Monochlorosilane ALD Silicon Nitride Film Formation
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Solution Overview
Problem
The existing methods for forming silicon nitride films at temperatures of 500° C. or less using dichlorosilane (DCS) result in films with high wet etching rates, leading to low quality.
Innovation Solution
The use of monochlorosilane (MCS) as the Si source in an atomic layer deposition (ALD) process, with a temperature range of 150 to 550° C., and alternating supply of MCS and nitrogen-containing gas, including plasma excitation, to form high-quality silicon nitride films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If dichlorosilane (DCS) is used as the Si source in ALD at temperatures of 500°C or less, then film formation can be achieved at lower temperatures, but the resulting SiN film has high wet etching rate and low quality
Solution Approach 1:
The patent changes the chemical composition parameter of the Si source gas from dichlorosilane (DCS) to monochlorosilane (MCS). This parameter change enables the film formation process to achieve high-quality SiN films at lower temperatures (500°C or less) while maintaining low wet etching rates, thereby resolving the contradiction between low temperature processing and film quality
Solution Approach 2:
The patent introduces a plasma treatment step as an intermediary process between Si source supply and nitriding gas supply. This plasma treatment modifies the adsorbed Si layer to improve its reactivity and ensure complete nitridation, which enables high film quality to be achieved even when using MCS at lower temperatures
2Manufacturing precision
If monochlorosilane (MCS) is used as the Si source with plasma treatment, then film quality is improved, but the process complexity increases
Solution Approach 1:
The patent merges the plasma treatment step with the existing ALD process sequence, integrating it as an intermediate step between Si source supply and nitriding gas supply. This integration allows the plasma treatment to be performed using the same process equipment without requiring separate dedicated plasma processing equipment, thereby limiting the increase in process complexity while achieving improved film quality
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 results in improved film quality, refractive index closer to stoichiometric Si3N4, enhanced chemical solution resistance, and reduced chlorine content, maintaining high quality even at lower temperatures.
Implementation Method 1
supplying the monochlorosilane gas into the process container by spouting the monochlorosilane gas in horizontal directions from a plurality of gas spouting holes formed on a first nozzle extending vertically without supplying the nitrogen-containing gas into the process container, thereby forming a layer derived from the monochlorosilane gas and adsorbed on a surface of the target objects
Implementation Method 2
the second supply step includes turning the nitrogen-containing gas into plasma by a plasma generating mechanism disposed on a sidewall of the process container while supplying the nitrogen-containing gas into the process container, thereby using the nitrogen-containing gas thus excited to nitride the layer adsorbed on the surface of the target objects
Implementation Method 3
supplying a nitrogen-containing gas as a nitriding gas into the process container... thereby nitrided to form a silicon nitride film
Data Source
AI summary
A film formation method includes setting a target object at a temperature of 150 to 550° C., the target object being placed inside the process container configured to hold a vacuum state therein, and then, repeating a cycle alternately including a first supply step and a second supply step a plurality of times to form a silicon nitride film on the target object. The first supply step is a step of supplying monochlorosilane gas as an Si source into the process container while setting the process container at a pressure of 66.65 to 666.5 Pa therein. The second supply step is a step of supplying a nitrogen-containing gas as a nitriding gas into the process container.