HfO2 Plasma Etching with SiCl4/BCl3 Selectivity to SiGe
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current techniques fail to selectively laterally etch hafnium oxide HfO2 for gate insulating films in next-generation semiconductor devices, particularly in Gate All Around structures, and do not effectively differentiate between etching HfO2 and silicon germanium SiGe, leading to non-selective etching and vertical ion etching issues.
Innovation Solution
A plasma processing method using a vacuum apparatus with a specific flow rate ratio of silicon tetrachloride SiCl4 to boron trichloride BCl3 gases, where SiCl4 is added in a ratio of 3 to 20%, allowing radical etching that preferentially etches HfO2 over SiGe, utilizing a shield plate to control plasma generation and ensure radical-only etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If halogen-based gas plasma is used for etching HfO2, then etching capability is improved, but selectivity between HfO2 and SiGe deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the etching gas by adding SiCl4 to the BCl3-based gas mixture. This parameter change modifies the etching chemistry to achieve both high etching capability and high selectivity between HfO2 and SiGe, resolving the contradiction between productivity and manufacturing precision.
2Productivity
If ion injection is used for etching, then vertical etching rate is improved, but lateral etching selectivity deteriorates
Solution Approach 1:
The patent modifies the gas composition parameters to create a plasma environment that enables both vertical and lateral etching with high selectivity. The addition of SiCl4 to BCl3 changes the radical chemistry to achieve preferential etching of HfO2 over SiGe in both vertical and lateral directions, resolving the contradiction between productivity and manufacturing precision.
3Productivity
If conventional anisotropic etching is used, then vertical processing is improved, but lateral processing capability deteriorates
Solution Approach 1:
The patent changes the etching chemistry parameters by introducing SiCl4 to the BCl3 gas mixture, creating a plasma that exhibits both anisotropic (vertical) and isotropic (lateral) etching characteristics with high selectivity for HfO2 over SiGe. This resolves the contradiction between vertical processing efficiency and lateral processing capability.
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 method enables selective lateral etching of HfO2 over SiGe, optimizing etching rates and preventing vertical ion etching, thus addressing the need for high-selectivity etching in complex three-dimensional semiconductor device fabrication.
Implementation Method 1
a plasma processing method that laterally etches hafnium oxide HfO2 using a vacuum processing apparatus that is capable of perform radical etching
Implementation Method 2
perform radical etching in which a flow rate ratio is set such that a silicon tetrachloride SiCl4 gas is added to a boron trichloride BCl3 gas
Implementation Method 3
an SiClz deposition to be deposited on the silicon germanium SiGe larger than an SiClx deposition to be deposited on the hafnium oxide HfO2
Implementation Method 4
since the technique described in PTL 2 is not etching with the radical shielding ions, it is considered that etching in the vertical direction by ion injection proceeds
Implementation Method 5
anisotropic etching means etching using the ion assist reaction that promotes the reaction to a radical with ions
Data Source
AI summary
HfO2 is to be selectively laterally etched and to SiGe. In order to manufacture a device in a next generation three-dimensional structure such as GAA, in a plasma processing method that laterally etches HfO2 using a vacuum processing apparatus that is capable of perform radical etching, a flow rate ratio is set such that an SiCl4 gas is added to a BCl3 gas, a flow rate ratio of the SiCl4 gas at this time is lower than a flow rate ratio of the BCl3 gas, and an SiClx deposition to be deposited on SiGe is larger than an SiClx deposition to be deposited on HfO2, and thus HfO2 is selectively etched to SiGe.