Plasma Etching Mask Selectivity via SiF4 Gas
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Solution Overview
Problem
Current etching technologies face challenges in achieving high precision and in-plane uniformity while maintaining sufficient mask selectivity during microfabrication of semiconductor wafers, particularly in finer microfabrication processes.
Innovation Solution
A method involving the use of a plasma etching process in a process chamber with an upper and lower electrode, where fluorocarbon gas and silicon tetrafluoride (SiF4) are supplied, and high-frequency power is applied to generate plasma, improving mask selectivity by controlling the etching conditions, including the application of a negative DC voltage and adjusting the SiF4 gas flow ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to achieve fine microfabrication, then in-plain uniformity of etching is improved, but mask selectivity deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas by introducing silicon tetrafluoride (SiF4) and adjusting the ratio of fluorocarbon gas to other gases. This parameter change modifies the plasma chemistry to achieve both high in-plain uniformity and improved mask selectivity, resolving the technical contradiction between these two requirements.
Solution Approach 2:
The patent uses a composite gas mixture combining fluorocarbon gas (such as CF4 or C4F8) with silicon tetrafluoride (SiF4). This composite process gas creates a plasma environment that simultaneously provides the benefits of fluorocarbon-based etching (good uniformity) and silicon-based etching (high selectivity), thus resolving the contradiction between uniformity and selectivity.
2Manufacturing precision
If etching precision is increased for finer microfabrication, then manufacturing precision is improved, but mask selectivity deteriorates
Solution Approach 1:
The patent optimizes multiple process parameters including gas flow rates, pressure, and power conditions while introducing SiF4 gas. These parameter changes enable precise control over the etching process, achieving high etching precision for fine microfabrication while maintaining or improving mask selectivity through the modified plasma chemistry.
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 mask selectivity and maintains in-plane uniformity, preventing encroachment and ensuring precise etching results, particularly when using titanium nitride as a mask, with optimal results achieved within specific SiF4 gas flow ratios and etching conditions.
Implementation Method 1
applying high frequency power to at least one of the upper electrode and the lower electrode, to generate plasma
Implementation Method 2
etching the insulation layer by the generated plasma via a mask
Data Source
AI summary
A method of etching an insulation layer on an object to be processed in a process chamber in which an upper electrode and a lower electrode are placed facing each other, includes supplying a process gas that includes fluorocarbon gas and silicon tetrafluoride (SiF4) gas into the process chamber; applying high frequency power to at least one of the upper electrode and the lower electrode, to generate plasma; and etching the insulation layer by the generated plasma via a mask.