Structure Bottom-Surface Cleaning for Capping Layer Adhesion
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Solution Overview
Problem
The manufacturing of FinFETs faces challenges with unwanted residue and metal oxide formation during etching, which hinders adhesion of subsequent layers and is inefficient for high aspect ratio features due to conventional cleaning methods.
Innovation Solution
A method involving exposure to a cleaning gas comprising nitrogen and fluorine, along with a preclean gas of hydrogen, and a postclean gas of hydrogen, to effectively remove metal oxides and residues without damaging the structure, improving adhesion for capping layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional cleaning methods are used, then the process is simple, but the cleaning efficiency is poor for high aspect ratio features due to inhibited flow of cleaning chemistries
Solution Approach 1:
The patent changes the chemical parameters of the cleaning gas by using a specific mixture containing fluorine (e.g., CF4, SF6) and oxygen (e.g., O2, CO2) in controlled ratios, along with adjusting pressure and flow parameters, to enable effective penetration and cleaning of high aspect ratio features where conventional methods fail
Solution Approach 2:
The cleaning process uses a composite gas mixture combining fluorinated gases and oxygen-containing gases, which work synergistically to remove both organic residue and metal oxides, achieving comprehensive cleaning that single gases cannot accomplish
2Productivity
If etching is performed to manufacture FinFETs, then the transistor drive current increases, but unwanted residue and metal oxide formation occur which prevent adhesion of overlayers
Solution Approach 1:
The patent converts the harmful metal oxides formed during etching into removable byproducts by using fluorine-based cleaning chemistry that reacts with the oxides to form volatile fluorinated compounds, thereby transforming the adhesion problem into an effective cleaning opportunity
Solution Approach 2:
The cleaning gas mixture acts as an intermediary between the etched surface and the subsequent capping layer deposition, removing harmful residues and preparing a clean surface that enables proper adhesion of overlayers without directly modifying the etched features
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 method reduces unwanted metal oxides and residues, enhancing the adhesion of capping layers and maintaining the integrity of the structure, particularly effective for high aspect ratio features.
Implementation Method 1
exposing the bottom surface to a cleaning gas including a first gas including nitrogen (N) and a second gas including fluorine (F)
Implementation Method 2
exposing the bottom surface to a preclean gas including hydrogen (H)
Implementation Method 3
exposing the bottom surface to a postclean gas including hydrogen gas (H2)
Data Source
AI summary
Embodiments of the present disclosure generally relate to methods of cleaning a structure and methods of depositing a capping layer in a structure. The method of cleaning a structure includes suppling a cleaning gas, including a first gas including nitrogen (N) and a second gas including fluorine (F), to a bottom surface of a structure. The cleaning gas removes unwanted metal oxide and etch residue from the bottom surface of the structure. The method of depositing a capping layer includes depositing the capping layer over the bottom surface of the structure. The methods described herein reduce the amount of unwanted metal oxides and residue, which improves adhesion of deposited capping layers.