Atomic Layer Etching Monolayer Control for Sub-30 nm Patterning
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Solution Overview
Problem
Current semiconductor manufacturing techniques face challenges in achieving high device density and miniaturization, particularly in transferring circuit patterns to sub-30 nm technology nodes, due to limitations in etch selectivity, rate, and profile control during the patterning of semiconductor integrated circuitry.
Innovation Solution
A method involving atomic layer etching in a plasma processing system, where an etchant forms an adsorption monolayer on the substrate with electromagnetic power to achieve an etchant radical flux greater than the total ion flux, followed by desorption with gas ions to remove the monolayer, repeated until a target depth is reached, enhancing etch selectivity and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etching techniques are used to achieve high device density and miniaturization, then etch rate can be improved, but etch selectivity and profile control deteriorate
Solution Approach 1:
The etching process is segmented into distinct sequential steps: a first etching step using a first etchant to remove material, followed by a second etching step using a second etchant. This segmentation allows each etchant to be optimized for specific functions - the first etchant for high-rate removal and the second etchant for selective, controlled etching - thereby resolving the contradiction between achieving high etch rates and maintaining precise profile control.
2Productivity
If high power plasma is used to increase etch rate, then productivity improves, but damage to the substrate and loss of pattern integrity worsen
Solution Approach 1:
The patent employs periodic action by alternating between two distinct etching steps with different chemistries and power levels. The first etching step operates at higher power for rapid material removal, while the second etching step uses different conditions to complete the etch with minimal damage. This periodic alternation allows the system to achieve high overall etch rates while preventing substrate damage that would occur with continuous high-power plasma exposure.
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 method allows for precise and efficient removal of monolayers, achieving high etch rates and maintaining pattern integrity, thereby addressing the challenges of sub-30 nm feature patterning and enabling robust pattern transfer.
Implementation Method 1
forming an adsorption monolayer comprising an etchant on an exposed surface of the substrate
Implementation Method 2
introducing the etchant while concurrently coupling electromagnetic power to the plasma processing system at a power level targeted to achieve an etchant radical flux at the substrate greater than a total ion flux at the substrate
Implementation Method 3
desorbing the adsorption monolayer by exposing the adsorption monolayer to gas ions to activate a reaction of the etchant
Data Source
AI summary
A method of etching a layer on a substrate includes disposing a substrate in a plasma processing system configured to facilitate an etching process, performing an atomic layer etching process cycle to etch a monolayer of an exposed surface of the substrate, and repeating the atomic layer etching process cycle until a target depth is reached. Each process cycle etches the monolayer from the exposed surface. The atomic layer etching process cycle sequentially includes forming an adsorption monolayer comprising an etchant on an exposed surface of the substrate by introducing the etchant while concurrently coupling electromagnetic power to the plasma processing system at a power level targeted to achieve an etchant radical flux at the substrate greater than a total ion flux at the substrate, which power level is less than or equal to 50 W, purging the plasma processing system to remove any excess etchant, desorbing the adsorption monolayer by exposing the adsorption monolayer to gas ions to activate a reaction of the etchant, and purging the plasma processing system again.