repeated with a frequency of 5 kHz or more, utilizing a process gas comprising oxygen and sulfur-containing gases, and controlling the frequency and power levels to suppress profile distortion and enhance etching selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used on thick carbon-containing films, then etching can be performed, but profile distortion and bowing of recess side walls occur
Solution Approach 1:
The patent applies periodic pulsing of the process gas flow and bias power during the etching process. The gas flow is pulsed at a frequency of 1 kHz to 100 kHz, and bias power is applied in pulses with a duty cycle of 1% to 99%. This periodic action prevents profile distortion by allowing the plasma to refresh between pulses, maintaining vertical side walls while achieving high etching rates for thick films
Solution Approach 2:
The patent changes multiple process parameters simultaneously including gas flow rate, bias power level, pulse frequency, and duty cycle. By optimizing these parameters together, the method achieves both high etching speed for thick carbon-containing films and maintains precise profile control without side wall bowing
2Productivity
If high power is used to increase etching speed, then productivity improves, but profile distortion and chemical deposit blockage increase
Solution Approach 1:
By pulsing the bias power and gas flow periodically, the patent allows high power to be applied in controlled bursts rather than continuously. This periodic application maintains high average etching speed while preventing excessive chemical reactions that cause profile distortion and deposit blockage, achieving both productivity and precision
3Stability of the object's composition
If continuous gas flow is used, then etching process is stable, but chemical deposits block the recess opening
Solution Approach 1:
The patent pulses the process gas flow rather than maintaining continuous flow. This periodic gas supply stabilizes the plasma chemistry while preventing excessive chemical species from accumulating and blocking the recess opening, eliminating deposit blockage while maintaining process stability
Solution Approach 2:
By using pulse frequencies in the kHz range with appropriate duty cycles, the patent ensures that the etching action continues effectively without interruption. The rapid pulsing maintains continuous plasma presence and etching activity while preventing deposit accumulation, achieving both stability and preventing harmful effects
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 profile distortion and bowing of recesses in carbon-containing films, maintains etching selectivity, and reduces blockage by chemical deposits, even with thick films, thereby improving the precision and efficiency of the etching process.
Implementation Method 1
etching the carbon-containing film with plasma generated from a process gas including an oxygen-containing gas and a sulfur-containing gas
Implementation Method 2
etching the carbon-containing film with plasma generated from a process gas including an oxygen-containing gas and a sulfur-containing gas
Implementation Method 3
a pulse of bias power is supplied to a substrate support supporting the substrate
Data Source
AI summary
In one exemplary embodiment, an etching method may include (a) providing a substrate, the substrate including a carbon-containing film and a mask on the carbon-containing film; and (b) etching the carbon-containing film with plasma generated from a process gas including an oxygen-containing gas and a sulfur-containing gas, wherein in the (b), a pulse of bias power is supplied to a substrate support supporting the substrate, the pulse is periodically repeated, and a frequency defining a cycle of the pulse is 5 kHz or more.