Selective SiGe Etching Using High-Temperature Plasma-Free Chemistry
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Solution Overview
Problem
Conventional etching technologies face challenges in selectively removing silicon-and-germanium-containing materials without forming residues and damaging substrate structures, particularly in 3D device processing where aspect ratios are high, and they often operate at reduced temperatures with reduced selectivity and form plasma effluents.
Innovation Solution
A dry etch process using specific precursor combinations, including halogen-containing and secondary precursors, is performed at higher temperatures to uniformly etch silicon-and-germanium-containing materials without plasma, maintaining selectivity and preventing residue formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet HF etch is used to preferentially remove material, then etch selectivity is improved, but penetration into constrained trenches is poor and deformation of remaining material occurs
Solution Approach 1:
The patent replaces wet chemical etching with a thermal etching process using fluorine-containing precursors and secondary precursors at elevated temperatures (200-400°C). This substitution eliminates liquid handling issues and enables vapor-phase etching that can penetrate constrained trenches while maintaining selectivity through controlled thermal reactions.
Solution Approach 2:
The patent changes the temperature parameter from room temperature (wet etch) to elevated temperatures (200-400°C) to enable thermal etching. This parameter change transforms the etching mechanism from purely chemical to thermally-driven chemical reactions, improving penetration and reducing deformation while maintaining selectivity through precursor flow rate control.
2Ease of operation
If dry etch with local plasma is used to penetrate constrained trenches, then penetration capability is improved, but substrate damage occurs through electric arcs
Solution Approach 1:
The patent converts the harmful plasma-based dry etching into a beneficial thermal etching process. By using fluorine-containing precursors with secondary precursors (hydrogen, carbon, nitrogen, or oxygen) at elevated temperatures, the process achieves penetration capability without electric arcs, transforming the harmful plasma mechanism into a controlled thermal chemical reaction.
Solution Approach 2:
The patent introduces secondary precursors (hydrogen, carbon, nitrogen, or oxygen) as intermediaries that modify the etching chemistry. These intermediaries facilitate the removal of silicon-and-germanium-containing materials while preventing direct harmful interactions, acting as protective mediators in the thermal etching process.
3Reliability
If conventional etching is used at reduced temperatures, then processing safety is improved, but etch selectivity is reduced and residues form
Solution Approach 1:
The patent deliberately changes the temperature parameter from reduced temperatures to elevated temperatures (200-400°C) to achieve superior etch selectivity. The thermal energy enables specific chemical reactions with silicon-and-germanium-containing materials while leaving other materials unaffected, and the high temperature ensures complete reaction products without residues.
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
The process achieves selective etching of silicon-and-germanium-containing materials with uniformity and residue-free results, enhancing etch profiles and protecting substrate structures from damage.
Implementation Method 1
contacting the substrate with the fluorine-containing precursor and the secondary precursor. The methods include selectively removing at least a portion of the silicon-and-germanium-containing material from the substrate
Implementation Method 2
The processing region may be maintained at a temperature of greater than or about 200° C.
Data Source
AI summary
Exemplary semiconductor processing methods may include providing a fluorine-containing precursor and a secondary precursor to a processing region of a semiconductor processing chamber. The secondary precursor may be or include a carbon-containing precursor, a hydrogen-containing precursor, a nitrogen-containing precursor, or an oxygen-containing precursor. A substrate may be housed within the processing region. A silicon-containing material and a silicon-and-germanium-containing material may be disposed on the substrate. The methods may include contacting the substrate with the fluorine-containing precursor and the secondary precursor. The methods may include selectively removing at least a portion of the silicon-and-germanium-containing material from the substrate. The processing region may be maintained at a temperature of greater than or about 200° C.