Low-Temperature Epitaxial Gap Filling with Plasma Pre-Cleaning
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Solution Overview
Problem
High temperature bakes in semiconductor fabrication cause dopant diffusion and silicon migration, damaging hard masks and preventing selective atmospheric epitaxial processes, while low pressure epitaxial deposition results in low throughput.
Innovation Solution
A method involving plasma pre-cleaning substrates with aspect ratios over 5:1 at pressures of 1 to 5 Torr, followed by epitaxial deposition at 700 to 800 Torr, to control dopant diffusion and increase throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature bake is used to remove native oxide, then oxide removal is effective, but dopant diffusion and silicon migration occur
Solution Approach 1:
The patent changes the temperature parameter from high temperature (>1100°C) to low temperature (400-800°C) for the epitaxial deposition process. This parameter change allows effective oxide removal while preventing dopant diffusion and silicon migration, as the lower temperature does not provide sufficient thermal energy for these unwanted side reactions.
Solution Approach 2:
The patent introduces plasma as an intermediary means to remove native oxide before epitaxial deposition. Instead of using thermal energy directly, plasma provides a chemical cleaning mechanism that effectively removes oxide at lower temperatures, thereby avoiding the thermal damage associated with high temperature baking.
2Reliability
If high temperature bake is used to remove native oxide, then oxide removal is effective, but hard mask damage occurs
Solution Approach 1:
The patent reduces the process temperature from high temperature (>1100°C) to low temperature (400-800°C) range. This parameter change protects the hard mask structure from thermal damage while still achieving effective oxide removal through plasma treatment, thereby maintaining hard mask integrity.
Solution Approach 2:
The patent uses plasma as an intermediary cleaning mechanism that removes oxide without requiring high temperatures. This plasma-based approach avoids thermal stress and damage to the hard mask, providing a gentler cleaning method that preserves mask integrity.
3Manufacturing precision
If low pressure epitaxial deposition is used, then dopant diffusion control is improved, but throughput decreases
Solution Approach 1:
The patent changes the pressure parameter from low pressure to atmospheric pressure (700-800 Torr) for the epitaxial deposition process. This parameter change increases the deposition rate and throughput while maintaining dopant diffusion control through the combined effect of plasma pre-cleaning and controlled deposition conditions.
Solution Approach 2:
The patent performs plasma pre-cleaning as a preliminary action before the epitaxial deposition process. This pre-cleaning step prepares the substrate surface to enable faster and more controlled deposition at atmospheric pressure, thereby increasing throughput while maintaining precision.
4Manufacturing precision
If low temperature process is used, then dopant diffusion control is improved, but oxide removal effectiveness decreases
Solution Approach 1:
The patent introduces plasma as an intermediary cleaning mechanism that removes oxide at low temperatures. The plasma provides chemical reactivity that enables effective oxide removal without requiring high thermal energy, thus maintaining both low temperature benefit and effective cleaning.
Solution Approach 2:
The patent replaces thermal energy (heat) with plasma energy for oxide removal. Instead of using thermal processes that require high temperatures, the patent uses plasma chemistry to clean the substrate, enabling effective oxide removal at low temperatures.
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 method enhances dopant diffusion control and increases manufacturing throughput by enabling efficient gap filling and selective epitaxial deposition at lower temperatures.
Implementation Method 1
plasma pre-cleaning a substrate having openings with an aspect ratio of greater than 5:1
Implementation Method 2
depositing a material in the openings using epitaxial deposition
Data Source
AI summary
A method of epitaxial deposition is disclosed. The method includes plasma pre-cleaning a substrate having openings with an aspect ratio of greater than 5:1. The plasma pre-cleaning is performed at pre-clean pressure of less than 5 Torr. The method also includes, after the plasma pre-cleaning, depositing a material in the openings using epitaxial deposition at a deposition pressure of about 700 Torr to about 800 Torr. In another embodiment, a method of gap filling using epitaxial deposition includes patterning a substrate with openings having an aspect ratio of 5:1. The method also includes plasma pre-cleaning the substrate, the plasma pre-cleaning being performed at a pre-clean pressure of about 1 Torr to about 5 Torr. The method also includes, after the plasma pre-cleaning, depositing a gap fill material in the openings using epitaxial deposition at a deposition pressure of about 700 Torr to about 800 Torr.