FB_pALD Requirements Document.pdf

Procurement of a Fluidized Bed Particle Atomic Layer Deposition System and Supporting Accessories

Code 6880

Background

This procurement is directed to obtain an advanced fluidized bed (FB) particle atomic layer deposition (pALD) system and supporting accessories including Glovebox. The High Power Electronics Branch of the Electronics Science and Technology Division is already involved in developing the deposition of thin conformal oxide and metal shells on nanoparticles (NPs). The resultant core/shell NPs are of interest to the US Navy since they serve as building blocks for optical, electronic, thermoelectric, structural, refractory, and smart materials with application areas including ballistic and transparent armor, multifunctional sensors, catalysis, thermoelectric generators, hypersonic materials, and neuromorphic devices. Major challenges in the development of these core/shell NPs include (1) agglomeration of the NPs during shell deposition that can lead to nonuniform and/or noncomformal coatings, and (2) a relatively small library of currently available shell materials compared to the wide range of planar thin film materials that have been produced by conventional atomic layer deposition. Therefore, an FB pALD system optimized for breaking up NP agglomerates, depositing uniform and conformal shells, and developing new shell materials is critical for next-generation materials systems. This procurement will enable Branch personnel to continue to perform research and development in the production of core/shell nanoparticles for the targeted optical, electronic, thermoelectric, structural, refractory, and smart materials. The equipment will be housed in a laboratory in Bldg. 208.

General Specifications

The FB pALD system has the capability to deposit, with precisely tunable thickness, conformal shells of oxides, carbides, semiconductors, or metals on nanoparticle (NP) powders over a wide range of powder batch sizes. The apparatus is equipped with a precursor manifold capable of delivering high- and low-vapor-pressure precursors to deposit a wide variety of coating materials, with the option to deploy multiple precursors in a single pALD run to produce shells of binary or ternary compounds as well as double-shell (core/shell/shell) NPs in addition to standard core/shell NPs. Shell deposition occurs in a FB chamber, which can be uniformly heated across a wide temperature range, and in which the NP powder is fluidized by the flow of precursor vapor and carrier gas to ensure conformal and uniform coating of the NPs. Shell conformality is maximized by a jet-assist fluidization aid which continually breaks up NP agglomerates throughout the coating process. The system includes multiple removable FB reaction vessels, each of which can be dedicated to a single coating material (or set of coating materials) to allow work on multiple projects and multiple materials systems in parallel without cross-contamination. There are sets of reactors of different sizes to process different amount of powders. The FB pALD system includes an inert-atmosphere Glovebox in which NPs can be processed and characterized both before and after coating, and reactors can be loaded and unloaded, forming a completely air-free process chain.

Detailed FB pALD System Specifications

1. FB pALD Reaction Chambers

a. The FB pALD system must include multiple reaction vessels.

i. For the reaction vessel material, two options must be included: glass and stainless steel. Glass enables visualization of fluidization behavior, while stainless steel enables routine pALD processes.

ii. Multiple reactor size options must be included. The options must allow powder batch volumes ranging from 0.5 to at least 500 mL.

iii. More than 10 different materials should be processed in different reactors without cross-contamination.

b. The stainless steel reaction vessels must be uniformly heatable up to 400 °C or higher.

c. The stainless steel reaction vessels must be rated for internal pressure as low as 0.1

Torr.

d. All reaction vessels must be fitted with particle filters (0.5 micron filtration or smaller) that are removable for cleaning or replacement.

e. All reaction vessels must be fitted with isolation valves so that the vessels can be loaded in the inert atmosphere Glovebox, transferred out, connected to the pALD system, and transferred into the Glovebox without exposing the NP powder to air.

2. Powder Fluidization Assistance

a. The FB pALD system must be capable of transmitting vibrational force to reaction vessels to facilitate fluidization of the NP powder.

b. The FB pALD system must be capable of delivering high-velocity, high-shear gas to reaction vessels to facilitate fluidization of the NP powder and minimize NP agglomeration.

3. Gas Delivery System

a. The FB pALD system must include a gas delivery manifold capable of delivering various pALD precursor gasses and vapors to the reaction chambers.

i. The gas delivery manifold must contain six or more precursor delivery lines, some of which are designed for high-vapor-pressure liquid precursor containers (cylinders), and some of which are designed for low-vapor-pressure liquid precursor containers (bubblers).

ii. All precursor containers must have at least 50 mL capacity.

iii. All precursor lines must be uniformly heatable to 200 °C or higher, and the individual precursor temperatures must be individually controllable.

b. The FB pALD system must be capable of delivering various oxidizing and reducing gases to the reaction chambers, including water vapor, ozone, and hydrogen.

c. The FB pALD system must have an ozone generator.

4. Pumping System

a. The FB pALD system must be equipped with a vacuum pump capable of achieving a base pressure of 0.1 Torr or lower in the reaction chambers. It should also be equipped with a second identical pump to serve as a backup and eliminate downtime during pump maintenance.

b. The vacuum pumps should be oil-free to minimize required maintenance.

c. The vacuum pumps must be protected by foreline filtration and abatement systems:

i. Particle filtration (2 micron filtration or smaller)

ii. Abatement via absorbent media such as activated charcoal and/or alumina

5. In Situ Characterization

a. The FB pALD system must be equipped with a mass spectrometer capable of quantifying gaseous pALD reactants and byproducts.

b. The FB pALD system must be equipped with pressure gauges located at both the inlet and outlet of the reaction chamber in order to measure the pressure drop across the NP powder bed.

6. Control System

a. The FB pALD system must be equipped with a computer that enables software control of valves, gas flows, and temperatures.

b. The computer must support at least two monitors (primary + auxiliary).

c. The software must enable real-time viewing and saving of temperature, pressure, and mass spectrometry data.

d. The software must enable safety alarms and interlocks.

e. The software must enable user customization of pALD processes as well as fully automated process execution.

f. The Contractor must provide the option for software customization.

7. Installation, Training, and Warranty

a. Installation and commissioning of the FB pALD system must be performed by engineers supplied by the Contractor.

b. The Contractor must provide training for NRL personnel on the use, maintenance, and basic repair procedures for the FB pALD system.

c. The FB pALD system purchase must include a one-year factory warranty that covers all parts, labor, and travel expenses for on-site support of the equipment.