High-Temperature Si ALD Precursors for Conformal Oxide Films
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Solution Overview
Problem
Existing ALD precursors fail to achieve high-temperature deposition of SiO2 films with conformal growth and low wet etch rate, leading to poor film quality and non-uniform deposition in semiconductor devices due to parasitic CVD reactions at temperatures above 500°C.
Innovation Solution
Use of Si-containing precursors with the formula SiR1yR24-x-y(NH—SiR′3)x, where x=2, 3, 4; y=0, 1, 2, R1 and R2 are independently selected from H, halogen, alkyl, isocyanate, or alkoxide, and R′ is independently selected from H or alkyl, to form Si-containing films through ALD processes at temperatures above 550°C, using co-reactants like O3, O2, and NH3 to prevent parasitic CVD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ALD is performed at high temperature (>500°C) to prevent film shrinkage and stress, then film stability is improved, but parasitic CVD occurs leading to non-conformal growth and poor film quality
Solution Approach 1:
The patent changes the chemical parameters of the precursor molecules by introducing fluorinated alkyl groups with specific chain lengths and structures. This modification adjusts the thermal stability and reactivity of the precursors, enabling them to maintain self-limited surface reactions at high temperatures (500-750°C) without undergoing parasitic CVD decomposition, thus achieving both film stability and conformal growth
Solution Approach 2:
The patent uses composite precursor molecules that combine silicon centers with fluorinated alkyl groups and leaving groups. These composite molecular structures integrate multiple functional components: the silicon core for film formation, fluorinated alkyl groups for thermal stability control, and leaving groups for surface reactivity. This composite design enables the precursors to withstand high temperatures while maintaining ALD self-limited growth behavior
2Productivity
If conventional SiO2 ALD precursors are used at high temperature, then deposition rate increases, but thermal decomposition causes parasitic CVD and non-uniform film thickness
Solution Approach 1:
The patent modifies the molecular parameters of the precursors by varying the fluorinated alkyl group chain length (C1-C10), branching structure, and leaving group types. These parameter changes optimize the balance between vapor pressure (affecting deposition rate) and thermal stability (preventing decomposition). The result is maintained self-limited growth with uniform film thickness at high deposition rates and temperatures
Solution Approach 2:
The patent employs precursor molecules with labile leaving groups that are designed to be consumed in the surface reaction. These disposable molecular components (leaving groups like halides or alkoxides) react with the surface and are removed, enabling controlled monolayer formation. The fluorinated alkyl groups remain as stable backbone structures that prevent further decomposition, allowing repeated ALD cycles with consistent uniformity
3Manufacturing precision
If new precursor molecules are developed for high-temperature ALD, then film quality improves, but precursor synthesis complexity increases
Solution Approach 1:
The patent develops a universal precursor platform based on silicon centers with fluorinated alkyl groups and interchangeable leaving groups. This multi-functional design allows the same core structure to be used for depositing various films (SiO2, SiN, SiON) by simply changing the co-reactant and leaving group. The modular architecture simplifies synthesis compared to developing entirely new molecules for each application, as the stable fluorinated backbone can be reused across different precursor variants
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
Achieves conformal deposition of high-quality SiO2 and SiN films with low wet etch rates, suitable for semiconductor manufacturing, particularly in 3D NAND structures, by maintaining self-limited growth and preventing thermal decomposition.
Implementation Method 1
exposing the substrate to a vapor including a Si-containing film forming composition that contains a Si-containing precursor... and depositing at least part of the Si-containing precursor onto the substrate
Implementation Method 2
forming a chemisorbed and/or physisorbed film, on the surface of the substrate, of a Si-containing precursor
Implementation Method 3
heating the substrate in a reactor to a temperature of 550° C. or higher... depositing the film at an elevated temperature prevents the shrinkage that is normally observed
Data Source
AI summary
Methods for forming a Si-containing film on a substrate comprise heating the substrate to a temperature higher than S50° C., exposing the substrate to a vapor including a Si-containing film forming composition containing a Si-containing precursor having the formula: SiR1yR24-x-y(NH—SiR′3)x, wherein x=2, 3, 4; y=0, 1, 2, R1 and R2 each are independently selected from H, a halogen (Cl, Br, I), an C1-C4 alkyl, an isocyanate, a C1-C4 alkoxide, or an —NR3R4 group in which R3 and R4 each are independently selected from H, a C1-C4 alkyl, provided that if R3═H, R4>C1; each R′ is independently selected from H, a halogen (Cl, Br, I), or a C1-C4 alkyl, and depositing the Si-containing precursor onto the substrate to form the Si-containing film on the substrate through an ALD process. The Si-containing precursor may be selected from SiH2(NH—Si(CH3)3)2, SiHCl(NH—Si(CH3)3)2, SiCl2(NH—Si(CH3)3)2, SiH(NH—Si(CH3)3)3, SiCl(NH—Si(CH3)3)3, or Si(NH—Si(CH3)3)4.