Low Volume Showerhead Faceplate Holes for Flow Uniformity
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Solution Overview
Problem
Showerheads in semiconductor processing tools face challenges in achieving uniform gas distribution across semiconductor substrates, leading to non-uniform film deposition and compromised throughput due to the trade-off between film uniformity and volume constraints.
Innovation Solution
A low volume showerhead design featuring a porous baffle and small diameter faceplate through-holes, which reduces backstreaming and enhances spatial uniformity of gas flow, combined with edge through-holes for improved flow distribution at the substrate edges, to maintain film uniformity while increasing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If small diameter faceplate through-holes are used, then spatial uniformity of gas flow is improved, but gas flow rate is reduced
Solution Approach 1:
The faceplate is segmented into multiple small diameter through-holes (less than 0.04 inches) distributed across the surface. This segmentation creates numerous small flow paths that collectively provide both uniform spatial distribution and adequate total gas flow rate, resolving the contradiction between uniformity and flow quantity.
Solution Approach 2:
The through-holes are strategically positioned with different densities in different regions of the faceplate. Edge through-holes are added at the periphery to enhance flow uniformity at substrate edges, while central regions have different hole distributions. This local variation in hole quality and density optimizes both uniformity and flow rate in different zones.
2Productivity
If plenum volume is reduced, then throughput is improved, but film uniformity deteriorates
Solution Approach 1:
The reduced plenum volume is compensated by segmenting the gas distribution into numerous small through-holes in the faceplate. This segmentation allows the small plenum to effectively distribute gas uniformly across the substrate, maintaining film uniformity while enabling reduced plenum volume for higher throughput.
Solution Approach 2:
The through-hole diameter parameter is changed to less than 0.04 inches (specifically 0.01-0.03 inches in some implementations), and the hole count is increased. This parameter change allows the system to achieve uniform gas distribution with a smaller plenum volume, thus improving throughput without sacrificing film uniformity.
3Manufacturing precision
If baffle porosity is increased, then gas flow distribution is improved, but plasma backstreaming increases
Solution Approach 1:
The baffle is designed with non-uniform porosity distribution, with different porosity levels in different regions. The porosity is optimized to provide adequate gas flow distribution while maintaining sufficient plasma barrier function, resolving the contradiction between flow distribution and backstreaming prevention.
Solution Approach 2:
The baffle porosity parameter is optimized to be between 5% and 25%. This parameter range provides the optimal balance between allowing sufficient gas flow distribution through the baffle and maintaining enough plasma barrier function to prevent excessive backstreaming into the plenum.
4Manufacturing precision
If faceplate through-hole diameter is decreased, then spatial uniformity is improved, but plasma backstreaming is reduced
Solution Approach 1:
The through-hole diameter is changed to less than 0.04 inches (0.01-0.03 inches in some implementations), which simultaneously improves spatial uniformity of gas flow and reduces plasma backstreaming. The small diameter creates sufficient resistance to plasma backstreaming while maintaining adequate gas flow through the increased number of holes.
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 film non-uniformity of less than 0.5% and maintains high throughput by ensuring uniform gas distribution and reducing plasma backstreaming, thereby decoupling film uniformity from process parameters.
Implementation Method 1
The plurality of faceplate through-holes extend from a first side to a second side of the faceplate, where the first side of the faceplate defines the first surface of the plenum volume, and where each of the faceplate through-holes has a diameter of less than about 0.04 inches
Implementation Method 2
a baffle positioned proximate to the one or more gas inlets... reduce backstreaming of plasma coming into the plenum volume from outside the faceplate
Implementation Method 3
introducing reactant gas into the semiconductor processing station through the showerhead to adsorb onto the surface of the substrate
Implementation Method 4
applying a plasma to form a thin film layer from the adsorbed reactant gas on the surface of the substrate
Data Source
AI summary
A showerhead in a semiconductor processing apparatus can include faceplate through-holes configured to improve the flow uniformity during atomic layer deposition. The showerhead can include a faceplate having a plurality of through-holes for distributing gas onto a substrate, where the faceplate includes small diameter through-holes. For example, the diameter of each of the through-holes can be less than about 0.04 inches. In addition or in the alternative, the showerhead can include edge through-holes positioned circumferentially along a ring having a diameter greater than a diameter of the substrate being processed. The showerhead can be a low volume showerhead and can include a baffle proximate one or more gas inlets in communication with a plenum volume of the showerhead. The faceplate with small diameter through-holes and/or edge through-holes can improve overall film non-uniformity, improve azimuthal film non-uniformity at the edge of the substrate, and enable operation at higher RF powers.