Epitaxial Stack Formation via Periodic Unloading
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Solution Overview
Problem
The challenge in semiconductor processing is forming thicker epitaxial stacks without causing substrate damage or breakage, particularly in the manufacturing of 3DDRAM devices, where substrate sticking to the wafer boat leads to integrity issues and reduced throughput and yield.
Innovation Solution
A method involving a semiconductor processing apparatus with a carousel and process chamber, where the wafer boat is unloaded multiple times to prevent substrate sticking, using thermal stress and inert gas cooling to detach substrates, and employing a substrate handling robot for precise detachment, allowing for controlled epitaxial stack formation and monitoring of thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the epitaxial stack thickness is increased to overcome scaling limits, then the manufacturing capability for 3DDRAM devices is improved, but substrate sticking to the wafer boat increases causing substrate damage and breakage
Solution Approach 1:
The patent applies periodic action by periodically unloading the wafer boat from the process chamber during the epitaxial growth process. Instead of continuous processing, the system interrupts the growth at intervals to unload and reload the wafer boat, preventing substrate sticking while maintaining overall process continuity. This periodic interruption allows substrates to be detached before sticking becomes problematic, enabling thicker epitaxial stacks to be formed without compromising substrate integrity.
Solution Approach 2:
The patent applies preliminary action by performing a preliminary cooling step using inert gas before unloading the wafer boat. This preliminary cooling reduces the substrate temperature and minimizes thermal stress, preparing the substrates for safe removal. By cooling the substrates before the unloading operation, the system prevents thermal shock and reduces the risk of substrate breakage during the unloading process.
2Length of moving object
If the epitaxial stack thickness is increased, then the manufacturing capability for 3DDRAM devices is improved, but substrate breakage during unloading increases
Solution Approach 1:
The patent applies preliminary action by performing a preliminary cooling step using inert gas before unloading the wafer boat. This preliminary cooling reduces the substrate temperature and minimizes thermal stress, preparing the substrates for safe removal. By cooling the substrates before the unloading operation, the system prevents thermal shock and reduces the risk of substrate breakage during the unloading process.
Solution Approach 2:
The patent applies parameter changes by modifying the temperature parameter during the unloading process. The system cools the substrates to a lower temperature before unloading, changing the thermal state of the substrates to reduce thermal stress and prevent breakage. This parameter change enables safe handling of substrates with thicker epitaxial stacks.
3Reliability
If multiple unloading operations are performed to prevent substrate sticking, then substrate integrity is improved, but processing time increases
Solution Approach 1:
The patent applies periodic action by periodically unloading the wafer boat from the process chamber during the epitaxial growth process. Instead of continuous processing, the system interrupts the growth at intervals to unload and reload the wafer boat, preventing substrate sticking while maintaining overall process continuity. This periodic interruption allows substrates to be detached before sticking becomes problematic, enabling thicker epitaxial stacks to be formed without compromising substrate integrity.
Solution Approach 2:
The patent applies continuity of useful action by maintaining the epitaxial growth process as the primary continuous operation, with unloading interruptions minimized to essential intervals. The system ensures that the useful action of epitaxial growth continues uninterrupted during chamber residency, and only pauses briefly for wafer boat unloading/reloading operations. This approach maintains high process efficiency while still preventing substrate sticking through necessary periodic interruptions.
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 the probability of substrate damage and breakage, enabling the formation of thicker epitaxial stacks with improved integrity and process yield, enhancing semiconductor manufacturing throughput and reducing unplanned maintenance cycles.
Implementation Method 1
wherein the processing may comprise cooling the plurality of substrates using an inert gas
Implementation Method 2
using thermal stress and inert gas cooling to detach substrates
Data Source
AI summary
A method of forming an epitaxial stack on a plurality of substrates is provided. In a preferred embodiment, the method comprises providing a semiconductor processing apparatus. This semiconductor processing apparatus comprises a process chamber and a carousel for stationing a wafer boat before or after processing in the process chamber. The method further comprises loading the wafer boat into the process chamber, the wafer boat comprising the plurality of substrates. The method further comprises processing the plurality of substrates in the process chamber, thereby forming, on the plurality of substrates, the epitaxial stack. This epitaxial stack has a pre-determined thickness. The processing comprises unloading the wafer boat, one or more times, from the process chamber to the carousel until the epitaxial stack reaches the pre-determined thickness.