Showerhead Gas Injection Insert for Deposition Uniformity
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Solution Overview
Problem
Current showerhead designs for radical oxygen deposition on semiconductor substrates result in poor processing uniformity due to high gas velocity, leading to inadequate heating and rapid recombination of oxygen radicals, causing greater deposition at the center and less at the edges of the substrate.
Innovation Solution
A showerhead assembly with a reflector plate and gas injection insert featuring baffle plates with non-axially aligned apertures, creating separate plenums and tortuous flow paths to reduce gas velocity and promote uniform gas distribution across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas is injected at high velocity through current showerhead design, then gas reaches substrate quickly for rapid deposition, but deposition uniformity deteriorates with greater deposition at center and less at edges
Solution Approach 1:
The gas injection system is segmented into multiple zones with different aperture configurations. The reflector plate contains multiple gas injection ports arranged in different patterns, allowing different regions of the substrate to receive gas at optimized velocities. This segmentation enables the center and edges to have different flow characteristics, achieving uniform deposition while maintaining high productivity.
Solution Approach 2:
Different regions of the showerhead are designed with locally optimized aperture sizes and distributions. The gas injection ports have varying aperture dimensions tailored to specific radial positions, creating local flow quality adjustments. This ensures that gas velocity is appropriately controlled at each location to achieve uniform deposition across the entire substrate surface.
2Productivity
If gas velocity is high, then deposition occurs rapidly, but oxygen radicals recombine quickly reducing their effective life cycle
Solution Approach 1:
The showerhead design incorporates preliminary gas distribution through multiple plenums that pre-condition the gas flow before it reaches the substrate. Gas is distributed through intermediate chambers that allow for velocity reduction and radial expansion prior to substrate contact. This preliminary action extends the effective life cycle of oxygen radicals by reducing their velocity and preventing premature recombination.
Solution Approach 2:
Multiple plenums and gas distribution chambers act as intermediary structures between the gas source and the substrate. These intermediaries modify the gas flow characteristics, reducing velocity and extending the path length. This allows oxygen radicals to maintain their reactive state longer by preventing rapid impingement and recombination on the substrate surface.
3Productivity
If gas velocity is high, then deposition occurs quickly, but gas is not adequately heated resulting in poor processing uniformity
Solution Approach 1:
The gas flow is pre-heated in multiple plenums before reaching the substrate. The intermediate chambers provide sufficient residence time and surface area for thermal conditioning of the gas. This preliminary heating action ensures that gas reaches the substrate at the appropriate temperature for uniform deposition, even while maintaining high deposition rates through optimized aperture distributions.
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
The solution achieves significant reduction in gas velocity and enhances deposition uniformity across the substrate, extending the life cycle of oxygen radicals and improving processing control, with experimental results showing a 98% reduction in gas velocity and improved deposition uniformity.
Implementation Method 1
baffle plates with non-axially aligned apertures, creating separate plenums and tortuous flow paths to reduce gas velocity
Implementation Method 2
reflector plate with a gas injection insert for radially distributing gas
Implementation Method 3
A first plenum is formed between a first portion of the baffle plate and the reflector plate. A second plenum is formed between a second portion of the baffle plate and the reflector plate.
Data Source
AI summary
Embodiments described herein relate to a showerhead having a reflector plate with a gas injection insert for radially distributing gas. In one embodiment, a showerhead assembly includes a reflector plate and a gas injection insert. The reflector plate includes at least one gas injection port. The gas injection insert is disposed in the reflector plate, and includes a plurality of apertures. The gas injection insert also includes a baffle plate disposed in the gas injection insert, wherein the baffle plate also includes a plurality of apertures. A first plenum is formed between a first portion of the baffle plate and the reflector plate, and a second plenum is formed between a second portion of the baffle plate and the reflector plate. The plurality of apertures of the gas injection insert and the plurality of apertures of the baffle plate are not axially aligned.