Substrate Processing Method for Tungsten Oxide Removal
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Solution Overview
Problem
Selective oxidation methods for laminated gate structures in flash memory manufacturing contaminate the processing chamber due to tungsten from etching and sublimation of tungsten oxides during plasma processing.
Innovation Solution
A substrate processing method using a gas containing oxygen for oxidizing substrates with tungsten, followed by a cleaning process with a gas containing hydrogen to remove tungsten oxides, employing an MMT apparatus that generates high-density plasma to selectively oxidize polysilicon without oxidizing tungsten, and periodically cleaning the chamber with a hydrogen-rich gas mixture to prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If plasma containing oxygen and hydrogen is used to selectively oxidize polysilicon, then low temperature oxidation is achieved, but the processing chamber becomes contaminated with tungsten from etching and sublimation
Solution Approach 1:
The patent divides the oxidation process into two distinct stages: a first oxidation step using oxygen-containing plasma at lower temperature to selectively oxidize polysilicon, and a second oxidation step using oxygen-containing gas at higher temperature to oxidize tungsten. This segmentation allows each step to perform its specific function without the harmful side effects of combining them simultaneously.
Solution Approach 2:
The patent implements periodic alternation between oxidation steps and cleaning steps. After the first oxidation step, a cleaning step using hydrogen-containing plasma is performed to remove tungsten oxides before proceeding to the second oxidation step. This periodic cleaning action prevents tungsten contamination from accumulating in the processing chamber.
2Reliability
If selective oxidation is performed to oxidize polysilicon without oxidizing tungsten, then gate electrode resistance is maintained, but tungsten oxides sublime and contaminate the chamber
Solution Approach 1:
The patent performs a preliminary cleaning action using hydrogen-containing plasma between the first and second oxidation steps. This cleaning step removes tungsten oxides that have formed during the first oxidation step, preventing them from sublimating and contaminating the chamber during subsequent high-temperature processing.
Solution Approach 2:
The patent introduces hydrogen-containing plasma as an intermediary cleaning step between the two oxidation steps. This intermediary action removes tungsten oxides through reduction and volatilization, acting as a mediator that prevents contamination while allowing both oxidation steps to proceed effectively.
3Manufacturing precision
If multiple oxidation steps are performed to achieve selective oxidation, then oxidation precision is improved, but processing time increases
Solution Approach 1:
The patent maintains continuous useful action by performing the first oxidation step, immediately followed by a cleaning step, and then the second oxidation step without interrupting the processing sequence. The cleaning step using hydrogen-containing plasma is efficiently designed to remove tungsten oxides quickly, minimizing the time penalty while maintaining the precision benefits of multiple oxidation steps.
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
Prevents contamination in the processing chamber by effectively removing tungsten oxides, ensures high purity, and allows for reliable selective oxidation of polysilicon while maintaining low tungsten oxidation, improving productivity and reducing thermal damage.
Implementation Method 1
selective oxidation methods that utilize a gas containing oxygen and hydrogen to oxidize the polysilicon
Implementation Method 2
oxidize the polysilicon and that do not oxidize the control electrode made from metal
Implementation Method 3
a cleaning process for removing tungsten oxides with a gas containing hydrogen
Implementation Method 4
Modified Magnetron Typed apparatus
Data Source
AI summary
Substrate contamination from tungsten is prevented. A substrate processing method comprises a main treatment process for oxidizing a substrate containing tungsten with a gas containing oxygen, and a cleaning process for removing tungsten oxides with a gas containing hydrogen. The main treatment process includes loading the substrate containing metal into the processing chamber; supplying gas containing oxygen into the processing chamber; and supplying electric power to a high-frequency electric power supply to generate plasma containing oxygen elements, stopping the supply of electric power, and unloading the substrate from the processing chamber. The cleaning process includes supplying gas containing hydrogen into the processing chamber after unloading the substrate; supplying electric power to a high-frequency electric power supply to generate plasma containing hydrogen elements; and stopping the supply of electric power.