Plasma Etch Cleaning for Silicon Epitaxy
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Solution Overview
Problem
Current cleaning methods fail to effectively remove native oxides and contaminants from silicon surfaces, especially in high aspect ratio features, leading to poor quality epitaxial layers due to exposure to ambient conditions and inadequate ion reach.
Innovation Solution
A method involving inductively coupled plasma etching using gases like Ar/NF3 and H2/Cl2, with bias application to the substrate, to remove oxides and contaminants without exposing the substrate to atmosphere, followed by epitaxial deposition, ensuring pristine surface preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning methods are used to remove native oxides and contaminants from silicon surfaces, then some contaminants are removed, but ions fail to reach the silicon surface at the bottom of high aspect ratio features and cleaning is incomplete
Solution Approach 1:
The patent changes the physical parameters of the cleaning process by using plasma etching with specific gas compositions (fluorine-containing and hydrogen-containing precursors) and applying bias voltage to generate ions with sufficient energy to reach the bottom of high aspect ratio features, thereby achieving complete contaminant removal
Solution Approach 2:
The patent replaces conventional mechanical or chemical cleaning methods with plasma-based physical cleaning. The plasma etching process uses ion bombardment and chemical reactions to remove contaminants, providing superior cleaning effectiveness especially in high aspect ratio features where conventional methods fail
2Ease of manufacture
If the substrate is exposed to ambient conditions during cleaning, then cleaning can be performed, but native oxide layers form and contaminant deposition occurs on the silicon surface
Solution Approach 1:
The patent performs the cleaning process in a vacuum chamber with controlled atmosphere, preventing native oxide formation and contaminant deposition. The plasma environment provides an inert conditions that protect the silicon surface while enabling effective cleaning
Solution Approach 2:
The patent performs cleaning as a preliminary step before epitaxial deposition, ensuring the silicon surface is completely clean and free of contaminants before the next process step, thereby preventing defects in the final device
3Productivity
If aspect ratios of features increase to enable higher device density, then more transistors can be placed close together, but cleaning becomes more difficult as ions cannot reach the bottom of high aspect ratio features
Solution Approach 1:
The patent addresses the three-dimensional cleaning challenge by using plasma that can penetrate into high aspect ratio features. The combination of ion bombardment and chemical reactions in plasma allows cleaning of vertical sidewalls and bottom surfaces that are inaccessible to conventional cleaning methods
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 enhances the quality of epitaxial layers by reducing oxygen contaminants and native oxides, improving the cleanliness and integrity of the silicon surface, even in complex feature geometries.
Implementation Method 1
The plasma etch process comprises flowing an etchant gas mixture comprising a fluorine-containing precursor and a hydrogen-containing precursor into a substrate-processing region of a first processing chamber and forming a plasma from the etchant gas mixture
Implementation Method 2
etching a surface of a silicon-containing substrate by use of a plasma etch process
Implementation Method 3
forming an epitaxial layer on the etched surface of the silicon-containing substrate
Data Source
AI summary
Implementations of the present disclosure generally relate to methods and apparatuses for epitaxial deposition on substrate surfaces. More particularly, implementations of the present disclosure generally relate to methods and apparatuses for surface preparation prior to epitaxial deposition. In one implementation, a method of processing a substrate is provided. The method comprises etching a surface of a silicon-containing substrate by use of a plasma etch process to form an etched surface of the silicon-containing substrate and forming an epitaxial layer on the etched surface of the silicon-containing substrate. The plasma etch process comprises flowing an etchant gas mixture comprising a fluorine-containing precursor and a hydrogen-containing precursor into a substrate-processing region of a first processing chamber and forming a plasma from the etchant gas mixture flowed into the substrate-processing region.