Atomic Layer Deposition for Insulative Silicon Oxide Layers
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Solution Overview
Problem
The challenge lies in forming very thin layers of insulative silicon-containing oxides for integrated circuitry without consuming significant quantities of underlying elemental silicon, as traditional thermal oxidation methods consume excessive silicon, especially as circuit density increases and component sizes decrease.
Innovation Solution
An atomic layer deposition (ALD) method involving a four-step sequence: contacting a substrate with a Si-comprising precursor, increasing temperature to react with an O and/or N-comprising precursor, forming a monolayer, and then decreasing temperature, repeated to achieve the desired thickness of insulative material without consuming elemental silicon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal oxidation is used to form silicon-containing insulative oxides, then high-quality insulative material is achieved, but excessive consumption of underlying elemental silicon occurs
Solution Approach 1:
The patent changes the deposition method from thermal oxidation to atomic layer deposition (ALD), fundamentally altering the process parameters. ALD allows precise control of oxide layer formation through sequential exposure to precursor gases, enabling thin layer formation without the excessive silicon consumption inherent in thermal oxidation processes
Solution Approach 2:
The patent replaces the thermal oxidation mechanism with a chemical vapor deposition mechanism. Instead of using thermal energy to oxidize silicon directly from the substrate, the invention uses controlled chemical reactions with precursor gases (such as silane and ozone or water) to deposit silicon oxide layers, substituting the thermal-mechanical oxidation process with a controlled chemical deposition process
2Manufacturing precision
If thermal oxidation is used to form thin silicon-containing insulative oxides, then insulative layers are formed, but significant quantities of underlying silicon are consumed
Solution Approach 1:
The patent implements precise thickness control through ALD process parameters including number of deposition cycles, precursor exposure times, and temperature control. Each ALD cycle deposits a known thickness of oxide, allowing atomic-layer precision in thickness control while consuming minimal substrate silicon
Solution Approach 2:
The substitution of thermal oxidation with ALD chemical deposition enables precise thickness control without proportional silicon consumption. The chemical precursors provide silicon and oxygen atoms that deposit as oxide on the surface without requiring consumption of the underlying substrate silicon
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 allows for the precise formation of thin insulative layers with minimal silicon consumption, effectively addressing the challenge of maintaining high-quality insulative materials in dense integrated circuitry.
Implementation Method 1
contacting an outer substrate surface at a temperature T1 with a Si-comprising precursor to form a monolayer comprising Si from the Si-comprising precursor onto the outer substrate surface
Implementation Method 2
Temperature of the outer substrate surface and the Si-comprising monolayer thereon is increased to a temperature T2 that is at least 200° C. greater than a maximum of the temperature T1
Implementation Method 3
the Si-comprising monolayer is contacted with an O and/or N-comprising precursor that reacts with the Si-comprising monolayer to form a reaction product that comprises an insulative material
Implementation Method 4
the Si-comprising monolayer is contacted with an O and/or N-comprising precursor that reacts with the Si-comprising monolayer to form a reaction product
Implementation Method 5
temperature of the new outer substrate surface is decreased from the temperature T2 to a lower temperature TL that is at least 200° C. lower than a minimum of the temperature T2
Data Source
AI summary
An example method comprises an ALD sequence including contacting an outer substrate surface at a temperature T1 with a first precursor to form a monolayer onto the outer substrate surface. Temperature of the outer substrate surface and the monolayer thereon is increased to a temperature T2 that is at least 200° C. greater than a maximum of the temperature T1. The temperature-increasing is at a temperature-increasing rate that takes no more than 10 seconds to get the outer substrate surface and the monolayer thereon at least 200° C. above the maximum temperature T1. At the temperature T2, the monolayer is contacted with a second precursor that reacts with the monolayer to form a reaction product and a new outer substrate surface that each comprise a component from the monolayer and a component from the second precursor. With the monolayer not having been allowed to be at least 200° C. above the maximum temperature T1 for more than 10 seconds, temperature of the new outer substrate surface is decreased from the temperature T2 to a lower temperature TL that is at least 200° C. lower than a minimum of the temperature T2.