Semiconductor Reactor Diffuser for Uniform Gas Residence Time
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Solution Overview
Problem
In semiconductor processing, the existing gas delivery systems for atomic layer deposition (ALD) result in non-uniform film deposition across substrates due to varying residence times of process gases, leading to differences in deposition thickness from the center to the edges of the substrate.
Innovation Solution
A gas delivery system with a diffuser attached to the reaction chamber, featuring a distribution portion with specific surface orientations and texturing, ensures a uniform residence time distribution of process gases across the substrate, optimizing gas flow velocity and distribution to achieve consistent deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If process gases are introduced through a slot with constant flow velocity across the width, then the gas delivery system is simple, but the residence time varies across the substrate width causing non-uniform deposition
Solution Approach 1:
The slot geometry is modified to create different flow characteristics at different locations across the slot width. The slot has a first width at the leading edge and a second width at the trailing edge, creating varying flow velocities that compensate for the different distances gases must travel to reach various parts of the substrate, achieving uniform residence time and deposition uniformity.
Solution Approach 2:
The slot dimensions are specifically designed with varying width along its length, changing the geometric parameters to control gas flow velocity distribution. This parameter change in slot geometry directly addresses the residence time variation problem without requiring complex additional components.
2Manufacturing precision
If the slot width is reduced to increase gas velocity, then residence time uniformity improves, but the total gas flow capacity decreases
Solution Approach 1:
The slot width is varied locally along its length, being narrower where gases need to travel farther and wider where gases travel shorter distances. This local variation optimizes both residence time uniformity and maintains adequate overall gas flow capacity to 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
The solution ensures a uniform film deposition across the entire substrate by maintaining consistent gas flow velocities and residence times, reducing edge-to-center deposition thickness variations and enhancing processing uniformity.
Implementation Method 1
A diffuser is in fluid communication with the reaction chamber. A diffuser volume for distributing the process gas is defined between the diffuser and the upper surface of the reaction chamber.
Data Source
AI summary
A reactor having a housing that encloses a gas delivery system operatively connected to a reaction chamber and an exhaust assembly. The gas delivery system includes a plurality of gas lines for providing at least one process gas to the reaction chamber. The gas delivery system further includes a mixer for receiving the at least one process gas. The mixer is operatively connected to a diffuser that is configured to diffuse process gases. The diffuser is attached directly to an upper surface of the reaction chamber, thereby forming a diffuser volume therebetween. The diffuser includes at least one distribution surface that is configured to provide a flow restriction to the process gases as they pass through the diffuser volume before being introduced into the reaction chamber.