Titanium Oxide Etch Selectivity via Remote Plasma
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Solution Overview
Problem
There is a lack of effective dry etch processes for selectively removing titanium oxide relative to other dielectrics like silicon oxide and silicon nitride, which is essential for precise pattern transfer and material thinning in semiconductor manufacturing.
Innovation Solution
The method involves a remote plasma etch using plasma effluents formed from fluorine-containing or chlorine-containing precursors, combined with a directional sputtering pretreatment and an ion suppression element, to selectively remove titanium oxide while minimizing the etching of other materials, achieving high selectivity and directional control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dry etch processes are used, then other dielectrics can be removed, but titanium oxide cannot be selectively removed with high selectivity
Solution Approach 1:
The patent changes the chemical parameters of the etch process by using specific fluorine-containing precursors (NF3, CF4, SF6) and chlorine-containing precursors (Cl2, BCl3) in remote plasma configuration. This chemical parameter change enables selective titanium oxide etching with selectivity ratios exceeding 15:1 against silicon oxide and 20:1 against silicon nitride, resolving the selectivity issue while maintaining broad process applicability
Solution Approach 2:
The patent introduces a remote plasma region as an intermediary between the precursor gases and the substrate. The remote plasma generates reactive species that selectively react with titanium oxide, while an ion suppression element further mediates the process by filtering out ions that would cause non-selective etching. This intermediary approach achieves high selectivity without compromising process versatility
2Manufacturing precision
If isotropic etching is used, then material removal is achieved, but directional control is lost
Solution Approach 1:
The patent segments the etch process into two distinct stages: a pretreatment stage that creates directional pathways, and a main etch stage that removes material. The pretreatment step modifies the titanium oxide surface to enhance subsequent anisotropic etching, while maintaining high overall etch rates through the synergistic combination of both stages
Solution Approach 2:
The patent employs periodic alternation between pretreatment and etching phases. The pretreatment phase prepares the surface for directional etching, followed by the anisotropic etch phase that removes material with directional control. This periodic action maintains high productivity while achieving the required directional precision for pattern transfer
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 rapid and selective etching of titanium oxide compared to silicon oxide and silicon nitride, with etch selectivity ratios exceeding 15:1 and 20:1 respectively, enabling precise control and minimal disturbance to miniature structures.
Implementation Method 1
remote plasma etch using plasma effluents formed from a fluorine-containing precursor and/or a chlorine-containing precursor
Implementation Method 2
plasma effluents react with the titanium oxide... plasma effluents react with exposed surfaces and selectively remove titanium oxide
Implementation Method 3
direction sputtering pretreatment is performed prior to the etch
Implementation Method 4
accelerating ionized components of the pretreatment gas into the titanium oxide
Implementation Method 5
ion suppression element positioned between the remote plasma and the substrate processing region
Data Source
AI summary
Methods of selectively etching titanium oxide relative to silicon oxide, silicon nitride and/or other dielectrics are described. The methods include a remote plasma etch using plasma effluents formed from a fluorine-containing precursor and/or a chlorine-containing precursor. Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the titanium oxide. The plasmas effluents react with exposed surfaces and selectively remove titanium oxide while very slowly removing other exposed materials. A direction sputtering pretreatment is performed prior to the remote plasma etch and enables an increased selectivity as well as a directional selectivity. In some embodiments, the titanium oxide etch selectivity results partly from the presence of an ion suppression element positioned between the remote plasma and the substrate processing region.