Silicon Nitride Etch Selectivity via Plasma Silicon Scavenging
Solution Overview
Problem
Conventional silicon nitride etch processes often cause damage to exposed dielectric components like silicon oxide due to high polymerization and defects, leading to unsuitable selectivity and pattern defects in semiconductor fabrication.
Innovation Solution
The method involves introducing a silicon source to a plasma generator, forming fluorine-containing etching species, and exposing silicon nitride to these species to achieve high selectivity etching relative to other silicon-containing materials, reducing polymerization and enhancing etch selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional silicon nitride etch processes are used, then etching of silicon nitride can be achieved, but damage occurs to exposed dielectric components like silicon oxide due to high polymerization and defects
Solution Approach 1:
The patent changes the chemical parameters of the etching process by introducing a silicon source (such as silane, disilane, or solid silicon) into the plasma chamber. This modifies the plasma composition to create silicon-containing etching species that selectively etch silicon nitride while protecting other silicon-containing materials. The silicon source is introduced at controlled flow rates (e.g., 0.5-10% of total gas flow) to achieve the desired selectivity without excessive polymerization.
Solution Approach 2:
The silicon source acts as an intermediary substance that mediates the etching process. By introducing silicon into the plasma, it creates a protective effect on exposed silicon-containing materials (oxide, poly-silicon, silicon carbide) while allowing selective removal of silicon nitride. The silicon intermediates form a protective layer or modify the plasma chemistry to prevent damage to dielectric components.
2Productivity
If high polymerization is used in etching processes, then etching speed may increase, but defects are generated and selectivity is reduced
Solution Approach 1:
The patent optimizes process parameters by controlling the silicon source flow rate and plasma conditions. The silicon source is introduced at specific concentrations (0.5-10% of total gas flow) to maintain controlled polymerization that protects surfaces without creating excessive defects. This parameter optimization allows maintaining etching speed while reducing defect generation.
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 achieves etch selectivity of silicon nitride to silicon oxide and poly-silicon of up to 1000:1 or higher, reducing defects and improving the efficiency of semiconductor fabrication processes.
Implementation Method 1
introducing a fluorinating gas to a plasma generator and igniting a plasma to form fluorine-containing etching species
Implementation Method 2
The silicon source may scavenge atomic fluorine generated in the etching species
Data Source
AI summary
Methods of selectively etching silicon nitride on a semiconductor substrate by providing silicon to the plasma to achieve high etch selectivity of silicon nitride to silicon-containing materials are provided. Methods involve providing silicon from a solid or fluidic silicon source or both. A solid silicon source may be upstream of a substrate, such as at or near a showerhead of a process chamber, or in a remote plasma generator. A silicon gas source may be flowed to the plasma during etch.