Selective Etch for Metal-Containing Materials Using Remote Plasma
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Solution Overview
Problem
Current dry-etch processes are limited in their ability to selectively remove metal-containing materials from semiconductor substrates, with few developed methods available for selectively etching these materials relative to silicon-containing films.
Innovation Solution
The method involves exposing metal-containing materials to halogen-containing species in a substrate processing region, using a remote plasma to excite halogen-containing precursors and optionally a local plasma, with pretreatment using moisture or OH-containing precursors to enhance etch selectivity, allowing for the selective removal of metal-containing materials like aluminum oxide relative to silicon-containing films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dry-etch processes are used, then material removal is achieved, but etch selectivity for metal-containing materials relative to silicon-containing films is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the etch process by using halogen-containing precursors (such as BCl3, BBr3, CCl4, CBr4) instead of conventional etch chemicals. This parameter change enables high etch selectivity for metal-containing materials like aluminum oxide, titanium oxide, and tungsten relative to silicon-containing films, achieving selectivities greater than 10:1 while maintaining process versatility
Solution Approach 2:
The patent introduces halogen-containing species as intermediary chemical agents that mediate the etching reaction. These halogen species react selectively with metal-containing materials through chemical reactions (e.g., Al2O3 + 3BCl3 → 2AlCl3 + B2O3), enabling selective removal while sparing silicon-containing films. The halogen acts as a mediator that facilitates selective material removal without requiring direct contact between the substrate and reactive plasma
2Manufacturing precision
If selective etching of metal-containing materials is achieved, then pattern transfer precision is improved, but physical disturbance to miniature structures may increase
Solution Approach 1:
The patent replaces mechanical/physical sputtering mechanisms with chemical reaction mechanisms. Instead of using ion bombardment and physical sputtering to remove material, the process uses halogen-containing species that chemically react with metal-containing materials to form volatile products. This chemical mechanism achieves high pattern transfer precision while minimizing physical disturbance to miniature structures, as the reactions proceed at lower energies without aggressive ion bombardment
3Manufacturing precision
If remote plasma is used to excite halogen-containing precursors, then etch selectivity is enhanced, but process complexity increases
Solution Approach 1:
The patent segments the plasma generation process into two distinct zones: a remote plasma generation region where halogen-containing precursors are excited, and a substrate processing region where the excited species perform selective etching. This segmentation allows the plasma to be generated remotely and transported to the substrate without direct contact, reducing contamination and simplifying the overall system architecture while maintaining high etch selectivity through controlled chemical reactions
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 achieves high etch selectivity, enabling the conformal removal of metal-containing materials with etch selectivities greater than 10:1 relative to silicon-containing films, facilitating the creation of intricate patterns in semiconductor devices without significant physical disturbance.
Implementation Method 1
A remote plasma is used to excite the halogen-containing precursor and produce plasma effluents
Implementation Method 2
remote plasma excitation of ammonia and nitrogen trifluoride enables silicon oxide to be selectively removed
Implementation Method 3
Chemical etching is used for a variety of purposes including transferring a pattern in photoresist into underlying layers
Implementation Method 4
exposing metal-containing materials to halogen containing species in a substrate processing region
Implementation Method 5
Metal-containing materials on the substrate may be pretreated using moisture or another OH-containing precursor before exposing the resulting surface
Data Source
AI summary
Methods of selectively etching metal-containing materials from the surface of a substrate are described. The etch selectively removes metal-containing materials relative to silicon-containing films such as silicon, polysilicon, silicon oxide, silicon germanium and/or silicon nitride. The methods include exposing metal-containing materials to halogen containing species in a substrate processing region. A remote plasma is used to excite the halogen-containing precursor and a local plasma may be used in embodiments. Metal-containing materials on the substrate may be pretreated using moisture or another OH-containing precursor before exposing the resulting surface to remote plasma excited halogen effluents in embodiments.