Gas Supply Method for Semiconductor Etching
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Solution Overview
Problem
Existing gas control methods in semiconductor manufacturing require a long time to reach set flow rates after switching, leading to suboptimal gas supply and potential failure in achieving predetermined properties during etching processes.
Innovation Solution
A gas supplying method that periodically switches between four distinct flow rate values in a predetermined order, including a high flow rate, a low flow rate, and two intermediate flow rates, to quickly stabilize gas flow rates during rising and falling transitions, ensuring accurate gas supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a gas flow rate control method switches between two different flow rate values (high and low) is used, then pulse control for changing etching rate according to micro-loading is achieved, but a long time is required to reach the set flow rate after switching, causing the actually supplied gas flow rate to be lower than the preset flow rate
Solution Approach 1:
The gas flow rate control is segmented into four distinct stages: a first flow rate value (higher than target), a second flow rate value (lower than target), a third flow rate value (target value), and a fourth flow rate value (intermediate value). This segmentation divides the traditional two-state pulse control into a multi-stage transition process, allowing the system to manage the transient response more effectively and reduce the time to reach the target flow rate while maintaining precise etching rate control.
2Productivity
If the gas flow rate is switched between high and low values, then micro-loading effect is utilized to change etching rate, but the control for switching to next gas flow rate occurs before reaching the set flow rate value, resulting in gas flow rate lower than preset value
Solution Approach 1:
The control method performs preliminary actions by first supplying gas at a first flow rate value higher than the target, then transitioning through a second flow rate value lower than the target, before reaching the third flow rate value (target). This preliminary overshooting and undershooting approach allows the system to compensate for the inherent delay in flow rate response, ensuring that the actual flow rate reaches the preset value accurately by the time the etching process requires it, thereby maintaining both productivity and reliability.
Data Source
AI summary
A gas supplying method of supplying a process gas containing a gas of at least one gaseous species into a process space in a semiconductor manufacturing apparatus includes supplying the process gas by controlling a flow rate value of the gas to be a first value during a first period; supplying the process gas by controlling the flow rate value of the gas to be a second value smaller than the first value during a second period; supplying the process gas by controlling the flow rate value of the gas to be a third value greater than the first value during a third period; and supplying the process gas by controlling the flow rate value of the gas to be a fourth value smaller than the second value during a fourth period, wherein these steps are periodically repeated in a predetermined order.