Oxidized Silicon Etch Profile via Remote Plasma
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Solution Overview
Problem
Current semiconductor etching processes face challenges in selectively removing oxidized and non-oxidized materials from substrates, particularly in achieving high selectivity and minimizing damage to delicate structures, with conventional methods often requiring protective layers and resulting in anisotropic etching that limits SiGe growth.
Innovation Solution
The method involves oxidizing the silicon surface in a semiconductor processing chamber, forming an inert plasma to modify the oxidized silicon, and using remote plasma effluents from fluorine-containing precursors to selectively etch the modified silicon, allowing for both anisotropic and isotropic etching without protective layers, thereby increasing SiGe growth area without undercutting nitride spacers or gate materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet HF etch is used to preferentially remove silicon oxide, then etching selectivity is improved, but penetration into constrained trenches is poor and material deformation occurs
Solution Approach 1:
The patent changes the physical state and chemical composition parameters of the etching medium by using plasma instead of liquid HF, and by controlling plasma power, pressure, and gas flow parameters to achieve both high selectivity and deep trench penetration simultaneously
Solution Approach 2:
The patent replaces the chemical wet etching mechanism with a plasma-based physical-chemical etching mechanism, using ion bombardment and reactive species to achieve anisotropic etching with high selectivity and deep penetration without liquid contact
2Volume of moving object
If local plasma is used to penetrate constrained trenches, then trench penetration is improved, but substrate damage occurs due to electric arcs
Solution Approach 1:
The patent introduces a remote plasma unit as an intermediary that generates plasma effluents which then contact the substrate indirectly, preventing direct electric arc formation on the substrate while maintaining plasma etching benefits
Solution Approach 2:
The patent extracts the plasma generation function from the substrate processing region by using a remote plasma unit, separating the plasma source from the substrate to eliminate harmful electric arcs while retaining the reactive species needed for etching
3Productivity
If conventional etching methods are used, then material removal is achieved, but protective layers are required and SiGe growth area is limited
Solution Approach 1:
The patent performs preliminary oxidation of the silicon surface before etching, creating a modified oxide layer that enables selective removal of oxidized silicon while protecting unoxidized regions, eliminating the need for separate protective layers
Solution Approach 2:
The plasma etching process serves multiple functions simultaneously: it removes oxidized silicon selectively, defines patterns, and creates surfaces suitable for subsequent SiGe growth, reducing the need for separate process steps
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 enables controlled, selective removal of silicon with high etching selectivity (>100:1) and isotropic etching, reducing material deformation and allowing for increased SiGe growth without damaging the substrate, thus improving semiconductor processing efficiency and quality.
Implementation Method 1
oxidizing an exposed silicon surface on a semiconductor substrate within a processing region of a semiconductor processing chamber
Implementation Method 2
forming an inert plasma within the processing region of the processing chamber. Effluents of the inert plasma may be utilized to modify the oxidized silicon
Implementation Method 3
A remote plasma may be formed from a fluorine-containing precursor to produce plasma effluents. The methods may include flowing the plasma effluents to the processing region of the semiconductor processing chamber. The methods may also include removing the modified oxidized silicon from the semiconductor substrate
Data Source
AI summary
Processing methods may be performed to form recesses in a semiconductor substrate. The methods may include oxidizing an exposed silicon surface on a semiconductor substrate within a processing region of a semiconductor processing chamber. The methods may include forming an inert plasma within the processing region of the processing chamber. Effluents of the inert plasma may be utilized to modify the oxidized silicon. A remote plasma may be formed from a fluorine-containing precursor to produce plasma effluents. The methods may include flowing the plasma effluents to the processing region of the semiconductor processing chamber. The methods may also include removing the modified oxidized silicon from the semiconductor substrate. The methods may include isotropically etching a silicon-containing material from the semiconductor substrate.