Thermally Stable Silicon Precursors for High-Temperature ALD
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Solution Overview
Problem
The semiconductor industry faces challenges in depositing highly conformal silicon-containing films at high temperatures due to the limited thermal stability of existing silicon precursors, which are necessary for advanced 3D NAND memory manufacturing.
Innovation Solution
The use of thermally stable silicon precursors with structures such as RnSiX4-n, where X is a halide, azide, amino, or isocyanade group, and R is a linear or branched alkyl, allowing for high-temperature atomic layer deposition (ALD) of films like SiO2, SiN, and SiCN with good electrical properties and conformality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional silicon precursors are used for ALD deposition, then the deposition process can proceed at lower temperatures, but the precursors self-decompose at temperatures greater than 400°C, limiting the ability to deposit high-quality conformal films at high temperatures
Solution Approach 1:
The patent modifies the chemical parameters of the silicon precursor by introducing fluorinated alkyl groups (specifically perfluoroalkyl groups) to replace traditional alkyl groups. This chemical parameter change significantly enhances the thermal stability of the precursor, allowing it to withstand substrate temperatures above 400°C without self-decomposition, thereby resolving the contradiction between temperature requirement and precursor stability
Solution Approach 2:
The patent employs a composite molecular structure combining silicon center, fluorinated alkyl groups, and reactive functional groups (amino, hydrazide, cyanide, or isocyanade). This composite structure integrates the thermal stability provided by fluorinated alkyl groups with the reactivity needed for ALD deposition, enabling the precursor to maintain stability at high temperatures while still undergoing controlled surface reactions
2Manufacturing precision
If high temperature ALD is used to deposit conformal silicon-containing films, then film conformality and quality are improved, but few silicon precursors can withstand the high temperatures without self-decomposition
Solution Approach 1:
The patent changes the chemical parameters of the precursor by incorporating fluorinated alkyl groups, which fundamentally alter the thermal decomposition characteristics. This enables the precursor to maintain structural integrity at high temperatures (above 400°C), expanding the temperature range where conformal film deposition can be achieved without precursor decomposition
Solution Approach 2:
The patent applies different functional groups to different parts of the precursor molecule: fluorinated alkyl groups provide thermal stability at the hydrophobic regions, while amino, hydrazide, cyanide, or isocyanade groups provide controlled reactivity at the silicon center. This local differentiation of molecular properties allows the precursor to simultaneously achieve high temperature stability and controlled deposition
3Ease of manufacture
If existing silicon precursors are used, then the deposition process is simpler, but the films deposited at high temperatures have poor electrical properties and lack conformality due to precursor decomposition
Solution Approach 1:
The patent modifies the precursor structure by adding fluorinated alkyl groups, which changes the thermal decomposition parameters. This allows the deposition process to be conducted at higher temperatures without precursor breakdown, thereby improving film quality (electrical properties and conformality) while maintaining process simplicity through the use of standard ALD equipment and sequential deposition methodology
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 the deposition of high-quality, highly conformal silicon-containing films at temperatures above 400°C, suitable for 3D NAND structures, with improved electrical and wet etch properties, overcoming the limitations of traditional precursors that decompose at high temperatures.
Implementation Method 1
there are few silicon ALD precursors that can withstand temperatures of greater than 400° C. without self-decomposition
Implementation Method 2
One method for deposition of thin films with control and conformal deposition is atomic layer deposition (ALD), which employs sequential, surface reactions to form layers of precise thickness
Data Source
AI summary
Provided are methods of depositing silicon-containing films utilizing certain precursors at temperatures of 400° C. or higher. Certain methods comprise exposing a substrate surface to a silicon precursor and another precursor to achieve various films. Examples of silicon-containing films which can be deposited include SiN, SiC, SiO2, SiCN, etc.