Spatially Separated Wafer Processing for Faster Uniform ALD
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Solution Overview
Problem
Current atomic layer deposition (ALD) processes face challenges with incompatible chemistries leading to chemical vapor deposition, insufficient energy delivery to vertical ALD film surfaces, and non-uniform plasma exposure, resulting in defects and processing flexibility issues.
Innovation Solution
The development 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 precise control over gas and plasma exposure times.
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 lower throughput
Solution Approach 1:
The patent transitions from time-domain separation (sequential gas flow with purge time) to spatial-domain separation (physically separated processing stations). Multiple reactive gases are introduced simultaneously at different spatial locations (stations 210, 220, 230, 240) around the wafer, eliminating the need for long purge/pump out times while maintaining chemistry separation.
Solution Approach 2:
The processing chamber is divided into multiple spatially separated processing stations (210, 220, 230, 240), each capable of introducing different reactive gases. This segmentation allows simultaneous introduction of incompatible chemistries at different locations without mixing, while the wafer rotates to access each station sequentially during its rotation cycle.
2Use of energy by moving object
If ions are accelerated through a sheath above the wafer surface in a direction normal to the wafer surface, then energy is provided to horizontal ALD film surfaces, but insufficient energy is provided to vertical surfaces
Solution Approach 1:
The patent introduces a bias electrode (204) that creates a localized electric field configuration. The bias voltage applied to electrode 204 modifies the ion acceleration pattern specifically in regions corresponding to vertical film surfaces, providing enhanced ion energy delivery to these areas while maintaining appropriate energy levels for horizontal surfaces.
Solution Approach 2:
The bias electrode (204) acts as an intermediary component between the plasma generation region and the wafer surface. It mediates the ion energy distribution by creating an additional electric field that redirects and accelerates ions toward vertical surfaces, compensating for the insufficient energy delivery from the primary plasma source.
3Productivity
If the wafer is rotating about an offset axis in current spatial ALD processing chambers, then wafers are moved from one processing environment to an adjacent environment, but flow non-uniformities are created across the wafer surface
Solution Approach 1:
The patent deliberately positions the wafer rotation axis (202) at an offset from the wafer center, creating an asymmetric rotation path. This asymmetric rotation, combined with the specific geometric arrangement of processing stations (210, 220, 230, 240) at different radial distances and angular positions, optimizes the flow distribution across the wafer surface while maintaining high spatial processing speed.
Solution Approach 2:
The system allows dynamic adjustment of rotation speed and bias voltage to optimize flow uniformity. By changing operational parameters (rotation velocity, bias voltage magnitude), the system can compensate for flow non-uniformities while maintaining high throughput spatial processing.
4Productivity
If the constant speed rotation is used in current spatial ALD processing chambers, then wafers are continuously processed, but exposure times cannot be adjusted without changing chamber hardware
Solution Approach 1:
The patent implements dynamic control of the wafer rotation system, allowing variable rotation speeds to be applied during different phases of the processing cycle. The controller (208) can adjust rotation velocity in real-time to achieve precise exposure times at each processing station without requiring hardware changes, enabling flexible process optimization.
Solution Approach 2:
The system uses periodic rotation of the wafer to sequentially expose different regions to different processing stations (210, 220, 230, 240). By controlling the rotation period and speed, the system achieves precise temporal control over gas exposure and plasma treatment durations, with each station providing a specific exposure time based on the rotation velocity and station geometry.
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, reduced plasma damage, and enhanced control over processing conditions, resulting in higher quality films with better vertical ALD properties.
Implementation Method 1
heaters having a support surface positioned on the outer end of each of the support arms
Implementation Method 2
Plasma solutions can be used to provide the additional energy in the form of ions and radicals to the ALD film
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.