Substrate Cooling Sequence for Low-Resistance Metal Film Unloading
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Solution Overview
Problem
The electrical resistance of metal films used in NAND flash memory with a three-dimensional structure, particularly Mo-containing films, increases when the substrate is unloaded from a process chamber due to temperature variations.
Innovation Solution
A substrate processing technique involving loading the substrate at a specific temperature, setting the process chamber to a film formation temperature, forming the metal film, then lowering the chamber temperature before unloading, using a controlled gas supply system to manage thermal stress and impurity concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate is unloaded from the process chamber at high temperature, then the film formation process can be completed efficiently, but the electrical resistance of the metal film increases due to thermal stress
Solution Approach 1:
The patent applies preliminary anti-action by introducing a cooling gas (such as nitrogen or helium) into the process chamber before unloading the substrate. This cooling gas creates a protective atmosphere that prevents thermal stress and oxidation of the metal film during the temperature transition from film formation temperature to unloading temperature, thereby maintaining low electrical resistance while still allowing efficient film formation
Solution Approach 2:
The patent changes the temperature parameter dynamically during the process: maintaining high temperature (e.g., 400-600°C) during film formation for efficiency, then transitioning to a controlled cooling phase with cooling gas introduction to reduce temperature while protecting the metal film's electrical characteristics. This parameter change resolves the contradiction between productivity and reliability
2Loss of time
If the substrate is cooled rapidly after film formation, then the unloading time can be reduced, but impurity concentration in the metal film increases
Solution Approach 1:
The patent uses a cooling gas (nitrogen or helium) as an intermediary substance between the hot substrate and the ambient environment. This intermediary gas enables controlled heat transfer that is fast enough to reduce unloading time but gentle enough to prevent impurity incorporation. The cooling gas acts as a buffer that mediates the thermal transition while maintaining film purity
Solution Approach 2:
The patent creates an inert atmosphere using nitrogen or helium gas during the cooling phase. This inert environment prevents oxidation and contamination of the metal film during the cooling process, allowing rapid temperature reduction without increasing impurity concentration. The inert atmosphere protects the film while enabling time-efficient unloading
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 method improves the electrical characteristics of the metal film by reducing thermal stress and impurity concentration, leading to enhanced film quality and stability during the unloading process.
Implementation Method 1
setting an interior of the process container to a film formation temperature
Implementation Method 2
supplying a process gas into the process container
Implementation Method 3
setting the interior of the process container to an unloading temperature lower than the loading temperature
Implementation Method 4
supplying a process gas into the process container
Implementation Method 5
forming a metal film on a surface of the substrate by supplying a process gas into the process container
Implementation Method 6
forming a metal film on a surface of the substrate by supplying a process gas into the process container
Data Source
AI summary
There is provided a technique that includes: (a) loading a substrate into a process container at a loading temperature; (b) setting an interior of the process container to a film formation temperature; (c) forming a metal film on a surface of the substrate by supplying a process gas into the process container; (d) setting the interior of the process container to an unloading temperature lower than the loading temperature; and (e) unloading the substrate from the process container.