Ultrafast Atomic Layer Deposition of Alumina Layers for Solar Cell Passivation

Abstract

An ultrafast atomic layer deposition technique is presented, based on the spatial separation of the half-reactions, by which alumina layers can be deposited with deposition rates of more than 1 nm/s. The deposition rate is limited by the water half-reaction, for which a kinetic model has been developed. The alumina layers showed excellent passivation of silicon wafers for solar cell applications. Based on this concept, a high-throughput ALD deposition tool is being developed targeting throughput numbers of up to 3000 wafers/h.

Low temperature and roll-to-roll spatial atomic layer deposition for flexible electronics

“…A previously optimized water partial pressure for a deposition temperature of 200 C was 123 mbar, which corresponds to a RH of $1%, well below 10% RH. 7 However, using these same settings at a deposition temperature of 75 C, leads to a RH of 32%, which is much too high and leading to a deposition result as shown in Fig. 2.…”

“…On the other hand, the water half-reaction was shown to be rate limiting in spatial ALD reactions, and quite a high water concentration as compared to TMA is required to obtain good depositions. 7 Thus, optimizing the water half-reaction process for low deposition temperatures is essential.…”

Research Update: Atmospheric pressure spatial atomic layer deposition of ZnO thin films: Reactors, doping, and devices

“…As with the AP-SALD head designed by the Eastman Kodak Company, gas isolation is maintained by balancing the inlet and exhaust flow rates and having a large inert gas bearing between the precursor inlets. 32,41 The substrate is rotated at up to 3000 rpm, leading to deposition rates almost reaching 1 nm s −1 for ZnO (Table I) and 3-4 nm s −1 for Al 2 O 3 . 30,32 The deposition rate of AP-SALD is thus only limited by reaction rates for planar, featureless substrates, and maintaining an ALD growth regime (rather than a CVD growth regime) leads to uniform films to be deposited.…”

“…45,46 AP-SALD ZnO could be used as the semiconductor in TFTs. 9,20,40,41,47,48 This is particularly important because TFTs (acting as a switch) have become a crucial part of the electronics industry, especially for displays. Several million TFTs are produced each year for displays.…”

Template-based Approach for the Synthesis of 2D/3D Nanostructures

“…When carbon nanotubes are used as the template, it is interesting to study the template-based approach for the synthesis of nanomaterials through PECVD and ALD processes, as it shows that the synthesis of template (carbon nanotubes) and the template-based synthesis of other materials can be conducted in the same type of PECVD process tool. This may provide a way to integrate such kind of synthesis process with other related production processes in a continuous way, which can be beneficial to the renewable energy and semiconducting industries [4,5].…”