Distributed Electrostatic Chuck Cooling for Plasma Processing
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Solution Overview
Problem
Existing cooling methods for pedestals in plasma processing equipment are insufficient in achieving uniform temperature control, leading to thermal non-uniformities on workpieces, which can affect on-wafer performance due to increased power densities in microelectronics manufacturing.
Innovation Solution
A cooling base assembly that utilizes a plurality of jets or sprays of a cooling fluid to impinge nonparallelly on the surface of the pedestal, enhancing heat transfer through the placement, diameter, and pattern of nozzles, and the use of multiple fluid loops for efficient heat removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fluid is circulated through a channel at the bottom of the electrostatic chuck, then cooling is provided to the workpiece, but thermal non-uniformities occur on the workpiece surface
Solution Approach 1:
The cooling system is segmented into multiple independent cooling channels arranged in a specific pattern, allowing different regions of the chuck to be cooled independently. This segmentation enables precise control of temperature distribution across the workpiece surface, eliminating thermal non-uniformities while maintaining overall temperature control.
Solution Approach 2:
The cooling channels are positioned and dimensioned to provide non-uniform cooling distribution matched to the thermal load profile of the workpiece. By varying channel spacing, diameter, and depth according to local heat generation patterns, the system achieves uniform temperature distribution across the workpiece surface, directly improving on-wafer performance.
2Power
If power density is increased in plasma processing equipment, then processing capability is enhanced, but cooling requirements increase making temperature control more difficult
Solution Approach 1:
The cooling channels are positioned at multiple depths below the chuck surface, creating a three-dimensional cooling architecture. This vertical dimensionality allows heat to be extracted from different depths where thermal loads vary, enabling effective temperature control even at high power densities of 5-10 kilowatts for 300 mm substrates.
Solution Approach 2:
The system uses fluid circulation through precisely engineered channels to provide efficient heat removal. The hydraulic design of the cooling channels, including their spacing, diameter, and routing patterns, is optimized to handle the thermal loads generated at high power densities, maintaining uniform temperature control despite increased processing power.
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 solution achieves uniform cooling across the pedestal and workpiece, enabling substantial heat transfer rates of 10,000 watts or more, thereby improving temperature control and on-wafer performance.
Implementation Method 1
circulate fluid through a channel at the bottom of an electrostatic chuck so that the fluid flows through the channel
Implementation Method 2
an electrostatic chuck to which a workpiece is held
Data Source
AI summary
Embodiments of the invention include an apparatus, system, and method for cooling a pedestal for supporting a workpiece during plasma processing. An embodiment of a pedestal includes: a base over which the workpiece is to be disposed, a plurality of nozzles to supply a fluid from a supply plenum to impinge on a surface of the base, and a plurality of return conduits to return the supplied fluid to a return plenum. The fluid to be supplied by the plurality of nozzles can be projected as one or more jets submerged in surrounding fluid or as a spray that emerges from a surrounding fluid within a volume between the plurality of nozzles and the base to impinge on the surface of the base.