Silicon Mandrel Etch Using Fluorine Plasma
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Solution Overview
Problem
Conventional methods for removing silicon mandrels and replacement gates in semiconductor processing often result in damage to spacers and sublayers, and leave behind residues, due to the use of chlorine and hydrogen bromide gases, which also have corrosion concerns and lower selectivity.
Innovation Solution
The use of an inductively coupled plasma source with fluorine-containing gases like nitrogen trifluoride or tetrafluoromethane, combined with a capacitively coupled plasma for native oxide punch-through, to selectively remove silicon mandrels and replacement gates with reduced damage and residue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chlorine and hydrogen bromide gases are used for silicon mandrel removal, then material removal capability is improved, but selectivity to spacer and sublayer materials deteriorates causing damage
Solution Approach 1:
The patent changes the chemical parameters by switching from chlorine-based gases to fluorine-based gases (SF6, NF3, CF4). This parameter change fundamentally alters the etch chemistry to achieve high selectivity for silicon mandrel removal while preserving spacer and sublayer materials. The fluorine-based process provides the necessary manufacturing precision without sacrificing material removal capability.
2Productivity
If conventional etch methods are used, then silicon mandrel removal is achieved, but residue on sub layers increases
Solution Approach 1:
The patent changes the chemical composition parameter by using fluorine-based gases instead of conventional chlorine-based gases. This parameter change results in cleaner etching with minimal residue deposition on sublayer materials, while maintaining efficient silicon mandrel removal. The fluorine chemistry provides superior cleanliness without compromising removal efficiency.
3Device complexity
If chlorine and hydrogen bromide gases are used, then etching process is simplified, but corrosion concerns increase
Solution Approach 1:
The patent changes the gas composition parameter from corrosive chlorine and hydrogen bromide to fluorine-based gases (SF6, NF3, CF4). This parameter change reduces the harmful corrosion effects on equipment and materials while maintaining a relatively simple etching process. The fluorine-based gases provide lower corrosion potential without significantly increasing process complexity.
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 enables high-selectivity removal of silicon mandrels and replacement gates with minimal damage to spacer and sublayer materials, improving the overall precision and cleanliness of the semiconductor processing.
Implementation Method 1
generating species from a process gas in a first chamber using an inductive coupling element
Implementation Method 2
introducing a fluorine containing gas with the species to create a mixture. The mixture can include exposing the silicon structure of the workpiece to the mixture to remove at least a portion of the silicon structure
Data Source
AI summary
Apparatus, systems, and methods for conducting a silicon containing material removal process on a workpiece are provided. In one example implementation, the method can include generating species from a process gas in a first chamber using an inductive coupling element. The method can include introducing a fluorine containing gas with the species to create a mixture. The mixture can include exposing a silicon structure of the workpiece to the mixture to remove at least a portion of the silicon structure.