Electrostatic Chuck Electrode Layout for Etch and Temperature Uniformity
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Solution Overview
Problem
Existing electrostatic chucks in plasma processing apparatuses suffer from non-uniformity issues due to the layout of electrodes, leading to side-to-side etch rate variations and temperature control challenges, which current solutions fail to adequately address.
Innovation Solution
A radial layout of thermally isolated and electrically connected clamping electrodes with a pixelated array of micro-electrodes, each coupled to an RF bias source and a clamping power source, allowing independent control of RF parameters and chucking functionality to enhance uniformity and temperature control across the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrode layout is used in electrostatic chuck, then manufacturing is simpler, but workpiece uniformity deteriorates due to side-to-side etch rate variations
Solution Approach 1:
The electrostatic chuck is divided into multiple independently controllable electrode zones (e.g., first through fourth electrode zones) arranged in a radial pattern. Each zone can be controlled separately to compensate for non-uniformities across the workpiece surface, thereby improving workpiece uniformity while managing complexity through modular zone control
Solution Approach 2:
Different regions of the electrostatic chuck are assigned different electrical properties and control parameters. Specifically, opposite electrode zones are driven with different RF powers to locally compensate for edge effects and non-uniform plasma distribution, achieving improved workpiece uniformity through localized quality adjustment
2Temperature
If conventional heating control is used, then device complexity is lower, but temperature uniformity deteriorates across the workpiece
Solution Approach 1:
The heating system is segmented into multiple independently controllable heating zones corresponding to different electrode zones. Each heating zone can be controlled separately to maintain uniform temperature distribution across the workpiece, compensating for thermal non-uniformities through localized heating adjustment
Solution Approach 2:
Different heating zones are assigned different heating powers to locally compensate for temperature non-uniformities. The thermal control system adjusts heating parameters in specific regions to achieve overall temperature uniformity across the workpiece surface
3Reliability
If simple sealing is used, then device complexity is reduced, but heat exchange gas leakage occurs compromising processing consistency
Solution Approach 1:
A flexible sealing band made of elastomeric material is used to seal between the electrostatic chuck and the baseplate. The flexible nature of the sealing band allows it to conform to surface irregularities and maintain reliable sealing, preventing heat exchange gas leakage while accommodating thermal expansion and contraction
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 provides precise control over individual surface areas, improving workpiece uniformity and temperature distribution, while a robust sealing band prevents heat exchange gas leakage, ensuring consistent processing conditions.
Implementation Method 1
The plurality of micro-electrodes are configured to act as clamping electrodes for the workpiece when a voltage is applied across the plurality of micro-electrodes
Implementation Method 2
each of the plurality of micro-electrodes is coupled to at least one RF bias source. The controller is configured to control the at least one RF bias source to independently adjust one or more RF parameters of RF bias power
Implementation Method 3
The flow channels are interconnected to one or more inlet apertures configured to receive the thermal exchange gas. The thermal control system is configured to circulate the thermal exchange gas through the flow channels
Data Source
AI summary
An electrostatic chuck including a workpiece support surface, clamping layer, heating layer, thermal control system, and sealing band is disclosed. The sealing band surrounds an outer perimeter of the electrostatic chuck including at least a portion of the workpiece surface. The sealing band has a width greater than about 3 millimeters (mm) up to about 10 mm. Plasma processing apparatuses and systems incorporating the electrostatic chuck are also provided.