Sequential Non-Plasma and Plasma Etch for Carbon Removal
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Solution Overview
Problem
Conventional methods fail to effectively remove carbonaceous contaminants from substrate void regions without damaging other layers or structures, particularly in the context of replacement metal gate development, where carbonaceous contaminants are embedded within trench oxides and prevent complete oxide removal.
Innovation Solution
A method involving sequential non-plasma and plasma etch processes is used to selectively remove oxide materials relative to carbon contaminants, utilizing a chemical oxide removal process followed by plasma etching with reactive gases to expose and remove the contaminants without damaging adjacent layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional chemical oxide removal process is used, then oxide material can be removed, but carbonaceous contaminant remains embedded and prevents complete oxide removal
Solution Approach 1:
The etching process is divided into multiple sequential steps: first a non-plasma etch process removes oxide at a higher rate, then a plasma etch process removes carbonaceous contaminant, followed by additional non-plasma etching. This segmentation allows each process to target specific materials sequentially, achieving complete oxide removal while eliminating the contaminant that would otherwise prevent thorough cleaning.
Solution Approach 2:
The patent changes the etching parameters by alternating between non-plasma and plasma conditions. The non-plasma process uses chemical reactions optimized for oxide removal, while the plasma process introduces reactive species and ion bombardment optimized for carbon removal. By changing the physical and chemical parameters of the etching environment, the process selectively removes different materials at different stages.
2Manufacturing precision
If conventional etching procedures are used, then some oxide removal occurs, but the process damages other layers or structures on substrate
Solution Approach 1:
The patent applies different etching qualities to different materials through the sequential process. The non-plasma etch process is optimized with selectivity for oxide materials, removing oxide at a higher rate while sparing other layers. The subsequent plasma process is optimized for carbon removal with controlled damage to underlying structures. Each step has locally optimized conditions matched to the specific material being removed at that stage.
Solution Approach 2:
The non-plasma etch process performs preliminary oxide removal to expose the carbonaceous contaminant before the plasma process is applied. This preliminary action reduces the oxide burden, allowing the subsequent plasma process to focus on contaminant removal with minimal exposure time, thereby reducing damage risk to adjacent sensitive structures.
3Reliability
If photo-resist is left in desired location, then it serves its function, but conventional residual resist removal is not viable
Solution Approach 1:
The etching process exhibits local selectivity where the non-plasma process removes oxide containing carbonaceous contaminant while the plasma process selectively removes exposed carbon. This localized action allows photo-resist to remain in desired locations for subsequent processing steps, as the contaminant removal is confined to specific regions where oxide was present, leaving intact photo-resist structures elsewhere.
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 allows for the selective removal of carbonaceous contaminants without damaging other structures, ensuring complete oxide removal and maintaining the integrity of the substrate layers.
Implementation Method 1
The first material is etched using a first non-plasma etch process that etches the first material at a higher rate relative to a rate of etching the second material
Implementation Method 2
The second material is then etched using a plasma containing a reactive gas, which exposes a residual first material
Data Source
AI summary
A method of forming a semiconductor device. A substrate having first and second materials is provided, wherein the second material is occluded by the first material. The substrate is etched using a first non-plasma etch process that etches the first material at a higher rate relative to a rate of etching the second material. The first non-plasma etch process exposes the second material that is overlying at least a portion of the first material. The second material is then etched using a plasma containing a reactive gas, which exposes the at least a portion of the first material. The first material including the at least a portion of the first material that was exposed by etching the second material are etched using a second non-plasma etch process.