Mist CVD Chamber Ceiling Height for Film Uniformity
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Solution Overview
Problem
Mist CVD methods face challenges in achieving in-plane uniformity of film thickness due to thermal convection and gas mixing, leading to non-uniform semiconductor film formation, particularly on larger substrates like 6-inch wafers.
Innovation Solution
A film-forming apparatus and method that includes a mist-generating member, a carrier gas-supplying member, and a film-forming member with a film-forming chamber, nozzle, and gas-discharging member, where the height difference between the chamber ceiling and substrate-placing face is between 0.15 cm and 6.05 cm, and the gas flow is rectified to ensure uniform gas flow parallel to the substrate, enhancing film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mist is supplied from above the substrate, then film formation can be achieved, but thermal convection and gas mixing disturb mist flow causing poor in-plane uniformity of film thickness
Solution Approach 1:
The film-forming chamber is segmented into an upper chamber and a lower chamber by introducing a ceiling structure. This segmentation divides the mist flow path into distinct regions, allowing the upper chamber to control mist distribution and the lower chamber to manage thermal convection and gas flow, thereby achieving uniform film thickness across the substrate surface
Solution Approach 2:
The invention introduces a vertical dimension by positioning the ceiling at a specific height (0.15-6.05 cm) above the substrate. This vertical spacing creates a controlled three-dimensional flow path that utilizes both vertical and horizontal dimensions to rectify mist flow and eliminate thermal convection disturbances, resulting in improved in-plane uniformity
2Manufacturing precision
If substrate is rotated to improve film uniformity, then in-plane uniformity increases, but film formation on large substrates still yields poor uniformity (minimum/maximum thickness ratio of 55.0% for 4-inch substrate)
Solution Approach 1:
The invention changes critical parameters including the ceiling height (0.15-6.05 cm), mist flow rate, carrier gas flow rate, and substrate temperature. By optimizing these parameters, the system achieves uniform film formation without requiring substrate rotation, thereby maintaining high productivity while improving in-plane uniformity to achieve minimum/maximum thickness ratios of 80% or higher for large substrates
3Manufacturing precision
If ceiling height is reduced to improve mist flow control, then in-plane uniformity improves, but thermal convection effects increase causing non-uniform gas flow
Solution Approach 1:
The invention identifies and optimizes the ceiling height parameter to a specific range (0.15-6.05 cm) that balances two competing effects: sufficiently close to the substrate to control mist flow and achieve uniform deposition, yet far enough to minimize thermal convection disturbances. This parameter optimization enables simultaneous control of both mist flow uniformity and thermal effects
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 stable and uniform film thickness across larger substrate areas, improving yield and reducing production steps by generating a uniform gas flow that rectifies the mist and enhances film uniformity during the thermal treatment process.
Implementation Method 1
a carrier gas-supplying member to supply a carrier gas for carrying the mist generated in the mist-generating member
Implementation Method 2
a nozzle to supply the mist toward the inside of the film-forming chamber
Implementation Method 3
a film-forming member to thermally treat the mist carried with the carrier gas to form a film
Implementation Method 4
a gas-discharging member to discharge an exhaust gas from the inside to an outside of the film-forming chamber
Data Source
AI summary
A film-forming apparatus including: a mist-generating member to atomize a raw material solution into a mist; a carrier gas-supplying member to supply a carrier gas for carrying the mist generated in the mist-generating member; and a film-forming member to thermally treat mist carried with carrier gas to form a film, wherein film-forming member includes: a film-forming chamber; a substrate-placing member provided inside the film-forming chamber; a nozzle to supply the mist toward inside of film-forming chamber; and gas-discharging member to discharge an exhaust gas from the inside to an outside of the film-forming chamber, and a difference in a height position between an inner face of a ceiling of the film-forming chamber and a substrate-placing face of the substrate-placing member is 0.15 cm or longer and 6.05 cm or shorter. This provides a film-forming apparatus that can form a film with excellent in-plane uniformity of film thickness by mist CVD.