AlN Template Layer for Low-Temperature CVD Crystallinity

Solution Overview

Problem

Current methods for depositing high-quality aluminum nitride (AlN) films at lower temperatures face challenges such as non-stoichiometric films, nano-crystalline structures, and low deposition rates, which limit their integration in back-end-of-line processing and applications like heat spreading and buffer layers for GaN and InGaN on silicon or silicon carbide substrates.

Innovation Solution

A method involving pulsed chemical vapor deposition (CVD) using tris(dimethylamido) aluminum (TDMAA) and hydrazine at temperatures below 580°C, followed by sputter deposition, to achieve high-quality, low oxygen/carbon AlN films with large grain size, which can serve as a template for further metal nitride film growth, enhancing crystallinity and reducing strain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If low temperature deposition methods (PE-ALD, ALA) are used to deposit AlN films, then the deposition temperature is reduced and strain is reduced, but the films become non-stoichiometric and nano-crystalline with low deposition rates

Engineering Contradiction:

Improvedeposition temperatureVSAvoidfilm stoichiometry and crystallinity

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

A low-temperature AlN template layer is deposited first to establish a crystalline foundation, followed by a high-temperature annealing treatment that transforms the template and enables subsequent high-quality AlN growth at lower temperatures, thus achieving both low temperature operation and high film quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The deposition temperature and annealing temperature are optimized within specific ranges (300-500°C for deposition, 700-900°C for annealing) to achieve the desired balance between low temperature operation and high film quality, with temperature being a critical controlled parameter

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If high temperature deposition methods (MOCVD, MBE) are used to deposit crystalline AlN films, then the film quality and crystallinity are improved, but the deposition temperature exceeds 800°C which creates barriers to BEOL processing integration

Engineering Contradiction:

Improvefilm crystallinity and qualityVSAvoiddeposition temperature

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

A low-temperature AlN template layer is deposited first to establish a crystalline foundation, followed by a high-temperature annealing treatment that transforms the template and enables subsequent high-quality AlN growth at lower temperatures, thus achieving both low temperature operation and high film quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The deposition temperature and annealing temperature are optimized within specific ranges (300-500°C for deposition, 700-900°C for annealing) to achieve the desired balance between low temperature operation and high film quality, with temperature being a critical controlled parameter

Inventive Principle:

Principle #35Parameter changes

3Temperature

If low temperature deposition methods are used, then the deposition temperature is reduced, but the deposition rate becomes very low due to lengthy ion bombardment treatments

Engineering Contradiction:

Improvedeposition temperatureVSAvoiddeposition rate

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

A low-temperature AlN template layer is deposited first to establish a crystalline foundation, followed by a high-temperature annealing treatment that transforms the template and enables subsequent high-quality AlN growth at lower temperatures, thus achieving both low temperature operation and high film quality

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The deposition temperature and annealing temperature are optimized within specific ranges (300-500°C for deposition, 700-900°C for annealing) to achieve the desired balance between low temperature operation and high film quality, with temperature being a critical controlled parameter

Inventive Principle:

Principle #35Parameter changes

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 high-quality, crystalline metal nitride films with improved crystallinity and density, suitable for use as heat spreading and buffer layers, reducing the thickness of needed buffer layers and enabling integration in electronic devices like RF and microLED circuits.

Implementation Method 1

pulsed chemical vapor deposition (CVD) of TDMAA and N2H4

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 2

depositing a second metal nitride layer on the template layer to provide the crystalline metal nitride layer

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS20240052493A1Methods of depositing aluminum nitride templating layers using thermal pulsed chemical vapor deposition for the enhancement of aluminum nitride thick films and related films

Publication Date: 2024.02.15 RGT UNIV OF CALIFORNIA

AI summary

This invention allows for the deposition of aluminum nitride buffer layers and templating films that greatly enhance the quality of additional aluminum nitride deposited by alternate deposit ion techniques and reduce the overall thickness of needed buffer layers. Furthermore, these films can be deposited at substrate temperatures of 400° C. and 580° C. which is considerably lower than other techniques, such as molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD).