Concentration Controller Gas Overshoot Suppression
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Solution Overview
Problem
In semiconductor manufacturing, the concentration of material gas overshoots immediately after the start of a supply period due to the intermittent supply and stop periods in existing concentration controllers, leading to instability in gas concentration control.
Innovation Solution
A concentration controller that calculates an initial set flow rate based on actual concentrations and flow rates during a supply period, adjusting the flow rates of carrier and diluent gases to prevent overshooting, using a concentration monitor and flow rate control devices to stabilize gas concentration during subsequent supply periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If intermittent supply and stop periods are used in the vaporization apparatus, then the concentration controller can control the flow rates of carrier gas and diluent gas during the supply period, but the concentration of material gas in the vaporization tank gradually increases during the stop period, causing overshooting immediately after the start of the supply period
Solution Approach 1:
The control method performs preliminary actions by calculating and setting the flow rates of carrier gas and diluent gas before the supply period begins. Specifically, during the stop period, the system calculates the accumulated concentration of material gas in the vaporization tank and pre-adjusts the flow rates to compensate for the expected concentration increase, thereby preventing overshooting when the supply period starts.
Solution Approach 2:
The invention applies beforehand cushioning by introducing a compensation mechanism that accounts for the concentration accumulation during stop periods. The control system calculates the degree of concentration increase during the stop period and adjusts the initial flow rates accordingly, creating a cushioning effect that prevents the concentration from overshooting the target value when the supply period begins.
2Quantity of substance
If the concentration of material gas is allowed to accumulate during the stop period, then the vaporization tank maintains material availability, but the concentration of material gas in the mixed gas overshoots immediately after the start of the supply period
Solution Approach 1:
The control method implements feedback by continuously monitoring the concentration of material gas in the vaporization tank and using this information to adjust the flow rates of carrier gas and diluent gas. The system calculates the actual concentration during the stop period and uses this feedback to determine the appropriate flow rate adjustments for the upcoming supply period, ensuring that the target concentration is maintained without overshooting.
Solution Approach 2:
The invention applies parameter changes by dynamically adjusting the flow rates of carrier gas and diluent gas based on the concentration parameters measured during the stop period. The control system changes the flow rate parameters in advance of the supply period to compensate for the accumulated material gas concentration, thereby maintaining manufacturing precision while preserving material availability.
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 solution effectively suppresses the overshooting of material gas concentration immediately after the start of a supply period, ensuring stable gas control and reducing errors in flow rate calculations, thereby maintaining target concentrations.
Implementation Method 1
a concentration monitor provided on the downstream side of the merging point with the diluent gas supply path in the material gas lead-out path
Implementation Method 2
a flow rate control device provided in at least one of the carrier gas supply path and the diluent gas supply path
Implementation Method 3
material gas produced by vaporization of the material
Data Source
AI summary
In a concentration controller that intermittently leads out material gas from a vaporization tank, in order to control the flow rates of carrier and diluent gases so that the concentration of the material gas can be suppressed from overshooting immediately after the start of material gas supply period, the concentration controller is adapted to include: a concentration calculation part that calculates the concentration of the material gas on the basis of an output signal from a concentration monitor; and a set flow rate calculation part that, on the basis of actual concentration calculated by the concentration calculation part, an actual flow rate outputted from a flow rate control device or the set flow rate of the flow rate control device, and a preset target concentration, calculates the initial set flow rate of the flow rate control device.