Showerhead Vacuum Channel Geometry for ALD Precursor Containment
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Solution Overview
Problem
In Atomic Layer Deposition (ALD) chambers, deposition occurs on chamber parts other than the processed wafers, leading to defects, process drifts, and increased machine downtime due to the accumulation of unwanted films, especially on electrostatic chucks and process kits, which are difficult to clean and replace.
Innovation Solution
The implementation of gas distribution plates with staggered vacuum channels and localized pumping near the wafer edge, combined with a replaceable edge ring and backside purge, to minimize deposition on chamber surfaces by spatially isolating reactive precursors and creating an aerodynamic boundary to reduce film deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional showerhead pumping geometry is used, then wafer processing is maintained, but deposition accumulates on chamber parts including the electrostatic chuck and process kit
Solution Approach 1:
The pumping geometry is segmented into multiple zones with different pumping capacities. The showerhead incorporates both central pumping channels and peripheral pumping channels with different diameters and flow rates, allowing selective removal of precursors from different regions of the chamber to minimize deposition on chamber parts while maintaining wafer processing
Solution Approach 2:
Different regions of the showerhead are designed with different pumping characteristics. The peripheral regions have enhanced pumping capacity compared to the central region, creating localized precursor removal zones that prevent deposition on the electrostatic chuck and process kit while maintaining appropriate precursor exposure for wafer processing
2Reliability
If the process kit is cleaned ex-situ by removal, then deposition is removed, but machine downtime increases
Solution Approach 1:
The system provides self-cleaning functionality through the enhanced peripheral pumping geometry that continuously removes precursors during the deposition process itself. The electrostatic chuck and process kit are protected from deposition accumulation through the aerodynamic boundary and selective precursor removal, eliminating the need for periodic removal and ex-situ cleaning operations
3Manufacturing precision
If precursors are allowed to reach chamber surfaces, then deposition occurs on substrates, but unwanted deposition occurs on chamber parts
Solution Approach 1:
The showerhead design creates different precursor concentration zones: the central region allows precursor exposure for substrate deposition, while the peripheral regions have enhanced pumping that creates a precursor-depleted zone protecting chamber surfaces. This spatial differentiation of precursor distribution achieves selective deposition control
Solution Approach 2:
The enhanced peripheral pumping acts as an intermediary mechanism that selectively removes precursors before they can reach chamber surfaces. This intermediate precursor removal layer protects the electrostatic chuck and process kit while allowing controlled deposition on the substrate
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 reduces deposition on chamber parts outside the wafer boundary, minimizing film thickness non-uniformity and machine downtime by containing precursors effectively, thus improving processing efficiency and reducing operating costs.
Implementation Method 1
create an aerodynamic boundary to reduce film deposition
Implementation Method 2
deposition at the edge of electrostatic chucks can be limited to not extend beyond the pumping channels due to a backside purge flow in the chamber
Data Source
AI summary
Gas injector with a vacuum channel having an inlet opening in the front face and an outlet opening in the back face of the injector are described. The vacuum channel comprises a first leg extending a first length from the inlet opening in the front face at a first angle relative to the front face and a second leg extending a second length from the first leg to the outlet opening in the back face at a second angle relative to the front face. Processing chambers and methods of use comprising a plurality of processing regions bounded around an outer peripheral edge by one or more vacuum channel. A first processing region has a first vacuum channel with a first outer diameter and a second processing region has a second vacuum channel with a second outer diameter, the first outer diameter being less than the second outer diameter.