Spatially Separated Wafer Processing for Uniform Plasma ALD
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Solution Overview
Problem
Current atomic layer deposition (ALD) processes face challenges with incompatible chemistries leading to chemical vapor deposition, non-uniform plasma exposure, and difficulty in adjusting processing times, resulting in defects and reduced throughput in semiconductor film deposition, especially for vertical surfaces.
Innovation Solution
The implementation of a processing chamber with spatially separated processing stations and a rotatable support assembly featuring heaters and gas injectors, allowing for independent thermal dosing and plasma treatment environments, optimized plasma exposure, and adjustable processing times through a circular arrangement of stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single reactive gas is flowed into the processing chamber at a time in a traditional time-domain ALD process, then the chemistries are not mixed in the gas phase, but a long purge/pump out time occurs resulting in reduced throughput
Solution Approach 1:
The patent transitions from time-domain separation to spatial separation by arranging processing stations in a circular configuration around a rotatable wafer support. Multiple incompatible chemistries are separated in space rather than time, allowing simultaneous presence of multiple gases without mixing, thereby eliminating long purge times and improving throughput.
Solution Approach 2:
The processing chamber is segmented into multiple discrete processing stations (thermal dosing station, plasma treatment station, etc.) arranged circularly around the wafer support. Each station handles a specific chemistry or process step, allowing independent optimization and eliminating the need for complete chamber purging between steps.
2Power
If a CCP parallel plate plasma is used to provide high ion energies, then plasma treatment is effective, but vertical side wall surfaces receive insufficient energy because ions move parallel to the vertical surfaces
Solution Approach 1:
The patent implements different plasma treatment modes for different regions of the wafer. The plasma showerhead is positioned to provide optimized plasma exposure for vertical side walls, while the wafer rotation and plasma source configuration ensure appropriate energy delivery to both vertical and horizontal surfaces, addressing the local quality requirements of different surface orientations.
3Productivity
If the wafer rotates at constant speed in current spatial ALD chambers, then wafers move through processing environments, but non-uniform plasma exposure and plasma damage occur due to different flow streamlines at leading/trailing edges
Solution Approach 1:
The patent makes the wafer rotation speed variable rather than constant. The rotation speed can be dynamically adjusted based on the specific process requirements, allowing optimization of plasma exposure time and flow uniformity across the wafer surface, thereby reducing plasma damage and improving film uniformity while maintaining high productivity.
4Duration of action of moving object
If the plasma environment is made larger to accommodate longer exposure times in constant velocity rotation, then exposure time is increased, but hardware changes are needed for different process requirements
Solution Approach 1:
The patent enables adjustment of plasma exposure time by changing operational parameters (rotation speed, plasma source power, gas flow rates) rather than requiring hardware modifications. The variable rotation speed allows flexible control of exposure duration, and the plasma source parameters can be adjusted to match different process requirements without changing chamber hardware.
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 enables higher throughput, improved uniformity of film deposition on both horizontal and vertical surfaces, reduces plasma damage, and enhances the quality of films deposited at lower temperatures by ensuring precise control over gas and plasma exposure.
Implementation Method 1
heaters and gas injectors, allowing for independent thermal dosing and plasma treatment environments
Implementation Method 2
Plasma solutions can be used to provide the additional energy in the form of ions and radicals to the ALD film
Implementation Method 3
a processing chamber with spatially separated processing stations and a rotatable support assembly
Data Source
AI summary
Apparatus and methods to process one or more wafers are described. A plurality of process stations are arranged in a circular configuration around a rotational axis. A support assembly with a rotatable center base defining a rotational axis, at least two support arms extending from the center base and heaters on each of the support arms is positioned adjacent the processing stations so that the heaters can be moved amongst the various process stations to perform one or more process condition.