Self-Limiting Silicon Bilayer for Oxidation-Free ALD Seeding
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Solution Overview
Problem
Current semiconductor fabrication processes, particularly chemical vapor deposition (CVD) and atomic layer deposition (ALD), face challenges in producing self-limiting and saturating films without substrate oxidation, which hinders the reactivity and suitability of deposited films for subsequent processing.
Innovation Solution
A method involving heating substrates to specific temperatures and exposing them to chlorosilane and anhydrous HOOH precursors using CVD and ALD processes to form a chlorine-terminated saturated silicon bilayer, enabling self-limiting and saturating deposition of Si—Ox films without plasma or catalysts, thus preventing substrate oxidation and enhancing reactivity for metal ALD precursor nucleation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If CVD processes are used to deposit films, then film deposition is achieved, but substrate oxidation occurs which reduces reactivity and suitability for subsequent processing
Solution Approach 1:
The patent employs an inert processing environment by using molecular beam epitaxy (MBE) and atomic layer deposition (ALD) in vacuum conditions, preventing substrate oxidation during film deposition. The vacuum environment isolates the substrate from oxidative atmospheric conditions while allowing controlled precursor delivery for silicon bilayer formation.
Solution Approach 2:
The patent introduces chlorine-terminated silicon bilayer as an intermediary layer between the substrate and subsequent ALD processing. This intermediate layer serves as a protective and reactive interface that prevents direct substrate oxidation while providing controlled reactivity for subsequent metal precursor nucleation and gate oxide formation.
2Quantity of substance
If ALD processes are used to form films on CVD deposited materials, then film formation is possible, but the CVD deposited materials have reduced reactivity due to substrate oxidation
Solution Approach 1:
The patent changes the surface chemical state by forming a chlorine-terminated silicon bilayer through controlled MBE deposition parameters. This parameter change in surface termination chemistry creates highly reactive chlorine sites that enhance subsequent ALD precursor adsorption and metal nucleation, restoring and improving surface reactivity for ALD processing.
Solution Approach 2:
The patent performs preliminary MBE deposition of chlorine-terminated silicon bilayer before ALD processing to pre-condition the substrate surface. This preliminary action creates optimal surface chemistry with exposed chlorine atoms that are highly reactive toward ALD precursors, ensuring excellent nucleation and uniform film formation in subsequent ALD steps.
3Manufacturing precision
If self-limiting and saturating deposition is achieved, then precise thickness control is possible, but complex processing conditions are required
Solution Approach 1:
The patent employs self-limiting deposition mechanisms where the MBE and ALD processes automatically terminate when surface sites are saturated. The chlorine-terminated silicon bilayer formation is self-limiting as chlorine sites become occupied, and subsequent ALD cycles are self-limiting as precursor adsorption reaches monolayer coverage. This self-service mechanism provides precise thickness control through inherent process saturation rather than complex external control systems.
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 highly reactive substrate surfaces for ALD precursor seeding, leading to improved nucleation and growth of gate oxide materials, reduced border trap density, and lower equivalent oxide thickness, while maintaining surface stability and preventing unwanted oxidation.
Implementation Method 1
heating a substrate in a reaction chamber to a temperature of between about 300° C. and about 500° C.
Implementation Method 2
exposing the substrate to a chlorosilane precursor utilizing a chemical vapor deposition process
Implementation Method 3
exposing the substrate to an anhydrous HOOH precursor utilizing the chemical vapor deposition process to deposit a chlorine terminated saturated silicon bilayer
Implementation Method 4
The substrate is exposed to an Si2Cl6 precursor utilizing an atomic layer deposition process and the substrate is also exposed to an anhydrous HOOH precursor utilizing the atomic layer deposition process. The atomic layer deposition process cyclically exposes the substrate to Si2Cl6 and anhydrous HOOH in an alternating manner.
Data Source
AI summary
Embodiments described herein provide a self-limiting and saturating Si—Ox bilayer process which does not require the use of a plasma or catalyst and that does not lead to undesirable substrate oxidation. Methods of the disclosure do not produce SiO2, but instead produce a saturated Si—Ox film with —OH termination to make substrate surfaces highly reactive towards metal ALD precursors to seed high nucleation and growth of gate oxide ALD materials.