Spatial ALD Wafer Rotation for Uniform Plasma Deposition
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Solution Overview
Problem
Current atomic layer deposition (ALD) processes face challenges with incompatible chemistries mixing, leading to chemical vapor deposition (CVD) processes, non-uniform plasma exposure, and plasma damage, resulting in defects and non-uniform film deposition due to rotational motion and fixed processing stations.
Innovation Solution
A processing chamber with spatially separated isolated processing stations and a substrate support assembly that rotates wafers through multiple stations to optimize plasma exposure and thermal conditions, allowing independent control of each station for uniform film deposition.
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 prevented from mixing, but a long purge/pump out time occurs resulting in low throughput
Solution Approach 1:
The processing chamber is divided into multiple spatially separated isolated processing stations, each capable of holding different reactive gases. The wafer is physically moved between these stations, allowing simultaneous presence of incompatible chemistries in different spatial locations without mixing, thereby eliminating the need for long purge times while maintaining chemistry separation.
Solution Approach 2:
The patent transitions from a time-domain approach (sequential gas flow with purging) to a spatial approach (multiple isolated stations arranged in space). By adding the spatial dimension with multiple isolated processing stations, the system achieves both chemistry separation and high throughput simultaneously.
2Use of energy by moving object
If a capacitively coupled plasma (CCP) is created between a top electrode and the wafer, then high ion energies are generated, but the ions provide insufficient energy to vertical surfaces because they move parallel to the vertical surfaces
Solution Approach 1:
The patent implements different plasma environments at different spatial locations: a first plasma environment optimized for horizontal surfaces and a second plasma environment optimized for vertical surfaces. This local quality approach allows each surface orientation to receive plasma treatment with the appropriate ion energy and angular distribution characteristics.
Solution Approach 2:
The system changes plasma parameters (ion energy, angular distribution, flux density) by moving the wafer between different plasma environments. The first plasma environment provides high ion energies for horizontal surfaces, while the second plasma environment provides lower energies with wider angular distribution for vertical surfaces.
3Productivity
If the substrate support assembly rotates at constant speed through spatially separated processing stations, then throughput is improved, but leading edge and trailing edge non-uniformities occur due to different flow streamlines
Solution Approach 1:
The substrate support assembly rotates back and forth periodically between the first and second processing stations, exposing each wafer surface to both processing environments in a repeating cycle. This periodic action ensures that all areas of the wafer receive equivalent cumulative exposure to both plasma environments, eliminating leading/trailing edge non-uniformities.
Solution Approach 2:
The system uses asymmetric processing by exposing different surfaces of the wafer to different plasma environments during rotation. The front surface receives treatment from the first plasma environment while the back surface receives treatment from the second plasma environment, and vice versa during the return rotation, achieving overall uniformity through asymmetric local treatment.
4Adaptability or versatility
If the wafer is rotated about an offset axis in current spatial ALD processing chambers, then processing flexibility is achieved, but non-uniform plasma exposure and plasma damage occur
Solution Approach 1:
The wafer rotates continuously through the plasma environments, ensuring continuous and uniform exposure of all wafer surfaces to the optimized plasma treatment. This continuous rotation eliminates stagnant zones and ensures consistent plasma exposure across the entire wafer surface, reducing plasma damage while maintaining processing flexibility.
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
Enhances film uniformity and throughput by optimizing plasma exposure and thermal conditions, reducing plasma damage and leading/trailing edge differences, achieving higher quality films at lower temperatures.
Implementation Method 1
rotating a substrate support assembly having a plurality of substrate support surfaces aligned with the x number of spatially separated isolated processing stations
Implementation Method 2
the processing chamber having a processing chamber temperature and each processing station independently having a processing station temperature
Implementation Method 3
Plasma solutions can be used to provide the additional energy in the form of ions and radicals to the ALD film
Implementation Method 4
Such plasma sources include microwave, inductively coupled plasma (ICP), or higher frequency CCP solutions
Implementation Method 5
Current atomic layer deposition (ALD) processes have a number of potential issues and difficulties
Implementation Method 6
If the incompatible chemistries mix, a chemical vapor deposition (CVD) process, instead of the ALD process could occur
Data Source
AI summary
Apparatus and methods to process one or more wafers are described. A spatial deposition tool comprises a plurality of substrate support surfaces on a substrate support assembly and a plurality of spatially separated and isolated processing stations. The spatially separated isolated processing stations have independently controlled temperature, processing gas types, and gas flows. In some embodiments, the processing gases on one or multiple processing stations are activated using plasma sources. The operation of the spatial tool comprises rotating the substrate assembly in a first direction, and rotating the substrate assembly in a second direction, and repeating the rotations in the first direction and the second direction until a predetermined thickness is deposited on the substrate surface(s).