Silicon Oxide Etching Selectivity Using HF-Alcohol Gas Mixture
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Solution Overview
Problem
Conventional methods for removing silicon oxide from wafers in integrated circuit manufacturing, such as wet etching and plasma dry etching, often result in low etching selectivity and excessive removal of silicon nitride spacers, leading to increased resistivity and device performance issues.
Innovation Solution
A method involving the introduction of dehydrated hydrogen fluoride and alcohol gases into a process chamber to generate gaseous etchants, which react with silicon oxide under high pressure, improving etching selectivity and efficiency while protecting silicon nitride structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wet etching or plasma dry etching is used to remove silicon oxide, then the etching process can proceed, but the etching selectivity to silicon nitride is low causing excessive spacer removal
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using dehydrated hydrogen fluoride gas mixed with dehydrated alcohol gas under high pressure. This parameter change creates highly selective etching conditions where silicon oxide is removed rapidly while silicon nitride remains protected, achieving over 100:1 selectivity ratio and preventing spacer material loss
Solution Approach 2:
The patent introduces dehydrated alcohol gas as an intermediary substance that modifies the etching chemistry. The alcohol acts as a mediator that enhances the selectivity between silicon oxide and silicon nitride etching rates, allowing precise removal of oxide while preserving the nitride spacer structures
2Manufacturing precision
If high pressure is applied in the process chamber, then the etching selectivity is improved, but the chamber pressure control becomes more complex
Solution Approach 1:
The patent employs a multi-functional process chamber that can maintain high pressure conditions while integrating gas delivery, temperature control, and pressure regulation systems. The chamber design allows it to perform multiple functions simultaneously - maintaining high pressure for selectivity while managing gas flows and heat transfer, reducing the need for separate complex control systems
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 enhances the selectivity and efficiency of silicon oxide removal, reducing damage to silicon nitride and other structures, and maintains a clean chamber environment without generating solid by-products, thus improving device performance and manufacturing efficiency.
Implementation Method 1
mixing the dehydrated hydrogen fluoride gas with the dehydrated alcohol gas to generate gaseous etchants; allowing reactions between the etchants and the wafer
Implementation Method 2
under a high pressure maintained in the process chamber to improve an etching selectivity
Data Source
AI summary
A method for removing silicon oxide from a wafer and an integrated circuit manufacturing process are provided. The method includes: introducing a dehydrated hydrogen fluoride gas and a dehydrated alcohol gas into a process chamber; mixing the dehydrated hydrogen fluoride gas with the dehydrated alcohol gas to generate gaseous etchants; allowing reactions between the etchants and the wafer in the process chamber under a high pressure maintained in the process chamber to improve an etching selectivity; and pumping out reaction products from the process chamber.