Biomedical Engineering Reference
In-Depth Information
can be readily deposited using this flexible reactor configuration and
virtually any particle substrate with the appropriate surface functionality
can be coated using this gas-phase adsorption process. Internal surfaces of
porous particle substrates can also be easily coated. Particle ALD has been
used to deposit many types of ceramic metal oxides on different kinds of
particle substrates. In addition, particle ALD provides an opportunity to
use unconventional precursors that normally would have been cost
prohibitive. The quality of the deposited layers is unparalleled from a
particle functionalization perspective.
Particle ALD has been successfully demonstrated at lab scale and pilot
scale. Scale-up of the reactors, reproducibility, and uniformality of the film
properties in large-scale production and carrying out the thin film
deposition process under atmospheric pressure are other important
deposition technology related issues that need further attention and work.
If integrated into the function of a system, the lifetime and technical
performance of the resulting components (cutting tools, batteries, phos-
phors, flexible polymers for organic photovoltaics and light emitting diodes,
etc.) can be significantly increased. For many applications, the benefits
obtained through thin films far exceed their manufacturing costs. Even if
these costs are high, the resulting increase in performance of the components
for their applications is justified by highly competitive improvements.
Ideally, however, ALD processes can also be used to reduce production
costs for manufacturers of existing products without sacrificing perfor-
mance. Specifically, particle ALD processes are anticipated to be a cost-
effective alternative to replace some conventional CVD and sol-gel liquid
solution processes on the basis of reduction in raw materials usage to
achieve a given level of performance (i.e. improved cost/performance
benefit). A multitude of applications can be addressed in a competitive
fashion using ultra-fine particles that have been surface-modified using the
ALD technique in scalable, high-throughput unit operations. There is no
doubt that the emerging technology of thin film coating by particle ALD
will play a major role in the field of advanced materials.
8.7 References
Aaltonen T, Ritala M, Sajavaara T, Keinonen J, and Leskela M (2003), 'Atomic
layer deposition of platinum thin films,' Chemistry of Materials 15[9] 1924-1928.
Belharouak I, Johnson C, and Amine K (2005), 'Synthesis and electrochemical
analysis of
vapor-deposited
carbon-coated LiFePO
4
,' Electrochemistry
Communications 7[10] 983-988.
Bose S and Bogner R H (2007), 'Solventless pharmaceutical coating processes: A
review,' Pharmaceutical Development and Technology 12[2] 115-131.
Bosund M, Sajavaara T, Laitinen M, Huhtio T, Putkonen M, Airaksinen V M, and
