Inert Gas Flow Control for Semiconductor Oxidation
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Solution Overview
Problem
Existing methods for oxidizing semiconductor wafers using multiple reacting gases struggle to maintain constant partial pressures of oxidizing gases under varying atmospheric pressure, leading to inconsistencies in oxide film uniformity and quality.
Innovation Solution
A method and apparatus that control the flow rate of an inert gas in response to atmospheric pressure variations, using multiple flow rate control devices with different full scales to maintain constant partial pressures of oxidizing gases by calculating the inert gas flow rate based on pre-calculated values of reacting gases and remaining gases, ensuring precise control and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the flow rate of inert gas is controlled based on total gas flow rate without considering gas reactions, then the control method is simple, but the partial pressure of oxidizing gas cannot be kept constant under varying atmospheric pressure
Solution Approach 1:
The patent implements feedback control by measuring the actual total gas flow rate after reaction occurs in the external combustion device, and using this measured value to calculate and adjust the inert gas flow rate. This closed-loop feedback mechanism ensures that the partial pressure of oxidizing gas remains constant despite atmospheric pressure variations, resolving the contradiction between simple control and precise partial pressure maintenance.
Solution Approach 2:
The patent performs preliminary calculation of the inert gas flow rate based on pre-determined relationships between gas flow rates and atmospheric pressure. By pre-calculating the required inert gas flow rate adjustments for different atmospheric pressure conditions, the system can rapidly respond to pressure changes without complex real-time computations, maintaining both simplicity and precision.
2Manufacturing precision
If multiple flow rate control devices with different full scales are used to control inert gas flow rate, then the partial pressure control precision is improved, but the device complexity increases
Solution Approach 1:
The patent divides the inert gas flow rate control into multiple segments, each handled by a separate flow rate control device with a specific full scale range. This segmentation allows each device to operate within its optimal range, providing precise control across the entire required flow rate spectrum while managing system complexity through modular design.
Solution Approach 2:
The patent changes the parameter of flow rate control by using multiple devices with different full scale parameters. Each device is selected and configured with an appropriate full scale range to handle specific portions of the total flow rate requirement, enabling precise control without requiring a single overly complex high-capacity device.
3Manufacturing precision
If absolute pressure control system is used to maintain constant oxidizing conditions, then the oxide film uniformity is improved, but the manufacturing cost increases significantly
Solution Approach 1:
The patent introduces inert gas as an intermediary substance to indirectly control the partial pressure of oxidizing gas. Instead of directly controlling absolute pressure with expensive equipment, the system uses inert gas flow rate adjustment as a mediator to achieve the desired oxidizing conditions, significantly reducing manufacturing costs while maintaining oxide film uniformity.
Solution Approach 2:
The patent replaces the mechanical/physical absolute pressure control system with a chemical/compositional control approach. By controlling the flow rates of reacting gases and inert gas to maintain constant partial pressure of oxidizing gas, the system achieves the same oxide film uniformity without requiring complex absolute pressure control machinery, thereby reducing manufacturing costs.
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 allows for precise control of oxidizing gas partial pressures, enhancing the uniformity and reproducibility of oxide films, thereby improving the quality and stability of semiconductor devices and substrates, while reducing the need for costly absolute pressure control systems.
Implementation Method 1
a flow rate of the inert gas is varied in accordance with a variation of the atmospheric pressure to keep constant at partial pressure of an oxidizing gas or partial pressures of oxidizing gases in the reaction tube
Implementation Method 2
supplying a plurality of kinds of gases which react with each other and an inert gas into the reaction tube
Implementation Method 3
when oxygen and hydrogen are used for oxidizing in a pyrogenic oxidizing
Implementation Method 4
heating a wafer by a heater and flowing an oxidizing gas such as oxygen
Data Source
AI summary
Disclosed is a producing method of a semiconductor device, including: loading a substrate into a reaction tube; oxidizing the substrate under an atmospheric pressure by supplying a plurality of kinds of gases which react with each other and an inert gas into the reaction tube; and unloading, from the reaction tube, the substrate after the oxidizing, wherein in the oxidizing, a flow rate of the inert gas is varied in accordance with a variation of the atmospheric pressure to keep constant a partial pressure of an oxidizing gas or partial pressures of oxidizing gases in the reaction tube, and the flow rate of the inert gas is calculated based on a pre-calculated flow rate of a gas or pre-calculated flow rates of gases produced by reaction of the plurality of gases and a pre-calculated flow rate of a gas which is not consumed by the reaction and which remains or pre-calculated flow rates of gases which are not consumed by the reaction and which remain.