Inner Spacer Structure Using Oxygen-Free Halogen Radical Etching
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Solution Overview
Problem
The inner spacer trimming process in semiconductor manufacturing faces challenges with reduced etching rate and uniformity due to the use of oxygen-containing etchants, which degrades the yield and throughput of integrated circuit (IC) manufacturing.
Innovation Solution
A cyclic dry etching process is employed, which is oxygen-free and includes alternating cycles of first and second radical etching processes using halogen radicals such as fluorine and chlorine, respectively, to selectively etch the dielectric layer and form an interfacial layer that protects the nano-sheet channel layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If oxygen-containing etchants are used in the inner spacer trimming process, then the etching process can proceed, but the etching rate and uniformity are reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the etchant by eliminating oxygen-containing compounds and using only oxygen-free radical etchants. This parameter change resolves the contradiction by enabling fast etching rates while maintaining uniformity, as the oxygen-free radical mechanism provides both high reactivity and consistent etching behavior across the wafer surface.
Solution Approach 2:
The patent creates an inert oxygen-free etching environment by using oxygen-free radical etchants. This inert environment prevents unwanted oxidation reactions that cause non-uniform etching, while still allowing the etching process to proceed at high rates through the radical mechanism's high reactivity with the spacer material.
2Productivity
If oxygen-containing etchants are used in the inner spacer trimming process, then the etching process can proceed, but the yield and throughput of IC manufacturing are degraded
Solution Approach 1:
The patent changes the etchant composition to oxygen-free radicals, which improves both etching rate and uniformity. This dual improvement directly enhances throughput by reducing process time while maintaining yield through consistent, defect-free etching across all devices on the wafer.
Solution Approach 2:
The patent uses a cyclic etching process that deposits and removes sacrificial layers in repeating cycles. This copying approach allows precise control over the inner spacer dimensions by replicating the etching pattern uniformly across multiple cycles, thereby improving both throughput through automation and yield through consistency.
3Manufacturing precision
If conventional etching processes are used, then the process is simple, but the inner spacer formation uniformity and reliability are reduced
Solution Approach 1:
The patent segments the etching process into multiple cyclic steps, each depositing and removing a sacrificial layer. This segmentation transforms a single complex etching operation into multiple simpler, repeatable steps, improving inner spacer uniformity through consistent replication while managing complexity through modular process design.
Solution Approach 2:
The patent employs periodic cyclic etching actions where sacrificial layers are deposited and removed in repeating cycles. This periodic action enhances inner spacer uniformity by ensuring consistent material removal patterns across all cycles, while the regularity of the cyclic process actually simplifies process control and monitoring.
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 etching rate and selectivity of the inner spacer trimming process, thereby improving the uniformity and reliability of the inner spacer formation, ultimately increasing the yield and throughput of IC manufacturing.
Implementation Method 1
a cyclic dry etching process is employed, which is oxygen-free and includes alternating cycles of first and second radical etching processes using halogen radicals such as fluorine and chlorine, respectively, to selectively etch the dielectric layer
Implementation Method 2
alternating cycles of first and second radical etching processes using halogen radicals such as fluorine and chlorine, respectively, to selectively etch the dielectric layer and form an interfacial layer that protects the nano-sheet channel layer
Data Source
AI summary
The present disclosure describes a semiconductor structure and a method for forming the same. The method can include forming a fin structure over a substrate. The fin structure can include a channel layer and a sacrificial layer. The method can further include forming a first recess structure in a first portion of the fin structure, forming a second recess structure in the sacrificial layer of a second portion of the fin structure, forming a dielectric layer in the first and second recess structures, and performing an oxygen-free cyclic etching process to etch the dielectric layer to expose the channel layer of the second portion of the fin structure. The oxygen-free cyclic etching process can include two etching processes to selectively etch the dielectric layer over the channel layer.