Electrostatic Chuck Mesa Configuration for Temperature Uniformity
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Solution Overview
Problem
Electrostatic chucks in semiconductor processing face challenges in achieving uniform temperature and capacitance control, leading to process variations and errors in wafer etching due to natural variations in manufacturing and component deviations.
Innovation Solution
The method involves modifying the heat transfer coefficient and capacitance profiles of electrostatic chucks by adjusting the areal density and height of the mesa configuration on the insulating layer using heat flux and capacitance probes, followed by mechanical corrections through techniques like laser machining or grit blast machining to achieve target profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard mesa configuration is used in electrostatic chuck, then the chuck can operate in vacuum chambers and provide electrostatic clamping, but variations in clamping and natural manufacturing variations cause undesirable process variations and non-uniform temperature/capacitance distribution
Solution Approach 1:
The patent applies local quality by varying the mesa areal density across different regions of the electrostatic chuck. Instead of using a uniform mesa configuration, the invention creates non-uniform mesa distributions where the areal density is specifically adjusted in different zones to compensate for expected temperature and capacitance variations, thereby achieving improved temperature uniformity and capacitance distribution across the wafer surface.
2Ease of manufacture
If uniform mesa distribution is used, then manufacturing is simpler, but temperature and capacitance uniformity across the wafer surface deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the mesa areal density parameter across different regions of the chuck. The invention transitions from a uniform mesa distribution to a non-uniform distribution where the areal density parameter is specifically adjusted in different zones based on measured temperature and capacitance profiles, thereby achieving improved thermal and electrical uniformity while maintaining manufacturing feasibility through systematic modification.
3Ease of operation
If traditional electrostatic chuck design is used, then basic clamping function is achieved, but process variations occur due to component deviations and manufacturing variations
Solution Approach 1:
The patent applies feedback by using measured temperature and capacitance profiles from the chuck surface to determine target mesa areal density distributions. The process involves measuring the actual temperature and capacitance variations, calculating the required mesa areal density adjustments, and then modifying the mesa configuration accordingly. This closed-loop feedback approach compensates for manufacturing variations and achieves improved process repeatability and wafer-to-wafer uniformity.
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 approach enables improved temperature uniformity and capacitance control across the wafer surface, reducing process variations and enhancing the accuracy and repeatability of semiconductor processing, particularly in critical etch applications.
Implementation Method 1
The heat conduction at a given site can be measured by use of a heat flux probe
Implementation Method 2
A target mesa height can be determined by use of a capacitance probe
Implementation Method 3
the electrostatic chuck, is used to retain a semiconductor wafer or other workpiece in a stationary position during processing
Data Source
AI summary
A method of modifying the heat transfer coefficient profile of an electrostatic chuck by configuring the areal density of a mesa configuration of an insulating layer of the chuck is provided. A method of modifying the capacitance profile of an electrostatic chuck by adjustment or initial fabrication of the height of a mesa configuration of an insulating layer of the chuck is further provided. The heat transfer coefficient at a given site can be measured by use of a heat flux probe, whereas the capacitance at a given site can be measured by use of a capacitance probe. The probes are placed on the insulating surface of the chuck and may include a plurality of mesas in a single measurement. A plurality of measurements made across the chuck provide a heat transfer coefficient profile or a capacitance profile, from which a target mesa areal density and a target mesa height are determined. The target density and height are achieved mechanically; the target density by mechanically adjusting the areal density of existing mesas; and the target height by creating or deepening low areas surrounding planned or existing mesas, respectively. This can be accomplished using any of known techniques for controlled material removal such as laser machining or grit blast machining on an X-Y table.