Gas Cluster Plasma Etching for Ultra-High Aspect Ratio Openings
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Solution Overview
Problem
Current plasma processing technologies face challenges in achieving high aspect ratio structures with the required precision, uniformity, and repeatability for semiconductor device manufacturing, particularly in delivering sufficient radical flux deep inside narrow and deep openings, which limits the maximum aspect ratio achievable in etching processes.
Innovation Solution
The method involves generating a flux of gas clusters containing radical precursors and directing positively charged ions towards the substrate to enhance the radical to ion flux ratio, using a hybrid gas cluster and plasma processing technique that includes forming gas clusters through adiabatic expansion and sustaining plasma to facilitate anisotropic etching, thereby increasing the radical density deep inside high aspect ratio cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma processing is used, then the process can be performed with standard equipment, but the maximum aspect ratio of etched features is limited to around 60 due to insufficient radical flux deep inside narrow openings
Solution Approach 1:
The patent changes the physical state and delivery mechanism of radical precursors by forming them into gas clusters that can penetrate deep into narrow openings, transforming the radical delivery parameter from conventional plasma to cluster-based delivery, thereby achieving aspect ratios of 100 or 150
Solution Approach 2:
The patent uses a hybrid approach combining gas cluster technology with plasma processing, where gas clusters containing radical precursors are generated and then activated by plasma to create a composite processing method that delivers both the chemical reactivity of plasma and the deep penetration capability of gas clusters
2Productivity
If the opening width is reduced to increase component packing density, then the component packing density increases, but the radical flux becomes insufficient to reach the bottom of the opening
Solution Approach 1:
The patent changes the delivery parameter of radicals from conventional molecular diffusion to cluster-based transport, where gas clusters can maintain their integrity and deliver radical precursors deep into narrow openings with aspect ratios of 100 or 150, enabling higher component packing density
Solution Approach 2:
Gas clusters act as intermediary carriers that transport radical precursors deep into narrow openings without decomposing prematurely, serving as a mediator between the radical source and the substrate, thereby maintaining sufficient radical flux at the bottom of high aspect ratio openings
3Manufacturing precision
If the opening depth is increased to achieve higher aspect ratios, then the aspect ratio increases, but the uniformity and precision of the etching process deteriorate
Solution Approach 1:
The patent performs preliminary action by pre-forming gas clusters containing radical precursors before they enter the opening, ensuring that the radicals are delivered in a controlled manner to the bottom of the opening, which maintains uniformity and precision even at aspect ratios of 100 or 150
Solution Approach 2:
The patent changes the physical form of radical delivery from conventional plasma to gas cluster beams, which can be precisely controlled and directed, thereby maintaining etching uniformity and repeatability at ultra-high aspect ratios
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 effectively increases the maximum achievable aspect ratio of etched features from 60 to 100 or 150, improving the precision and uniformity of semiconductor device manufacturing by maintaining a high radical to ion flux ratio and enabling the formation of ultra-high aspect ratio openings.
Implementation Method 1
generating a flux of gas clusters over the substrate in a first process chamber, where the gas clusters include radical precursors
Implementation Method 2
sustaining plasma including ions in a second process chamber; and exposing the substrate to the ions by directing the ions toward the bottom wall of the opening
Implementation Method 3
a gas flow system connected to the gas inlet and a gas outlet of the gas cluster process chamber, where the gas flow system is configured to generate a flux of gas clusters in the gas cluster process chamber
Data Source
AI summary
A method for processing a substrate includes forming a patterned layer over the substrate, the layer including an opening, where a surface of the opening includes a sidewall and a bottom wall. The method includes processing the patterned layer with an anisotropic process by generating a flux of gas clusters over the substrate in a first process chamber, where the gas clusters include radical precursors; exposing the substrate to the flux of gas clusters. The method includes sustaining plasma including ions in a second process chamber; and exposing the substrate to the ions by directing the ions toward the bottom wall of the opening.