Heated Filter Assembly Thermal Bridge for Substrate Processing
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Solution Overview
Problem
Heated filters in substrate processing systems face challenges such as large heating time lags, thermal decomposition of precursors, clogging due to unvaporized droplets, and incomplete purging of atmospheric moisture, leading to temperature instability and wafer defects.
Innovation Solution
A heated filter assembly with a direct heat transfer element that connects the filter element to both the heater and temperature monitoring system, providing a short and direct heating path, and a secondary heat transfer element on the housing for precise temperature control, ensuring uniform heating and preventing clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If an external heater jacket is used to heat the filter element, then the filter can be heated, but the heating time lag is large and temperature control is unstable
Solution Approach 1:
A heat transfer element is introduced as an intermediary component between the heater and the filter element. This heat transfer element directly contacts both the heater and the filter element, creating an efficient thermal bridge that eliminates the long heating time lag associated with external heater jackets while maintaining stable temperature control.
2Reliability
If the filter element is heated to vaporize droplets, then clogging is prevented, but thermal decomposition of precursors may occur
Solution Approach 1:
A temperature sensor is positioned to directly monitor the temperature of the filter element and provide feedback to the control system. This feedback mechanism enables precise temperature control, ensuring the filter maintains sufficient heat to vaporize droplets and prevent clogging while avoiding temperatures that would cause precursor decomposition.
3Reliability
If the filter housing is purged for 48 hours with inert gas, then atmospheric moisture is removed, but the process is time-consuming
Solution Approach 1:
The filter element is pre-heated to elevated temperatures before precursor introduction to actively remove atmospheric moisture through thermal desorption. This preliminary heating action significantly reduces the purging time from 48 hours to a much shorter duration while maintaining effective moisture removal, as the thermal energy accelerates the evaporation and removal of water molecules from the filter pores.
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 achieves stable and uniform temperature control, reducing wafer defects, shortening purging and maintenance times, and preventing precursor decomposition and condensation, while maintaining the filter at the desired operating temperature.
Implementation Method 1
heat travels through the filter housing to the center of the filter via convection or conduction
Implementation Method 2
An external heater jacket may be arranged around the filter housing to heat the filter element
Implementation Method 3
Vaporized liquids, in particular, are almost always incompletely vaporized, and the resultant vapor contains liquid droplets of varying sizes
Data Source
AI summary
A heated filter assembly for heating gas supplied to a substrate processing system includes a housing defining a cavity, an inner surface and an outer surface. A filter element is arranged inside the cavity of the housing with an outer surface thereof in a spaced relationship relative to the inner surface of the housing. A heat transfer element is arranged inside of the filter element and includes an outer surface and an inner cavity. A plurality of projections is arranged on the outer surface of the heat transfer element in direct physical contact with an inner surface of the filter element. A plurality of portions is arranged on the outer surface of the heat transfer element, is spaced from the inner surface of the filter element and is located between the plurality of projections.