Source Gas Supply Unit Vaporization Flow Rate Control
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Solution Overview
Problem
Existing methods for controlling the flow rate of vaporized raw materials in source gases for film formation, such as in CVD and ALD processes, are inefficient as they rely on trial and error and require a long time to achieve accurate control, especially when the amount of raw material decreases or residence time changes.
Innovation Solution
A source gas supply unit that includes a carrier gas flow rate control system, a flow rate measuring unit, and a control unit to create and update a vaporization flow rate table, allowing for precise adjustment of carrier gas flow rates to maintain consistent vaporization of raw materials, thereby ensuring accurate film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the flow rate of carrier gas is controlled at a constant level, then the operation is simple, but the flow rate of vaporized raw material changes due to decrease in raw material amount and residence time changes
Solution Approach 1:
The system measures the actual flow rate of the source gas (containing vaporized raw material) and uses this measurement to calculate the actual vaporized raw material flow rate by subtracting the carrier gas flow rate. This feedback information is then used to adjust the carrier gas flow rate set value to achieve the desired raw material flow rate, creating a closed-loop control system that maintains reliability despite changes in raw material amount or residence time.
Solution Approach 2:
The system dynamically adjusts the carrier gas flow rate parameter based on measured data and calculations. By changing the carrier gas flow rate set value in response to measured source gas flow rate and calculated vaporized raw material flow rate, the system compensates for changes in raw material amount or residence time, thereby maintaining stable control of the vaporized raw material flow rate.
2Measurement precision
If the flow rate of vaporized raw material is monitored, then the measurement is available, but the flow rate set value of carrier gas must be adjusted by trial and error requiring long time
Solution Approach 1:
The system uses the measured source gas flow rate as feedback to calculate the actual vaporized raw material flow rate. This calculated value is then compared with the desired flow rate, and the carrier gas flow rate set value is adjusted accordingly. This feedback-based approach eliminates the need for time-consuming trial and error adjustments, as the system directly calculates the required adjustment based on measured data.
Solution Approach 2:
The system replaces the manual trial-and-error adjustment process with an automated calculation and control system. The control unit automatically calculates the vaporized raw material flow rate from measured source gas flow rate and carrier gas flow rate set value, and automatically adjusts the carrier gas flow rate to achieve the desired raw material flow rate. This substitution of automated calculation for manual trial-and-error significantly reduces the time required to achieve accurate flow rate control.
3Quantity of substance
If the amount of raw material in the raw material tank decreases, then the raw material is consumed, but the flow rate of vaporized raw material changes requiring re-adjustment
Solution Approach 1:
The system continuously monitors the source gas flow rate and calculates the vaporized raw material flow rate. When the raw material amount in the tank decreases, the measured source gas flow rate changes, and this feedback is used to recalculate and adjust the carrier gas flow rate set value. This ensures that the vaporized raw material flow rate remains consistent even as the raw material is consumed and the tank level decreases.
Solution Approach 2:
The system dynamically adjusts the carrier gas flow rate set value in response to changes in raw material amount. Rather than using a fixed carrier gas flow rate, the system continuously adapts the flow rate parameter based on current conditions (measured source gas flow rate and calculated vaporized raw material flow rate). This dynamic adjustment maintains reliable control of the vaporized raw material flow rate throughout the raw material consumption process.
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 solution enables quick and stable control of the vaporization flow rate of raw materials, reducing the time required to achieve the desired film formation conditions and improving the accuracy of film thickness and quality.
Implementation Method 1
supplying a carrier gas to the raw material tank accommodating a liquid or solid raw material and vaporizing the raw material in the carrier gas
Data Source
AI summary
A source gas supply unit includes a carrier gas supply unit for supplying a carrier gas into a raw material tank, and a control unit. The control unit executes steps of: supplying the carrier gas to the raw material tank while varying a flow rate of the carrier gas without forming a film on a substrate, and storing a vaporization flow rate table showing the correspondence between a vaporization flow rate of the vaporized raw material contained in a source gas and a carrier gas flow rate set value; obtaining a carrier gas flow rate set value corresponding to a specified vaporization flow rate set value by using the vaporization flow rate table; and generating the source gas by supplying the carrier gas into the raw material tank based on the obtained carrier gas flow rate set value and supplying the generated source gas to a film forming unit.