Atomic Layer Etching Using Single Gas and Periodic Bias
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Solution Overview
Problem
The atomic layer etching (ALE) method requires lengthy gas substitution steps, leading to increased etching time due to the necessity of several tens of seconds for each substitution step, which repetitive execution prolongs the overall etching process.
Innovation Solution
A method involving alternately repeating adsorption and etching steps without gas substitution, where radicals are adsorbed without high-frequency bias and ions are drawn in with a low-power high-frequency bias, using the same processing gas throughout, with a radical density 200 times that of ions and a bias power density of 0.07 W/cm2 or less for 2 seconds or less, to achieve efficient etching similar to ALE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gas substitution is performed in the ALE method to alternately supply different processing gases, then the etching precision and in-plane uniformity are improved, but the etching time becomes excessively long due to the several tens of seconds required for each substitution step
Solution Approach 1:
The patent merges the functions of multiple processing gases into a single processing gas that contains both radical-generating components and ion-generating components. This eliminates the need for gas substitution between adsorption and etching steps, thereby resolving the contradiction between maintaining precise alternating gas supply and reducing etching time.
Solution Approach 2:
The patent applies periodic action by alternately applying high-frequency bias and low-frequency bias to the same processing gas in a single cycle. This periodic modulation of bias conditions enables the single gas to sequentially perform both radical adsorption and ion etching functions, eliminating the need for physical gas substitution while maintaining precise temporal control.
2Productivity
If the high-frequency bias power density is increased to enhance ion drawing efficiency, then the etching speed is improved, but the damage to the layer to be etched and loss of precision increase
Solution Approach 1:
The patent uses periodic action by alternating between high-frequency bias application (for rapid ion drawing and high etching speed) and low-frequency bias application (for gentle radical adsorption with minimal damage). This temporal separation of functions within a single gas environment enables both high productivity and high precision without the need for gas substitution.
Solution Approach 2:
The patent changes the bias frequency and power density parameters dynamically within a single processing gas environment. By modulating these parameters over time, the system achieves different functional states (radical adsorption vs. ion etching) from the same gas, resolving the contradiction between etching speed and precision.
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 significantly shortens the etching time by eliminating the need for gas substitution and stabilizing high-frequency bias power, allowing for continuous execution of adsorption and etching steps while maintaining the precision of ALE.
Implementation Method 1
a step of adsorbing radicals, which are generated from a processing gas, to the layer to be etched without applying a high-frequency bias to the lower electrode
Implementation Method 2
a step of generating a plasma of the second processing gas and of drawing ions into the layer to be etched
Implementation Method 3
a step of drawing ions, which are generated from the processing gas, into the layer to be etched by applying a high-frequency bias to the lower electrode
Data Source
AI summary
In a method of an embodiment, radicals, which are generated from a processing gas, is adsorbed to a layer to be etched without applying a high-frequency bias to a lower electrode, in an adsorption step. In the subsequent etching step, ions, which are generated from the processing gas, are drawn into the layer to be etched by applying a high-frequency bias to the lower electrode. The adsorption step and the etching step are alternately repeated. In the adsorption step, a density of radicals is 200 or greater times a density of ions. In the etching step, RF energy having a power density of 0.07 W/cm2 or less is supplied to the lower electrode or a high-frequency bias having a power density of 0.14 W/cm2 or less is supplied to the lower electrode for a period of 0.5 seconds or less.