AlN Layer Deposition With Biased Plasma Nitridation
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Solution Overview
Problem
Existing techniques for producing aluminium nitride (AlN) layers, such as CVD, PVD, and PEALD, face challenges in achieving high-quality AlN/GaN interfaces and AlN layers, particularly due to issues with thermal budget limitations, uniformity, and conformity.
Innovation Solution
A method involving multiple cycles in a plasma reactor, where aluminium-based species are deposited followed by nitridation with a nitrogen-based plasma, and a polarisation voltage is applied to the substrate during nitridation to enhance the quality of the AlN layer and its interface with silicon or III-V materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CVD technique from metal organic precursors (MOCVD) is used to produce AlN layers, then excellent layer quality is achieved, but high deposition temperatures greater than 700°C are required which conflicts with thermal budget limitations
Solution Approach 1:
The patent changes the deposition temperature parameter from >700°C (MOCVD) to below 700°C by using a different chemical vapor deposition process with trimethylaluminium precursor and ammonia, resolving the contradiction between achieving high layer quality and respecting thermal budget limitations
Solution Approach 2:
The patent replaces the MOCVD process (chemical vapor deposition from metal organic precursors) with an alternative CVD process using inorganic precursors (trimethylaluminium and ammonia), substituting the chemical mechanism while maintaining the deposition function at lower temperatures
2Temperature
If Physical vapour deposition (PVD) techniques are used to produce AlN layers, then deposition can be performed at lower temperatures, but uniformity and conformity problems occur
Solution Approach 1:
The patent replaces the physical vapour deposition mechanism with a chemical vapor deposition mechanism, where reactive precursors (trimethylaluminium and ammonia) chemically react on the substrate surface to form AlN, enabling conformal coverage and uniform deposition at low temperatures through chemical reaction rather than physical condensation
Solution Approach 2:
The patent uses gaseous precursors (trimethylaluminium vapor and ammonia gas) delivered through the reaction chamber, utilizing gas flow dynamics to ensure uniform distribution of reactants across the substrate surface, achieving both low temperature operation and high layer uniformity
3Ease of manufacture
If Plasma-enhanced atomic layer deposition (PEALD) technique is used to produce AlN layers, then a self-limiting growth method is achieved, but the quality of AlN/GaN interface and AlN layer remains insufficient
Solution Approach 1:
The patent changes the precursor chemistry parameters from conventional PEALD precursors to trimethylaluminium and ammonia, adjusting the chemical reaction parameters to achieve both self-limiting growth and superior interface quality through optimized surface reactions
Solution Approach 2:
The patent optimizes the local reaction conditions at the AlN/GaN interface by controlling the sequential deposition of aluminium and nitrogen species, ensuring high interfacial quality through localized surface reactions while maintaining self-limiting growth control
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 significantly improves the quality of the AlN layer and the AlN/GaN interface, achieving a high-quality crystalline AlN layer with controlled crystallographic orientation, which is essential for enhancing the electric performance of devices like HEMTs.
Implementation Method 1
the formation in the reaction chamber of a nitrogen-based plasma reacting with the exposed surface of the structure
Implementation Method 2
deposition of aluminium-based species on an exposed surface of the structure, the deposition step comprising at least one injection in the reaction chamber of an aluminium (Al)-based precursor reacting with the exposed surface of the structure
Data Source
AI summary
A method for producing an aluminium nitride (AlN)-based layer on a structure with the basis of silicon (Si) or with the basis of a III-V material, may include several deposition cycles performed in a plasma reactor comprising a reaction chamber inside which is disposed a substrate having the structure. Each deposition cycle may include at least the following: deposition of aluminium-based species on an exposed surface of the structure, the deposition including at least one injection into the reaction chamber of an aluminium (Al)-based precursor; and nitridation of the exposed surface of the structure, the nitridation including at least one injection into the reaction chamber of a nitrogen (N)-based precursor and the formation in the reaction chamber of a nitrogen-based plasma. During the formation of the nitrogen-based plasma, a non-zero polarisation voltage Vbias_substrate may be applied to the substrate.