Epitaxial Layer Thickness Control via Real-Time Dopant Feedback
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Solution Overview
Problem
The existing epitaxial growth processes face challenges in accurately controlling the layer thickness and composition ratio of epitaxial layers due to the introduction of dopants, as x-ray diffractometry is insufficient to detect dopant amounts, leading to unpredictable mass flow relationships with source gases.
Innovation Solution
A system is implemented that continuously monitors and controls both the mass flow of source gases and dopants in real-time using x-ray diffractometry and fluorescence spectrometry to detect layer thickness and dopant concentration, allowing for precise control of epitaxial layer characteristics through feedback mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dopants are provided during the epitaxial process to improve layer process characteristics, then carrier mobility is increased, but the relationship between mass flow of source gases and layer thickness/composition ratio becomes unpredictable
Solution Approach 1:
The patent implements real-time feedback control by continuously monitoring the mass flow of dopants using a flow sensor and adjusting the dopant supply accordingly. The controller receives feedback signals from the flow sensor and modifies the dopant mass flow to maintain the desired relationship between source gases and layer characteristics, thereby restoring predictability to the epitaxial growth process while preserving the benefits of dopant addition.
2Measurement precision
If x-ray diffractometry is used to detect layer thickness and composition ratio, then in-line control is achieved, but dopant concentration cannot be detected
Solution Approach 1:
The patent combines multiple detection methods by integrating both x-ray diffractometry for layer thickness and composition ratio measurement, and flow sensor-based mass flow monitoring for dopant concentration detection. The controller merges the information from both detection systems to achieve comprehensive in-line control of all critical parameters including dopant concentration, which x-ray diffractometry alone cannot provide.
3Ease of manufacture
If the mass flow of dopants is not controlled, then the epitaxial process is simpler, but the layer characteristics cannot be accurately controlled
Solution Approach 1:
The patent implements a self-regulating system where the flow sensor automatically monitors dopant mass flow and the controller autonomously adjusts the dopant supply to maintain optimal conditions. This self-service mechanism eliminates the need for complex manual intervention while ensuring accurate layer characteristics control, thereby maintaining ease of manufacture without sacrificing precision.
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 ensures accurate in-line control of epitaxial layer thickness and composition ratio, enhancing the precision and reliability of epitaxial layer formation, particularly for SiGe layers by accounting for the complementary nature of germanium and boron, thereby improving device performance.
Implementation Method 1
an x-ray source configured to irradiate the epitaxial layer with x-rays to generate diffraction rays
Implementation Method 2
a detector configured to detect the diffraction rays
Implementation Method 3
an epitaxial growth process to form an epitaxial layer on a substrate
Data Source
AI summary
An apparatus and method of forming an epitaxial layer are provided. The apparatus includes a process chamber in which an epitaxial process is performed to form epitaxial layer on a substrate. A first supplier supplies source gases for the epitaxial layer into the process chamber. A second supplier supplies dopants into the process chamber. A detector detects a composition ratio of the epitaxial layer and a concentration of the dopants in the epitaxial layer during the epitaxial growth process. And a controller controls a mass flow of at least one of the source gases and a mass flow of the dopants in-line with the epitaxial growth process. Accordingly, the layer thickness of the epitaxial layer can be accurately controlled in real time in line with the epitaxial process.