Silicon Nitride Etching Selectivity Using High Pressure Hydrogen Fluoride
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Solution Overview
Problem
Current chemical etching techniques face challenges in achieving high selectivity for etching silicon nitride (SiN) films relative to silicon oxide (SiO2) and silicon germanium (SiGe) films, particularly in semiconductor manufacturing, where SiN films are often adjacent to SiO2 films, leading to damage of the SiO2 film during etching due to impurities.
Innovation Solution
An etching method involving the use of hydrogen fluoride (HF) gas at high pressures (1,333 Pa or more) to selectively etch SiN films with respect to SiO2 and SiGe, while also incorporating a surface modification treatment to remove impurities and prevent damage to the SiO2 film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching or chemical etching techniques are used to etch silicon nitride films, then etching can be performed, but selectivity with respect to silicon oxide and silicon germanium films deteriorates, causing damage to adjacent films
Solution Approach 1:
The patent changes the pressure parameter to 1,333 Pa or more (high pressure condition) and uses hydrogen fluoride gas as the etching gas, which fundamentally alters the etching mechanism to achieve high selectivity for silicon nitride while minimizing damage to silicon oxide and silicon germanium films
Solution Approach 2:
The patent introduces a surface modification treatment as an intermediary step before etching. This treatment modifies the surface of the silicon oxide film to prevent damage during subsequent etching, acting as a protective intermediary that enables high selectivity etching
2Manufacturing precision
If hydrogen fluoride gas is used for chemical etching of silicon nitride, then etching can be performed, but selectivity with respect to silicon and silicon germanium deteriorates
Solution Approach 1:
By setting the pressure to 1,333 Pa or more, the patent changes the physical conditions of the etching process, which enhances the selectivity of hydrogen fluoride gas for silicon nitride over silicon and silicon germanium, achieving selection ratios of 50 or more
3Manufacturing precision
If high pressure (1,333 Pa or more) is used with hydrogen fluoride gas, then selectivity to silicon nitride improves, but this is a departure from conventional low pressure etching conditions
Solution Approach 1:
The patent deliberately changes the pressure parameter from conventional low pressure to high pressure (1,333 Pa or more), which simplifies the process by achieving high selectivity through a single dominant parameter change rather than requiring complex combinations of multiple parameters
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 high selectivity etching of SiN films with selection ratios of 5 or more to SiO2 and 50 or more to SiGe, while minimizing damage to the SiO2 film, thereby improving the precision and reliability of semiconductor device manufacturing.
Implementation Method 1
selectively etching the silicon nitride film with respect to the silicon oxide film, silicon, and the silicon germanium by supplying a hydrogen fluoride gas into the chamber
Implementation Method 2
setting a pressure in the chamber to 1,333 Pa or more
Data Source
AI summary
There is provided an etching method including: a step of disposing a substrate in a chamber, the substrate having a silicon nitride film, a silicon oxide film, a silicon, and a silicon germanium; a step of setting a pressure in the chamber to 1,333 Pa or more; and a step of selectively etching the silicon nitride film with respect to the silicon oxide film, the silicon, and the silicon germanium by supplying a hydrogen fluoride gas into the chamber.