Semiconductor Film Uniformity via Cyclic Gas Purging
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Solution Overview
Problem
The uniformity of film thickness on semiconductor substrates decreases as the surface area increases, particularly in finer and three-dimensional structures, due to non-uniform distribution of reactive gases during the film formation process.
Innovation Solution
A method involving a cycle of alternating steps of supplying source and reactive gases, including vacuuming and purging with inert gases, to ensure uniform deposition of films on substrates, specifically using HCDS and NH3 gases for forming silicon nitride films, with controlled pressure and flow rates to enhance film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cycle of supplying source gas and reactive gas is performed to form a film on a substrate, then film formation is achieved, but the uniformity of film thickness across the substrate surface decreases as substrate surface area increases
Solution Approach 1:
The patent applies periodic action by alternating between source gas supply and reactive gas supply in cyclic manner. Each cycle consists of: (a) supplying source gas, (b) removing source gas through exhausting and purging, (c) supplying reactive gas, and (d) removing reactive gas through alternating exhausting and purging. This periodic cyclic process ensures uniform film thickness across large substrate surfaces by controlling gas distribution timing and pressure changes.
2Manufacturing precision
If reactive gas is supplied to form film on larger substrate area, then film coverage is improved, but non-uniform distribution of reactive gas reduces film thickness uniformity
Solution Approach 1:
The patent applies preliminary action by thoroughly removing source gas through alternating exhausting and purging operations before supplying reactive gas. This preliminary removal of source gas prevents non-uniform reactions and ensures that reactive gas distributes uniformly across the substrate surface, achieving uniform film thickness even on large substrates.
Solution Approach 2:
The patent uses inert gas for purging the process chamber between source gas and reactive gas supply. This inert atmosphere prevents unwanted reactions, controls pressure changes, and facilitates uniform distribution of reactive gas across the substrate surface by creating a controlled environment that promotes even gas flow and reaction.
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 improves the uniformity of silicon nitride film thickness across the substrate surface, reduces impurity concentration, and increases film forming efficiency, while maintaining high productivity and HF-resistance properties.
Implementation Method 1
exhausting an inside of the process chamber to depressurize the inside of the process chamber
Implementation Method 2
purging the inside of the process chamber using an inert gas
Implementation Method 3
purging the inside of the process chamber using an inert gas
Implementation Method 4
supplying a source gas to the substrate... supplying a reactive gas having a chemical structure different from that of the source gas to the substrate... forming a film on a substrate
Data Source
AI summary
A method of manufacturing a semiconductor device is provided which includes a step of performing a cycle, a predetermined number of times, to form a film on a substrate, the cycle including non-simultaneously performing: (a) a step of supplying a source gas to the substrate in a process chamber; (b) a step of removing the source gas from the process chamber; (c) a step of supplying a reactive gas having a chemical structure different from that of the source gas to the substrate in the process chamber; and (d) a step of removing the reactive gas from the process chamber, wherein the (d) includes alternately repeating: (d-1) a step of exhausting an inside of the process chamber to depressurize the inside of the process chamber; and (d-2) a step of purging the inside of the process chamber using an inert gas.