Exhaust Lid Structure for Precise Plasma Chamber Pressure Control
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in accurately controlling pressure in a processing chamber, particularly at high pressures, due to difficulties in adjusting the conductance of the exhaust gas at extremely low opening degrees, which leads to variations in pressure control.
Innovation Solution
The apparatus includes an exhaust portion lid with a protruding portion that can be moved to adjust the conductance of the exhaust gas by changing the distance between the lid and the exhaust opening, allowing for precise control of pressure in the processing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gate valve is used to adjust the exhaust gas flow, then the exhaust amount can be controlled, but at extremely low opening degrees the adjustment accuracy deteriorates and conductance control becomes coarse
Solution Approach 1:
The invention extracts the flow control function from the traditional gate valve mechanism and relocates it to a movable plate that can be precisely positioned. The movable plate with opening selectively blocks the exhaust gas passage, separating the sealing function (O-ring) from the flow control function, enabling independent optimization of both.
Solution Approach 2:
The invention replaces the mechanical gate valve system with a movable plate system driven by a linear actuator. This substitution enables more precise control at low opening degrees through controlled movement rather than rotational adjustment, improving pressure control accuracy in the high pressure region.
2Reliability
If the O-ring protrusion from the groove is increased to improve sealing, then sealing performance improves, but conductance varies due to machine differences and compression amount variations
Solution Approach 1:
The invention segments the sealing and flow control functions into separate components: the O-ring handles sealing while the movable plate with opening handles flow control. This segmentation eliminates the coupling between sealing requirements and conductance control, allowing each to be optimized independently without mutual interference.
Solution Approach 2:
The movable plate acts as an intermediary between the sealed chamber and the exhaust pump. It provides a controlled interface for exhaust gas flow while the O-ring provides sealing, mediating between the two functions and eliminating the need for the O-ring to simultaneously provide both sealing and flow control.
3Adaptability or versatility
If the exhaust portion lid is moved to extremely low opening degrees for high pressure control, then pressure control range extends to high pressure region, but conductance becomes highly sensitive to O-ring protrusion and compression variations
Solution Approach 1:
The invention extracts the flow control function from the O-ring and relocates it to the movable plate with opening. This allows the system to operate at extremely low opening degrees for high pressure control without the conductance being sensitive to O-ring protrusion and compression variations, as these variations no longer directly affect the flow path.
Data Source
AI summary
A plasma processing apparatus for finely adjusting conductance of exhaust gas and controlling pressure in a processing chamber with high accuracy, including a processing chamber; a base plate formed with an exhaust opening; an exhaust portion lid disposed in the processing chamber so as to face the exhaust opening; an exhaust device configured to exhaust a gas in the processing chamber via the exhaust opening; and an actuator configured to drive the exhaust portion lid. An axis of the exhaust opening coincides with a central axis of the processing chamber. The exhaust portion lid includes a circular plate portion and a protruding portion protruding from the circular plate portion toward the exhaust opening. The exhaust portion lid is driven by the actuator to be movable to various positions with respect to the exhaust opening and the base plate.