GaN Deposition Liner Cooling to Reduce Substrate Bow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gallium nitride (GaN) deposition on substrates with different lattice constants leads to significant substrate bow, crystallographic defects, and mechanical strain due to thermal expansion coefficient mismatch, and conventional deposition chambers suffer from premature precursor decomposition and errant depositions on hot surfaces, causing clogging and optical interference.
Innovation Solution
A process chamber system with an optically transparent divider and a liner assembly that includes cooling fluid channels to maintain precursor gas temperature below decomposition point, prevent mixing of processing and precursor gases, and utilize a reflector plate with perforations for cooling and maintaining transparency, reducing substrate bow and defects in GaN layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If GaN is deposited at elevated temperature to improve deposition quality, then the GaN layer quality improves, but substrate bow increases significantly
Solution Approach 1:
The patent applies parameter changes by precisely controlling deposition temperature profiles and using in-situ heating to maintain optimal temperatures during GaN deposition. This allows high-quality GaN growth while managing thermal stress to reduce substrate bowing.
Solution Approach 2:
The patent employs preliminary anti-action through the use of buffer layers and controlled cooling rates after deposition. These measures preemptively counteract the thermal stress that would otherwise cause excessive substrate bowing, allowing elevated temperature deposition without severe bowing consequences.
2Productivity
If conventional deposition chambers are used, then deposition can proceed, but premature precursor decomposition occurs causing clogging and errant depositions
Solution Approach 1:
The patent uses an intermediary approach by introducing a separate heating zone and controlled gas flow paths. This mediates between the precursor delivery system and the substrate, preventing premature decomposition while ensuring proper deposition conditions at the substrate surface.
Solution Approach 2:
The deposition chamber is segmented into distinct zones with independent temperature and flow control. This segmentation allows the precursor gas to remain cool and stable in the delivery region while only heating the substrate area where deposition is needed, preventing premature decomposition.
3Productivity
If hot surfaces are used in the chamber, then deposition can occur, but errant deposition on chamber components blocks optical energy and causes delamination
Solution Approach 1:
The patent applies local quality by providing selective heating only to the substrate region while keeping other chamber components, particularly optical components, at lower temperatures. This localized thermal control enables deposition to proceed on the hot substrate while preventing errant deposition on cooler optical surfaces that would block light transmission.
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 system achieves GaN substrates with reduced bowing (less than 50 μm) and minimized defects, maintaining transparency and preventing particle formation, thus enhancing the quality and reliability of GaN deposition.
Implementation Method 1
a cooling fluid channel is formed in the injector plate adjacent to the gas injector liner
Implementation Method 2
heating the precursor gas to a temperature of about 400 degrees Celsius to about 1,200 degrees Celsius above the substrate
Implementation Method 3
the large difference (around 46%) in thermal expansion coefficients between Si and GaN. When GaN is deposited at an elevated temperature (greater than 400° C.) and then cooled (about 23° C.), the substrate bows very noticeably
Data Source
AI summary
Embodiment disclosed herein include a liner assembly, comprising an injector plate liner, a gas injector liner coupled to the injector plate liner, an upper process gas liner coupled to the gas injector liner, a lower process gas liner coupled to the upper process gas liner, and an injector plate positioned between the injector plate liner and the upper process gas liner, wherein a cooling fluid channel is formed in the injector plate adjacent to the gas injector liner.