Substrate Pressure Cycling for Uniform SiO2 Film Etching
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Solution Overview
Problem
Existing substrate processing methods for semiconductor wafers, such as chemical oxide removal (COR), face challenges in achieving uniform etching of silicon-containing films like SiO2, particularly in maintaining consistent thickness and uniformity across the wafer surface due to variations in reaction product sublimation and gas concentration.
Innovation Solution
A substrate processing method involving a substrate processing apparatus that alternately repeats processes of modifying a silicon-containing film with a halogen-containing gas and a basic gas, and vaporizing the reaction product by adjusting internal pressure, ensuring the reaction product remains on the film during subsequent modifications to maintain uniform etching across the wafer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reaction product is completely vaporized by depressurizing the processing container, then the etching speed increases, but the uniformity of etching across the wafer surface deteriorates
Solution Approach 1:
The patent applies periodic action by alternately repeating cycles of pressure increase (to suppress sublimation and maintain reaction product on film) and pressure decrease (to vaporize reaction product and enable etching). This periodic pressure cycling allows the system to achieve both high etching speed and uniformity by controlling the presence and removal of reaction product in controlled intervals across the wafer surface.
2Productivity
If the processing gas is continuously supplied to accelerate the modification process, then the throughput improves, but the uniformity of gas concentration across the wafer deteriorates
Solution Approach 1:
The patent uses periodic action by supplying processing gas only during specific phases of the pressure cycle (when pressure is increased to suppress sublimation) and stopping gas supply during depressurization phases. This periodic gas supply pattern maintains high throughput while ensuring uniform gas concentration distribution across the wafer surface, avoiding the uniformity problems associated with continuous gas supply.
3Loss of time
If the pressure is rapidly decreased to vaporize the reaction product, then the processing time is reduced, but the uniformity of reaction product removal deteriorates
Solution Approach 1:
The patent applies periodic action with controlled pressure cycling between increased and decreased states. The pressure decrease phase is optimized to vaporize reaction product uniformly across the wafer surface while maintaining acceptable processing time. This periodic pressure control ensures that reaction product is removed uniformly without sacrificing excessive processing time, resolving the contradiction between speed and uniformity.
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 ensures high uniformity in etching the SiO2 films across the wafer surface, aligning the thickness and height positions of etched regions, and improves throughput by controlling the processing gas's presence and pressure changes within the processing container.
Implementation Method 1
a first process of modifying the silicon-containing film by supplying a processing gas containing a halogen-containing gas and a basic gas to the substrate, in a state in which an internal pressure of the processing container is set to a first pressure, to generate a reaction product
Implementation Method 2
a second process of vaporizing the reaction product by setting the internal pressure of the processing container to a second pressure lower than the first pressure
Data Source
AI summary
A method of processing a substrate, includes: loading the substrate having a silicon-containing film formed thereon into a processing container; a first process of modifying the silicon-containing film by supplying a processing gas containing a halogen-containing gas and a basic gas to the substrate, in a state in which an internal pressure of the processing container is set to a first pressure, to generate a reaction product; a second process of vaporizing the reaction product by setting the internal pressure of the processing container to a second pressure lower than the first pressure; and alternately repeating the modifying the silicon-containing film and the vaporizing the reaction product, wherein subsequent rounds of the first process following the initial first process in the alternately repeating the modifying the silicon-containing film and the vaporizing the reaction product includes supplying the processing gas to the substrate on which the reaction product remains.