Vacuum Chamber Evacuation Method Preventing Moisture Freezing
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Solution Overview
Problem
In vacuum processing apparatuses, the etching process is delayed due to moisture freezing inside the vacuum chamber during evacuation, leading to prolonged evacuation times and potential component failures.
Innovation Solution
An evacuation method that alternates between evacuating the vacuum chamber and increasing pressure to maintain a pressure between 6.7 Pa and 13.3×10^2 Pa, preventing moisture from freezing and ensuring efficient evacuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If continuous evacuation is performed to reduce pressure quickly, then evacuation speed is improved, but moisture freezes on chamber surfaces extending evacuation time
Solution Approach 1:
The patent applies periodic action by alternating between evacuation phases and pressure increase phases. During evacuation, the pressure is reduced to remove moisture. When moisture begins to freeze (detected by temperature sensors or pressure stabilization), the system temporarily increases pressure to allow ice to melt and evaporate. This periodic cycling continues until all moisture is removed, achieving both fast evacuation and complete moisture removal without prolonged freezing conditions.
Solution Approach 2:
The system dynamically changes pressure and temperature parameters during the evacuation process. By monitoring chamber conditions and adjusting pressure levels in real-time, the system prevents moisture from entering the freezing state. When freezing is detected or anticipated, the pressure parameter is modified to raise the sublimation point, preventing ice formation and the associated time delays.
2Productivity
If pressure is reduced rapidly to shorten evacuation time, then productivity is improved, but moisture freezing causes component damage and process delays
Solution Approach 1:
The patent implements feedback control by using sensors to monitor temperature, pressure, and moisture levels in the vacuum chamber. When the system detects conditions approaching the freezing point of moisture (through temperature sensors or pressure stabilization indicating ice formation), it automatically adjusts the evacuation rate or temporarily increases pressure. This closed-loop feedback prevents component damage from frozen moisture while maintaining efficient evacuation overall.
Solution Approach 2:
The system applies beforehand cushioning by preemptively slowing the evacuation rate or increasing pressure when sensors indicate approaching freezing conditions, even before actual ice formation occurs. This preventive approach protects components from thermal stress and moisture-related damage while still achieving rapid evacuation when conditions permit.
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 method accelerates the evacuation process by preventing moisture from freezing, reducing the time required to reach the desired pressure and minimizing the risk of component damage.
Implementation Method 1
a vacuum processing chamber is evacuated by an exhaust device for a first predetermined period of time by opening a valve connecting the exhaust device with the vacuum processing chamber
Implementation Method 2
when the pressure inside the vacuum chamber is reduced, moisture having attached to wall surfaces and surfaces of component parts that are exposed to the atmosphere during the maintenance, starts evaporating
Implementation Method 3
when the pressure inside the vacuum chamber continues to be reduced, the temperature of moisture decreases by adiabatic expansion eventually to a temperature lower than zero degrees C.
Implementation Method 4
the temperature of moisture decreases by adiabatic expansion eventually to a temperature lower than zero degrees C., and sometimes to a temperature between about −15 degrees C. to about −30 degrees C. At this time, moisture inside the vacuum chamber not having evaporated may freeze
Data Source
AI summary
An evacuation method used for a vacuum processing apparatus including a vacuum processing chamber is provided. The vacuum processing chamber is evacuated by an exhaust device for a first predetermined period of time by opening a valve connecting the exhaust device with the vacuum processing chamber. A pressure in the vacuum processing chamber is urged to increase by closing the valve and leaving the valve closed for a second predetermined period of time after evacuating the vacuum processing chamber. Evacuating the vacuum processing chamber and urging the pressure in the vacuum processing chamber to increase are performed so as to reduce the pressure in the vacuum processing chamber to a pressure between 6.7 Pa and 13.3×102 Pa (between 5 Torr and 10 Torr) without freezing moisture in the vacuum processing chamber.