Bottom Purge Gas Flow for PECVD Chamber Residue Reduction
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Solution Overview
Problem
In semiconductor device manufacturing, chemical vapor deposition (CVD) and plasma enhanced CVD (PECVD) processes face challenges with undesirable deposition of unreacted precursors and byproducts on chamber surfaces, leading to residue material buildup, which affects substrate quality and increases maintenance needs, resulting in lower throughput and production capacity.
Innovation Solution
A method and apparatus that simultaneously flow a purge gas from beneath the substrate support in a CVD chamber while depositing a material layer on the substrate, using a combined gas exhaust volume to evacuate unreacted precursors and byproducts, preventing their deposition on chamber surfaces by positioning inlets below and above the substrate support surfaces, ensuring efficient removal without impacting deposition rates or film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CVD processing is performed continuously without cleaning, then substrate throughput is maintained, but residue material deposits on chamber surfaces leading to particulate contamination
Solution Approach 1:
The patent extracts and removes processing gases from the second volume (chamber base region) separately from the first volume (showerhead region) by introducing a purge gas flow that creates a pressure gradient, directing unreacted precursors and byproducts away from chamber surfaces before they can deposit as residue material
Solution Approach 2:
A purge gas is introduced as an intermediary substance into the second volume to mediate the removal of processing gases. The purge gas creates a controlled flow pattern that sweeps unreacted precursors and byproducts from the chamber base region through dedicated exhaust paths, preventing their deposition on chamber surfaces
2Object-affected harmful factors
If chamber cleaning is performed frequently to remove residue material, then particulate contamination is reduced, but chamber downtime increases
Solution Approach 1:
The patent performs preliminary action by continuously removing processing gases from the second volume during substrate processing operations. The purge gas flow actively sweeps unreacted precursors and byproducts from the chamber base region before they can accumulate and form residue material deposits, preventing contamination rather than treating it
Solution Approach 2:
The purge gas flow operates continuously during CVD processing to maintain continuous removal of processing gases from the second volume. This continuous action prevents residue material buildup over time, eliminating the need for periodic cleaning interruptions and maintaining uninterrupted substrate throughput
3Object-affected harmful factors
If purge gas flow rate is increased to improve gas evacuation, then residue material deposition is reduced, but deposition rate on substrate may be affected
Solution Approach 1:
The patent segments the processing volume into two distinct regions with separate gas evacuation paths: the first volume (showerhead region) where material layer deposition occurs on the substrate, and the second volume (chamber base region) where purge gas removes unreacted precursors and byproducts. This segmentation allows independent control of gas flows in each region
Solution Approach 2:
The patent applies local quality by providing different gas flow conditions in different regions: the first volume maintains conditions optimal for material layer deposition on the substrate, while the second volume uses enhanced purge gas flow specifically targeted at removing processing gases from chamber surfaces. Each region has optimized gas flow characteristics suited to its specific function
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 residue material deposition on chamber walls, decreases the frequency of cleaning cycles, and increases production capacity by maintaining high substrate throughput and film quality through efficient gas evacuation and purge gas management.
Implementation Method 1
flowing a purge gas from beneath the substrate support
Implementation Method 2
evacuating unreacted precursors and byproducts from the processing volume
Implementation Method 3
forming a plasma of the one or more gaseous precursors
Implementation Method 4
depositing a material layer on the substrate
Data Source
AI summary
Apparatus and methods for depositing a film in a PECVD chamber while simultaneously flowing a purge gas from beneath a substrate support are provided herein. In embodiments disclosed herein, a combined gas exhaust volume circumferentially disposed about the substrate support, below a first volume and above a second volume, draws processing gases from the first volume down over an edge of a first surface of the substrate support and simultaneously draws purge gases from the second volume upward over an edge of a second surface of the substrate support. The gases are than evacuated from the combined exhaust volume through an exhaust port fluidly coupled to a vacuum source.