Epitaxial Substrate Rotation Control via Gas Flow
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Solution Overview
Problem
Existing methods for measuring and controlling the rotation speed of substrates in hot-wall reaction chambers of epitaxial deposition reactors are complex, hinder maintenance operations, and do not ensure precise uniformity in film deposition.
Innovation Solution
A method and assembly that utilize a lifting element with gas flow-induced rotation and pressure sensors to precisely measure and control the rotation speed of substrates, reducing mechanical complexity and facilitating maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical actuating means are used to rotate the substrate support system, then the rotation speed can be precisely controlled, but the system complexity and maintenance difficulty increase due to multiple interconnected mechanical parts
Solution Approach 1:
The patent replaces mechanical actuating means with a gas flow-based rotation system. Gas flows through channels in the substrate support system, creating pressure differences that drive rotation without mechanical contact. This eliminates complex mechanical transmission parts while maintaining precise rotation speed control through gas flow regulation.
Solution Approach 2:
The patent employs pneumatic principles by using controlled gas flow through integrated channels to generate rotational motion. The gas pressure differential created across the support system drives rotation, replacing mechanical actuators with a clean, contactless pneumatic drive mechanism that reduces complexity.
2Measurement precision
If a shaft and structural elements are added to measure and adjust angular speed, then rotation speed measurement precision improves, but maintenance operations are hindered and reactor downtime increases
Solution Approach 1:
The patent replaces mechanical measurement systems (shafts, encoders, or mechanical sensors) with optical detection methods. A marker on the rotating support system is detected by an optical sensor positioned outside the reaction chamber, enabling precise angular speed measurement without any mechanical measurement components inside the chamber that would complicate maintenance.
Solution Approach 2:
The patent introduces an optical marker as an intermediary element that enables measurement without direct mechanical contact. The marker attached to the rotating support system interacts with external optical sensors, transmitting rotation information across the chamber boundary without requiring internal measurement hardware that would impede maintenance.
3Speed
If gas flow rate is controlled via Mass Flow Controller, then gas flow speed can be precisely regulated, but the rotation speed of the support system cannot be precisely determined since it is influenced by other factors such as support system placement and sediment buildup
Solution Approach 1:
The patent implements a feedback control system where optical sensors continuously monitor the rotation speed of the support system by tracking the marker's position. This real-time measurement feedback is used to adjust the gas flow rate via the Mass Flow Controller, creating a closed-loop system that compensates for variations in support system placement and sediment buildup, thereby maintaining precise rotation speed control.
Solution Approach 2:
The patent makes the gas flow system multi-functional: it serves both as the actuation mechanism (driving rotation through pressure differential) and as the measurement reference (gas flow rate becomes a proxy for rotation speed when combined with optical feedback). This universal approach allows precise rotation control without requiring separate measurement systems.
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
Achieves precise control of substrate rotation speed, ensuring uniform epitaxial deposition while simplifying maintenance operations and reducing mechanical complexity in hot-wall reactors.
Implementation Method 1
the support system experiences a torque which sets it into rotation
Implementation Method 2
recording a pressure signal from a pressure sensor that varies as a function of the rotation speed of the lifting element
Data Source
AI summary
The present invention discloses a method for measuring and controlling the angular speed of a substrate in an epitaxial reactor for semiconductor film deposition. The present invention further discloses an assembly suitable to execute said method, as well as a reaction chamber and a reactor comprising said assembly. In particular, though not exclusively, the above assembly, reaction chamber, and method may be used in a hot-wall, crossflow reactor for the epitaxial deposition of silicon, silicon carbide or gallium nitride.